nextcloud / server

apps/dav/lib/CalDAV/Reminder/ReminderService.php

Indentation +817 added lines, -817 removed lines

@@ -55,821 +55,821 @@
 
 class ReminderService {
 
-	/** @var Backend */
-	private $backend;
-
-	/** @var NotificationProviderManager */
-	private $notificationProviderManager;
-
-	/** @var IUserManager */
-	private $userManager;
-
-	/** @var IGroupManager */
-	private $groupManager;
-
-	/** @var CalDavBackend */
-	private $caldavBackend;
-
-	/** @var ITimeFactory */
-	private $timeFactory;
-
-	/** @var IConfig */
-	private $config;
-
-	/** @var LoggerInterface */
-	private $logger;
-
-	/** @var Principal */
-	private $principalConnector;
-
-	public const REMINDER_TYPE_EMAIL = 'EMAIL';
-	public const REMINDER_TYPE_DISPLAY = 'DISPLAY';
-	public const REMINDER_TYPE_AUDIO = 'AUDIO';
-
-	/**
-	 * @var String[]
-	 *
-	 * Official RFC5545 reminder types
-	 */
-	public const REMINDER_TYPES = [
-		self::REMINDER_TYPE_EMAIL,
-		self::REMINDER_TYPE_DISPLAY,
-		self::REMINDER_TYPE_AUDIO
-	];
-
-	public function __construct(Backend $backend,
-								NotificationProviderManager $notificationProviderManager,
-								IUserManager $userManager,
-								IGroupManager $groupManager,
-								CalDavBackend $caldavBackend,
-								ITimeFactory $timeFactory,
-								IConfig $config,
-								LoggerInterface $logger,
-								Principal $principalConnector) {
-		$this->backend = $backend;
-		$this->notificationProviderManager = $notificationProviderManager;
-		$this->userManager = $userManager;
-		$this->groupManager = $groupManager;
-		$this->caldavBackend = $caldavBackend;
-		$this->timeFactory = $timeFactory;
-		$this->config = $config;
-		$this->logger = $logger;
-		$this->principalConnector = $principalConnector;
-	}
-
-	/**
-	 * Process reminders to activate
-	 *
-	 * @throws NotificationProvider\ProviderNotAvailableException
-	 * @throws NotificationTypeDoesNotExistException
-	 */
-	public function processReminders() :void {
-		$reminders = $this->backend->getRemindersToProcess();
-		$this->logger->debug('{numReminders} reminders to process', [
-			'numReminders' => count($reminders),
-		]);
-
-		foreach ($reminders as $reminder) {
-			$calendarData = is_resource($reminder['calendardata'])
-				? stream_get_contents($reminder['calendardata'])
-				: $reminder['calendardata'];
-
-			if (!$calendarData) {
-				continue;
-			}
-
-			$vcalendar = $this->parseCalendarData($calendarData);
-			if (!$vcalendar) {
-				$this->logger->debug('Reminder {id} does not belong to a valid calendar', [
-					'id' => $reminder['id'],
-				]);
-				$this->backend->removeReminder($reminder['id']);
-				continue;
-			}
-
-			$vevent = $this->getVEventByRecurrenceId($vcalendar, $reminder['recurrence_id'], $reminder['is_recurrence_exception']);
-			if (!$vevent) {
-				$this->logger->debug('Reminder {id} does not belong to a valid event', [
-					'id' => $reminder['id'],
-				]);
-				$this->backend->removeReminder($reminder['id']);
-				continue;
-			}
-
-			if ($this->wasEventCancelled($vevent)) {
-				$this->logger->debug('Reminder {id} belongs to a cancelled event', [
-					'id' => $reminder['id'],
-				]);
-				$this->deleteOrProcessNext($reminder, $vevent);
-				continue;
-			}
-
-			if (!$this->notificationProviderManager->hasProvider($reminder['type'])) {
-				$this->logger->debug('Reminder {id} does not belong to a valid notification provider', [
-					'id' => $reminder['id'],
-				]);
-				$this->deleteOrProcessNext($reminder, $vevent);
-				continue;
-			}
-
-			if ($this->config->getAppValue('dav', 'sendEventRemindersToSharedGroupMembers', 'yes') === 'no') {
-				$users = $this->getAllUsersWithWriteAccessToCalendar($reminder['calendar_id']);
-			} else {
-				$users = [];
-			}
-
-			$user = $this->getUserFromPrincipalURI($reminder['principaluri']);
-			if ($user) {
-				$users[] = $user;
-			}
-
-			$userPrincipalEmailAddresses = [];
-			$userPrincipal = $this->principalConnector->getPrincipalByPath($reminder['principaluri']);
-			if ($userPrincipal) {
-				$userPrincipalEmailAddresses = $this->principalConnector->getEmailAddressesOfPrincipal($userPrincipal);
-			}
-
-			$this->logger->debug('Reminder {id} will be sent to {numUsers} users', [
-				'id' => $reminder['id'],
-				'numUsers' => count($users),
-			]);
-			$notificationProvider = $this->notificationProviderManager->getProvider($reminder['type']);
-			$notificationProvider->send($vevent, $reminder['displayname'], $userPrincipalEmailAddresses, $users);
-
-			$this->deleteOrProcessNext($reminder, $vevent);
-		}
-	}
-
-	/**
-	 * @param array $objectData
-	 * @throws VObject\InvalidDataException
-	 */
-	public function onCalendarObjectCreate(array $objectData):void {
-		// We only support VEvents for now
-		if (strcasecmp($objectData['component'], 'vevent') !== 0) {
-			return;
-		}
-
-		$calendarData = is_resource($objectData['calendardata'])
-			? stream_get_contents($objectData['calendardata'])
-			: $objectData['calendardata'];
-
-		if (!$calendarData) {
-			return;
-		}
-
-		$vcalendar = $this->parseCalendarData($calendarData);
-		if (!$vcalendar) {
-			return;
-		}
-		$calendarTimeZone = $this->getCalendarTimeZone((int) $objectData['calendarid']);
-
-		$vevents = $this->getAllVEventsFromVCalendar($vcalendar);
-		if (count($vevents) === 0) {
-			return;
-		}
-
-		$uid = (string) $vevents[0]->UID;
-		$recurrenceExceptions = $this->getRecurrenceExceptionFromListOfVEvents($vevents);
-		$masterItem = $this->getMasterItemFromListOfVEvents($vevents);
-		$now = $this->timeFactory->getDateTime();
-		$isRecurring = $masterItem ? $this->isRecurring($masterItem) : false;
-
-		foreach ($recurrenceExceptions as $recurrenceException) {
-			$eventHash = $this->getEventHash($recurrenceException);
-
-			if (!isset($recurrenceException->VALARM)) {
-				continue;
-			}
-
-			foreach ($recurrenceException->VALARM as $valarm) {
-				/** @var VAlarm $valarm */
-				$alarmHash = $this->getAlarmHash($valarm);
-				$triggerTime = $valarm->getEffectiveTriggerTime();
-				$diff = $now->diff($triggerTime);
-				if ($diff->invert === 1) {
-					continue;
-				}
-
-				$alarms = $this->getRemindersForVAlarm($valarm, $objectData, $calendarTimeZone,
-					$eventHash, $alarmHash, true, true);
-				$this->writeRemindersToDatabase($alarms);
-			}
-		}
-
-		if ($masterItem) {
-			$processedAlarms = [];
-			$masterAlarms = [];
-			$masterHash = $this->getEventHash($masterItem);
-
-			if (!isset($masterItem->VALARM)) {
-				return;
-			}
-
-			foreach ($masterItem->VALARM as $valarm) {
-				$masterAlarms[] = $this->getAlarmHash($valarm);
-			}
-
-			try {
-				$iterator = new EventIterator($vevents, $uid);
-			} catch (NoInstancesException $e) {
-				// This event is recurring, but it doesn't have a single
-				// instance. We are skipping this event from the output
-				// entirely.
-				return;
-			} catch (MaxInstancesExceededException $e) {
-				// The event has more than 3500 recurring-instances
-				// so we can ignore it
-				return;
-			}
-
-			while ($iterator->valid() && count($processedAlarms) < count($masterAlarms)) {
-				$event = $iterator->getEventObject();
-
-				// Recurrence-exceptions are handled separately, so just ignore them here
-				if (\in_array($event, $recurrenceExceptions, true)) {
-					$iterator->next();
-					continue;
-				}
-
-				foreach ($event->VALARM as $valarm) {
-					/** @var VAlarm $valarm */
-					$alarmHash = $this->getAlarmHash($valarm);
-					if (\in_array($alarmHash, $processedAlarms, true)) {
-						continue;
-					}
-
-					if (!\in_array((string) $valarm->ACTION, self::REMINDER_TYPES, true)) {
-						// Action allows x-name, we don't insert reminders
-						// into the database if they are not standard
-						$processedAlarms[] = $alarmHash;
-						continue;
-					}
-
-					try {
-						$triggerTime = $valarm->getEffectiveTriggerTime();
-						/**
-						 * @psalm-suppress DocblockTypeContradiction
-						 *   https://github.com/vimeo/psalm/issues/9244
-						 */
-						if ($triggerTime->getTimezone() === false || $triggerTime->getTimezone()->getName() === 'UTC') {
-							$triggerTime = new DateTimeImmutable(
-								$triggerTime->format('Y-m-d H:i:s'),
-								$calendarTimeZone
-							);
-						}
-					} catch (InvalidDataException $e) {
-						continue;
-					}
-
-					// If effective trigger time is in the past
-					// just skip and generate for next event
-					$diff = $now->diff($triggerTime);
-					if ($diff->invert === 1) {
-						// If an absolute alarm is in the past,
-						// just add it to processedAlarms, so
-						// we don't extend till eternity
-						if (!$this->isAlarmRelative($valarm)) {
-							$processedAlarms[] = $alarmHash;
-						}
-
-						continue;
-					}
-
-					$alarms = $this->getRemindersForVAlarm($valarm, $objectData, $calendarTimeZone, $masterHash, $alarmHash, $isRecurring, false);
-					$this->writeRemindersToDatabase($alarms);
-					$processedAlarms[] = $alarmHash;
-				}
-
-				$iterator->next();
-			}
-		}
-	}
-
-	/**
-	 * @param array $objectData
-	 * @throws VObject\InvalidDataException
-	 */
-	public function onCalendarObjectEdit(array $objectData):void {
-		// TODO - this can be vastly improved
-		//  - get cached reminders
-		//  - ...
-
-		$this->onCalendarObjectDelete($objectData);
-		$this->onCalendarObjectCreate($objectData);
-	}
-
-	/**
-	 * @param array $objectData
-	 * @throws VObject\InvalidDataException
-	 */
-	public function onCalendarObjectDelete(array $objectData):void {
-		// We only support VEvents for now
-		if (strcasecmp($objectData['component'], 'vevent') !== 0) {
-			return;
-		}
-
-		$this->backend->cleanRemindersForEvent((int) $objectData['id']);
-	}
-
-	/**
-	 * @param VAlarm $valarm
-	 * @param array $objectData
-	 * @param DateTimeZone $calendarTimeZone
-	 * @param string|null $eventHash
-	 * @param string|null $alarmHash
-	 * @param bool $isRecurring
-	 * @param bool $isRecurrenceException
-	 * @return array
-	 */
-	private function getRemindersForVAlarm(VAlarm $valarm,
-										   array $objectData,
-										   DateTimeZone $calendarTimeZone,
-										   string $eventHash = null,
-										   string $alarmHash = null,
-										   bool $isRecurring = false,
-										   bool $isRecurrenceException = false):array {
-		if ($eventHash === null) {
-			$eventHash = $this->getEventHash($valarm->parent);
-		}
-		if ($alarmHash === null) {
-			$alarmHash = $this->getAlarmHash($valarm);
-		}
-
-		$recurrenceId = $this->getEffectiveRecurrenceIdOfVEvent($valarm->parent);
-		$isRelative = $this->isAlarmRelative($valarm);
-		/** @var DateTimeImmutable $notificationDate */
-		$notificationDate = $valarm->getEffectiveTriggerTime();
-		/**
-		 * @psalm-suppress DocblockTypeContradiction
-		 *   https://github.com/vimeo/psalm/issues/9244
-		 */
-		if ($notificationDate->getTimezone() === false || $notificationDate->getTimezone()->getName() === 'UTC') {
-			$notificationDate = new DateTimeImmutable(
-				$notificationDate->format('Y-m-d H:i:s'),
-				$calendarTimeZone
-			);
-		}
-		$clonedNotificationDate = new \DateTime('now', $notificationDate->getTimezone());
-		$clonedNotificationDate->setTimestamp($notificationDate->getTimestamp());
-
-		$alarms = [];
-
-		$alarms[] = [
-			'calendar_id' => $objectData['calendarid'],
-			'object_id' => $objectData['id'],
-			'uid' => (string) $valarm->parent->UID,
-			'is_recurring' => $isRecurring,
-			'recurrence_id' => $recurrenceId,
-			'is_recurrence_exception' => $isRecurrenceException,
-			'event_hash' => $eventHash,
-			'alarm_hash' => $alarmHash,
-			'type' => (string) $valarm->ACTION,
-			'is_relative' => $isRelative,
-			'notification_date' => $notificationDate->getTimestamp(),
-			'is_repeat_based' => false,
-		];
-
-		$repeat = isset($valarm->REPEAT) ? (int) $valarm->REPEAT->getValue() : 0;
-		for ($i = 0; $i < $repeat; $i++) {
-			if ($valarm->DURATION === null) {
-				continue;
-			}
-
-			$clonedNotificationDate->add($valarm->DURATION->getDateInterval());
-			$alarms[] = [
-				'calendar_id' => $objectData['calendarid'],
-				'object_id' => $objectData['id'],
-				'uid' => (string) $valarm->parent->UID,
-				'is_recurring' => $isRecurring,
-				'recurrence_id' => $recurrenceId,
-				'is_recurrence_exception' => $isRecurrenceException,
-				'event_hash' => $eventHash,
-				'alarm_hash' => $alarmHash,
-				'type' => (string) $valarm->ACTION,
-				'is_relative' => $isRelative,
-				'notification_date' => $clonedNotificationDate->getTimestamp(),
-				'is_repeat_based' => true,
-			];
-		}
-
-		return $alarms;
-	}
-
-	/**
-	 * @param array $reminders
-	 */
-	private function writeRemindersToDatabase(array $reminders): void {
-		foreach ($reminders as $reminder) {
-			$this->backend->insertReminder(
-				(int) $reminder['calendar_id'],
-				(int) $reminder['object_id'],
-				$reminder['uid'],
-				$reminder['is_recurring'],
-				(int) $reminder['recurrence_id'],
-				$reminder['is_recurrence_exception'],
-				$reminder['event_hash'],
-				$reminder['alarm_hash'],
-				$reminder['type'],
-				$reminder['is_relative'],
-				(int) $reminder['notification_date'],
-				$reminder['is_repeat_based']
-			);
-		}
-	}
-
-	/**
-	 * @param array $reminder
-	 * @param VEvent $vevent
-	 */
-	private function deleteOrProcessNext(array $reminder,
-										 VObject\Component\VEvent $vevent):void {
-		if ($reminder['is_repeat_based'] ||
-			!$reminder['is_recurring'] ||
-			!$reminder['is_relative'] ||
-			$reminder['is_recurrence_exception']) {
-			$this->backend->removeReminder($reminder['id']);
-			return;
-		}
-
-		$vevents = $this->getAllVEventsFromVCalendar($vevent->parent);
-		$recurrenceExceptions = $this->getRecurrenceExceptionFromListOfVEvents($vevents);
-		$now = $this->timeFactory->getDateTime();
-		$calendarTimeZone = $this->getCalendarTimeZone((int) $reminder['calendar_id']);
-
-		try {
-			$iterator = new EventIterator($vevents, $reminder['uid']);
-		} catch (NoInstancesException $e) {
-			// This event is recurring, but it doesn't have a single
-			// instance. We are skipping this event from the output
-			// entirely.
-			return;
-		}
-
-		try {
-			while ($iterator->valid()) {
-				$event = $iterator->getEventObject();
-
-				// Recurrence-exceptions are handled separately, so just ignore them here
-				if (\in_array($event, $recurrenceExceptions, true)) {
-					$iterator->next();
-					continue;
-				}
-
-				$recurrenceId = $this->getEffectiveRecurrenceIdOfVEvent($event);
-				if ($reminder['recurrence_id'] >= $recurrenceId) {
-					$iterator->next();
-					continue;
-				}
-
-				foreach ($event->VALARM as $valarm) {
-					/** @var VAlarm $valarm */
-					$alarmHash = $this->getAlarmHash($valarm);
-					if ($alarmHash !== $reminder['alarm_hash']) {
-						continue;
-					}
-
-					$triggerTime = $valarm->getEffectiveTriggerTime();
-
-					// If effective trigger time is in the past
-					// just skip and generate for next event
-					$diff = $now->diff($triggerTime);
-					if ($diff->invert === 1) {
-						continue;
-					}
-
-					$this->backend->removeReminder($reminder['id']);
-					$alarms = $this->getRemindersForVAlarm($valarm, [
-						'calendarid' => $reminder['calendar_id'],
-						'id' => $reminder['object_id'],
-					], $calendarTimeZone, $reminder['event_hash'], $alarmHash, true, false);
-					$this->writeRemindersToDatabase($alarms);
-
-					// Abort generating reminders after creating one successfully
-					return;
-				}
-
-				$iterator->next();
-			}
-		} catch (MaxInstancesExceededException $e) {
-			// Using debug logger as this isn't really an error
-			$this->logger->debug('Recurrence with too many instances detected, skipping VEVENT', ['exception' => $e]);
-		}
-
-		$this->backend->removeReminder($reminder['id']);
-	}
-
-	/**
-	 * @param int $calendarId
-	 * @return IUser[]
-	 */
-	private function getAllUsersWithWriteAccessToCalendar(int $calendarId):array {
-		$shares = $this->caldavBackend->getShares($calendarId);
-
-		$users = [];
-		$userIds = [];
-		$groups = [];
-		foreach ($shares as $share) {
-			// Only consider writable shares
-			if ($share['readOnly']) {
-				continue;
-			}
-
-			$principal = explode('/', $share['{http://owncloud.org/ns}principal']);
-			if ($principal[1] === 'users') {
-				$user = $this->userManager->get($principal[2]);
-				if ($user) {
-					$users[] = $user;
-					$userIds[] = $principal[2];
-				}
-			} elseif ($principal[1] === 'groups') {
-				$groups[] = $principal[2];
-			}
-		}
-
-		foreach ($groups as $gid) {
-			$group = $this->groupManager->get($gid);
-			if ($group instanceof IGroup) {
-				foreach ($group->getUsers() as $user) {
-					if (!\in_array($user->getUID(), $userIds, true)) {
-						$users[] = $user;
-						$userIds[] = $user->getUID();
-					}
-				}
-			}
-		}
-
-		return $users;
-	}
-
-	/**
-	 * Gets a hash of the event.
-	 * If the hash changes, we have to update all relative alarms.
-	 *
-	 * @param VEvent $vevent
-	 * @return string
-	 */
-	private function getEventHash(VEvent $vevent):string {
-		$properties = [
-			(string) $vevent->DTSTART->serialize(),
-		];
-
-		if ($vevent->DTEND) {
-			$properties[] = (string) $vevent->DTEND->serialize();
-		}
-		if ($vevent->DURATION) {
-			$properties[] = (string) $vevent->DURATION->serialize();
-		}
-		if ($vevent->{'RECURRENCE-ID'}) {
-			$properties[] = (string) $vevent->{'RECURRENCE-ID'}->serialize();
-		}
-		if ($vevent->RRULE) {
-			$properties[] = (string) $vevent->RRULE->serialize();
-		}
-		if ($vevent->EXDATE) {
-			$properties[] = (string) $vevent->EXDATE->serialize();
-		}
-		if ($vevent->RDATE) {
-			$properties[] = (string) $vevent->RDATE->serialize();
-		}
-
-		return md5(implode('::', $properties));
-	}
-
-	/**
-	 * Gets a hash of the alarm.
-	 * If the hash changes, we have to update oc_dav_reminders.
-	 *
-	 * @param VAlarm $valarm
-	 * @return string
-	 */
-	private function getAlarmHash(VAlarm $valarm):string {
-		$properties = [
-			(string) $valarm->ACTION->serialize(),
-			(string) $valarm->TRIGGER->serialize(),
-		];
-
-		if ($valarm->DURATION) {
-			$properties[] = (string) $valarm->DURATION->serialize();
-		}
-		if ($valarm->REPEAT) {
-			$properties[] = (string) $valarm->REPEAT->serialize();
-		}
-
-		return md5(implode('::', $properties));
-	}
-
-	/**
-	 * @param VObject\Component\VCalendar $vcalendar
-	 * @param int $recurrenceId
-	 * @param bool $isRecurrenceException
-	 * @return VEvent|null
-	 */
-	private function getVEventByRecurrenceId(VObject\Component\VCalendar $vcalendar,
-											 int $recurrenceId,
-											 bool $isRecurrenceException):?VEvent {
-		$vevents = $this->getAllVEventsFromVCalendar($vcalendar);
-		if (count($vevents) === 0) {
-			return null;
-		}
-
-		$uid = (string) $vevents[0]->UID;
-		$recurrenceExceptions = $this->getRecurrenceExceptionFromListOfVEvents($vevents);
-		$masterItem = $this->getMasterItemFromListOfVEvents($vevents);
-
-		// Handle recurrence-exceptions first, because recurrence-expansion is expensive
-		if ($isRecurrenceException) {
-			foreach ($recurrenceExceptions as $recurrenceException) {
-				if ($this->getEffectiveRecurrenceIdOfVEvent($recurrenceException) === $recurrenceId) {
-					return $recurrenceException;
-				}
-			}
-
-			return null;
-		}
-
-		if ($masterItem) {
-			try {
-				$iterator = new EventIterator($vevents, $uid);
-			} catch (NoInstancesException $e) {
-				// This event is recurring, but it doesn't have a single
-				// instance. We are skipping this event from the output
-				// entirely.
-				return null;
-			}
-
-			while ($iterator->valid()) {
-				$event = $iterator->getEventObject();
-
-				// Recurrence-exceptions are handled separately, so just ignore them here
-				if (\in_array($event, $recurrenceExceptions, true)) {
-					$iterator->next();
-					continue;
-				}
-
-				if ($this->getEffectiveRecurrenceIdOfVEvent($event) === $recurrenceId) {
-					return $event;
-				}
-
-				$iterator->next();
-			}
-		}
-
-		return null;
-	}
-
-	/**
-	 * @param VEvent $vevent
-	 * @return string
-	 */
-	private function getStatusOfEvent(VEvent $vevent):string {
-		if ($vevent->STATUS) {
-			return (string) $vevent->STATUS;
-		}
-
-		// Doesn't say so in the standard,
-		// but we consider events without a status
-		// to be confirmed
-		return 'CONFIRMED';
-	}
-
-	/**
-	 * @param VObject\Component\VEvent $vevent
-	 * @return bool
-	 */
-	private function wasEventCancelled(VObject\Component\VEvent $vevent):bool {
-		return $this->getStatusOfEvent($vevent) === 'CANCELLED';
-	}
-
-	/**
-	 * @param string $calendarData
-	 * @return VObject\Component\VCalendar|null
-	 */
-	private function parseCalendarData(string $calendarData):?VObject\Component\VCalendar {
-		try {
-			return VObject\Reader::read($calendarData,
-				VObject\Reader::OPTION_FORGIVING);
-		} catch (ParseException $ex) {
-			return null;
-		}
-	}
-
-	/**
-	 * @param string $principalUri
-	 * @return IUser|null
-	 */
-	private function getUserFromPrincipalURI(string $principalUri):?IUser {
-		if (!$principalUri) {
-			return null;
-		}
-
-		if (stripos($principalUri, 'principals/users/') !== 0) {
-			return null;
-		}
-
-		$userId = substr($principalUri, 17);
-		return $this->userManager->get($userId);
-	}
-
-	/**
-	 * @param VObject\Component\VCalendar $vcalendar
-	 * @return VObject\Component\VEvent[]
-	 */
-	private function getAllVEventsFromVCalendar(VObject\Component\VCalendar $vcalendar):array {
-		$vevents = [];
-
-		foreach ($vcalendar->children() as $child) {
-			if (!($child instanceof VObject\Component)) {
-				continue;
-			}
-
-			if ($child->name !== 'VEVENT') {
-				continue;
-			}
-
-			$vevents[] = $child;
-		}
-
-		return $vevents;
-	}
-
-	/**
-	 * @param array $vevents
-	 * @return VObject\Component\VEvent[]
-	 */
-	private function getRecurrenceExceptionFromListOfVEvents(array $vevents):array {
-		return array_values(array_filter($vevents, function (VEvent $vevent) {
-			return $vevent->{'RECURRENCE-ID'} !== null;
-		}));
-	}
-
-	/**
-	 * @param array $vevents
-	 * @return VEvent|null
-	 */
-	private function getMasterItemFromListOfVEvents(array $vevents):?VEvent {
-		$elements = array_values(array_filter($vevents, function (VEvent $vevent) {
-			return $vevent->{'RECURRENCE-ID'} === null;
-		}));
-
-		if (count($elements) === 0) {
-			return null;
-		}
-		if (count($elements) > 1) {
-			throw new \TypeError('Multiple master objects');
-		}
-
-		return $elements[0];
-	}
-
-	/**
-	 * @param VAlarm $valarm
-	 * @return bool
-	 */
-	private function isAlarmRelative(VAlarm $valarm):bool {
-		$trigger = $valarm->TRIGGER;
-		return $trigger instanceof VObject\Property\ICalendar\Duration;
-	}
-
-	/**
-	 * @param VEvent $vevent
-	 * @return int
-	 */
-	private function getEffectiveRecurrenceIdOfVEvent(VEvent $vevent):int {
-		if (isset($vevent->{'RECURRENCE-ID'})) {
-			return $vevent->{'RECURRENCE-ID'}->getDateTime()->getTimestamp();
-		}
-
-		return $vevent->DTSTART->getDateTime()->getTimestamp();
-	}
-
-	/**
-	 * @param VEvent $vevent
-	 * @return bool
-	 */
-	private function isRecurring(VEvent $vevent):bool {
-		return isset($vevent->RRULE) || isset($vevent->RDATE);
-	}
-
-	/**
-	 * @param int $calendarid
-	 *
-	 * @return DateTimeZone
-	 */
-	private function getCalendarTimeZone(int $calendarid): DateTimeZone {
-		$calendarInfo = $this->caldavBackend->getCalendarById($calendarid);
-		$tzProp = '{urn:ietf:params:xml:ns:caldav}calendar-timezone';
-		if (!isset($calendarInfo[$tzProp])) {
-			// Defaulting to UTC
-			return new DateTimeZone('UTC');
-		}
-		// This property contains a VCALENDAR with a single VTIMEZONE
-		/** @var string $timezoneProp */
-		$timezoneProp = $calendarInfo[$tzProp];
-		/** @var VObject\Component\VCalendar $vtimezoneObj */
-		$vtimezoneObj = VObject\Reader::read($timezoneProp);
-		/** @var VObject\Component\VTimeZone $vtimezone */
-		$vtimezone = $vtimezoneObj->VTIMEZONE;
-		return $vtimezone->getTimeZone();
-	}
+    /** @var Backend */
+    private $backend;
+
+    /** @var NotificationProviderManager */
+    private $notificationProviderManager;
+
+    /** @var IUserManager */
+    private $userManager;
+
+    /** @var IGroupManager */
+    private $groupManager;
+
+    /** @var CalDavBackend */
+    private $caldavBackend;
+
+    /** @var ITimeFactory */
+    private $timeFactory;
+
+    /** @var IConfig */
+    private $config;
+
+    /** @var LoggerInterface */
+    private $logger;
+
+    /** @var Principal */
+    private $principalConnector;
+
+    public const REMINDER_TYPE_EMAIL = 'EMAIL';
+    public const REMINDER_TYPE_DISPLAY = 'DISPLAY';
+    public const REMINDER_TYPE_AUDIO = 'AUDIO';
+
+    /**
+     * @var String[]
+     *
+     * Official RFC5545 reminder types
+     */
+    public const REMINDER_TYPES = [
+        self::REMINDER_TYPE_EMAIL,
+        self::REMINDER_TYPE_DISPLAY,
+        self::REMINDER_TYPE_AUDIO
+    ];
+
+    public function __construct(Backend $backend,
+                                NotificationProviderManager $notificationProviderManager,
+                                IUserManager $userManager,
+                                IGroupManager $groupManager,
+                                CalDavBackend $caldavBackend,
+                                ITimeFactory $timeFactory,
+                                IConfig $config,
+                                LoggerInterface $logger,
+                                Principal $principalConnector) {
+        $this->backend = $backend;
+        $this->notificationProviderManager = $notificationProviderManager;
+        $this->userManager = $userManager;
+        $this->groupManager = $groupManager;
+        $this->caldavBackend = $caldavBackend;
+        $this->timeFactory = $timeFactory;
+        $this->config = $config;
+        $this->logger = $logger;
+        $this->principalConnector = $principalConnector;
+    }
+
+    /**
+     * Process reminders to activate
+     *
+     * @throws NotificationProvider\ProviderNotAvailableException
+     * @throws NotificationTypeDoesNotExistException
+     */
+    public function processReminders() :void {
+        $reminders = $this->backend->getRemindersToProcess();
+        $this->logger->debug('{numReminders} reminders to process', [
+            'numReminders' => count($reminders),
+        ]);
+
+        foreach ($reminders as $reminder) {
+            $calendarData = is_resource($reminder['calendardata'])
+                ? stream_get_contents($reminder['calendardata'])
+                : $reminder['calendardata'];
+
+            if (!$calendarData) {
+                continue;
+            }
+
+            $vcalendar = $this->parseCalendarData($calendarData);
+            if (!$vcalendar) {
+                $this->logger->debug('Reminder {id} does not belong to a valid calendar', [
+                    'id' => $reminder['id'],
+                ]);
+                $this->backend->removeReminder($reminder['id']);
+                continue;
+            }
+
+            $vevent = $this->getVEventByRecurrenceId($vcalendar, $reminder['recurrence_id'], $reminder['is_recurrence_exception']);
+            if (!$vevent) {
+                $this->logger->debug('Reminder {id} does not belong to a valid event', [
+                    'id' => $reminder['id'],
+                ]);
+                $this->backend->removeReminder($reminder['id']);
+                continue;
+            }
+
+            if ($this->wasEventCancelled($vevent)) {
+                $this->logger->debug('Reminder {id} belongs to a cancelled event', [
+                    'id' => $reminder['id'],
+                ]);
+                $this->deleteOrProcessNext($reminder, $vevent);
+                continue;
+            }
+
+            if (!$this->notificationProviderManager->hasProvider($reminder['type'])) {
+                $this->logger->debug('Reminder {id} does not belong to a valid notification provider', [
+                    'id' => $reminder['id'],
+                ]);
+                $this->deleteOrProcessNext($reminder, $vevent);
+                continue;
+            }
+
+            if ($this->config->getAppValue('dav', 'sendEventRemindersToSharedGroupMembers', 'yes') === 'no') {
+                $users = $this->getAllUsersWithWriteAccessToCalendar($reminder['calendar_id']);
+            } else {
+                $users = [];
+            }
+
+            $user = $this->getUserFromPrincipalURI($reminder['principaluri']);
+            if ($user) {
+                $users[] = $user;
+            }
+
+            $userPrincipalEmailAddresses = [];
+            $userPrincipal = $this->principalConnector->getPrincipalByPath($reminder['principaluri']);
+            if ($userPrincipal) {
+                $userPrincipalEmailAddresses = $this->principalConnector->getEmailAddressesOfPrincipal($userPrincipal);
+            }
+
+            $this->logger->debug('Reminder {id} will be sent to {numUsers} users', [
+                'id' => $reminder['id'],
+                'numUsers' => count($users),
+            ]);
+            $notificationProvider = $this->notificationProviderManager->getProvider($reminder['type']);
+            $notificationProvider->send($vevent, $reminder['displayname'], $userPrincipalEmailAddresses, $users);
+
+            $this->deleteOrProcessNext($reminder, $vevent);
+        }
+    }
+
+    /**
+     * @param array $objectData
+     * @throws VObject\InvalidDataException
+     */
+    public function onCalendarObjectCreate(array $objectData):void {
+        // We only support VEvents for now
+        if (strcasecmp($objectData['component'], 'vevent') !== 0) {
+            return;
+        }
+
+        $calendarData = is_resource($objectData['calendardata'])
+            ? stream_get_contents($objectData['calendardata'])
+            : $objectData['calendardata'];
+
+        if (!$calendarData) {
+            return;
+        }
+
+        $vcalendar = $this->parseCalendarData($calendarData);
+        if (!$vcalendar) {
+            return;
+        }
+        $calendarTimeZone = $this->getCalendarTimeZone((int) $objectData['calendarid']);
+
+        $vevents = $this->getAllVEventsFromVCalendar($vcalendar);
+        if (count($vevents) === 0) {
+            return;
+        }
+
+        $uid = (string) $vevents[0]->UID;
+        $recurrenceExceptions = $this->getRecurrenceExceptionFromListOfVEvents($vevents);
+        $masterItem = $this->getMasterItemFromListOfVEvents($vevents);
+        $now = $this->timeFactory->getDateTime();
+        $isRecurring = $masterItem ? $this->isRecurring($masterItem) : false;
+
+        foreach ($recurrenceExceptions as $recurrenceException) {
+            $eventHash = $this->getEventHash($recurrenceException);
+
+            if (!isset($recurrenceException->VALARM)) {
+                continue;
+            }
+
+            foreach ($recurrenceException->VALARM as $valarm) {
+                /** @var VAlarm $valarm */
+                $alarmHash = $this->getAlarmHash($valarm);
+                $triggerTime = $valarm->getEffectiveTriggerTime();
+                $diff = $now->diff($triggerTime);
+                if ($diff->invert === 1) {
+                    continue;
+                }
+
+                $alarms = $this->getRemindersForVAlarm($valarm, $objectData, $calendarTimeZone,
+                    $eventHash, $alarmHash, true, true);
+                $this->writeRemindersToDatabase($alarms);
+            }
+        }
+
+        if ($masterItem) {
+            $processedAlarms = [];
+            $masterAlarms = [];
+            $masterHash = $this->getEventHash($masterItem);
+
+            if (!isset($masterItem->VALARM)) {
+                return;
+            }
+
+            foreach ($masterItem->VALARM as $valarm) {
+                $masterAlarms[] = $this->getAlarmHash($valarm);
+            }
+
+            try {
+                $iterator = new EventIterator($vevents, $uid);
+            } catch (NoInstancesException $e) {
+                // This event is recurring, but it doesn't have a single
+                // instance. We are skipping this event from the output
+                // entirely.
+                return;
+            } catch (MaxInstancesExceededException $e) {
+                // The event has more than 3500 recurring-instances
+                // so we can ignore it
+                return;
+            }
+
+            while ($iterator->valid() && count($processedAlarms) < count($masterAlarms)) {
+                $event = $iterator->getEventObject();
+
+                // Recurrence-exceptions are handled separately, so just ignore them here
+                if (\in_array($event, $recurrenceExceptions, true)) {
+                    $iterator->next();
+                    continue;
+                }
+
+                foreach ($event->VALARM as $valarm) {
+                    /** @var VAlarm $valarm */
+                    $alarmHash = $this->getAlarmHash($valarm);
+                    if (\in_array($alarmHash, $processedAlarms, true)) {
+                        continue;
+                    }
+
+                    if (!\in_array((string) $valarm->ACTION, self::REMINDER_TYPES, true)) {
+                        // Action allows x-name, we don't insert reminders
+                        // into the database if they are not standard
+                        $processedAlarms[] = $alarmHash;
+                        continue;
+                    }
+
+                    try {
+                        $triggerTime = $valarm->getEffectiveTriggerTime();
+                        /**
+                         * @psalm-suppress DocblockTypeContradiction
+                         *   https://github.com/vimeo/psalm/issues/9244
+                         */
+                        if ($triggerTime->getTimezone() === false || $triggerTime->getTimezone()->getName() === 'UTC') {
+                            $triggerTime = new DateTimeImmutable(
+                                $triggerTime->format('Y-m-d H:i:s'),
+                                $calendarTimeZone
+                            );
+                        }
+                    } catch (InvalidDataException $e) {
+                        continue;
+                    }
+
+                    // If effective trigger time is in the past
+                    // just skip and generate for next event
+                    $diff = $now->diff($triggerTime);
+                    if ($diff->invert === 1) {
+                        // If an absolute alarm is in the past,
+                        // just add it to processedAlarms, so
+                        // we don't extend till eternity
+                        if (!$this->isAlarmRelative($valarm)) {
+                            $processedAlarms[] = $alarmHash;
+                        }
+
+                        continue;
+                    }
+
+                    $alarms = $this->getRemindersForVAlarm($valarm, $objectData, $calendarTimeZone, $masterHash, $alarmHash, $isRecurring, false);
+                    $this->writeRemindersToDatabase($alarms);
+                    $processedAlarms[] = $alarmHash;
+                }
+
+                $iterator->next();
+            }
+        }
+    }
+
+    /**
+     * @param array $objectData
+     * @throws VObject\InvalidDataException
+     */
+    public function onCalendarObjectEdit(array $objectData):void {
+        // TODO - this can be vastly improved
+        //  - get cached reminders
+        //  - ...
+
+        $this->onCalendarObjectDelete($objectData);
+        $this->onCalendarObjectCreate($objectData);
+    }
+
+    /**
+     * @param array $objectData
+     * @throws VObject\InvalidDataException
+     */
+    public function onCalendarObjectDelete(array $objectData):void {
+        // We only support VEvents for now
+        if (strcasecmp($objectData['component'], 'vevent') !== 0) {
+            return;
+        }
+
+        $this->backend->cleanRemindersForEvent((int) $objectData['id']);
+    }
+
+    /**
+     * @param VAlarm $valarm
+     * @param array $objectData
+     * @param DateTimeZone $calendarTimeZone
+     * @param string|null $eventHash
+     * @param string|null $alarmHash
+     * @param bool $isRecurring
+     * @param bool $isRecurrenceException
+     * @return array
+     */
+    private function getRemindersForVAlarm(VAlarm $valarm,
+                                            array $objectData,
+                                            DateTimeZone $calendarTimeZone,
+                                            string $eventHash = null,
+                                            string $alarmHash = null,
+                                            bool $isRecurring = false,
+                                            bool $isRecurrenceException = false):array {
+        if ($eventHash === null) {
+            $eventHash = $this->getEventHash($valarm->parent);
+        }
+        if ($alarmHash === null) {
+            $alarmHash = $this->getAlarmHash($valarm);
+        }
+
+        $recurrenceId = $this->getEffectiveRecurrenceIdOfVEvent($valarm->parent);
+        $isRelative = $this->isAlarmRelative($valarm);
+        /** @var DateTimeImmutable $notificationDate */
+        $notificationDate = $valarm->getEffectiveTriggerTime();
+        /**
+         * @psalm-suppress DocblockTypeContradiction
+         *   https://github.com/vimeo/psalm/issues/9244
+         */
+        if ($notificationDate->getTimezone() === false || $notificationDate->getTimezone()->getName() === 'UTC') {
+            $notificationDate = new DateTimeImmutable(
+                $notificationDate->format('Y-m-d H:i:s'),
+                $calendarTimeZone
+            );
+        }
+        $clonedNotificationDate = new \DateTime('now', $notificationDate->getTimezone());
+        $clonedNotificationDate->setTimestamp($notificationDate->getTimestamp());
+
+        $alarms = [];
+
+        $alarms[] = [
+            'calendar_id' => $objectData['calendarid'],
+            'object_id' => $objectData['id'],
+            'uid' => (string) $valarm->parent->UID,
+            'is_recurring' => $isRecurring,
+            'recurrence_id' => $recurrenceId,
+            'is_recurrence_exception' => $isRecurrenceException,
+            'event_hash' => $eventHash,
+            'alarm_hash' => $alarmHash,
+            'type' => (string) $valarm->ACTION,
+            'is_relative' => $isRelative,
+            'notification_date' => $notificationDate->getTimestamp(),
+            'is_repeat_based' => false,
+        ];
+
+        $repeat = isset($valarm->REPEAT) ? (int) $valarm->REPEAT->getValue() : 0;
+        for ($i = 0; $i < $repeat; $i++) {
+            if ($valarm->DURATION === null) {
+                continue;
+            }
+
+            $clonedNotificationDate->add($valarm->DURATION->getDateInterval());
+            $alarms[] = [
+                'calendar_id' => $objectData['calendarid'],
+                'object_id' => $objectData['id'],
+                'uid' => (string) $valarm->parent->UID,
+                'is_recurring' => $isRecurring,
+                'recurrence_id' => $recurrenceId,
+                'is_recurrence_exception' => $isRecurrenceException,
+                'event_hash' => $eventHash,
+                'alarm_hash' => $alarmHash,
+                'type' => (string) $valarm->ACTION,
+                'is_relative' => $isRelative,
+                'notification_date' => $clonedNotificationDate->getTimestamp(),
+                'is_repeat_based' => true,
+            ];
+        }
+
+        return $alarms;
+    }
+
+    /**
+     * @param array $reminders
+     */
+    private function writeRemindersToDatabase(array $reminders): void {
+        foreach ($reminders as $reminder) {
+            $this->backend->insertReminder(
+                (int) $reminder['calendar_id'],
+                (int) $reminder['object_id'],
+                $reminder['uid'],
+                $reminder['is_recurring'],
+                (int) $reminder['recurrence_id'],
+                $reminder['is_recurrence_exception'],
+                $reminder['event_hash'],
+                $reminder['alarm_hash'],
+                $reminder['type'],
+                $reminder['is_relative'],
+                (int) $reminder['notification_date'],
+                $reminder['is_repeat_based']
+            );
+        }
+    }
+
+    /**
+     * @param array $reminder
+     * @param VEvent $vevent
+     */
+    private function deleteOrProcessNext(array $reminder,
+                                            VObject\Component\VEvent $vevent):void {
+        if ($reminder['is_repeat_based'] ||
+            !$reminder['is_recurring'] ||
+            !$reminder['is_relative'] ||
+            $reminder['is_recurrence_exception']) {
+            $this->backend->removeReminder($reminder['id']);
+            return;
+        }
+
+        $vevents = $this->getAllVEventsFromVCalendar($vevent->parent);
+        $recurrenceExceptions = $this->getRecurrenceExceptionFromListOfVEvents($vevents);
+        $now = $this->timeFactory->getDateTime();
+        $calendarTimeZone = $this->getCalendarTimeZone((int) $reminder['calendar_id']);
+
+        try {
+            $iterator = new EventIterator($vevents, $reminder['uid']);
+        } catch (NoInstancesException $e) {
+            // This event is recurring, but it doesn't have a single
+            // instance. We are skipping this event from the output
+            // entirely.
+            return;
+        }
+
+        try {
+            while ($iterator->valid()) {
+                $event = $iterator->getEventObject();
+
+                // Recurrence-exceptions are handled separately, so just ignore them here
+                if (\in_array($event, $recurrenceExceptions, true)) {
+                    $iterator->next();
+                    continue;
+                }
+
+                $recurrenceId = $this->getEffectiveRecurrenceIdOfVEvent($event);
+                if ($reminder['recurrence_id'] >= $recurrenceId) {
+                    $iterator->next();
+                    continue;
+                }
+
+                foreach ($event->VALARM as $valarm) {
+                    /** @var VAlarm $valarm */
+                    $alarmHash = $this->getAlarmHash($valarm);
+                    if ($alarmHash !== $reminder['alarm_hash']) {
+                        continue;
+                    }
+
+                    $triggerTime = $valarm->getEffectiveTriggerTime();
+
+                    // If effective trigger time is in the past
+                    // just skip and generate for next event
+                    $diff = $now->diff($triggerTime);
+                    if ($diff->invert === 1) {
+                        continue;
+                    }
+
+                    $this->backend->removeReminder($reminder['id']);
+                    $alarms = $this->getRemindersForVAlarm($valarm, [
+                        'calendarid' => $reminder['calendar_id'],
+                        'id' => $reminder['object_id'],
+                    ], $calendarTimeZone, $reminder['event_hash'], $alarmHash, true, false);
+                    $this->writeRemindersToDatabase($alarms);
+
+                    // Abort generating reminders after creating one successfully
+                    return;
+                }
+
+                $iterator->next();
+            }
+        } catch (MaxInstancesExceededException $e) {
+            // Using debug logger as this isn't really an error
+            $this->logger->debug('Recurrence with too many instances detected, skipping VEVENT', ['exception' => $e]);
+        }
+
+        $this->backend->removeReminder($reminder['id']);
+    }
+
+    /**
+     * @param int $calendarId
+     * @return IUser[]
+     */
+    private function getAllUsersWithWriteAccessToCalendar(int $calendarId):array {
+        $shares = $this->caldavBackend->getShares($calendarId);
+
+        $users = [];
+        $userIds = [];
+        $groups = [];
+        foreach ($shares as $share) {
+            // Only consider writable shares
+            if ($share['readOnly']) {
+                continue;
+            }
+
+            $principal = explode('/', $share['{http://owncloud.org/ns}principal']);
+            if ($principal[1] === 'users') {
+                $user = $this->userManager->get($principal[2]);
+                if ($user) {
+                    $users[] = $user;
+                    $userIds[] = $principal[2];
+                }
+            } elseif ($principal[1] === 'groups') {
+                $groups[] = $principal[2];
+            }
+        }
+
+        foreach ($groups as $gid) {
+            $group = $this->groupManager->get($gid);
+            if ($group instanceof IGroup) {
+                foreach ($group->getUsers() as $user) {
+                    if (!\in_array($user->getUID(), $userIds, true)) {
+                        $users[] = $user;
+                        $userIds[] = $user->getUID();
+                    }
+                }
+            }
+        }
+
+        return $users;
+    }
+
+    /**
+     * Gets a hash of the event.
+     * If the hash changes, we have to update all relative alarms.
+     *
+     * @param VEvent $vevent
+     * @return string
+     */
+    private function getEventHash(VEvent $vevent):string {
+        $properties = [
+            (string) $vevent->DTSTART->serialize(),
+        ];
+
+        if ($vevent->DTEND) {
+            $properties[] = (string) $vevent->DTEND->serialize();
+        }
+        if ($vevent->DURATION) {
+            $properties[] = (string) $vevent->DURATION->serialize();
+        }
+        if ($vevent->{'RECURRENCE-ID'}) {
+            $properties[] = (string) $vevent->{'RECURRENCE-ID'}->serialize();
+        }
+        if ($vevent->RRULE) {
+            $properties[] = (string) $vevent->RRULE->serialize();
+        }
+        if ($vevent->EXDATE) {
+            $properties[] = (string) $vevent->EXDATE->serialize();
+        }
+        if ($vevent->RDATE) {
+            $properties[] = (string) $vevent->RDATE->serialize();
+        }
+
+        return md5(implode('::', $properties));
+    }
+
+    /**
+     * Gets a hash of the alarm.
+     * If the hash changes, we have to update oc_dav_reminders.
+     *
+     * @param VAlarm $valarm
+     * @return string
+     */
+    private function getAlarmHash(VAlarm $valarm):string {
+        $properties = [
+            (string) $valarm->ACTION->serialize(),
+            (string) $valarm->TRIGGER->serialize(),
+        ];
+
+        if ($valarm->DURATION) {
+            $properties[] = (string) $valarm->DURATION->serialize();
+        }
+        if ($valarm->REPEAT) {
+            $properties[] = (string) $valarm->REPEAT->serialize();
+        }
+
+        return md5(implode('::', $properties));
+    }
+
+    /**
+     * @param VObject\Component\VCalendar $vcalendar
+     * @param int $recurrenceId
+     * @param bool $isRecurrenceException
+     * @return VEvent|null
+     */
+    private function getVEventByRecurrenceId(VObject\Component\VCalendar $vcalendar,
+                                                int $recurrenceId,
+                                                bool $isRecurrenceException):?VEvent {
+        $vevents = $this->getAllVEventsFromVCalendar($vcalendar);
+        if (count($vevents) === 0) {
+            return null;
+        }
+
+        $uid = (string) $vevents[0]->UID;
+        $recurrenceExceptions = $this->getRecurrenceExceptionFromListOfVEvents($vevents);
+        $masterItem = $this->getMasterItemFromListOfVEvents($vevents);
+
+        // Handle recurrence-exceptions first, because recurrence-expansion is expensive
+        if ($isRecurrenceException) {
+            foreach ($recurrenceExceptions as $recurrenceException) {
+                if ($this->getEffectiveRecurrenceIdOfVEvent($recurrenceException) === $recurrenceId) {
+                    return $recurrenceException;
+                }
+            }
+
+            return null;
+        }
+
+        if ($masterItem) {
+            try {
+                $iterator = new EventIterator($vevents, $uid);
+            } catch (NoInstancesException $e) {
+                // This event is recurring, but it doesn't have a single
+                // instance. We are skipping this event from the output
+                // entirely.
+                return null;
+            }
+
+            while ($iterator->valid()) {
+                $event = $iterator->getEventObject();
+
+                // Recurrence-exceptions are handled separately, so just ignore them here
+                if (\in_array($event, $recurrenceExceptions, true)) {
+                    $iterator->next();
+                    continue;
+                }
+
+                if ($this->getEffectiveRecurrenceIdOfVEvent($event) === $recurrenceId) {
+                    return $event;
+                }
+
+                $iterator->next();
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * @param VEvent $vevent
+     * @return string
+     */
+    private function getStatusOfEvent(VEvent $vevent):string {
+        if ($vevent->STATUS) {
+            return (string) $vevent->STATUS;
+        }
+
+        // Doesn't say so in the standard,
+        // but we consider events without a status
+        // to be confirmed
+        return 'CONFIRMED';
+    }
+
+    /**
+     * @param VObject\Component\VEvent $vevent
+     * @return bool
+     */
+    private function wasEventCancelled(VObject\Component\VEvent $vevent):bool {
+        return $this->getStatusOfEvent($vevent) === 'CANCELLED';
+    }
+
+    /**
+     * @param string $calendarData
+     * @return VObject\Component\VCalendar|null
+     */
+    private function parseCalendarData(string $calendarData):?VObject\Component\VCalendar {
+        try {
+            return VObject\Reader::read($calendarData,
+                VObject\Reader::OPTION_FORGIVING);
+        } catch (ParseException $ex) {
+            return null;
+        }
+    }
+
+    /**
+     * @param string $principalUri
+     * @return IUser|null
+     */
+    private function getUserFromPrincipalURI(string $principalUri):?IUser {
+        if (!$principalUri) {
+            return null;
+        }
+
+        if (stripos($principalUri, 'principals/users/') !== 0) {
+            return null;
+        }
+
+        $userId = substr($principalUri, 17);
+        return $this->userManager->get($userId);
+    }
+
+    /**
+     * @param VObject\Component\VCalendar $vcalendar
+     * @return VObject\Component\VEvent[]
+     */
+    private function getAllVEventsFromVCalendar(VObject\Component\VCalendar $vcalendar):array {
+        $vevents = [];
+
+        foreach ($vcalendar->children() as $child) {
+            if (!($child instanceof VObject\Component)) {
+                continue;
+            }
+
+            if ($child->name !== 'VEVENT') {
+                continue;
+            }
+
+            $vevents[] = $child;
+        }
+
+        return $vevents;
+    }
+
+    /**
+     * @param array $vevents
+     * @return VObject\Component\VEvent[]
+     */
+    private function getRecurrenceExceptionFromListOfVEvents(array $vevents):array {
+        return array_values(array_filter($vevents, function (VEvent $vevent) {
+            return $vevent->{'RECURRENCE-ID'} !== null;
+        }));
+    }
+
+    /**
+     * @param array $vevents
+     * @return VEvent|null
+     */
+    private function getMasterItemFromListOfVEvents(array $vevents):?VEvent {
+        $elements = array_values(array_filter($vevents, function (VEvent $vevent) {
+            return $vevent->{'RECURRENCE-ID'} === null;
+        }));
+
+        if (count($elements) === 0) {
+            return null;
+        }
+        if (count($elements) > 1) {
+            throw new \TypeError('Multiple master objects');
+        }
+
+        return $elements[0];
+    }
+
+    /**
+     * @param VAlarm $valarm
+     * @return bool
+     */
+    private function isAlarmRelative(VAlarm $valarm):bool {
+        $trigger = $valarm->TRIGGER;
+        return $trigger instanceof VObject\Property\ICalendar\Duration;
+    }
+
+    /**
+     * @param VEvent $vevent
+     * @return int
+     */
+    private function getEffectiveRecurrenceIdOfVEvent(VEvent $vevent):int {
+        if (isset($vevent->{'RECURRENCE-ID'})) {
+            return $vevent->{'RECURRENCE-ID'}->getDateTime()->getTimestamp();
+        }
+
+        return $vevent->DTSTART->getDateTime()->getTimestamp();
+    }
+
+    /**
+     * @param VEvent $vevent
+     * @return bool
+     */
+    private function isRecurring(VEvent $vevent):bool {
+        return isset($vevent->RRULE) || isset($vevent->RDATE);
+    }
+
+    /**
+     * @param int $calendarid
+     *
+     * @return DateTimeZone
+     */
+    private function getCalendarTimeZone(int $calendarid): DateTimeZone {
+        $calendarInfo = $this->caldavBackend->getCalendarById($calendarid);
+        $tzProp = '{urn:ietf:params:xml:ns:caldav}calendar-timezone';
+        if (!isset($calendarInfo[$tzProp])) {
+            // Defaulting to UTC
+            return new DateTimeZone('UTC');
+        }
+        // This property contains a VCALENDAR with a single VTIMEZONE
+        /** @var string $timezoneProp */
+        $timezoneProp = $calendarInfo[$tzProp];
+        /** @var VObject\Component\VCalendar $vtimezoneObj */
+        $vtimezoneObj = VObject\Reader::read($timezoneProp);
+        /** @var VObject\Component\VTimeZone $vtimezone */
+        $vtimezone = $vtimezoneObj->VTIMEZONE;
+        return $vtimezone->getTimeZone();
+    }
 }

apps/dav/lib/CalDAV/CalDavBackend.php

Indentation +3067 added lines, -3067 removed lines

@@ -119,3071 +119,3071 @@
  * @package OCA\DAV\CalDAV
  */
 class CalDavBackend extends AbstractBackend implements SyncSupport, SubscriptionSupport, SchedulingSupport {
-	use TTransactional;
-
-	public const CALENDAR_TYPE_CALENDAR = 0;
-	public const CALENDAR_TYPE_SUBSCRIPTION = 1;
-
-	public const PERSONAL_CALENDAR_URI = 'personal';
-	public const PERSONAL_CALENDAR_NAME = 'Personal';
-
-	public const RESOURCE_BOOKING_CALENDAR_URI = 'calendar';
-	public const RESOURCE_BOOKING_CALENDAR_NAME = 'Calendar';
-
-	/**
-	 * We need to specify a max date, because we need to stop *somewhere*
-	 *
-	 * On 32 bit system the maximum for a signed integer is 2147483647, so
-	 * MAX_DATE cannot be higher than date('Y-m-d', 2147483647) which results
-	 * in 2038-01-19 to avoid problems when the date is converted
-	 * to a unix timestamp.
-	 */
-	public const MAX_DATE = '2038-01-01';
-
-	public const ACCESS_PUBLIC = 4;
-	public const CLASSIFICATION_PUBLIC = 0;
-	public const CLASSIFICATION_PRIVATE = 1;
-	public const CLASSIFICATION_CONFIDENTIAL = 2;
-
-	/**
-	 * List of CalDAV properties, and how they map to database field names and their type
-	 * Add your own properties by simply adding on to this array.
-	 *
-	 * @var array
-	 * @psalm-var array<string, string[]>
-	 */
-	public array $propertyMap = [
-		'{DAV:}displayname' => ['displayname', 'string'],
-		'{urn:ietf:params:xml:ns:caldav}calendar-description' => ['description', 'string'],
-		'{urn:ietf:params:xml:ns:caldav}calendar-timezone' => ['timezone', 'string'],
-		'{http://apple.com/ns/ical/}calendar-order' => ['calendarorder', 'int'],
-		'{http://apple.com/ns/ical/}calendar-color' => ['calendarcolor', 'string'],
-		'{' . \OCA\DAV\DAV\Sharing\Plugin::NS_NEXTCLOUD . '}deleted-at' => ['deleted_at', 'int'],
-	];
-
-	/**
-	 * List of subscription properties, and how they map to database field names.
-	 *
-	 * @var array
-	 */
-	public array $subscriptionPropertyMap = [
-		'{DAV:}displayname' => ['displayname', 'string'],
-		'{http://apple.com/ns/ical/}refreshrate' => ['refreshrate', 'string'],
-		'{http://apple.com/ns/ical/}calendar-order' => ['calendarorder', 'int'],
-		'{http://apple.com/ns/ical/}calendar-color' => ['calendarcolor', 'string'],
-		'{http://calendarserver.org/ns/}subscribed-strip-todos' => ['striptodos', 'bool'],
-		'{http://calendarserver.org/ns/}subscribed-strip-alarms' => ['stripalarms', 'string'],
-		'{http://calendarserver.org/ns/}subscribed-strip-attachments' => ['stripattachments', 'string'],
-	];
-
-	/**
-	 * properties to index
-	 *
-	 * This list has to be kept in sync with ICalendarQuery::SEARCH_PROPERTY_*
-	 *
-	 * @see \OCP\Calendar\ICalendarQuery
-	 */
-	private const INDEXED_PROPERTIES = [
-		'CATEGORIES',
-		'COMMENT',
-		'DESCRIPTION',
-		'LOCATION',
-		'RESOURCES',
-		'STATUS',
-		'SUMMARY',
-		'ATTENDEE',
-		'CONTACT',
-		'ORGANIZER'
-	];
-
-	/** @var array parameters to index */
-	public static array $indexParameters = [
-		'ATTENDEE' => ['CN'],
-		'ORGANIZER' => ['CN'],
-	];
-
-	/**
-	 * @var string[] Map of uid => display name
-	 */
-	protected array $userDisplayNames;
-
-	private IDBConnection $db;
-	private Backend $calendarSharingBackend;
-	private Principal $principalBackend;
-	private IUserManager $userManager;
-	private ISecureRandom $random;
-	private LoggerInterface $logger;
-	private IEventDispatcher $dispatcher;
-	private IConfig $config;
-	private bool $legacyEndpoint;
-	private string $dbObjectPropertiesTable = 'calendarobjects_props';
-
-	public function __construct(IDBConnection $db,
-								Principal $principalBackend,
-								IUserManager $userManager,
-								IGroupManager $groupManager,
-								ISecureRandom $random,
-								LoggerInterface $logger,
-								IEventDispatcher $dispatcher,
-								IConfig $config,
-								bool $legacyEndpoint = false) {
-		$this->db = $db;
-		$this->principalBackend = $principalBackend;
-		$this->userManager = $userManager;
-		$this->calendarSharingBackend = new Backend($this->db, $this->userManager, $groupManager, $principalBackend, 'calendar');
-		$this->random = $random;
-		$this->logger = $logger;
-		$this->dispatcher = $dispatcher;
-		$this->config = $config;
-		$this->legacyEndpoint = $legacyEndpoint;
-	}
-
-	/**
-	 * Return the number of calendars for a principal
-	 *
-	 * By default this excludes the automatically generated birthday calendar
-	 *
-	 * @param $principalUri
-	 * @param bool $excludeBirthday
-	 * @return int
-	 */
-	public function getCalendarsForUserCount($principalUri, $excludeBirthday = true) {
-		$principalUri = $this->convertPrincipal($principalUri, true);
-		$query = $this->db->getQueryBuilder();
-		$query->select($query->func()->count('*'))
-			->from('calendars');
-
-		if ($principalUri === '') {
-			$query->where($query->expr()->emptyString('principaluri'));
-		} else {
-			$query->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)));
-		}
-
-		if ($excludeBirthday) {
-			$query->andWhere($query->expr()->neq('uri', $query->createNamedParameter(BirthdayService::BIRTHDAY_CALENDAR_URI)));
-		}
-
-		$result = $query->executeQuery();
-		$column = (int)$result->fetchOne();
-		$result->closeCursor();
-		return $column;
-	}
-
-	/**
-	 * @return array{id: int, deleted_at: int}[]
-	 */
-	public function getDeletedCalendars(int $deletedBefore): array {
-		$qb = $this->db->getQueryBuilder();
-		$qb->select(['id', 'deleted_at'])
-			->from('calendars')
-			->where($qb->expr()->isNotNull('deleted_at'))
-			->andWhere($qb->expr()->lt('deleted_at', $qb->createNamedParameter($deletedBefore)));
-		$result = $qb->executeQuery();
-		$raw = $result->fetchAll();
-		$result->closeCursor();
-		return array_map(function ($row) {
-			return [
-				'id' => (int) $row['id'],
-				'deleted_at' => (int) $row['deleted_at'],
-			];
-		}, $raw);
-	}
-
-	/**
-	 * Returns a list of calendars for a principal.
-	 *
-	 * Every project is an array with the following keys:
-	 *  * id, a unique id that will be used by other functions to modify the
-	 *    calendar. This can be the same as the uri or a database key.
-	 *  * uri, which the basename of the uri with which the calendar is
-	 *    accessed.
-	 *  * principaluri. The owner of the calendar. Almost always the same as
-	 *    principalUri passed to this method.
-	 *
-	 * Furthermore it can contain webdav properties in clark notation. A very
-	 * common one is '{DAV:}displayname'.
-	 *
-	 * Many clients also require:
-	 * {urn:ietf:params:xml:ns:caldav}supported-calendar-component-set
-	 * For this property, you can just return an instance of
-	 * Sabre\CalDAV\Property\SupportedCalendarComponentSet.
-	 *
-	 * If you return {http://sabredav.org/ns}read-only and set the value to 1,
-	 * ACL will automatically be put in read-only mode.
-	 *
-	 * @param string $principalUri
-	 * @return array
-	 */
-	public function getCalendarsForUser($principalUri) {
-		$principalUriOriginal = $principalUri;
-		$principalUri = $this->convertPrincipal($principalUri, true);
-		$fields = array_column($this->propertyMap, 0);
-		$fields[] = 'id';
-		$fields[] = 'uri';
-		$fields[] = 'synctoken';
-		$fields[] = 'components';
-		$fields[] = 'principaluri';
-		$fields[] = 'transparent';
-
-		// Making fields a comma-delimited list
-		$query = $this->db->getQueryBuilder();
-		$query->select($fields)
-			->from('calendars')
-			->orderBy('calendarorder', 'ASC');
-
-		if ($principalUri === '') {
-			$query->where($query->expr()->emptyString('principaluri'));
-		} else {
-			$query->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)));
-		}
-
-		$result = $query->executeQuery();
-
-		$calendars = [];
-		while ($row = $result->fetch()) {
-			$row['principaluri'] = (string) $row['principaluri'];
-			$components = [];
-			if ($row['components']) {
-				$components = explode(',', $row['components']);
-			}
-
-			$calendar = [
-				'id' => $row['id'],
-				'uri' => $row['uri'],
-				'principaluri' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
-				'{' . Plugin::NS_CALENDARSERVER . '}getctag' => 'http://sabre.io/ns/sync/' . ($row['synctoken']?$row['synctoken']:'0'),
-				'{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
-				'{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet($components),
-				'{' . Plugin::NS_CALDAV . '}schedule-calendar-transp' => new ScheduleCalendarTransp($row['transparent']?'transparent':'opaque'),
-				'{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}owner-principal' => $this->convertPrincipal($principalUri, !$this->legacyEndpoint),
-			];
-
-			$calendar = $this->rowToCalendar($row, $calendar);
-			$calendar = $this->addOwnerPrincipalToCalendar($calendar);
-			$calendar = $this->addResourceTypeToCalendar($row, $calendar);
-
-			if (!isset($calendars[$calendar['id']])) {
-				$calendars[$calendar['id']] = $calendar;
-			}
-		}
-		$result->closeCursor();
-
-		// query for shared calendars
-		$principals = $this->principalBackend->getGroupMembership($principalUriOriginal, true);
-		$principals = array_merge($principals, $this->principalBackend->getCircleMembership($principalUriOriginal));
-
-		$principals[] = $principalUri;
-
-		$fields = array_column($this->propertyMap, 0);
-		$fields[] = 'a.id';
-		$fields[] = 'a.uri';
-		$fields[] = 'a.synctoken';
-		$fields[] = 'a.components';
-		$fields[] = 'a.principaluri';
-		$fields[] = 'a.transparent';
-		$fields[] = 's.access';
-		$query = $this->db->getQueryBuilder();
-		$query->select($fields)
-			->from('dav_shares', 's')
-			->join('s', 'calendars', 'a', $query->expr()->eq('s.resourceid', 'a.id'))
-			->where($query->expr()->in('s.principaluri', $query->createParameter('principaluri')))
-			->andWhere($query->expr()->eq('s.type', $query->createParameter('type')))
-			->setParameter('type', 'calendar')
-			->setParameter('principaluri', $principals, \Doctrine\DBAL\Connection::PARAM_STR_ARRAY);
-
-		$result = $query->executeQuery();
-
-		$readOnlyPropertyName = '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}read-only';
-		while ($row = $result->fetch()) {
-			$row['principaluri'] = (string) $row['principaluri'];
-			if ($row['principaluri'] === $principalUri) {
-				continue;
-			}
-
-			$readOnly = (int) $row['access'] === Backend::ACCESS_READ;
-			if (isset($calendars[$row['id']])) {
-				if ($readOnly) {
-					// New share can not have more permissions then the old one.
-					continue;
-				}
-				if (isset($calendars[$row['id']][$readOnlyPropertyName]) &&
-					$calendars[$row['id']][$readOnlyPropertyName] === 0) {
-					// Old share is already read-write, no more permissions can be gained
-					continue;
-				}
-			}
-
-			[, $name] = Uri\split($row['principaluri']);
-			$uri = $row['uri'] . '_shared_by_' . $name;
-			$row['displayname'] = $row['displayname'] . ' (' . ($this->userManager->getDisplayName($name) ?? ($name ?? '')) . ')';
-			$components = [];
-			if ($row['components']) {
-				$components = explode(',', $row['components']);
-			}
-			$calendar = [
-				'id' => $row['id'],
-				'uri' => $uri,
-				'principaluri' => $this->convertPrincipal($principalUri, !$this->legacyEndpoint),
-				'{' . Plugin::NS_CALENDARSERVER . '}getctag' => 'http://sabre.io/ns/sync/' . ($row['synctoken']?$row['synctoken']:'0'),
-				'{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
-				'{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet($components),
-				'{' . Plugin::NS_CALDAV . '}schedule-calendar-transp' => new ScheduleCalendarTransp('transparent'),
-				'{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}owner-principal' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
-				$readOnlyPropertyName => $readOnly,
-			];
-
-			$calendar = $this->rowToCalendar($row, $calendar);
-			$calendar = $this->addOwnerPrincipalToCalendar($calendar);
-			$calendar = $this->addResourceTypeToCalendar($row, $calendar);
-
-			$calendars[$calendar['id']] = $calendar;
-		}
-		$result->closeCursor();
-
-		return array_values($calendars);
-	}
-
-	/**
-	 * @param $principalUri
-	 * @return array
-	 */
-	public function getUsersOwnCalendars($principalUri) {
-		$principalUri = $this->convertPrincipal($principalUri, true);
-		$fields = array_column($this->propertyMap, 0);
-		$fields[] = 'id';
-		$fields[] = 'uri';
-		$fields[] = 'synctoken';
-		$fields[] = 'components';
-		$fields[] = 'principaluri';
-		$fields[] = 'transparent';
-		// Making fields a comma-delimited list
-		$query = $this->db->getQueryBuilder();
-		$query->select($fields)->from('calendars')
-			->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)))
-			->orderBy('calendarorder', 'ASC');
-		$stmt = $query->executeQuery();
-		$calendars = [];
-		while ($row = $stmt->fetch()) {
-			$row['principaluri'] = (string) $row['principaluri'];
-			$components = [];
-			if ($row['components']) {
-				$components = explode(',', $row['components']);
-			}
-			$calendar = [
-				'id' => $row['id'],
-				'uri' => $row['uri'],
-				'principaluri' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
-				'{' . Plugin::NS_CALENDARSERVER . '}getctag' => 'http://sabre.io/ns/sync/' . ($row['synctoken']?$row['synctoken']:'0'),
-				'{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
-				'{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet($components),
-				'{' . Plugin::NS_CALDAV . '}schedule-calendar-transp' => new ScheduleCalendarTransp($row['transparent']?'transparent':'opaque'),
-			];
-
-			$calendar = $this->rowToCalendar($row, $calendar);
-			$calendar = $this->addOwnerPrincipalToCalendar($calendar);
-			$calendar = $this->addResourceTypeToCalendar($row, $calendar);
-
-			if (!isset($calendars[$calendar['id']])) {
-				$calendars[$calendar['id']] = $calendar;
-			}
-		}
-		$stmt->closeCursor();
-		return array_values($calendars);
-	}
-
-	/**
-	 * @return array
-	 */
-	public function getPublicCalendars() {
-		$fields = array_column($this->propertyMap, 0);
-		$fields[] = 'a.id';
-		$fields[] = 'a.uri';
-		$fields[] = 'a.synctoken';
-		$fields[] = 'a.components';
-		$fields[] = 'a.principaluri';
-		$fields[] = 'a.transparent';
-		$fields[] = 's.access';
-		$fields[] = 's.publicuri';
-		$calendars = [];
-		$query = $this->db->getQueryBuilder();
-		$result = $query->select($fields)
-			->from('dav_shares', 's')
-			->join('s', 'calendars', 'a', $query->expr()->eq('s.resourceid', 'a.id'))
-			->where($query->expr()->in('s.access', $query->createNamedParameter(self::ACCESS_PUBLIC)))
-			->andWhere($query->expr()->eq('s.type', $query->createNamedParameter('calendar')))
-			->executeQuery();
-
-		while ($row = $result->fetch()) {
-			$row['principaluri'] = (string) $row['principaluri'];
-			[, $name] = Uri\split($row['principaluri']);
-			$row['displayname'] = $row['displayname'] . "($name)";
-			$components = [];
-			if ($row['components']) {
-				$components = explode(',', $row['components']);
-			}
-			$calendar = [
-				'id' => $row['id'],
-				'uri' => $row['publicuri'],
-				'principaluri' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
-				'{' . Plugin::NS_CALENDARSERVER . '}getctag' => 'http://sabre.io/ns/sync/' . ($row['synctoken']?$row['synctoken']:'0'),
-				'{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
-				'{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet($components),
-				'{' . Plugin::NS_CALDAV . '}schedule-calendar-transp' => new ScheduleCalendarTransp($row['transparent']?'transparent':'opaque'),
-				'{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}owner-principal' => $this->convertPrincipal($row['principaluri'], $this->legacyEndpoint),
-				'{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}read-only' => (int)$row['access'] === Backend::ACCESS_READ,
-				'{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}public' => (int)$row['access'] === self::ACCESS_PUBLIC,
-			];
-
-			$calendar = $this->rowToCalendar($row, $calendar);
-			$calendar = $this->addOwnerPrincipalToCalendar($calendar);
-			$calendar = $this->addResourceTypeToCalendar($row, $calendar);
-
-			if (!isset($calendars[$calendar['id']])) {
-				$calendars[$calendar['id']] = $calendar;
-			}
-		}
-		$result->closeCursor();
-
-		return array_values($calendars);
-	}
-
-	/**
-	 * @param string $uri
-	 * @return array
-	 * @throws NotFound
-	 */
-	public function getPublicCalendar($uri) {
-		$fields = array_column($this->propertyMap, 0);
-		$fields[] = 'a.id';
-		$fields[] = 'a.uri';
-		$fields[] = 'a.synctoken';
-		$fields[] = 'a.components';
-		$fields[] = 'a.principaluri';
-		$fields[] = 'a.transparent';
-		$fields[] = 's.access';
-		$fields[] = 's.publicuri';
-		$query = $this->db->getQueryBuilder();
-		$result = $query->select($fields)
-			->from('dav_shares', 's')
-			->join('s', 'calendars', 'a', $query->expr()->eq('s.resourceid', 'a.id'))
-			->where($query->expr()->in('s.access', $query->createNamedParameter(self::ACCESS_PUBLIC)))
-			->andWhere($query->expr()->eq('s.type', $query->createNamedParameter('calendar')))
-			->andWhere($query->expr()->eq('s.publicuri', $query->createNamedParameter($uri)))
-			->executeQuery();
-
-		$row = $result->fetch();
-
-		$result->closeCursor();
-
-		if ($row === false) {
-			throw new NotFound('Node with name \'' . $uri . '\' could not be found');
-		}
-
-		$row['principaluri'] = (string) $row['principaluri'];
-		[, $name] = Uri\split($row['principaluri']);
-		$row['displayname'] = $row['displayname'] . ' ' . "($name)";
-		$components = [];
-		if ($row['components']) {
-			$components = explode(',', $row['components']);
-		}
-		$calendar = [
-			'id' => $row['id'],
-			'uri' => $row['publicuri'],
-			'principaluri' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
-			'{' . Plugin::NS_CALENDARSERVER . '}getctag' => 'http://sabre.io/ns/sync/' . ($row['synctoken']?$row['synctoken']:'0'),
-			'{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
-			'{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet($components),
-			'{' . Plugin::NS_CALDAV . '}schedule-calendar-transp' => new ScheduleCalendarTransp($row['transparent']?'transparent':'opaque'),
-			'{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}owner-principal' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
-			'{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}read-only' => (int)$row['access'] === Backend::ACCESS_READ,
-			'{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}public' => (int)$row['access'] === self::ACCESS_PUBLIC,
-		];
-
-		$calendar = $this->rowToCalendar($row, $calendar);
-		$calendar = $this->addOwnerPrincipalToCalendar($calendar);
-		$calendar = $this->addResourceTypeToCalendar($row, $calendar);
-
-		return $calendar;
-	}
-
-	/**
-	 * @param string $principal
-	 * @param string $uri
-	 * @return array|null
-	 */
-	public function getCalendarByUri($principal, $uri) {
-		$fields = array_column($this->propertyMap, 0);
-		$fields[] = 'id';
-		$fields[] = 'uri';
-		$fields[] = 'synctoken';
-		$fields[] = 'components';
-		$fields[] = 'principaluri';
-		$fields[] = 'transparent';
-
-		// Making fields a comma-delimited list
-		$query = $this->db->getQueryBuilder();
-		$query->select($fields)->from('calendars')
-			->where($query->expr()->eq('uri', $query->createNamedParameter($uri)))
-			->andWhere($query->expr()->eq('principaluri', $query->createNamedParameter($principal)))
-			->setMaxResults(1);
-		$stmt = $query->executeQuery();
-
-		$row = $stmt->fetch();
-		$stmt->closeCursor();
-		if ($row === false) {
-			return null;
-		}
-
-		$row['principaluri'] = (string) $row['principaluri'];
-		$components = [];
-		if ($row['components']) {
-			$components = explode(',', $row['components']);
-		}
-
-		$calendar = [
-			'id' => $row['id'],
-			'uri' => $row['uri'],
-			'principaluri' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
-			'{' . Plugin::NS_CALENDARSERVER . '}getctag' => 'http://sabre.io/ns/sync/' . ($row['synctoken']?$row['synctoken']:'0'),
-			'{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
-			'{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet($components),
-			'{' . Plugin::NS_CALDAV . '}schedule-calendar-transp' => new ScheduleCalendarTransp($row['transparent']?'transparent':'opaque'),
-		];
-
-		$calendar = $this->rowToCalendar($row, $calendar);
-		$calendar = $this->addOwnerPrincipalToCalendar($calendar);
-		$calendar = $this->addResourceTypeToCalendar($row, $calendar);
-
-		return $calendar;
-	}
-
-	/**
-	 * @return array{id: int, uri: string, '{http://calendarserver.org/ns/}getctag': string, '{http://sabredav.org/ns}sync-token': int, '{urn:ietf:params:xml:ns:caldav}supported-calendar-component-set': SupportedCalendarComponentSet, '{urn:ietf:params:xml:ns:caldav}schedule-calendar-transp': ScheduleCalendarTransp, '{urn:ietf:params:xml:ns:caldav}calendar-timezone': ?string }|null
-	 */
-	public function getCalendarById(int $calendarId): ?array {
-		$fields = array_column($this->propertyMap, 0);
-		$fields[] = 'id';
-		$fields[] = 'uri';
-		$fields[] = 'synctoken';
-		$fields[] = 'components';
-		$fields[] = 'principaluri';
-		$fields[] = 'transparent';
-
-		// Making fields a comma-delimited list
-		$query = $this->db->getQueryBuilder();
-		$query->select($fields)->from('calendars')
-			->where($query->expr()->eq('id', $query->createNamedParameter($calendarId)))
-			->setMaxResults(1);
-		$stmt = $query->executeQuery();
-
-		$row = $stmt->fetch();
-		$stmt->closeCursor();
-		if ($row === false) {
-			return null;
-		}
-
-		$row['principaluri'] = (string) $row['principaluri'];
-		$components = [];
-		if ($row['components']) {
-			$components = explode(',', $row['components']);
-		}
-
-		$calendar = [
-			'id' => $row['id'],
-			'uri' => $row['uri'],
-			'principaluri' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
-			'{' . Plugin::NS_CALENDARSERVER . '}getctag' => 'http://sabre.io/ns/sync/' . ($row['synctoken']?$row['synctoken']:'0'),
-			'{http://sabredav.org/ns}sync-token' => $row['synctoken'] ?? 0,
-			'{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet($components),
-			'{' . Plugin::NS_CALDAV . '}schedule-calendar-transp' => new ScheduleCalendarTransp($row['transparent']?'transparent':'opaque'),
-		];
-
-		$calendar = $this->rowToCalendar($row, $calendar);
-		$calendar = $this->addOwnerPrincipalToCalendar($calendar);
-		$calendar = $this->addResourceTypeToCalendar($row, $calendar);
-
-		return $calendar;
-	}
-
-	/**
-	 * @param $subscriptionId
-	 */
-	public function getSubscriptionById($subscriptionId) {
-		$fields = array_column($this->subscriptionPropertyMap, 0);
-		$fields[] = 'id';
-		$fields[] = 'uri';
-		$fields[] = 'source';
-		$fields[] = 'synctoken';
-		$fields[] = 'principaluri';
-		$fields[] = 'lastmodified';
-
-		$query = $this->db->getQueryBuilder();
-		$query->select($fields)
-			->from('calendarsubscriptions')
-			->where($query->expr()->eq('id', $query->createNamedParameter($subscriptionId)))
-			->orderBy('calendarorder', 'asc');
-		$stmt = $query->executeQuery();
-
-		$row = $stmt->fetch();
-		$stmt->closeCursor();
-		if ($row === false) {
-			return null;
-		}
-
-		$row['principaluri'] = (string) $row['principaluri'];
-		$subscription = [
-			'id' => $row['id'],
-			'uri' => $row['uri'],
-			'principaluri' => $row['principaluri'],
-			'source' => $row['source'],
-			'lastmodified' => $row['lastmodified'],
-			'{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet(['VTODO', 'VEVENT']),
-			'{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
-		];
-
-		return $this->rowToSubscription($row, $subscription);
-	}
-
-	/**
-	 * Creates a new calendar for a principal.
-	 *
-	 * If the creation was a success, an id must be returned that can be used to reference
-	 * this calendar in other methods, such as updateCalendar.
-	 *
-	 * @param string $principalUri
-	 * @param string $calendarUri
-	 * @param array $properties
-	 * @return int
-	 *
-	 * @throws CalendarException
-	 */
-	public function createCalendar($principalUri, $calendarUri, array $properties) {
-		if (strlen($calendarUri) > 255) {
-			throw new CalendarException('URI too long. Calendar not created');
-		}
-
-		$values = [
-			'principaluri' => $this->convertPrincipal($principalUri, true),
-			'uri' => $calendarUri,
-			'synctoken' => 1,
-			'transparent' => 0,
-			'components' => 'VEVENT,VTODO',
-			'displayname' => $calendarUri
-		];
-
-		// Default value
-		$sccs = '{urn:ietf:params:xml:ns:caldav}supported-calendar-component-set';
-		if (isset($properties[$sccs])) {
-			if (!($properties[$sccs] instanceof SupportedCalendarComponentSet)) {
-				throw new DAV\Exception('The ' . $sccs . ' property must be of type: \Sabre\CalDAV\Property\SupportedCalendarComponentSet');
-			}
-			$values['components'] = implode(',', $properties[$sccs]->getValue());
-		} elseif (isset($properties['components'])) {
-			// Allow to provide components internally without having
-			// to create a SupportedCalendarComponentSet object
-			$values['components'] = $properties['components'];
-		}
-
-		$transp = '{' . Plugin::NS_CALDAV . '}schedule-calendar-transp';
-		if (isset($properties[$transp])) {
-			$values['transparent'] = (int) ($properties[$transp]->getValue() === 'transparent');
-		}
-
-		foreach ($this->propertyMap as $xmlName => [$dbName, $type]) {
-			if (isset($properties[$xmlName])) {
-				$values[$dbName] = $properties[$xmlName];
-			}
-		}
-
-		[$calendarId, $calendarData] = $this->atomic(function () use ($values) {
-			$query = $this->db->getQueryBuilder();
-			$query->insert('calendars');
-			foreach ($values as $column => $value) {
-				$query->setValue($column, $query->createNamedParameter($value));
-			}
-			$query->executeStatement();
-			$calendarId = $query->getLastInsertId();
-
-			$calendarData = $this->getCalendarById($calendarId);
-			return [$calendarId, $calendarData];
-		}, $this->db);
-
-		$this->dispatcher->dispatchTyped(new CalendarCreatedEvent((int)$calendarId, $calendarData));
-
-		return $calendarId;
-	}
-
-	/**
-	 * Updates properties for a calendar.
-	 *
-	 * The list of mutations is stored in a Sabre\DAV\PropPatch object.
-	 * To do the actual updates, you must tell this object which properties
-	 * you're going to process with the handle() method.
-	 *
-	 * Calling the handle method is like telling the PropPatch object "I
-	 * promise I can handle updating this property".
-	 *
-	 * Read the PropPatch documentation for more info and examples.
-	 *
-	 * @param mixed $calendarId
-	 * @param PropPatch $propPatch
-	 * @return void
-	 */
-	public function updateCalendar($calendarId, PropPatch $propPatch) {
-		$supportedProperties = array_keys($this->propertyMap);
-		$supportedProperties[] = '{' . Plugin::NS_CALDAV . '}schedule-calendar-transp';
-
-		$propPatch->handle($supportedProperties, function ($mutations) use ($calendarId) {
-			$newValues = [];
-			foreach ($mutations as $propertyName => $propertyValue) {
-				switch ($propertyName) {
-					case '{' . Plugin::NS_CALDAV . '}schedule-calendar-transp':
-						$fieldName = 'transparent';
-						$newValues[$fieldName] = (int) ($propertyValue->getValue() === 'transparent');
-						break;
-					default:
-						$fieldName = $this->propertyMap[$propertyName][0];
-						$newValues[$fieldName] = $propertyValue;
-						break;
-				}
-			}
-			$query = $this->db->getQueryBuilder();
-			$query->update('calendars');
-			foreach ($newValues as $fieldName => $value) {
-				$query->set($fieldName, $query->createNamedParameter($value));
-			}
-			$query->where($query->expr()->eq('id', $query->createNamedParameter($calendarId)));
-			$query->executeStatement();
-
-			$this->addChange($calendarId, "", 2);
-
-			$calendarData = $this->getCalendarById($calendarId);
-			$shares = $this->getShares($calendarId);
-			$this->dispatcher->dispatchTyped(new CalendarUpdatedEvent($calendarId, $calendarData, $shares, $mutations));
-
-			return true;
-		});
-	}
-
-	/**
-	 * Delete a calendar and all it's objects
-	 *
-	 * @param mixed $calendarId
-	 * @return void
-	 */
-	public function deleteCalendar($calendarId, bool $forceDeletePermanently = false) {
-		// The calendar is deleted right away if this is either enforced by the caller
-		// or the special contacts birthday calendar or when the preference of an empty
-		// retention (0 seconds) is set, which signals a disabled trashbin.
-		$calendarData = $this->getCalendarById($calendarId);
-		$isBirthdayCalendar = isset($calendarData['uri']) && $calendarData['uri'] === BirthdayService::BIRTHDAY_CALENDAR_URI;
-		$trashbinDisabled = $this->config->getAppValue(Application::APP_ID, RetentionService::RETENTION_CONFIG_KEY) === '0';
-		if ($forceDeletePermanently || $isBirthdayCalendar || $trashbinDisabled) {
-			$calendarData = $this->getCalendarById($calendarId);
-			$shares = $this->getShares($calendarId);
-
-			$qbDeleteCalendarObjectProps = $this->db->getQueryBuilder();
-			$qbDeleteCalendarObjectProps->delete($this->dbObjectPropertiesTable)
-				->where($qbDeleteCalendarObjectProps->expr()->eq('calendarid', $qbDeleteCalendarObjectProps->createNamedParameter($calendarId)))
-				->andWhere($qbDeleteCalendarObjectProps->expr()->eq('calendartype', $qbDeleteCalendarObjectProps->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)))
-				->executeStatement();
-
-			$qbDeleteCalendarObjects = $this->db->getQueryBuilder();
-			$qbDeleteCalendarObjects->delete('calendarobjects')
-				->where($qbDeleteCalendarObjects->expr()->eq('calendarid', $qbDeleteCalendarObjects->createNamedParameter($calendarId)))
-				->andWhere($qbDeleteCalendarObjects->expr()->eq('calendartype', $qbDeleteCalendarObjects->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)))
-				->executeStatement();
-
-			$qbDeleteCalendarChanges = $this->db->getQueryBuilder();
-			$qbDeleteCalendarChanges->delete('calendarchanges')
-				->where($qbDeleteCalendarChanges->expr()->eq('calendarid', $qbDeleteCalendarChanges->createNamedParameter($calendarId)))
-				->andWhere($qbDeleteCalendarChanges->expr()->eq('calendartype', $qbDeleteCalendarChanges->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)))
-				->executeStatement();
-
-			$this->calendarSharingBackend->deleteAllShares($calendarId);
-
-			$qbDeleteCalendar = $this->db->getQueryBuilder();
-			$qbDeleteCalendar->delete('calendars')
-				->where($qbDeleteCalendar->expr()->eq('id', $qbDeleteCalendar->createNamedParameter($calendarId)))
-				->executeStatement();
-
-			// Only dispatch if we actually deleted anything
-			if ($calendarData) {
-				$this->dispatcher->dispatchTyped(new CalendarDeletedEvent($calendarId, $calendarData, $shares));
-			}
-		} else {
-			$qbMarkCalendarDeleted = $this->db->getQueryBuilder();
-			$qbMarkCalendarDeleted->update('calendars')
-				->set('deleted_at', $qbMarkCalendarDeleted->createNamedParameter(time()))
-				->where($qbMarkCalendarDeleted->expr()->eq('id', $qbMarkCalendarDeleted->createNamedParameter($calendarId)))
-				->executeStatement();
-
-			$calendarData = $this->getCalendarById($calendarId);
-			$shares = $this->getShares($calendarId);
-			if ($calendarData) {
-				$this->dispatcher->dispatchTyped(new CalendarMovedToTrashEvent(
-					$calendarId,
-					$calendarData,
-					$shares
-				));
-			}
-		}
-	}
-
-	public function restoreCalendar(int $id): void {
-		$qb = $this->db->getQueryBuilder();
-		$update = $qb->update('calendars')
-			->set('deleted_at', $qb->createNamedParameter(null))
-			->where($qb->expr()->eq('id', $qb->createNamedParameter($id, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT));
-		$update->executeStatement();
-
-		$calendarData = $this->getCalendarById($id);
-		$shares = $this->getShares($id);
-		if ($calendarData === null) {
-			throw new RuntimeException('Calendar data that was just written can\'t be read back. Check your database configuration.');
-		}
-		$this->dispatcher->dispatchTyped(new CalendarRestoredEvent(
-			$id,
-			$calendarData,
-			$shares
-		));
-	}
-
-	/**
-	 * Delete all of an user's shares
-	 *
-	 * @param string $principaluri
-	 * @return void
-	 */
-	public function deleteAllSharesByUser($principaluri) {
-		$this->calendarSharingBackend->deleteAllSharesByUser($principaluri);
-	}
-
-	/**
-	 * Returns all calendar objects within a calendar.
-	 *
-	 * Every item contains an array with the following keys:
-	 *   * calendardata - The iCalendar-compatible calendar data
-	 *   * uri - a unique key which will be used to construct the uri. This can
-	 *     be any arbitrary string, but making sure it ends with '.ics' is a
-	 *     good idea. This is only the basename, or filename, not the full
-	 *     path.
-	 *   * lastmodified - a timestamp of the last modification time
-	 *   * etag - An arbitrary string, surrounded by double-quotes. (e.g.:
-	 *   '"abcdef"')
-	 *   * size - The size of the calendar objects, in bytes.
-	 *   * component - optional, a string containing the type of object, such
-	 *     as 'vevent' or 'vtodo'. If specified, this will be used to populate
-	 *     the Content-Type header.
-	 *
-	 * Note that the etag is optional, but it's highly encouraged to return for
-	 * speed reasons.
-	 *
-	 * The calendardata is also optional. If it's not returned
-	 * 'getCalendarObject' will be called later, which *is* expected to return
-	 * calendardata.
-	 *
-	 * If neither etag or size are specified, the calendardata will be
-	 * used/fetched to determine these numbers. If both are specified the
-	 * amount of times this is needed is reduced by a great degree.
-	 *
-	 * @param mixed $calendarId
-	 * @param int $calendarType
-	 * @return array
-	 */
-	public function getCalendarObjects($calendarId, $calendarType = self::CALENDAR_TYPE_CALENDAR):array {
-		$query = $this->db->getQueryBuilder();
-		$query->select(['id', 'uri', 'lastmodified', 'etag', 'calendarid', 'size', 'componenttype', 'classification'])
-			->from('calendarobjects')
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)))
-			->andWhere($query->expr()->isNull('deleted_at'));
-		$stmt = $query->executeQuery();
-
-		$result = [];
-		foreach ($stmt->fetchAll() as $row) {
-			$result[] = [
-				'id' => $row['id'],
-				'uri' => $row['uri'],
-				'lastmodified' => $row['lastmodified'],
-				'etag' => '"' . $row['etag'] . '"',
-				'calendarid' => $row['calendarid'],
-				'size' => (int)$row['size'],
-				'component' => strtolower($row['componenttype']),
-				'classification' => (int)$row['classification']
-			];
-		}
-		$stmt->closeCursor();
-
-		return $result;
-	}
-
-	public function getDeletedCalendarObjects(int $deletedBefore): array {
-		$query = $this->db->getQueryBuilder();
-		$query->select(['co.id', 'co.uri', 'co.lastmodified', 'co.etag', 'co.calendarid', 'co.calendartype', 'co.size', 'co.componenttype', 'co.classification', 'co.deleted_at'])
-			->from('calendarobjects', 'co')
-			->join('co', 'calendars', 'c', $query->expr()->eq('c.id', 'co.calendarid', IQueryBuilder::PARAM_INT))
-			->where($query->expr()->isNotNull('co.deleted_at'))
-			->andWhere($query->expr()->lt('co.deleted_at', $query->createNamedParameter($deletedBefore)));
-		$stmt = $query->executeQuery();
-
-		$result = [];
-		foreach ($stmt->fetchAll() as $row) {
-			$result[] = [
-				'id' => $row['id'],
-				'uri' => $row['uri'],
-				'lastmodified' => $row['lastmodified'],
-				'etag' => '"' . $row['etag'] . '"',
-				'calendarid' => (int) $row['calendarid'],
-				'calendartype' => (int) $row['calendartype'],
-				'size' => (int) $row['size'],
-				'component' => strtolower($row['componenttype']),
-				'classification' => (int) $row['classification'],
-				'{' . \OCA\DAV\DAV\Sharing\Plugin::NS_NEXTCLOUD . '}deleted-at' => $row['deleted_at'] === null ? $row['deleted_at'] : (int) $row['deleted_at'],
-			];
-		}
-		$stmt->closeCursor();
-
-		return $result;
-	}
-
-	/**
-	 * Return all deleted calendar objects by the given principal that are not
-	 * in deleted calendars.
-	 *
-	 * @param string $principalUri
-	 * @return array
-	 * @throws Exception
-	 */
-	public function getDeletedCalendarObjectsByPrincipal(string $principalUri): array {
-		$query = $this->db->getQueryBuilder();
-		$query->select(['co.id', 'co.uri', 'co.lastmodified', 'co.etag', 'co.calendarid', 'co.size', 'co.componenttype', 'co.classification', 'co.deleted_at'])
-			->selectAlias('c.uri', 'calendaruri')
-			->from('calendarobjects', 'co')
-			->join('co', 'calendars', 'c', $query->expr()->eq('c.id', 'co.calendarid', IQueryBuilder::PARAM_INT))
-			->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)))
-			->andWhere($query->expr()->isNotNull('co.deleted_at'))
-			->andWhere($query->expr()->isNull('c.deleted_at'));
-		$stmt = $query->executeQuery();
-
-		$result = [];
-		while ($row = $stmt->fetch()) {
-			$result[] = [
-				'id' => $row['id'],
-				'uri' => $row['uri'],
-				'lastmodified' => $row['lastmodified'],
-				'etag' => '"' . $row['etag'] . '"',
-				'calendarid' => $row['calendarid'],
-				'calendaruri' => $row['calendaruri'],
-				'size' => (int)$row['size'],
-				'component' => strtolower($row['componenttype']),
-				'classification' => (int)$row['classification'],
-				'{' . \OCA\DAV\DAV\Sharing\Plugin::NS_NEXTCLOUD . '}deleted-at' => $row['deleted_at'] === null ? $row['deleted_at'] : (int) $row['deleted_at'],
-			];
-		}
-		$stmt->closeCursor();
-
-		return $result;
-	}
-
-	/**
-	 * Returns information from a single calendar object, based on it's object
-	 * uri.
-	 *
-	 * The object uri is only the basename, or filename and not a full path.
-	 *
-	 * The returned array must have the same keys as getCalendarObjects. The
-	 * 'calendardata' object is required here though, while it's not required
-	 * for getCalendarObjects.
-	 *
-	 * This method must return null if the object did not exist.
-	 *
-	 * @param mixed $calendarId
-	 * @param string $objectUri
-	 * @param int $calendarType
-	 * @return array|null
-	 */
-	public function getCalendarObject($calendarId, $objectUri, int $calendarType = self::CALENDAR_TYPE_CALENDAR) {
-		$query = $this->db->getQueryBuilder();
-		$query->select(['id', 'uri', 'lastmodified', 'etag', 'calendarid', 'size', 'calendardata', 'componenttype', 'classification', 'deleted_at'])
-			->from('calendarobjects')
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)))
-			->andWhere($query->expr()->eq('uri', $query->createNamedParameter($objectUri)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)));
-		$stmt = $query->executeQuery();
-		$row = $stmt->fetch();
-		$stmt->closeCursor();
-
-		if (!$row) {
-			return null;
-		}
-
-		return [
-			'id' => $row['id'],
-			'uri' => $row['uri'],
-			'lastmodified' => $row['lastmodified'],
-			'etag' => '"' . $row['etag'] . '"',
-			'calendarid' => $row['calendarid'],
-			'size' => (int)$row['size'],
-			'calendardata' => $this->readBlob($row['calendardata']),
-			'component' => strtolower($row['componenttype']),
-			'classification' => (int)$row['classification'],
-			'{' . \OCA\DAV\DAV\Sharing\Plugin::NS_NEXTCLOUD . '}deleted-at' => $row['deleted_at'] === null ? $row['deleted_at'] : (int) $row['deleted_at'],
-		];
-	}
-
-	/**
-	 * Returns a list of calendar objects.
-	 *
-	 * This method should work identical to getCalendarObject, but instead
-	 * return all the calendar objects in the list as an array.
-	 *
-	 * If the backend supports this, it may allow for some speed-ups.
-	 *
-	 * @param mixed $calendarId
-	 * @param string[] $uris
-	 * @param int $calendarType
-	 * @return array
-	 */
-	public function getMultipleCalendarObjects($calendarId, array $uris, $calendarType = self::CALENDAR_TYPE_CALENDAR):array {
-		if (empty($uris)) {
-			return [];
-		}
-
-		$chunks = array_chunk($uris, 100);
-		$objects = [];
-
-		$query = $this->db->getQueryBuilder();
-		$query->select(['id', 'uri', 'lastmodified', 'etag', 'calendarid', 'size', 'calendardata', 'componenttype', 'classification'])
-			->from('calendarobjects')
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)))
-			->andWhere($query->expr()->in('uri', $query->createParameter('uri')))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)))
-			->andWhere($query->expr()->isNull('deleted_at'));
-
-		foreach ($chunks as $uris) {
-			$query->setParameter('uri', $uris, IQueryBuilder::PARAM_STR_ARRAY);
-			$result = $query->executeQuery();
-
-			while ($row = $result->fetch()) {
-				$objects[] = [
-					'id' => $row['id'],
-					'uri' => $row['uri'],
-					'lastmodified' => $row['lastmodified'],
-					'etag' => '"' . $row['etag'] . '"',
-					'calendarid' => $row['calendarid'],
-					'size' => (int)$row['size'],
-					'calendardata' => $this->readBlob($row['calendardata']),
-					'component' => strtolower($row['componenttype']),
-					'classification' => (int)$row['classification']
-				];
-			}
-			$result->closeCursor();
-		}
-
-		return $objects;
-	}
-
-	/**
-	 * Creates a new calendar object.
-	 *
-	 * The object uri is only the basename, or filename and not a full path.
-	 *
-	 * It is possible return an etag from this function, which will be used in
-	 * the response to this PUT request. Note that the ETag must be surrounded
-	 * by double-quotes.
-	 *
-	 * However, you should only really return this ETag if you don't mangle the
-	 * calendar-data. If the result of a subsequent GET to this object is not
-	 * the exact same as this request body, you should omit the ETag.
-	 *
-	 * @param mixed $calendarId
-	 * @param string $objectUri
-	 * @param string $calendarData
-	 * @param int $calendarType
-	 * @return string
-	 */
-	public function createCalendarObject($calendarId, $objectUri, $calendarData, $calendarType = self::CALENDAR_TYPE_CALENDAR) {
-		$extraData = $this->getDenormalizedData($calendarData);
-
-		// Try to detect duplicates
-		$qb = $this->db->getQueryBuilder();
-		$qb->select($qb->func()->count('*'))
-			->from('calendarobjects')
-			->where($qb->expr()->eq('calendarid', $qb->createNamedParameter($calendarId)))
-			->andWhere($qb->expr()->eq('uid', $qb->createNamedParameter($extraData['uid'])))
-			->andWhere($qb->expr()->eq('calendartype', $qb->createNamedParameter($calendarType)))
-			->andWhere($qb->expr()->isNull('deleted_at'));
-		$result = $qb->executeQuery();
-		$count = (int) $result->fetchOne();
-		$result->closeCursor();
-
-		if ($count !== 0) {
-			throw new BadRequest('Calendar object with uid already exists in this calendar collection.');
-		}
-		// For a more specific error message we also try to explicitly look up the UID but as a deleted entry
-		$qbDel = $this->db->getQueryBuilder();
-		$qbDel->select($qb->func()->count('*'))
-			->from('calendarobjects')
-			->where($qbDel->expr()->eq('calendarid', $qbDel->createNamedParameter($calendarId)))
-			->andWhere($qbDel->expr()->eq('uid', $qbDel->createNamedParameter($extraData['uid'])))
-			->andWhere($qbDel->expr()->eq('calendartype', $qbDel->createNamedParameter($calendarType)))
-			->andWhere($qbDel->expr()->isNotNull('deleted_at'));
-		$result = $qbDel->executeQuery();
-		$count = (int) $result->fetchOne();
-		$result->closeCursor();
-		if ($count !== 0) {
-			throw new BadRequest('Deleted calendar object with uid already exists in this calendar collection.');
-		}
-
-		$query = $this->db->getQueryBuilder();
-		$query->insert('calendarobjects')
-			->values([
-				'calendarid' => $query->createNamedParameter($calendarId),
-				'uri' => $query->createNamedParameter($objectUri),
-				'calendardata' => $query->createNamedParameter($calendarData, IQueryBuilder::PARAM_LOB),
-				'lastmodified' => $query->createNamedParameter(time()),
-				'etag' => $query->createNamedParameter($extraData['etag']),
-				'size' => $query->createNamedParameter($extraData['size']),
-				'componenttype' => $query->createNamedParameter($extraData['componentType']),
-				'firstoccurence' => $query->createNamedParameter($extraData['firstOccurence']),
-				'lastoccurence' => $query->createNamedParameter($extraData['lastOccurence']),
-				'classification' => $query->createNamedParameter($extraData['classification']),
-				'uid' => $query->createNamedParameter($extraData['uid']),
-				'calendartype' => $query->createNamedParameter($calendarType),
-			])
-			->executeStatement();
-
-		$this->updateProperties($calendarId, $objectUri, $calendarData, $calendarType);
-		$this->addChange($calendarId, $objectUri, 1, $calendarType);
-
-		$objectRow = $this->getCalendarObject($calendarId, $objectUri, $calendarType);
-		assert($objectRow !== null);
-
-		if ($calendarType === self::CALENDAR_TYPE_CALENDAR) {
-			$calendarRow = $this->getCalendarById($calendarId);
-			$shares = $this->getShares($calendarId);
-
-			$this->dispatcher->dispatchTyped(new CalendarObjectCreatedEvent($calendarId, $calendarRow, $shares, $objectRow));
-		} else {
-			$subscriptionRow = $this->getSubscriptionById($calendarId);
-
-			$this->dispatcher->dispatchTyped(new CachedCalendarObjectCreatedEvent($calendarId, $subscriptionRow, [], $objectRow));
-		}
-
-		return '"' . $extraData['etag'] . '"';
-	}
-
-	/**
-	 * Updates an existing calendarobject, based on it's uri.
-	 *
-	 * The object uri is only the basename, or filename and not a full path.
-	 *
-	 * It is possible return an etag from this function, which will be used in
-	 * the response to this PUT request. Note that the ETag must be surrounded
-	 * by double-quotes.
-	 *
-	 * However, you should only really return this ETag if you don't mangle the
-	 * calendar-data. If the result of a subsequent GET to this object is not
-	 * the exact same as this request body, you should omit the ETag.
-	 *
-	 * @param mixed $calendarId
-	 * @param string $objectUri
-	 * @param string $calendarData
-	 * @param int $calendarType
-	 * @return string
-	 */
-	public function updateCalendarObject($calendarId, $objectUri, $calendarData, $calendarType = self::CALENDAR_TYPE_CALENDAR) {
-		$extraData = $this->getDenormalizedData($calendarData);
-		$query = $this->db->getQueryBuilder();
-		$query->update('calendarobjects')
-				->set('calendardata', $query->createNamedParameter($calendarData, IQueryBuilder::PARAM_LOB))
-				->set('lastmodified', $query->createNamedParameter(time()))
-				->set('etag', $query->createNamedParameter($extraData['etag']))
-				->set('size', $query->createNamedParameter($extraData['size']))
-				->set('componenttype', $query->createNamedParameter($extraData['componentType']))
-				->set('firstoccurence', $query->createNamedParameter($extraData['firstOccurence']))
-				->set('lastoccurence', $query->createNamedParameter($extraData['lastOccurence']))
-				->set('classification', $query->createNamedParameter($extraData['classification']))
-				->set('uid', $query->createNamedParameter($extraData['uid']))
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)))
-			->andWhere($query->expr()->eq('uri', $query->createNamedParameter($objectUri)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)))
-			->executeStatement();
-
-		$this->updateProperties($calendarId, $objectUri, $calendarData, $calendarType);
-		$this->addChange($calendarId, $objectUri, 2, $calendarType);
-
-		$objectRow = $this->getCalendarObject($calendarId, $objectUri, $calendarType);
-		if (is_array($objectRow)) {
-			if ($calendarType === self::CALENDAR_TYPE_CALENDAR) {
-				$calendarRow = $this->getCalendarById($calendarId);
-				$shares = $this->getShares($calendarId);
-
-				$this->dispatcher->dispatchTyped(new CalendarObjectUpdatedEvent($calendarId, $calendarRow, $shares, $objectRow));
-			} else {
-				$subscriptionRow = $this->getSubscriptionById($calendarId);
-
-				$this->dispatcher->dispatchTyped(new CachedCalendarObjectUpdatedEvent($calendarId, $subscriptionRow, [], $objectRow));
-			}
-		}
-
-		return '"' . $extraData['etag'] . '"';
-	}
-
-	/**
-	 * Moves a calendar object from calendar to calendar.
-	 *
-	 * @param int $sourceCalendarId
-	 * @param int $targetCalendarId
-	 * @param int $objectId
-	 * @param string $oldPrincipalUri
-	 * @param string $newPrincipalUri
-	 * @param int $calendarType
-	 * @return bool
-	 * @throws Exception
-	 */
-	public function moveCalendarObject(int $sourceCalendarId, int $targetCalendarId, int $objectId, string $oldPrincipalUri, string $newPrincipalUri, int $calendarType = self::CALENDAR_TYPE_CALENDAR): bool {
-		$object = $this->getCalendarObjectById($oldPrincipalUri, $objectId);
-		if (empty($object)) {
-			return false;
-		}
-
-		$query = $this->db->getQueryBuilder();
-		$query->update('calendarobjects')
-			->set('calendarid', $query->createNamedParameter($targetCalendarId, IQueryBuilder::PARAM_INT))
-			->where($query->expr()->eq('id', $query->createNamedParameter($objectId, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT))
-			->executeStatement();
-
-		$this->purgeProperties($sourceCalendarId, $objectId);
-		$this->updateProperties($targetCalendarId, $object['uri'], $object['calendardata'], $calendarType);
-
-		$this->addChange($sourceCalendarId, $object['uri'], 1, $calendarType);
-		$this->addChange($targetCalendarId, $object['uri'], 3, $calendarType);
-
-		$object = $this->getCalendarObjectById($newPrincipalUri, $objectId);
-		// Calendar Object wasn't found - possibly because it was deleted in the meantime by a different client
-		if (empty($object)) {
-			return false;
-		}
-
-		$targetCalendarRow = $this->getCalendarById($targetCalendarId);
-		// the calendar this event is being moved to does not exist any longer
-		if (empty($targetCalendarRow)) {
-			return false;
-		}
-
-		if ($calendarType === self::CALENDAR_TYPE_CALENDAR) {
-			$sourceShares = $this->getShares($sourceCalendarId);
-			$targetShares = $this->getShares($targetCalendarId);
-			$sourceCalendarRow = $this->getCalendarById($sourceCalendarId);
-			$this->dispatcher->dispatchTyped(new CalendarObjectMovedEvent($sourceCalendarId, $sourceCalendarRow, $targetCalendarId, $targetCalendarRow, $sourceShares, $targetShares, $object));
-		}
-		return true;
-	}
-
-
-	/**
-	 * @param int $calendarObjectId
-	 * @param int $classification
-	 */
-	public function setClassification($calendarObjectId, $classification) {
-		if (!in_array($classification, [
-			self::CLASSIFICATION_PUBLIC, self::CLASSIFICATION_PRIVATE, self::CLASSIFICATION_CONFIDENTIAL
-		])) {
-			throw new \InvalidArgumentException();
-		}
-		$query = $this->db->getQueryBuilder();
-		$query->update('calendarobjects')
-			->set('classification', $query->createNamedParameter($classification))
-			->where($query->expr()->eq('id', $query->createNamedParameter($calendarObjectId)))
-			->executeStatement();
-	}
-
-	/**
-	 * Deletes an existing calendar object.
-	 *
-	 * The object uri is only the basename, or filename and not a full path.
-	 *
-	 * @param mixed $calendarId
-	 * @param string $objectUri
-	 * @param int $calendarType
-	 * @param bool $forceDeletePermanently
-	 * @return void
-	 */
-	public function deleteCalendarObject($calendarId, $objectUri, $calendarType = self::CALENDAR_TYPE_CALENDAR, bool $forceDeletePermanently = false) {
-		$data = $this->getCalendarObject($calendarId, $objectUri, $calendarType);
-
-		if ($data === null) {
-			// Nothing to delete
-			return;
-		}
-
-		if ($forceDeletePermanently || $this->config->getAppValue(Application::APP_ID, RetentionService::RETENTION_CONFIG_KEY) === '0') {
-			$stmt = $this->db->prepare('DELETE FROM `*PREFIX*calendarobjects` WHERE `calendarid` = ? AND `uri` = ? AND `calendartype` = ?');
-			$stmt->execute([$calendarId, $objectUri, $calendarType]);
-
-			$this->purgeProperties($calendarId, $data['id']);
-
-			if ($calendarType === self::CALENDAR_TYPE_CALENDAR) {
-				$calendarRow = $this->getCalendarById($calendarId);
-				$shares = $this->getShares($calendarId);
-
-				$this->dispatcher->dispatchTyped(new CalendarObjectDeletedEvent($calendarId, $calendarRow, $shares, $data));
-			} else {
-				$subscriptionRow = $this->getSubscriptionById($calendarId);
-
-				$this->dispatcher->dispatchTyped(new CachedCalendarObjectDeletedEvent($calendarId, $subscriptionRow, [], $data));
-			}
-		} else {
-			$pathInfo = pathinfo($data['uri']);
-			if (!empty($pathInfo['extension'])) {
-				// Append a suffix to "free" the old URI for recreation
-				$newUri = sprintf(
-					"%s-deleted.%s",
-					$pathInfo['filename'],
-					$pathInfo['extension']
-				);
-			} else {
-				$newUri = sprintf(
-					"%s-deleted",
-					$pathInfo['filename']
-				);
-			}
-
-			// Try to detect conflicts before the DB does
-			// As unlikely as it seems, this can happen when the user imports, then deletes, imports and deletes again
-			$newObject = $this->getCalendarObject($calendarId, $newUri, $calendarType);
-			if ($newObject !== null) {
-				throw new Forbidden("A calendar object with URI $newUri already exists in calendar $calendarId, therefore this object can't be moved into the trashbin");
-			}
-
-			$qb = $this->db->getQueryBuilder();
-			$markObjectDeletedQuery = $qb->update('calendarobjects')
-				->set('deleted_at', $qb->createNamedParameter(time(), IQueryBuilder::PARAM_INT))
-				->set('uri', $qb->createNamedParameter($newUri))
-				->where(
-					$qb->expr()->eq('calendarid', $qb->createNamedParameter($calendarId)),
-					$qb->expr()->eq('calendartype', $qb->createNamedParameter($calendarType, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT),
-					$qb->expr()->eq('uri', $qb->createNamedParameter($objectUri))
-				);
-			$markObjectDeletedQuery->executeStatement();
-
-			$calendarData = $this->getCalendarById($calendarId);
-			if ($calendarData !== null) {
-				$this->dispatcher->dispatchTyped(
-					new CalendarObjectMovedToTrashEvent(
-						$calendarId,
-						$calendarData,
-						$this->getShares($calendarId),
-						$data
-					)
-				);
-			}
-		}
-
-		$this->addChange($calendarId, $objectUri, 3, $calendarType);
-	}
-
-	/**
-	 * @param mixed $objectData
-	 *
-	 * @throws Forbidden
-	 */
-	public function restoreCalendarObject(array $objectData): void {
-		$id = (int) $objectData['id'];
-		$restoreUri = str_replace("-deleted.ics", ".ics", $objectData['uri']);
-		$targetObject = $this->getCalendarObject(
-			$objectData['calendarid'],
-			$restoreUri
-		);
-		if ($targetObject !== null) {
-			throw new Forbidden("Can not restore calendar $id because a calendar object with the URI $restoreUri already exists");
-		}
-
-		$qb = $this->db->getQueryBuilder();
-		$update = $qb->update('calendarobjects')
-			->set('uri', $qb->createNamedParameter($restoreUri))
-			->set('deleted_at', $qb->createNamedParameter(null))
-			->where($qb->expr()->eq('id', $qb->createNamedParameter($id, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT));
-		$update->executeStatement();
-
-		// Make sure this change is tracked in the changes table
-		$qb2 = $this->db->getQueryBuilder();
-		$selectObject = $qb2->select('calendardata', 'uri', 'calendarid', 'calendartype')
-			->selectAlias('componenttype', 'component')
-			->from('calendarobjects')
-			->where($qb2->expr()->eq('id', $qb2->createNamedParameter($id, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT));
-		$result = $selectObject->executeQuery();
-		$row = $result->fetch();
-		$result->closeCursor();
-		if ($row === false) {
-			// Welp, this should possibly not have happened, but let's ignore
-			return;
-		}
-		$this->addChange($row['calendarid'], $row['uri'], 1, (int) $row['calendartype']);
-
-		$calendarRow = $this->getCalendarById((int) $row['calendarid']);
-		if ($calendarRow === null) {
-			throw new RuntimeException('Calendar object data that was just written can\'t be read back. Check your database configuration.');
-		}
-		$this->dispatcher->dispatchTyped(
-			new CalendarObjectRestoredEvent(
-				(int) $objectData['calendarid'],
-				$calendarRow,
-				$this->getShares((int) $row['calendarid']),
-				$row
-			)
-		);
-	}
-
-	/**
-	 * Performs a calendar-query on the contents of this calendar.
-	 *
-	 * The calendar-query is defined in RFC4791 : CalDAV. Using the
-	 * calendar-query it is possible for a client to request a specific set of
-	 * object, based on contents of iCalendar properties, date-ranges and
-	 * iCalendar component types (VTODO, VEVENT).
-	 *
-	 * This method should just return a list of (relative) urls that match this
-	 * query.
-	 *
-	 * The list of filters are specified as an array. The exact array is
-	 * documented by Sabre\CalDAV\CalendarQueryParser.
-	 *
-	 * Note that it is extremely likely that getCalendarObject for every path
-	 * returned from this method will be called almost immediately after. You
-	 * may want to anticipate this to speed up these requests.
-	 *
-	 * This method provides a default implementation, which parses *all* the
-	 * iCalendar objects in the specified calendar.
-	 *
-	 * This default may well be good enough for personal use, and calendars
-	 * that aren't very large. But if you anticipate high usage, big calendars
-	 * or high loads, you are strongly advised to optimize certain paths.
-	 *
-	 * The best way to do so is override this method and to optimize
-	 * specifically for 'common filters'.
-	 *
-	 * Requests that are extremely common are:
-	 *   * requests for just VEVENTS
-	 *   * requests for just VTODO
-	 *   * requests with a time-range-filter on either VEVENT or VTODO.
-	 *
-	 * ..and combinations of these requests. It may not be worth it to try to
-	 * handle every possible situation and just rely on the (relatively
-	 * easy to use) CalendarQueryValidator to handle the rest.
-	 *
-	 * Note that especially time-range-filters may be difficult to parse. A
-	 * time-range filter specified on a VEVENT must for instance also handle
-	 * recurrence rules correctly.
-	 * A good example of how to interpret all these filters can also simply
-	 * be found in Sabre\CalDAV\CalendarQueryFilter. This class is as correct
-	 * as possible, so it gives you a good idea on what type of stuff you need
-	 * to think of.
-	 *
-	 * @param mixed $calendarId
-	 * @param array $filters
-	 * @param int $calendarType
-	 * @return array
-	 */
-	public function calendarQuery($calendarId, array $filters, $calendarType = self::CALENDAR_TYPE_CALENDAR):array {
-		$componentType = null;
-		$requirePostFilter = true;
-		$timeRange = null;
-
-		// if no filters were specified, we don't need to filter after a query
-		if (!$filters['prop-filters'] && !$filters['comp-filters']) {
-			$requirePostFilter = false;
-		}
-
-		// Figuring out if there's a component filter
-		if (count($filters['comp-filters']) > 0 && !$filters['comp-filters'][0]['is-not-defined']) {
-			$componentType = $filters['comp-filters'][0]['name'];
-
-			// Checking if we need post-filters
-			if (!$filters['prop-filters'] && !$filters['comp-filters'][0]['comp-filters'] && !$filters['comp-filters'][0]['time-range'] && !$filters['comp-filters'][0]['prop-filters']) {
-				$requirePostFilter = false;
-			}
-			// There was a time-range filter
-			if ($componentType === 'VEVENT' && isset($filters['comp-filters'][0]['time-range']) && is_array($filters['comp-filters'][0]['time-range'])) {
-				$timeRange = $filters['comp-filters'][0]['time-range'];
-
-				// If start time OR the end time is not specified, we can do a
-				// 100% accurate mysql query.
-				if (!$filters['prop-filters'] && !$filters['comp-filters'][0]['comp-filters'] && !$filters['comp-filters'][0]['prop-filters'] && (!$timeRange['start'] || !$timeRange['end'])) {
-					$requirePostFilter = false;
-				}
-			}
-		}
-		$columns = ['uri'];
-		if ($requirePostFilter) {
-			$columns = ['uri', 'calendardata'];
-		}
-		$query = $this->db->getQueryBuilder();
-		$query->select($columns)
-			->from('calendarobjects')
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)))
-			->andWhere($query->expr()->isNull('deleted_at'));
-
-		if ($componentType) {
-			$query->andWhere($query->expr()->eq('componenttype', $query->createNamedParameter($componentType)));
-		}
-
-		if ($timeRange && $timeRange['start']) {
-			$query->andWhere($query->expr()->gt('lastoccurence', $query->createNamedParameter($timeRange['start']->getTimeStamp())));
-		}
-		if ($timeRange && $timeRange['end']) {
-			$query->andWhere($query->expr()->lt('firstoccurence', $query->createNamedParameter($timeRange['end']->getTimeStamp())));
-		}
-
-		$stmt = $query->executeQuery();
-
-		$result = [];
-		while ($row = $stmt->fetch()) {
-			if ($requirePostFilter) {
-				// validateFilterForObject will parse the calendar data
-				// catch parsing errors
-				try {
-					$matches = $this->validateFilterForObject($row, $filters);
-				} catch (ParseException $ex) {
-					$this->logger->error('Caught parsing exception for calendar data. This usually indicates invalid calendar data. calendar-id:'.$calendarId.' uri:'.$row['uri'], [
-						'app' => 'dav',
-						'exception' => $ex,
-					]);
-					continue;
-				} catch (InvalidDataException $ex) {
-					$this->logger->error('Caught invalid data exception for calendar data. This usually indicates invalid calendar data. calendar-id:'.$calendarId.' uri:'.$row['uri'], [
-						'app' => 'dav',
-						'exception' => $ex,
-					]);
-					continue;
-				}
-
-				if (!$matches) {
-					continue;
-				}
-			}
-			$result[] = $row['uri'];
-		}
-
-		return $result;
-	}
-
-	/**
-	 * custom Nextcloud search extension for CalDAV
-	 *
-	 * TODO - this should optionally cover cached calendar objects as well
-	 *
-	 * @param string $principalUri
-	 * @param array $filters
-	 * @param integer|null $limit
-	 * @param integer|null $offset
-	 * @return array
-	 */
-	public function calendarSearch($principalUri, array $filters, $limit = null, $offset = null) {
-		$calendars = $this->getCalendarsForUser($principalUri);
-		$ownCalendars = [];
-		$sharedCalendars = [];
-
-		$uriMapper = [];
-
-		foreach ($calendars as $calendar) {
-			if ($calendar['{http://owncloud.org/ns}owner-principal'] === $principalUri) {
-				$ownCalendars[] = $calendar['id'];
-			} else {
-				$sharedCalendars[] = $calendar['id'];
-			}
-			$uriMapper[$calendar['id']] = $calendar['uri'];
-		}
-		if (count($ownCalendars) === 0 && count($sharedCalendars) === 0) {
-			return [];
-		}
-
-		$query = $this->db->getQueryBuilder();
-		// Calendar id expressions
-		$calendarExpressions = [];
-		foreach ($ownCalendars as $id) {
-			$calendarExpressions[] = $query->expr()->andX(
-				$query->expr()->eq('c.calendarid',
-					$query->createNamedParameter($id)),
-				$query->expr()->eq('c.calendartype',
-					$query->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)));
-		}
-		foreach ($sharedCalendars as $id) {
-			$calendarExpressions[] = $query->expr()->andX(
-				$query->expr()->eq('c.calendarid',
-					$query->createNamedParameter($id)),
-				$query->expr()->eq('c.classification',
-					$query->createNamedParameter(self::CLASSIFICATION_PUBLIC)),
-				$query->expr()->eq('c.calendartype',
-					$query->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)));
-		}
-
-		if (count($calendarExpressions) === 1) {
-			$calExpr = $calendarExpressions[0];
-		} else {
-			$calExpr = call_user_func_array([$query->expr(), 'orX'], $calendarExpressions);
-		}
-
-		// Component expressions
-		$compExpressions = [];
-		foreach ($filters['comps'] as $comp) {
-			$compExpressions[] = $query->expr()
-				->eq('c.componenttype', $query->createNamedParameter($comp));
-		}
-
-		if (count($compExpressions) === 1) {
-			$compExpr = $compExpressions[0];
-		} else {
-			$compExpr = call_user_func_array([$query->expr(), 'orX'], $compExpressions);
-		}
-
-		if (!isset($filters['props'])) {
-			$filters['props'] = [];
-		}
-		if (!isset($filters['params'])) {
-			$filters['params'] = [];
-		}
-
-		$propParamExpressions = [];
-		foreach ($filters['props'] as $prop) {
-			$propParamExpressions[] = $query->expr()->andX(
-				$query->expr()->eq('i.name', $query->createNamedParameter($prop)),
-				$query->expr()->isNull('i.parameter')
-			);
-		}
-		foreach ($filters['params'] as $param) {
-			$propParamExpressions[] = $query->expr()->andX(
-				$query->expr()->eq('i.name', $query->createNamedParameter($param['property'])),
-				$query->expr()->eq('i.parameter', $query->createNamedParameter($param['parameter']))
-			);
-		}
-
-		if (count($propParamExpressions) === 1) {
-			$propParamExpr = $propParamExpressions[0];
-		} else {
-			$propParamExpr = call_user_func_array([$query->expr(), 'orX'], $propParamExpressions);
-		}
-
-		$query->select(['c.calendarid', 'c.uri'])
-			->from($this->dbObjectPropertiesTable, 'i')
-			->join('i', 'calendarobjects', 'c', $query->expr()->eq('i.objectid', 'c.id'))
-			->where($calExpr)
-			->andWhere($compExpr)
-			->andWhere($propParamExpr)
-			->andWhere($query->expr()->iLike('i.value',
-				$query->createNamedParameter('%'.$this->db->escapeLikeParameter($filters['search-term']).'%')))
-			->andWhere($query->expr()->isNull('deleted_at'));
-
-		if ($offset) {
-			$query->setFirstResult($offset);
-		}
-		if ($limit) {
-			$query->setMaxResults($limit);
-		}
-
-		$stmt = $query->executeQuery();
-
-		$result = [];
-		while ($row = $stmt->fetch()) {
-			$path = $uriMapper[$row['calendarid']] . '/' . $row['uri'];
-			if (!in_array($path, $result)) {
-				$result[] = $path;
-			}
-		}
-
-		return $result;
-	}
-
-	/**
-	 * used for Nextcloud's calendar API
-	 *
-	 * @param array $calendarInfo
-	 * @param string $pattern
-	 * @param array $searchProperties
-	 * @param array $options
-	 * @param integer|null $limit
-	 * @param integer|null $offset
-	 *
-	 * @return array
-	 */
-	public function search(array $calendarInfo, $pattern, array $searchProperties,
-						   array $options, $limit, $offset) {
-		$outerQuery = $this->db->getQueryBuilder();
-		$innerQuery = $this->db->getQueryBuilder();
-
-		$innerQuery->selectDistinct('op.objectid')
-			->from($this->dbObjectPropertiesTable, 'op')
-			->andWhere($innerQuery->expr()->eq('op.calendarid',
-				$outerQuery->createNamedParameter($calendarInfo['id'])))
-			->andWhere($innerQuery->expr()->eq('op.calendartype',
-				$outerQuery->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)));
-
-		// only return public items for shared calendars for now
-		if (isset($calendarInfo['{http://owncloud.org/ns}owner-principal']) === false || $calendarInfo['principaluri'] !== $calendarInfo['{http://owncloud.org/ns}owner-principal']) {
-			$innerQuery->andWhere($innerQuery->expr()->eq('c.classification',
-				$outerQuery->createNamedParameter(self::CLASSIFICATION_PUBLIC)));
-		}
-
-		if (!empty($searchProperties)) {
-			$or = $innerQuery->expr()->orX();
-			foreach ($searchProperties as $searchProperty) {
-				$or->add($innerQuery->expr()->eq('op.name',
-					$outerQuery->createNamedParameter($searchProperty)));
-			}
-			$innerQuery->andWhere($or);
-		}
-
-		if ($pattern !== '') {
-			$innerQuery->andWhere($innerQuery->expr()->iLike('op.value',
-				$outerQuery->createNamedParameter('%' .
-					$this->db->escapeLikeParameter($pattern) . '%')));
-		}
-
-		$outerQuery->select('c.id', 'c.calendardata', 'c.componenttype', 'c.uid', 'c.uri')
-			->from('calendarobjects', 'c')
-			->where($outerQuery->expr()->isNull('deleted_at'));
-
-		if (isset($options['timerange'])) {
-			if (isset($options['timerange']['start']) && $options['timerange']['start'] instanceof DateTimeInterface) {
-				$outerQuery->andWhere($outerQuery->expr()->gt('lastoccurence',
-					$outerQuery->createNamedParameter($options['timerange']['start']->getTimeStamp())));
-			}
-			if (isset($options['timerange']['end']) && $options['timerange']['end'] instanceof DateTimeInterface) {
-				$outerQuery->andWhere($outerQuery->expr()->lt('firstoccurence',
-					$outerQuery->createNamedParameter($options['timerange']['end']->getTimeStamp())));
-			}
-		}
-
-		if (isset($options['uid'])) {
-			$outerQuery->andWhere($outerQuery->expr()->eq('uid', $outerQuery->createNamedParameter($options['uid'])));
-		}
-
-		if (!empty($options['types'])) {
-			$or = $outerQuery->expr()->orX();
-			foreach ($options['types'] as $type) {
-				$or->add($outerQuery->expr()->eq('componenttype',
-					$outerQuery->createNamedParameter($type)));
-			}
-			$outerQuery->andWhere($or);
-		}
-
-		$outerQuery->andWhere($outerQuery->expr()->in('c.id', $outerQuery->createFunction($innerQuery->getSQL())));
-
-		if ($offset) {
-			$outerQuery->setFirstResult($offset);
-		}
-		if ($limit) {
-			$outerQuery->setMaxResults($limit);
-		}
-
-		$result = $outerQuery->executeQuery();
-		$calendarObjects = array_filter($result->fetchAll(), function (array $row) use ($options) {
-			$start = $options['timerange']['start'] ?? null;
-			$end = $options['timerange']['end'] ?? null;
-
-			if ($start === null || !($start instanceof DateTimeInterface) || $end === null || !($end instanceof DateTimeInterface)) {
-				// No filter required
-				return true;
-			}
-
-			$isValid = $this->validateFilterForObject($row, [
-				'name' => 'VCALENDAR',
-				'comp-filters' => [
-					[
-						'name' => 'VEVENT',
-						'comp-filters' => [],
-						'prop-filters' => [],
-						'is-not-defined' => false,
-						'time-range' => [
-							'start' => $start,
-							'end' => $end,
-						],
-					],
-				],
-				'prop-filters' => [],
-				'is-not-defined' => false,
-				'time-range' => null,
-			]);
-			if (is_resource($row['calendardata'])) {
-				// Put the stream back to the beginning so it can be read another time
-				rewind($row['calendardata']);
-			}
-			return $isValid;
-		});
-		$result->closeCursor();
-
-		return array_map(function ($o) {
-			$calendarData = Reader::read($o['calendardata']);
-			$comps = $calendarData->getComponents();
-			$objects = [];
-			$timezones = [];
-			foreach ($comps as $comp) {
-				if ($comp instanceof VTimeZone) {
-					$timezones[] = $comp;
-				} else {
-					$objects[] = $comp;
-				}
-			}
-
-			return [
-				'id' => $o['id'],
-				'type' => $o['componenttype'],
-				'uid' => $o['uid'],
-				'uri' => $o['uri'],
-				'objects' => array_map(function ($c) {
-					return $this->transformSearchData($c);
-				}, $objects),
-				'timezones' => array_map(function ($c) {
-					return $this->transformSearchData($c);
-				}, $timezones),
-			];
-		}, $calendarObjects);
-	}
-
-	/**
-	 * @param Component $comp
-	 * @return array
-	 */
-	private function transformSearchData(Component $comp) {
-		$data = [];
-		/** @var Component[] $subComponents */
-		$subComponents = $comp->getComponents();
-		/** @var Property[] $properties */
-		$properties = array_filter($comp->children(), function ($c) {
-			return $c instanceof Property;
-		});
-		$validationRules = $comp->getValidationRules();
-
-		foreach ($subComponents as $subComponent) {
-			$name = $subComponent->name;
-			if (!isset($data[$name])) {
-				$data[$name] = [];
-			}
-			$data[$name][] = $this->transformSearchData($subComponent);
-		}
-
-		foreach ($properties as $property) {
-			$name = $property->name;
-			if (!isset($validationRules[$name])) {
-				$validationRules[$name] = '*';
-			}
-
-			$rule = $validationRules[$property->name];
-			if ($rule === '+' || $rule === '*') { // multiple
-				if (!isset($data[$name])) {
-					$data[$name] = [];
-				}
-
-				$data[$name][] = $this->transformSearchProperty($property);
-			} else { // once
-				$data[$name] = $this->transformSearchProperty($property);
-			}
-		}
-
-		return $data;
-	}
-
-	/**
-	 * @param Property $prop
-	 * @return array
-	 */
-	private function transformSearchProperty(Property $prop) {
-		// No need to check Date, as it extends DateTime
-		if ($prop instanceof Property\ICalendar\DateTime) {
-			$value = $prop->getDateTime();
-		} else {
-			$value = $prop->getValue();
-		}
-
-		return [
-			$value,
-			$prop->parameters()
-		];
-	}
-
-	/**
-	 * @param string $principalUri
-	 * @param string $pattern
-	 * @param array $componentTypes
-	 * @param array $searchProperties
-	 * @param array $searchParameters
-	 * @param array $options
-	 * @return array
-	 */
-	public function searchPrincipalUri(string $principalUri,
-									   string $pattern,
-									   array $componentTypes,
-									   array $searchProperties,
-									   array $searchParameters,
-									   array $options = []): array {
-		$escapePattern = !\array_key_exists('escape_like_param', $options) || $options['escape_like_param'] !== false;
-
-		$calendarObjectIdQuery = $this->db->getQueryBuilder();
-		$calendarOr = $calendarObjectIdQuery->expr()->orX();
-		$searchOr = $calendarObjectIdQuery->expr()->orX();
-
-		// Fetch calendars and subscription
-		$calendars = $this->getCalendarsForUser($principalUri);
-		$subscriptions = $this->getSubscriptionsForUser($principalUri);
-		foreach ($calendars as $calendar) {
-			$calendarAnd = $calendarObjectIdQuery->expr()->andX();
-			$calendarAnd->add($calendarObjectIdQuery->expr()->eq('cob.calendarid', $calendarObjectIdQuery->createNamedParameter((int)$calendar['id'])));
-			$calendarAnd->add($calendarObjectIdQuery->expr()->eq('cob.calendartype', $calendarObjectIdQuery->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)));
-
-			// If it's shared, limit search to public events
-			if (isset($calendar['{http://owncloud.org/ns}owner-principal'])
-				&& $calendar['principaluri'] !== $calendar['{http://owncloud.org/ns}owner-principal']) {
-				$calendarAnd->add($calendarObjectIdQuery->expr()->eq('co.classification', $calendarObjectIdQuery->createNamedParameter(self::CLASSIFICATION_PUBLIC)));
-			}
-
-			$calendarOr->add($calendarAnd);
-		}
-		foreach ($subscriptions as $subscription) {
-			$subscriptionAnd = $calendarObjectIdQuery->expr()->andX();
-			$subscriptionAnd->add($calendarObjectIdQuery->expr()->eq('cob.calendarid', $calendarObjectIdQuery->createNamedParameter((int)$subscription['id'])));
-			$subscriptionAnd->add($calendarObjectIdQuery->expr()->eq('cob.calendartype', $calendarObjectIdQuery->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)));
-
-			// If it's shared, limit search to public events
-			if (isset($subscription['{http://owncloud.org/ns}owner-principal'])
-				&& $subscription['principaluri'] !== $subscription['{http://owncloud.org/ns}owner-principal']) {
-				$subscriptionAnd->add($calendarObjectIdQuery->expr()->eq('co.classification', $calendarObjectIdQuery->createNamedParameter(self::CLASSIFICATION_PUBLIC)));
-			}
-
-			$calendarOr->add($subscriptionAnd);
-		}
-
-		foreach ($searchProperties as $property) {
-			$propertyAnd = $calendarObjectIdQuery->expr()->andX();
-			$propertyAnd->add($calendarObjectIdQuery->expr()->eq('cob.name', $calendarObjectIdQuery->createNamedParameter($property, IQueryBuilder::PARAM_STR)));
-			$propertyAnd->add($calendarObjectIdQuery->expr()->isNull('cob.parameter'));
-
-			$searchOr->add($propertyAnd);
-		}
-		foreach ($searchParameters as $property => $parameter) {
-			$parameterAnd = $calendarObjectIdQuery->expr()->andX();
-			$parameterAnd->add($calendarObjectIdQuery->expr()->eq('cob.name', $calendarObjectIdQuery->createNamedParameter($property, IQueryBuilder::PARAM_STR)));
-			$parameterAnd->add($calendarObjectIdQuery->expr()->eq('cob.parameter', $calendarObjectIdQuery->createNamedParameter($parameter, IQueryBuilder::PARAM_STR_ARRAY)));
-
-			$searchOr->add($parameterAnd);
-		}
-
-		if ($calendarOr->count() === 0) {
-			return [];
-		}
-		if ($searchOr->count() === 0) {
-			return [];
-		}
-
-		$calendarObjectIdQuery->selectDistinct('cob.objectid')
-			->from($this->dbObjectPropertiesTable, 'cob')
-			->leftJoin('cob', 'calendarobjects', 'co', $calendarObjectIdQuery->expr()->eq('co.id', 'cob.objectid'))
-			->andWhere($calendarObjectIdQuery->expr()->in('co.componenttype', $calendarObjectIdQuery->createNamedParameter($componentTypes, IQueryBuilder::PARAM_STR_ARRAY)))
-			->andWhere($calendarOr)
-			->andWhere($searchOr)
-			->andWhere($calendarObjectIdQuery->expr()->isNull('deleted_at'));
-
-		if ('' !== $pattern) {
-			if (!$escapePattern) {
-				$calendarObjectIdQuery->andWhere($calendarObjectIdQuery->expr()->ilike('cob.value', $calendarObjectIdQuery->createNamedParameter($pattern)));
-			} else {
-				$calendarObjectIdQuery->andWhere($calendarObjectIdQuery->expr()->ilike('cob.value', $calendarObjectIdQuery->createNamedParameter('%' . $this->db->escapeLikeParameter($pattern) . '%')));
-			}
-		}
-
-		if (isset($options['limit'])) {
-			$calendarObjectIdQuery->setMaxResults($options['limit']);
-		}
-		if (isset($options['offset'])) {
-			$calendarObjectIdQuery->setFirstResult($options['offset']);
-		}
-
-		$result = $calendarObjectIdQuery->executeQuery();
-		$matches = $result->fetchAll();
-		$result->closeCursor();
-		$matches = array_map(static function (array $match):int {
-			return (int) $match['objectid'];
-		}, $matches);
-
-		$query = $this->db->getQueryBuilder();
-		$query->select('calendardata', 'uri', 'calendarid', 'calendartype')
-			->from('calendarobjects')
-			->where($query->expr()->in('id', $query->createNamedParameter($matches, IQueryBuilder::PARAM_INT_ARRAY)));
-
-		$result = $query->executeQuery();
-		$calendarObjects = $result->fetchAll();
-		$result->closeCursor();
-
-		return array_map(function (array $array): array {
-			$array['calendarid'] = (int)$array['calendarid'];
-			$array['calendartype'] = (int)$array['calendartype'];
-			$array['calendardata'] = $this->readBlob($array['calendardata']);
-
-			return $array;
-		}, $calendarObjects);
-	}
-
-	/**
-	 * Searches through all of a users calendars and calendar objects to find
-	 * an object with a specific UID.
-	 *
-	 * This method should return the path to this object, relative to the
-	 * calendar home, so this path usually only contains two parts:
-	 *
-	 * calendarpath/objectpath.ics
-	 *
-	 * If the uid is not found, return null.
-	 *
-	 * This method should only consider * objects that the principal owns, so
-	 * any calendars owned by other principals that also appear in this
-	 * collection should be ignored.
-	 *
-	 * @param string $principalUri
-	 * @param string $uid
-	 * @return string|null
-	 */
-	public function getCalendarObjectByUID($principalUri, $uid) {
-		$query = $this->db->getQueryBuilder();
-		$query->selectAlias('c.uri', 'calendaruri')->selectAlias('co.uri', 'objecturi')
-			->from('calendarobjects', 'co')
-			->leftJoin('co', 'calendars', 'c', $query->expr()->eq('co.calendarid', 'c.id'))
-			->where($query->expr()->eq('c.principaluri', $query->createNamedParameter($principalUri)))
-			->andWhere($query->expr()->eq('co.uid', $query->createNamedParameter($uid)))
-			->andWhere($query->expr()->isNull('co.deleted_at'));
-		$stmt = $query->executeQuery();
-		$row = $stmt->fetch();
-		$stmt->closeCursor();
-		if ($row) {
-			return $row['calendaruri'] . '/' . $row['objecturi'];
-		}
-
-		return null;
-	}
-
-	public function getCalendarObjectById(string $principalUri, int $id): ?array {
-		$query = $this->db->getQueryBuilder();
-		$query->select(['co.id', 'co.uri', 'co.lastmodified', 'co.etag', 'co.calendarid', 'co.size', 'co.calendardata', 'co.componenttype', 'co.classification', 'co.deleted_at'])
-			->selectAlias('c.uri', 'calendaruri')
-			->from('calendarobjects', 'co')
-			->join('co', 'calendars', 'c', $query->expr()->eq('c.id', 'co.calendarid', IQueryBuilder::PARAM_INT))
-			->where($query->expr()->eq('c.principaluri', $query->createNamedParameter($principalUri)))
-			->andWhere($query->expr()->eq('co.id', $query->createNamedParameter($id, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT));
-		$stmt = $query->executeQuery();
-		$row = $stmt->fetch();
-		$stmt->closeCursor();
-
-		if (!$row) {
-			return null;
-		}
-
-		return [
-			'id' => $row['id'],
-			'uri' => $row['uri'],
-			'lastmodified' => $row['lastmodified'],
-			'etag' => '"' . $row['etag'] . '"',
-			'calendarid' => $row['calendarid'],
-			'calendaruri' => $row['calendaruri'],
-			'size' => (int)$row['size'],
-			'calendardata' => $this->readBlob($row['calendardata']),
-			'component' => strtolower($row['componenttype']),
-			'classification' => (int)$row['classification'],
-			'deleted_at' => isset($row['deleted_at']) ? ((int) $row['deleted_at']) : null,
-		];
-	}
-
-	/**
-	 * The getChanges method returns all the changes that have happened, since
-	 * the specified syncToken in the specified calendar.
-	 *
-	 * This function should return an array, such as the following:
-	 *
-	 * [
-	 *   'syncToken' => 'The current synctoken',
-	 *   'added'   => [
-	 *      'new.txt',
-	 *   ],
-	 *   'modified'   => [
-	 *      'modified.txt',
-	 *   ],
-	 *   'deleted' => [
-	 *      'foo.php.bak',
-	 *      'old.txt'
-	 *   ]
-	 * );
-	 *
-	 * The returned syncToken property should reflect the *current* syncToken
-	 * of the calendar, as reported in the {http://sabredav.org/ns}sync-token
-	 * property This is * needed here too, to ensure the operation is atomic.
-	 *
-	 * If the $syncToken argument is specified as null, this is an initial
-	 * sync, and all members should be reported.
-	 *
-	 * The modified property is an array of nodenames that have changed since
-	 * the last token.
-	 *
-	 * The deleted property is an array with nodenames, that have been deleted
-	 * from collection.
-	 *
-	 * The $syncLevel argument is basically the 'depth' of the report. If it's
-	 * 1, you only have to report changes that happened only directly in
-	 * immediate descendants. If it's 2, it should also include changes from
-	 * the nodes below the child collections. (grandchildren)
-	 *
-	 * The $limit argument allows a client to specify how many results should
-	 * be returned at most. If the limit is not specified, it should be treated
-	 * as infinite.
-	 *
-	 * If the limit (infinite or not) is higher than you're willing to return,
-	 * you should throw a Sabre\DAV\Exception\TooMuchMatches() exception.
-	 *
-	 * If the syncToken is expired (due to data cleanup) or unknown, you must
-	 * return null.
-	 *
-	 * The limit is 'suggestive'. You are free to ignore it.
-	 *
-	 * @param string $calendarId
-	 * @param string $syncToken
-	 * @param int $syncLevel
-	 * @param int|null $limit
-	 * @param int $calendarType
-	 * @return array
-	 */
-	public function getChangesForCalendar($calendarId, $syncToken, $syncLevel, $limit = null, $calendarType = self::CALENDAR_TYPE_CALENDAR) {
-		// Current synctoken
-		$qb = $this->db->getQueryBuilder();
-		$qb->select('synctoken')
-			->from('calendars')
-			->where(
-				$qb->expr()->eq('id', $qb->createNamedParameter($calendarId))
-			);
-		$stmt = $qb->executeQuery();
-		$currentToken = $stmt->fetchOne();
-
-		if ($currentToken === false) {
-			return null;
-		}
-
-		$result = [
-			'syncToken' => $currentToken,
-			'added' => [],
-			'modified' => [],
-			'deleted' => [],
-		];
-
-		if ($syncToken) {
-			$qb = $this->db->getQueryBuilder();
-
-			$qb->select('uri', 'operation')
-				->from('calendarchanges')
-				->where(
-					$qb->expr()->andX(
-						$qb->expr()->gte('synctoken', $qb->createNamedParameter($syncToken)),
-						$qb->expr()->lt('synctoken', $qb->createNamedParameter($currentToken)),
-						$qb->expr()->eq('calendarid', $qb->createNamedParameter($calendarId)),
-						$qb->expr()->eq('calendartype', $qb->createNamedParameter($calendarType))
-					)
-				)->orderBy('synctoken');
-			if (is_int($limit) && $limit > 0) {
-				$qb->setMaxResults($limit);
-			}
-
-			// Fetching all changes
-			$stmt = $qb->executeQuery();
-			$changes = [];
-
-			// This loop ensures that any duplicates are overwritten, only the
-			// last change on a node is relevant.
-			while ($row = $stmt->fetch()) {
-				$changes[$row['uri']] = $row['operation'];
-			}
-			$stmt->closeCursor();
-
-			foreach ($changes as $uri => $operation) {
-				switch ($operation) {
-					case 1:
-						$result['added'][] = $uri;
-						break;
-					case 2:
-						$result['modified'][] = $uri;
-						break;
-					case 3:
-						$result['deleted'][] = $uri;
-						break;
-				}
-			}
-		} else {
-			// No synctoken supplied, this is the initial sync.
-			$qb = $this->db->getQueryBuilder();
-			$qb->select('uri')
-				->from('calendarobjects')
-				->where(
-					$qb->expr()->andX(
-						$qb->expr()->eq('calendarid', $qb->createNamedParameter($calendarId)),
-						$qb->expr()->eq('calendartype', $qb->createNamedParameter($calendarType))
-					)
-				);
-			$stmt = $qb->executeQuery();
-			$result['added'] = $stmt->fetchAll(\PDO::FETCH_COLUMN);
-			$stmt->closeCursor();
-		}
-		return $result;
-	}
-
-	/**
-	 * Returns a list of subscriptions for a principal.
-	 *
-	 * Every subscription is an array with the following keys:
-	 *  * id, a unique id that will be used by other functions to modify the
-	 *    subscription. This can be the same as the uri or a database key.
-	 *  * uri. This is just the 'base uri' or 'filename' of the subscription.
-	 *  * principaluri. The owner of the subscription. Almost always the same as
-	 *    principalUri passed to this method.
-	 *
-	 * Furthermore, all the subscription info must be returned too:
-	 *
-	 * 1. {DAV:}displayname
-	 * 2. {http://apple.com/ns/ical/}refreshrate
-	 * 3. {http://calendarserver.org/ns/}subscribed-strip-todos (omit if todos
-	 *    should not be stripped).
-	 * 4. {http://calendarserver.org/ns/}subscribed-strip-alarms (omit if alarms
-	 *    should not be stripped).
-	 * 5. {http://calendarserver.org/ns/}subscribed-strip-attachments (omit if
-	 *    attachments should not be stripped).
-	 * 6. {http://calendarserver.org/ns/}source (Must be a
-	 *     Sabre\DAV\Property\Href).
-	 * 7. {http://apple.com/ns/ical/}calendar-color
-	 * 8. {http://apple.com/ns/ical/}calendar-order
-	 * 9. {urn:ietf:params:xml:ns:caldav}supported-calendar-component-set
-	 *    (should just be an instance of
-	 *    Sabre\CalDAV\Property\SupportedCalendarComponentSet, with a bunch of
-	 *    default components).
-	 *
-	 * @param string $principalUri
-	 * @return array
-	 */
-	public function getSubscriptionsForUser($principalUri) {
-		$fields = array_column($this->subscriptionPropertyMap, 0);
-		$fields[] = 'id';
-		$fields[] = 'uri';
-		$fields[] = 'source';
-		$fields[] = 'principaluri';
-		$fields[] = 'lastmodified';
-		$fields[] = 'synctoken';
-
-		$query = $this->db->getQueryBuilder();
-		$query->select($fields)
-			->from('calendarsubscriptions')
-			->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)))
-			->orderBy('calendarorder', 'asc');
-		$stmt = $query->executeQuery();
-
-		$subscriptions = [];
-		while ($row = $stmt->fetch()) {
-			$subscription = [
-				'id' => $row['id'],
-				'uri' => $row['uri'],
-				'principaluri' => $row['principaluri'],
-				'source' => $row['source'],
-				'lastmodified' => $row['lastmodified'],
-
-				'{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet(['VTODO', 'VEVENT']),
-				'{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
-			];
-
-			$subscriptions[] = $this->rowToSubscription($row, $subscription);
-		}
-
-		return $subscriptions;
-	}
-
-	/**
-	 * Creates a new subscription for a principal.
-	 *
-	 * If the creation was a success, an id must be returned that can be used to reference
-	 * this subscription in other methods, such as updateSubscription.
-	 *
-	 * @param string $principalUri
-	 * @param string $uri
-	 * @param array $properties
-	 * @return mixed
-	 */
-	public function createSubscription($principalUri, $uri, array $properties) {
-		if (!isset($properties['{http://calendarserver.org/ns/}source'])) {
-			throw new Forbidden('The {http://calendarserver.org/ns/}source property is required when creating subscriptions');
-		}
-
-		$values = [
-			'principaluri' => $principalUri,
-			'uri' => $uri,
-			'source' => $properties['{http://calendarserver.org/ns/}source']->getHref(),
-			'lastmodified' => time(),
-		];
-
-		$propertiesBoolean = ['striptodos', 'stripalarms', 'stripattachments'];
-
-		foreach ($this->subscriptionPropertyMap as $xmlName => [$dbName, $type]) {
-			if (array_key_exists($xmlName, $properties)) {
-				$values[$dbName] = $properties[$xmlName];
-				if (in_array($dbName, $propertiesBoolean)) {
-					$values[$dbName] = true;
-				}
-			}
-		}
-
-		[$subscriptionId, $subscriptionRow] = $this->atomic(function () use ($values) {
-			$valuesToInsert = [];
-			$query = $this->db->getQueryBuilder();
-			foreach (array_keys($values) as $name) {
-				$valuesToInsert[$name] = $query->createNamedParameter($values[$name]);
-			}
-			$query->insert('calendarsubscriptions')
-				->values($valuesToInsert)
-				->executeStatement();
-
-			$subscriptionId = $query->getLastInsertId();
-
-			$subscriptionRow = $this->getSubscriptionById($subscriptionId);
-			return [$subscriptionId, $subscriptionRow];
-		}, $this->db);
-
-		$this->dispatcher->dispatchTyped(new SubscriptionCreatedEvent($subscriptionId, $subscriptionRow));
-
-		return $subscriptionId;
-	}
-
-	/**
-	 * Updates a subscription
-	 *
-	 * The list of mutations is stored in a Sabre\DAV\PropPatch object.
-	 * To do the actual updates, you must tell this object which properties
-	 * you're going to process with the handle() method.
-	 *
-	 * Calling the handle method is like telling the PropPatch object "I
-	 * promise I can handle updating this property".
-	 *
-	 * Read the PropPatch documentation for more info and examples.
-	 *
-	 * @param mixed $subscriptionId
-	 * @param PropPatch $propPatch
-	 * @return void
-	 */
-	public function updateSubscription($subscriptionId, PropPatch $propPatch) {
-		$supportedProperties = array_keys($this->subscriptionPropertyMap);
-		$supportedProperties[] = '{http://calendarserver.org/ns/}source';
-
-		$propPatch->handle($supportedProperties, function ($mutations) use ($subscriptionId) {
-			$newValues = [];
-
-			foreach ($mutations as $propertyName => $propertyValue) {
-				if ($propertyName === '{http://calendarserver.org/ns/}source') {
-					$newValues['source'] = $propertyValue->getHref();
-				} else {
-					$fieldName = $this->subscriptionPropertyMap[$propertyName][0];
-					$newValues[$fieldName] = $propertyValue;
-				}
-			}
-
-			$query = $this->db->getQueryBuilder();
-			$query->update('calendarsubscriptions')
-				->set('lastmodified', $query->createNamedParameter(time()));
-			foreach ($newValues as $fieldName => $value) {
-				$query->set($fieldName, $query->createNamedParameter($value));
-			}
-			$query->where($query->expr()->eq('id', $query->createNamedParameter($subscriptionId)))
-				->executeStatement();
-
-			$subscriptionRow = $this->getSubscriptionById($subscriptionId);
-			$this->dispatcher->dispatchTyped(new SubscriptionUpdatedEvent((int)$subscriptionId, $subscriptionRow, [], $mutations));
-
-			return true;
-		});
-	}
-
-	/**
-	 * Deletes a subscription.
-	 *
-	 * @param mixed $subscriptionId
-	 * @return void
-	 */
-	public function deleteSubscription($subscriptionId) {
-		$subscriptionRow = $this->getSubscriptionById($subscriptionId);
-
-		$query = $this->db->getQueryBuilder();
-		$query->delete('calendarsubscriptions')
-			->where($query->expr()->eq('id', $query->createNamedParameter($subscriptionId)))
-			->executeStatement();
-
-		$query = $this->db->getQueryBuilder();
-		$query->delete('calendarobjects')
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
-			->executeStatement();
-
-		$query->delete('calendarchanges')
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
-			->executeStatement();
-
-		$query->delete($this->dbObjectPropertiesTable)
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
-			->executeStatement();
-
-		if ($subscriptionRow) {
-			$this->dispatcher->dispatchTyped(new SubscriptionDeletedEvent((int)$subscriptionId, $subscriptionRow, []));
-		}
-	}
-
-	/**
-	 * Returns a single scheduling object for the inbox collection.
-	 *
-	 * The returned array should contain the following elements:
-	 *   * uri - A unique basename for the object. This will be used to
-	 *           construct a full uri.
-	 *   * calendardata - The iCalendar object
-	 *   * lastmodified - The last modification date. Can be an int for a unix
-	 *                    timestamp, or a PHP DateTime object.
-	 *   * etag - A unique token that must change if the object changed.
-	 *   * size - The size of the object, in bytes.
-	 *
-	 * @param string $principalUri
-	 * @param string $objectUri
-	 * @return array
-	 */
-	public function getSchedulingObject($principalUri, $objectUri) {
-		$query = $this->db->getQueryBuilder();
-		$stmt = $query->select(['uri', 'calendardata', 'lastmodified', 'etag', 'size'])
-			->from('schedulingobjects')
-			->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)))
-			->andWhere($query->expr()->eq('uri', $query->createNamedParameter($objectUri)))
-			->executeQuery();
-
-		$row = $stmt->fetch();
-
-		if (!$row) {
-			return null;
-		}
-
-		return [
-			'uri' => $row['uri'],
-			'calendardata' => $row['calendardata'],
-			'lastmodified' => $row['lastmodified'],
-			'etag' => '"' . $row['etag'] . '"',
-			'size' => (int)$row['size'],
-		];
-	}
-
-	/**
-	 * Returns all scheduling objects for the inbox collection.
-	 *
-	 * These objects should be returned as an array. Every item in the array
-	 * should follow the same structure as returned from getSchedulingObject.
-	 *
-	 * The main difference is that 'calendardata' is optional.
-	 *
-	 * @param string $principalUri
-	 * @return array
-	 */
-	public function getSchedulingObjects($principalUri) {
-		$query = $this->db->getQueryBuilder();
-		$stmt = $query->select(['uri', 'calendardata', 'lastmodified', 'etag', 'size'])
-				->from('schedulingobjects')
-				->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)))
-				->executeQuery();
-
-		$result = [];
-		foreach ($stmt->fetchAll() as $row) {
-			$result[] = [
-				'calendardata' => $row['calendardata'],
-				'uri' => $row['uri'],
-				'lastmodified' => $row['lastmodified'],
-				'etag' => '"' . $row['etag'] . '"',
-				'size' => (int)$row['size'],
-			];
-		}
-		$stmt->closeCursor();
-
-		return $result;
-	}
-
-	/**
-	 * Deletes a scheduling object from the inbox collection.
-	 *
-	 * @param string $principalUri
-	 * @param string $objectUri
-	 * @return void
-	 */
-	public function deleteSchedulingObject($principalUri, $objectUri) {
-		$query = $this->db->getQueryBuilder();
-		$query->delete('schedulingobjects')
-				->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)))
-				->andWhere($query->expr()->eq('uri', $query->createNamedParameter($objectUri)))
-				->executeStatement();
-	}
-
-	/**
-	 * Creates a new scheduling object. This should land in a users' inbox.
-	 *
-	 * @param string $principalUri
-	 * @param string $objectUri
-	 * @param string $objectData
-	 * @return void
-	 */
-	public function createSchedulingObject($principalUri, $objectUri, $objectData) {
-		$query = $this->db->getQueryBuilder();
-		$query->insert('schedulingobjects')
-			->values([
-				'principaluri' => $query->createNamedParameter($principalUri),
-				'calendardata' => $query->createNamedParameter($objectData, IQueryBuilder::PARAM_LOB),
-				'uri' => $query->createNamedParameter($objectUri),
-				'lastmodified' => $query->createNamedParameter(time()),
-				'etag' => $query->createNamedParameter(md5($objectData)),
-				'size' => $query->createNamedParameter(strlen($objectData))
-			])
-			->executeStatement();
-	}
-
-	/**
-	 * Adds a change record to the calendarchanges table.
-	 *
-	 * @param mixed $calendarId
-	 * @param string $objectUri
-	 * @param int $operation 1 = add, 2 = modify, 3 = delete.
-	 * @param int $calendarType
-	 * @return void
-	 */
-	protected function addChange($calendarId, $objectUri, $operation, $calendarType = self::CALENDAR_TYPE_CALENDAR) {
-		$table = $calendarType === self::CALENDAR_TYPE_CALENDAR ? 'calendars': 'calendarsubscriptions';
-
-		$query = $this->db->getQueryBuilder();
-		$query->select('synctoken')
-			->from($table)
-			->where($query->expr()->eq('id', $query->createNamedParameter($calendarId)));
-		$result = $query->executeQuery();
-		$syncToken = (int)$result->fetchOne();
-		$result->closeCursor();
-
-		$query = $this->db->getQueryBuilder();
-		$query->insert('calendarchanges')
-			->values([
-				'uri' => $query->createNamedParameter($objectUri),
-				'synctoken' => $query->createNamedParameter($syncToken),
-				'calendarid' => $query->createNamedParameter($calendarId),
-				'operation' => $query->createNamedParameter($operation),
-				'calendartype' => $query->createNamedParameter($calendarType),
-			])
-			->executeStatement();
-
-		$stmt = $this->db->prepare("UPDATE `*PREFIX*$table` SET `synctoken` = `synctoken` + 1 WHERE `id` = ?");
-		$stmt->execute([
-			$calendarId
-		]);
-	}
-
-	/**
-	 * Parses some information from calendar objects, used for optimized
-	 * calendar-queries.
-	 *
-	 * Returns an array with the following keys:
-	 *   * etag - An md5 checksum of the object without the quotes.
-	 *   * size - Size of the object in bytes
-	 *   * componentType - VEVENT, VTODO or VJOURNAL
-	 *   * firstOccurence
-	 *   * lastOccurence
-	 *   * uid - value of the UID property
-	 *
-	 * @param string $calendarData
-	 * @return array
-	 */
-	public function getDenormalizedData($calendarData) {
-		$vObject = Reader::read($calendarData);
-		$vEvents = [];
-		$componentType = null;
-		$component = null;
-		$firstOccurrence = null;
-		$lastOccurrence = null;
-		$uid = null;
-		$classification = self::CLASSIFICATION_PUBLIC;
-		$hasDTSTART = false;
-		foreach ($vObject->getComponents() as $component) {
-			if ($component->name !== 'VTIMEZONE') {
-				// Finding all VEVENTs, and track them
-				if ($component->name === 'VEVENT') {
-					array_push($vEvents, $component);
-					if ($component->DTSTART) {
-						$hasDTSTART = true;
-					}
-				}
-				// Track first component type and uid
-				if ($uid === null) {
-					$componentType = $component->name;
-					$uid = (string)$component->UID;
-				}
-			}
-		}
-		if (!$componentType) {
-			throw new BadRequest('Calendar objects must have a VJOURNAL, VEVENT or VTODO component');
-		}
-
-		if ($hasDTSTART) {
-			$component = $vEvents[0];
-
-			// Finding the last occurrence is a bit harder
-			if (!isset($component->RRULE) && count($vEvents) === 1) {
-				$firstOccurrence = $component->DTSTART->getDateTime()->getTimeStamp();
-				if (isset($component->DTEND)) {
-					$lastOccurrence = $component->DTEND->getDateTime()->getTimeStamp();
-				} elseif (isset($component->DURATION)) {
-					$endDate = clone $component->DTSTART->getDateTime();
-					$endDate->add(DateTimeParser::parse($component->DURATION->getValue()));
-					$lastOccurrence = $endDate->getTimeStamp();
-				} elseif (!$component->DTSTART->hasTime()) {
-					$endDate = clone $component->DTSTART->getDateTime();
-					$endDate->modify('+1 day');
-					$lastOccurrence = $endDate->getTimeStamp();
-				} else {
-					$lastOccurrence = $firstOccurrence;
-				}
-			} else {
-				$it = new EventIterator($vEvents);
-				$maxDate = new DateTime(self::MAX_DATE);
-				$firstOccurrence = $it->getDtStart()->getTimestamp();
-				if ($it->isInfinite()) {
-					$lastOccurrence = $maxDate->getTimestamp();
-				} else {
-					$end = $it->getDtEnd();
-					while ($it->valid() && $end < $maxDate) {
-						$end = $it->getDtEnd();
-						$it->next();
-					}
-					$lastOccurrence = $end->getTimestamp();
-				}
-			}
-		}
-
-		if ($component->CLASS) {
-			$classification = CalDavBackend::CLASSIFICATION_PRIVATE;
-			switch ($component->CLASS->getValue()) {
-				case 'PUBLIC':
-					$classification = CalDavBackend::CLASSIFICATION_PUBLIC;
-					break;
-				case 'CONFIDENTIAL':
-					$classification = CalDavBackend::CLASSIFICATION_CONFIDENTIAL;
-					break;
-			}
-		}
-		return [
-			'etag' => md5($calendarData),
-			'size' => strlen($calendarData),
-			'componentType' => $componentType,
-			'firstOccurence' => is_null($firstOccurrence) ? null : max(0, $firstOccurrence),
-			'lastOccurence' => $lastOccurrence,
-			'uid' => $uid,
-			'classification' => $classification
-		];
-	}
-
-	/**
-	 * @param $cardData
-	 * @return bool|string
-	 */
-	private function readBlob($cardData) {
-		if (is_resource($cardData)) {
-			return stream_get_contents($cardData);
-		}
-
-		return $cardData;
-	}
-
-	/**
-	 * @param list<array{href: string, commonName: string, readOnly: bool}> $add
-	 * @param list<string> $remove
-	 */
-	public function updateShares(IShareable $shareable, array $add, array $remove): void {
-		$calendarId = $shareable->getResourceId();
-		$calendarRow = $this->getCalendarById($calendarId);
-		if ($calendarRow === null) {
-			throw new \RuntimeException('Trying to update shares for innexistant calendar: ' . $calendarId);
-		}
-		$oldShares = $this->getShares($calendarId);
-
-		$this->calendarSharingBackend->updateShares($shareable, $add, $remove);
-
-		$this->dispatcher->dispatchTyped(new CalendarShareUpdatedEvent($calendarId, $calendarRow, $oldShares, $add, $remove));
-	}
-
-	/**
-	 * @return list<array{href: string, commonName: string, status: int, readOnly: bool, '{http://owncloud.org/ns}principal': string, '{http://owncloud.org/ns}group-share': bool}>
-	 */
-	public function getShares(int $resourceId): array {
-		return $this->calendarSharingBackend->getShares($resourceId);
-	}
-
-	/**
-	 * @param boolean $value
-	 * @param \OCA\DAV\CalDAV\Calendar $calendar
-	 * @return string|null
-	 */
-	public function setPublishStatus($value, $calendar) {
-		$calendarId = $calendar->getResourceId();
-		$calendarData = $this->getCalendarById($calendarId);
-
-		$query = $this->db->getQueryBuilder();
-		if ($value) {
-			$publicUri = $this->random->generate(16, ISecureRandom::CHAR_HUMAN_READABLE);
-			$query->insert('dav_shares')
-				->values([
-					'principaluri' => $query->createNamedParameter($calendar->getPrincipalURI()),
-					'type' => $query->createNamedParameter('calendar'),
-					'access' => $query->createNamedParameter(self::ACCESS_PUBLIC),
-					'resourceid' => $query->createNamedParameter($calendar->getResourceId()),
-					'publicuri' => $query->createNamedParameter($publicUri)
-				]);
-			$query->executeStatement();
-
-			$this->dispatcher->dispatchTyped(new CalendarPublishedEvent($calendarId, $calendarData, $publicUri));
-			return $publicUri;
-		}
-		$query->delete('dav_shares')
-			->where($query->expr()->eq('resourceid', $query->createNamedParameter($calendar->getResourceId())))
-			->andWhere($query->expr()->eq('access', $query->createNamedParameter(self::ACCESS_PUBLIC)));
-		$query->executeStatement();
-
-		$this->dispatcher->dispatchTyped(new CalendarUnpublishedEvent($calendarId, $calendarData));
-		return null;
-	}
-
-	/**
-	 * @param \OCA\DAV\CalDAV\Calendar $calendar
-	 * @return mixed
-	 */
-	public function getPublishStatus($calendar) {
-		$query = $this->db->getQueryBuilder();
-		$result = $query->select('publicuri')
-			->from('dav_shares')
-			->where($query->expr()->eq('resourceid', $query->createNamedParameter($calendar->getResourceId())))
-			->andWhere($query->expr()->eq('access', $query->createNamedParameter(self::ACCESS_PUBLIC)))
-			->executeQuery();
-
-		$row = $result->fetch();
-		$result->closeCursor();
-		return $row ? reset($row) : false;
-	}
-
-	/**
-	 * @param int $resourceId
-	 * @param list<array{privilege: string, principal: string, protected: bool}> $acl
-	 * @return list<array{privilege: string, principal: string, protected: bool}>
-	 */
-	public function applyShareAcl(int $resourceId, array $acl): array {
-		return $this->calendarSharingBackend->applyShareAcl($resourceId, $acl);
-	}
-
-	/**
-	 * update properties table
-	 *
-	 * @param int $calendarId
-	 * @param string $objectUri
-	 * @param string $calendarData
-	 * @param int $calendarType
-	 */
-	public function updateProperties($calendarId, $objectUri, $calendarData, $calendarType = self::CALENDAR_TYPE_CALENDAR) {
-		$objectId = $this->getCalendarObjectId($calendarId, $objectUri, $calendarType);
-
-		try {
-			$vCalendar = $this->readCalendarData($calendarData);
-		} catch (\Exception $ex) {
-			return;
-		}
-
-		$this->purgeProperties($calendarId, $objectId);
-
-		$query = $this->db->getQueryBuilder();
-		$query->insert($this->dbObjectPropertiesTable)
-			->values(
-				[
-					'calendarid' => $query->createNamedParameter($calendarId),
-					'calendartype' => $query->createNamedParameter($calendarType),
-					'objectid' => $query->createNamedParameter($objectId),
-					'name' => $query->createParameter('name'),
-					'parameter' => $query->createParameter('parameter'),
-					'value' => $query->createParameter('value'),
-				]
-			);
-
-		$indexComponents = ['VEVENT', 'VJOURNAL', 'VTODO'];
-		foreach ($vCalendar->getComponents() as $component) {
-			if (!in_array($component->name, $indexComponents)) {
-				continue;
-			}
-
-			foreach ($component->children() as $property) {
-				if (in_array($property->name, self::INDEXED_PROPERTIES, true)) {
-					$value = $property->getValue();
-					// is this a shitty db?
-					if (!$this->db->supports4ByteText()) {
-						$value = preg_replace('/[\x{10000}-\x{10FFFF}]/u', "\xEF\xBF\xBD", $value);
-					}
-					$value = mb_strcut($value, 0, 254);
-
-					$query->setParameter('name', $property->name);
-					$query->setParameter('parameter', null);
-					$query->setParameter('value', $value);
-					$query->executeStatement();
-				}
-
-				if (array_key_exists($property->name, self::$indexParameters)) {
-					$parameters = $property->parameters();
-					$indexedParametersForProperty = self::$indexParameters[$property->name];
-
-					foreach ($parameters as $key => $value) {
-						if (in_array($key, $indexedParametersForProperty)) {
-							// is this a shitty db?
-							if ($this->db->supports4ByteText()) {
-								$value = preg_replace('/[\x{10000}-\x{10FFFF}]/u', "\xEF\xBF\xBD", $value);
-							}
-
-							$query->setParameter('name', $property->name);
-							$query->setParameter('parameter', mb_strcut($key, 0, 254));
-							$query->setParameter('value', mb_strcut($value, 0, 254));
-							$query->executeStatement();
-						}
-					}
-				}
-			}
-		}
-	}
-
-	/**
-	 * deletes all birthday calendars
-	 */
-	public function deleteAllBirthdayCalendars() {
-		$query = $this->db->getQueryBuilder();
-		$result = $query->select(['id'])->from('calendars')
-			->where($query->expr()->eq('uri', $query->createNamedParameter(BirthdayService::BIRTHDAY_CALENDAR_URI)))
-			->executeQuery();
-
-		$ids = $result->fetchAll();
-		$result->closeCursor();
-		foreach ($ids as $id) {
-			$this->deleteCalendar(
-				$id['id'],
-				true // No data to keep in the trashbin, if the user re-enables then we regenerate
-			);
-		}
-	}
-
-	/**
-	 * @param $subscriptionId
-	 */
-	public function purgeAllCachedEventsForSubscription($subscriptionId) {
-		$query = $this->db->getQueryBuilder();
-		$query->select('uri')
-			->from('calendarobjects')
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)));
-		$stmt = $query->executeQuery();
-
-		$uris = [];
-		foreach ($stmt->fetchAll() as $row) {
-			$uris[] = $row['uri'];
-		}
-		$stmt->closeCursor();
-
-		$query = $this->db->getQueryBuilder();
-		$query->delete('calendarobjects')
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
-			->executeStatement();
-
-		$query->delete('calendarchanges')
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
-			->executeStatement();
-
-		$query->delete($this->dbObjectPropertiesTable)
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
-			->executeStatement();
-
-		foreach ($uris as $uri) {
-			$this->addChange($subscriptionId, $uri, 3, self::CALENDAR_TYPE_SUBSCRIPTION);
-		}
-	}
-
-	/**
-	 * Move a calendar from one user to another
-	 *
-	 * @param string $uriName
-	 * @param string $uriOrigin
-	 * @param string $uriDestination
-	 * @param string $newUriName (optional) the new uriName
-	 */
-	public function moveCalendar($uriName, $uriOrigin, $uriDestination, $newUriName = null) {
-		$query = $this->db->getQueryBuilder();
-		$query->update('calendars')
-			->set('principaluri', $query->createNamedParameter($uriDestination))
-			->set('uri', $query->createNamedParameter($newUriName ?: $uriName))
-			->where($query->expr()->eq('principaluri', $query->createNamedParameter($uriOrigin)))
-			->andWhere($query->expr()->eq('uri', $query->createNamedParameter($uriName)))
-			->executeStatement();
-	}
-
-	/**
-	 * read VCalendar data into a VCalendar object
-	 *
-	 * @param string $objectData
-	 * @return VCalendar
-	 */
-	protected function readCalendarData($objectData) {
-		return Reader::read($objectData);
-	}
-
-	/**
-	 * delete all properties from a given calendar object
-	 *
-	 * @param int $calendarId
-	 * @param int $objectId
-	 */
-	protected function purgeProperties($calendarId, $objectId) {
-		$query = $this->db->getQueryBuilder();
-		$query->delete($this->dbObjectPropertiesTable)
-			->where($query->expr()->eq('objectid', $query->createNamedParameter($objectId)))
-			->andWhere($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)));
-		$query->executeStatement();
-	}
-
-	/**
-	 * get ID from a given calendar object
-	 *
-	 * @param int $calendarId
-	 * @param string $uri
-	 * @param int $calendarType
-	 * @return int
-	 */
-	protected function getCalendarObjectId($calendarId, $uri, $calendarType):int {
-		$query = $this->db->getQueryBuilder();
-		$query->select('id')
-			->from('calendarobjects')
-			->where($query->expr()->eq('uri', $query->createNamedParameter($uri)))
-			->andWhere($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)));
-
-		$result = $query->executeQuery();
-		$objectIds = $result->fetch();
-		$result->closeCursor();
-
-		if (!isset($objectIds['id'])) {
-			throw new \InvalidArgumentException('Calendarobject does not exists: ' . $uri);
-		}
-
-		return (int)$objectIds['id'];
-	}
-
-	/**
-	 * @throws \InvalidArgumentException
-	 */
-	public function pruneOutdatedSyncTokens(int $keep = 10_000): int {
-		if ($keep < 0) {
-			throw new \InvalidArgumentException();
-		}
-		$query = $this->db->getQueryBuilder();
-		$query->delete('calendarchanges')
-			->orderBy('id', 'DESC')
-			->setFirstResult($keep);
-		return $query->executeStatement();
-	}
-
-	/**
-	 * return legacy endpoint principal name to new principal name
-	 *
-	 * @param $principalUri
-	 * @param $toV2
-	 * @return string
-	 */
-	private function convertPrincipal($principalUri, $toV2) {
-		if ($this->principalBackend->getPrincipalPrefix() === 'principals') {
-			[, $name] = Uri\split($principalUri);
-			if ($toV2 === true) {
-				return "principals/users/$name";
-			}
-			return "principals/$name";
-		}
-		return $principalUri;
-	}
-
-	/**
-	 * adds information about an owner to the calendar data
-	 *
-	 */
-	private function addOwnerPrincipalToCalendar(array $calendarInfo): array {
-		$ownerPrincipalKey = '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}owner-principal';
-		$displaynameKey = '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_NEXTCLOUD . '}owner-displayname';
-		if (isset($calendarInfo[$ownerPrincipalKey])) {
-			$uri = $calendarInfo[$ownerPrincipalKey];
-		} else {
-			$uri = $calendarInfo['principaluri'];
-		}
-
-		$principalInformation = $this->principalBackend->getPrincipalByPath($uri);
-		if (isset($principalInformation['{DAV:}displayname'])) {
-			$calendarInfo[$displaynameKey] = $principalInformation['{DAV:}displayname'];
-		}
-		return $calendarInfo;
-	}
-
-	private function addResourceTypeToCalendar(array $row, array $calendar): array {
-		if (isset($row['deleted_at'])) {
-			// Columns is set and not null -> this is a deleted calendar
-			// we send a custom resourcetype to hide the deleted calendar
-			// from ordinary DAV clients, but the Calendar app will know
-			// how to handle this special resource.
-			$calendar['{DAV:}resourcetype'] = new DAV\Xml\Property\ResourceType([
-				'{DAV:}collection',
-				sprintf('{%s}deleted-calendar', \OCA\DAV\DAV\Sharing\Plugin::NS_NEXTCLOUD),
-			]);
-		}
-		return $calendar;
-	}
-
-	/**
-	 * Amend the calendar info with database row data
-	 *
-	 * @param array $row
-	 * @param array $calendar
-	 *
-	 * @return array
-	 */
-	private function rowToCalendar($row, array $calendar): array {
-		foreach ($this->propertyMap as $xmlName => [$dbName, $type]) {
-			$value = $row[$dbName];
-			if ($value !== null) {
-				settype($value, $type);
-			}
-			$calendar[$xmlName] = $value;
-		}
-		return $calendar;
-	}
-
-	/**
-	 * Amend the subscription info with database row data
-	 *
-	 * @param array $row
-	 * @param array $subscription
-	 *
-	 * @return array
-	 */
-	private function rowToSubscription($row, array $subscription): array {
-		foreach ($this->subscriptionPropertyMap as $xmlName => [$dbName, $type]) {
-			$value = $row[$dbName];
-			if ($value !== null) {
-				settype($value, $type);
-			}
-			$subscription[$xmlName] = $value;
-		}
-		return $subscription;
-	}
+    use TTransactional;
+
+    public const CALENDAR_TYPE_CALENDAR = 0;
+    public const CALENDAR_TYPE_SUBSCRIPTION = 1;
+
+    public const PERSONAL_CALENDAR_URI = 'personal';
+    public const PERSONAL_CALENDAR_NAME = 'Personal';
+
+    public const RESOURCE_BOOKING_CALENDAR_URI = 'calendar';
+    public const RESOURCE_BOOKING_CALENDAR_NAME = 'Calendar';
+
+    /**
+     * We need to specify a max date, because we need to stop *somewhere*
+     *
+     * On 32 bit system the maximum for a signed integer is 2147483647, so
+     * MAX_DATE cannot be higher than date('Y-m-d', 2147483647) which results
+     * in 2038-01-19 to avoid problems when the date is converted
+     * to a unix timestamp.
+     */
+    public const MAX_DATE = '2038-01-01';
+
+    public const ACCESS_PUBLIC = 4;
+    public const CLASSIFICATION_PUBLIC = 0;
+    public const CLASSIFICATION_PRIVATE = 1;
+    public const CLASSIFICATION_CONFIDENTIAL = 2;
+
+    /**
+     * List of CalDAV properties, and how they map to database field names and their type
+     * Add your own properties by simply adding on to this array.
+     *
+     * @var array
+     * @psalm-var array<string, string[]>
+     */
+    public array $propertyMap = [
+        '{DAV:}displayname' => ['displayname', 'string'],
+        '{urn:ietf:params:xml:ns:caldav}calendar-description' => ['description', 'string'],
+        '{urn:ietf:params:xml:ns:caldav}calendar-timezone' => ['timezone', 'string'],
+        '{http://apple.com/ns/ical/}calendar-order' => ['calendarorder', 'int'],
+        '{http://apple.com/ns/ical/}calendar-color' => ['calendarcolor', 'string'],
+        '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_NEXTCLOUD . '}deleted-at' => ['deleted_at', 'int'],
+    ];
+
+    /**
+     * List of subscription properties, and how they map to database field names.
+     *
+     * @var array
+     */
+    public array $subscriptionPropertyMap = [
+        '{DAV:}displayname' => ['displayname', 'string'],
+        '{http://apple.com/ns/ical/}refreshrate' => ['refreshrate', 'string'],
+        '{http://apple.com/ns/ical/}calendar-order' => ['calendarorder', 'int'],
+        '{http://apple.com/ns/ical/}calendar-color' => ['calendarcolor', 'string'],
+        '{http://calendarserver.org/ns/}subscribed-strip-todos' => ['striptodos', 'bool'],
+        '{http://calendarserver.org/ns/}subscribed-strip-alarms' => ['stripalarms', 'string'],
+        '{http://calendarserver.org/ns/}subscribed-strip-attachments' => ['stripattachments', 'string'],
+    ];
+
+    /**
+     * properties to index
+     *
+     * This list has to be kept in sync with ICalendarQuery::SEARCH_PROPERTY_*
+     *
+     * @see \OCP\Calendar\ICalendarQuery
+     */
+    private const INDEXED_PROPERTIES = [
+        'CATEGORIES',
+        'COMMENT',
+        'DESCRIPTION',
+        'LOCATION',
+        'RESOURCES',
+        'STATUS',
+        'SUMMARY',
+        'ATTENDEE',
+        'CONTACT',
+        'ORGANIZER'
+    ];
+
+    /** @var array parameters to index */
+    public static array $indexParameters = [
+        'ATTENDEE' => ['CN'],
+        'ORGANIZER' => ['CN'],
+    ];
+
+    /**
+     * @var string[] Map of uid => display name
+     */
+    protected array $userDisplayNames;
+
+    private IDBConnection $db;
+    private Backend $calendarSharingBackend;
+    private Principal $principalBackend;
+    private IUserManager $userManager;
+    private ISecureRandom $random;
+    private LoggerInterface $logger;
+    private IEventDispatcher $dispatcher;
+    private IConfig $config;
+    private bool $legacyEndpoint;
+    private string $dbObjectPropertiesTable = 'calendarobjects_props';
+
+    public function __construct(IDBConnection $db,
+                                Principal $principalBackend,
+                                IUserManager $userManager,
+                                IGroupManager $groupManager,
+                                ISecureRandom $random,
+                                LoggerInterface $logger,
+                                IEventDispatcher $dispatcher,
+                                IConfig $config,
+                                bool $legacyEndpoint = false) {
+        $this->db = $db;
+        $this->principalBackend = $principalBackend;
+        $this->userManager = $userManager;
+        $this->calendarSharingBackend = new Backend($this->db, $this->userManager, $groupManager, $principalBackend, 'calendar');
+        $this->random = $random;
+        $this->logger = $logger;
+        $this->dispatcher = $dispatcher;
+        $this->config = $config;
+        $this->legacyEndpoint = $legacyEndpoint;
+    }
+
+    /**
+     * Return the number of calendars for a principal
+     *
+     * By default this excludes the automatically generated birthday calendar
+     *
+     * @param $principalUri
+     * @param bool $excludeBirthday
+     * @return int
+     */
+    public function getCalendarsForUserCount($principalUri, $excludeBirthday = true) {
+        $principalUri = $this->convertPrincipal($principalUri, true);
+        $query = $this->db->getQueryBuilder();
+        $query->select($query->func()->count('*'))
+            ->from('calendars');
+
+        if ($principalUri === '') {
+            $query->where($query->expr()->emptyString('principaluri'));
+        } else {
+            $query->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)));
+        }
+
+        if ($excludeBirthday) {
+            $query->andWhere($query->expr()->neq('uri', $query->createNamedParameter(BirthdayService::BIRTHDAY_CALENDAR_URI)));
+        }
+
+        $result = $query->executeQuery();
+        $column = (int)$result->fetchOne();
+        $result->closeCursor();
+        return $column;
+    }
+
+    /**
+     * @return array{id: int, deleted_at: int}[]
+     */
+    public function getDeletedCalendars(int $deletedBefore): array {
+        $qb = $this->db->getQueryBuilder();
+        $qb->select(['id', 'deleted_at'])
+            ->from('calendars')
+            ->where($qb->expr()->isNotNull('deleted_at'))
+            ->andWhere($qb->expr()->lt('deleted_at', $qb->createNamedParameter($deletedBefore)));
+        $result = $qb->executeQuery();
+        $raw = $result->fetchAll();
+        $result->closeCursor();
+        return array_map(function ($row) {
+            return [
+                'id' => (int) $row['id'],
+                'deleted_at' => (int) $row['deleted_at'],
+            ];
+        }, $raw);
+    }
+
+    /**
+     * Returns a list of calendars for a principal.
+     *
+     * Every project is an array with the following keys:
+     *  * id, a unique id that will be used by other functions to modify the
+     *    calendar. This can be the same as the uri or a database key.
+     *  * uri, which the basename of the uri with which the calendar is
+     *    accessed.
+     *  * principaluri. The owner of the calendar. Almost always the same as
+     *    principalUri passed to this method.
+     *
+     * Furthermore it can contain webdav properties in clark notation. A very
+     * common one is '{DAV:}displayname'.
+     *
+     * Many clients also require:
+     * {urn:ietf:params:xml:ns:caldav}supported-calendar-component-set
+     * For this property, you can just return an instance of
+     * Sabre\CalDAV\Property\SupportedCalendarComponentSet.
+     *
+     * If you return {http://sabredav.org/ns}read-only and set the value to 1,
+     * ACL will automatically be put in read-only mode.
+     *
+     * @param string $principalUri
+     * @return array
+     */
+    public function getCalendarsForUser($principalUri) {
+        $principalUriOriginal = $principalUri;
+        $principalUri = $this->convertPrincipal($principalUri, true);
+        $fields = array_column($this->propertyMap, 0);
+        $fields[] = 'id';
+        $fields[] = 'uri';
+        $fields[] = 'synctoken';
+        $fields[] = 'components';
+        $fields[] = 'principaluri';
+        $fields[] = 'transparent';
+
+        // Making fields a comma-delimited list
+        $query = $this->db->getQueryBuilder();
+        $query->select($fields)
+            ->from('calendars')
+            ->orderBy('calendarorder', 'ASC');
+
+        if ($principalUri === '') {
+            $query->where($query->expr()->emptyString('principaluri'));
+        } else {
+            $query->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)));
+        }
+
+        $result = $query->executeQuery();
+
+        $calendars = [];
+        while ($row = $result->fetch()) {
+            $row['principaluri'] = (string) $row['principaluri'];
+            $components = [];
+            if ($row['components']) {
+                $components = explode(',', $row['components']);
+            }
+
+            $calendar = [
+                'id' => $row['id'],
+                'uri' => $row['uri'],
+                'principaluri' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
+                '{' . Plugin::NS_CALENDARSERVER . '}getctag' => 'http://sabre.io/ns/sync/' . ($row['synctoken']?$row['synctoken']:'0'),
+                '{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
+                '{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet($components),
+                '{' . Plugin::NS_CALDAV . '}schedule-calendar-transp' => new ScheduleCalendarTransp($row['transparent']?'transparent':'opaque'),
+                '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}owner-principal' => $this->convertPrincipal($principalUri, !$this->legacyEndpoint),
+            ];
+
+            $calendar = $this->rowToCalendar($row, $calendar);
+            $calendar = $this->addOwnerPrincipalToCalendar($calendar);
+            $calendar = $this->addResourceTypeToCalendar($row, $calendar);
+
+            if (!isset($calendars[$calendar['id']])) {
+                $calendars[$calendar['id']] = $calendar;
+            }
+        }
+        $result->closeCursor();
+
+        // query for shared calendars
+        $principals = $this->principalBackend->getGroupMembership($principalUriOriginal, true);
+        $principals = array_merge($principals, $this->principalBackend->getCircleMembership($principalUriOriginal));
+
+        $principals[] = $principalUri;
+
+        $fields = array_column($this->propertyMap, 0);
+        $fields[] = 'a.id';
+        $fields[] = 'a.uri';
+        $fields[] = 'a.synctoken';
+        $fields[] = 'a.components';
+        $fields[] = 'a.principaluri';
+        $fields[] = 'a.transparent';
+        $fields[] = 's.access';
+        $query = $this->db->getQueryBuilder();
+        $query->select($fields)
+            ->from('dav_shares', 's')
+            ->join('s', 'calendars', 'a', $query->expr()->eq('s.resourceid', 'a.id'))
+            ->where($query->expr()->in('s.principaluri', $query->createParameter('principaluri')))
+            ->andWhere($query->expr()->eq('s.type', $query->createParameter('type')))
+            ->setParameter('type', 'calendar')
+            ->setParameter('principaluri', $principals, \Doctrine\DBAL\Connection::PARAM_STR_ARRAY);
+
+        $result = $query->executeQuery();
+
+        $readOnlyPropertyName = '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}read-only';
+        while ($row = $result->fetch()) {
+            $row['principaluri'] = (string) $row['principaluri'];
+            if ($row['principaluri'] === $principalUri) {
+                continue;
+            }
+
+            $readOnly = (int) $row['access'] === Backend::ACCESS_READ;
+            if (isset($calendars[$row['id']])) {
+                if ($readOnly) {
+                    // New share can not have more permissions then the old one.
+                    continue;
+                }
+                if (isset($calendars[$row['id']][$readOnlyPropertyName]) &&
+                    $calendars[$row['id']][$readOnlyPropertyName] === 0) {
+                    // Old share is already read-write, no more permissions can be gained
+                    continue;
+                }
+            }
+
+            [, $name] = Uri\split($row['principaluri']);
+            $uri = $row['uri'] . '_shared_by_' . $name;
+            $row['displayname'] = $row['displayname'] . ' (' . ($this->userManager->getDisplayName($name) ?? ($name ?? '')) . ')';
+            $components = [];
+            if ($row['components']) {
+                $components = explode(',', $row['components']);
+            }
+            $calendar = [
+                'id' => $row['id'],
+                'uri' => $uri,
+                'principaluri' => $this->convertPrincipal($principalUri, !$this->legacyEndpoint),
+                '{' . Plugin::NS_CALENDARSERVER . '}getctag' => 'http://sabre.io/ns/sync/' . ($row['synctoken']?$row['synctoken']:'0'),
+                '{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
+                '{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet($components),
+                '{' . Plugin::NS_CALDAV . '}schedule-calendar-transp' => new ScheduleCalendarTransp('transparent'),
+                '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}owner-principal' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
+                $readOnlyPropertyName => $readOnly,
+            ];
+
+            $calendar = $this->rowToCalendar($row, $calendar);
+            $calendar = $this->addOwnerPrincipalToCalendar($calendar);
+            $calendar = $this->addResourceTypeToCalendar($row, $calendar);
+
+            $calendars[$calendar['id']] = $calendar;
+        }
+        $result->closeCursor();
+
+        return array_values($calendars);
+    }
+
+    /**
+     * @param $principalUri
+     * @return array
+     */
+    public function getUsersOwnCalendars($principalUri) {
+        $principalUri = $this->convertPrincipal($principalUri, true);
+        $fields = array_column($this->propertyMap, 0);
+        $fields[] = 'id';
+        $fields[] = 'uri';
+        $fields[] = 'synctoken';
+        $fields[] = 'components';
+        $fields[] = 'principaluri';
+        $fields[] = 'transparent';
+        // Making fields a comma-delimited list
+        $query = $this->db->getQueryBuilder();
+        $query->select($fields)->from('calendars')
+            ->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)))
+            ->orderBy('calendarorder', 'ASC');
+        $stmt = $query->executeQuery();
+        $calendars = [];
+        while ($row = $stmt->fetch()) {
+            $row['principaluri'] = (string) $row['principaluri'];
+            $components = [];
+            if ($row['components']) {
+                $components = explode(',', $row['components']);
+            }
+            $calendar = [
+                'id' => $row['id'],
+                'uri' => $row['uri'],
+                'principaluri' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
+                '{' . Plugin::NS_CALENDARSERVER . '}getctag' => 'http://sabre.io/ns/sync/' . ($row['synctoken']?$row['synctoken']:'0'),
+                '{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
+                '{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet($components),
+                '{' . Plugin::NS_CALDAV . '}schedule-calendar-transp' => new ScheduleCalendarTransp($row['transparent']?'transparent':'opaque'),
+            ];
+
+            $calendar = $this->rowToCalendar($row, $calendar);
+            $calendar = $this->addOwnerPrincipalToCalendar($calendar);
+            $calendar = $this->addResourceTypeToCalendar($row, $calendar);
+
+            if (!isset($calendars[$calendar['id']])) {
+                $calendars[$calendar['id']] = $calendar;
+            }
+        }
+        $stmt->closeCursor();
+        return array_values($calendars);
+    }
+
+    /**
+     * @return array
+     */
+    public function getPublicCalendars() {
+        $fields = array_column($this->propertyMap, 0);
+        $fields[] = 'a.id';
+        $fields[] = 'a.uri';
+        $fields[] = 'a.synctoken';
+        $fields[] = 'a.components';
+        $fields[] = 'a.principaluri';
+        $fields[] = 'a.transparent';
+        $fields[] = 's.access';
+        $fields[] = 's.publicuri';
+        $calendars = [];
+        $query = $this->db->getQueryBuilder();
+        $result = $query->select($fields)
+            ->from('dav_shares', 's')
+            ->join('s', 'calendars', 'a', $query->expr()->eq('s.resourceid', 'a.id'))
+            ->where($query->expr()->in('s.access', $query->createNamedParameter(self::ACCESS_PUBLIC)))
+            ->andWhere($query->expr()->eq('s.type', $query->createNamedParameter('calendar')))
+            ->executeQuery();
+
+        while ($row = $result->fetch()) {
+            $row['principaluri'] = (string) $row['principaluri'];
+            [, $name] = Uri\split($row['principaluri']);
+            $row['displayname'] = $row['displayname'] . "($name)";
+            $components = [];
+            if ($row['components']) {
+                $components = explode(',', $row['components']);
+            }
+            $calendar = [
+                'id' => $row['id'],
+                'uri' => $row['publicuri'],
+                'principaluri' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
+                '{' . Plugin::NS_CALENDARSERVER . '}getctag' => 'http://sabre.io/ns/sync/' . ($row['synctoken']?$row['synctoken']:'0'),
+                '{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
+                '{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet($components),
+                '{' . Plugin::NS_CALDAV . '}schedule-calendar-transp' => new ScheduleCalendarTransp($row['transparent']?'transparent':'opaque'),
+                '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}owner-principal' => $this->convertPrincipal($row['principaluri'], $this->legacyEndpoint),
+                '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}read-only' => (int)$row['access'] === Backend::ACCESS_READ,
+                '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}public' => (int)$row['access'] === self::ACCESS_PUBLIC,
+            ];
+
+            $calendar = $this->rowToCalendar($row, $calendar);
+            $calendar = $this->addOwnerPrincipalToCalendar($calendar);
+            $calendar = $this->addResourceTypeToCalendar($row, $calendar);
+
+            if (!isset($calendars[$calendar['id']])) {
+                $calendars[$calendar['id']] = $calendar;
+            }
+        }
+        $result->closeCursor();
+
+        return array_values($calendars);
+    }
+
+    /**
+     * @param string $uri
+     * @return array
+     * @throws NotFound
+     */
+    public function getPublicCalendar($uri) {
+        $fields = array_column($this->propertyMap, 0);
+        $fields[] = 'a.id';
+        $fields[] = 'a.uri';
+        $fields[] = 'a.synctoken';
+        $fields[] = 'a.components';
+        $fields[] = 'a.principaluri';
+        $fields[] = 'a.transparent';
+        $fields[] = 's.access';
+        $fields[] = 's.publicuri';
+        $query = $this->db->getQueryBuilder();
+        $result = $query->select($fields)
+            ->from('dav_shares', 's')
+            ->join('s', 'calendars', 'a', $query->expr()->eq('s.resourceid', 'a.id'))
+            ->where($query->expr()->in('s.access', $query->createNamedParameter(self::ACCESS_PUBLIC)))
+            ->andWhere($query->expr()->eq('s.type', $query->createNamedParameter('calendar')))
+            ->andWhere($query->expr()->eq('s.publicuri', $query->createNamedParameter($uri)))
+            ->executeQuery();
+
+        $row = $result->fetch();
+
+        $result->closeCursor();
+
+        if ($row === false) {
+            throw new NotFound('Node with name \'' . $uri . '\' could not be found');
+        }
+
+        $row['principaluri'] = (string) $row['principaluri'];
+        [, $name] = Uri\split($row['principaluri']);
+        $row['displayname'] = $row['displayname'] . ' ' . "($name)";
+        $components = [];
+        if ($row['components']) {
+            $components = explode(',', $row['components']);
+        }
+        $calendar = [
+            'id' => $row['id'],
+            'uri' => $row['publicuri'],
+            'principaluri' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
+            '{' . Plugin::NS_CALENDARSERVER . '}getctag' => 'http://sabre.io/ns/sync/' . ($row['synctoken']?$row['synctoken']:'0'),
+            '{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
+            '{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet($components),
+            '{' . Plugin::NS_CALDAV . '}schedule-calendar-transp' => new ScheduleCalendarTransp($row['transparent']?'transparent':'opaque'),
+            '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}owner-principal' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
+            '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}read-only' => (int)$row['access'] === Backend::ACCESS_READ,
+            '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}public' => (int)$row['access'] === self::ACCESS_PUBLIC,
+        ];
+
+        $calendar = $this->rowToCalendar($row, $calendar);
+        $calendar = $this->addOwnerPrincipalToCalendar($calendar);
+        $calendar = $this->addResourceTypeToCalendar($row, $calendar);
+
+        return $calendar;
+    }
+
+    /**
+     * @param string $principal
+     * @param string $uri
+     * @return array|null
+     */
+    public function getCalendarByUri($principal, $uri) {
+        $fields = array_column($this->propertyMap, 0);
+        $fields[] = 'id';
+        $fields[] = 'uri';
+        $fields[] = 'synctoken';
+        $fields[] = 'components';
+        $fields[] = 'principaluri';
+        $fields[] = 'transparent';
+
+        // Making fields a comma-delimited list
+        $query = $this->db->getQueryBuilder();
+        $query->select($fields)->from('calendars')
+            ->where($query->expr()->eq('uri', $query->createNamedParameter($uri)))
+            ->andWhere($query->expr()->eq('principaluri', $query->createNamedParameter($principal)))
+            ->setMaxResults(1);
+        $stmt = $query->executeQuery();
+
+        $row = $stmt->fetch();
+        $stmt->closeCursor();
+        if ($row === false) {
+            return null;
+        }
+
+        $row['principaluri'] = (string) $row['principaluri'];
+        $components = [];
+        if ($row['components']) {
+            $components = explode(',', $row['components']);
+        }
+
+        $calendar = [
+            'id' => $row['id'],
+            'uri' => $row['uri'],
+            'principaluri' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
+            '{' . Plugin::NS_CALENDARSERVER . '}getctag' => 'http://sabre.io/ns/sync/' . ($row['synctoken']?$row['synctoken']:'0'),
+            '{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
+            '{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet($components),
+            '{' . Plugin::NS_CALDAV . '}schedule-calendar-transp' => new ScheduleCalendarTransp($row['transparent']?'transparent':'opaque'),
+        ];
+
+        $calendar = $this->rowToCalendar($row, $calendar);
+        $calendar = $this->addOwnerPrincipalToCalendar($calendar);
+        $calendar = $this->addResourceTypeToCalendar($row, $calendar);
+
+        return $calendar;
+    }
+
+    /**
+     * @return array{id: int, uri: string, '{http://calendarserver.org/ns/}getctag': string, '{http://sabredav.org/ns}sync-token': int, '{urn:ietf:params:xml:ns:caldav}supported-calendar-component-set': SupportedCalendarComponentSet, '{urn:ietf:params:xml:ns:caldav}schedule-calendar-transp': ScheduleCalendarTransp, '{urn:ietf:params:xml:ns:caldav}calendar-timezone': ?string }|null
+     */
+    public function getCalendarById(int $calendarId): ?array {
+        $fields = array_column($this->propertyMap, 0);
+        $fields[] = 'id';
+        $fields[] = 'uri';
+        $fields[] = 'synctoken';
+        $fields[] = 'components';
+        $fields[] = 'principaluri';
+        $fields[] = 'transparent';
+
+        // Making fields a comma-delimited list
+        $query = $this->db->getQueryBuilder();
+        $query->select($fields)->from('calendars')
+            ->where($query->expr()->eq('id', $query->createNamedParameter($calendarId)))
+            ->setMaxResults(1);
+        $stmt = $query->executeQuery();
+
+        $row = $stmt->fetch();
+        $stmt->closeCursor();
+        if ($row === false) {
+            return null;
+        }
+
+        $row['principaluri'] = (string) $row['principaluri'];
+        $components = [];
+        if ($row['components']) {
+            $components = explode(',', $row['components']);
+        }
+
+        $calendar = [
+            'id' => $row['id'],
+            'uri' => $row['uri'],
+            'principaluri' => $this->convertPrincipal($row['principaluri'], !$this->legacyEndpoint),
+            '{' . Plugin::NS_CALENDARSERVER . '}getctag' => 'http://sabre.io/ns/sync/' . ($row['synctoken']?$row['synctoken']:'0'),
+            '{http://sabredav.org/ns}sync-token' => $row['synctoken'] ?? 0,
+            '{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet($components),
+            '{' . Plugin::NS_CALDAV . '}schedule-calendar-transp' => new ScheduleCalendarTransp($row['transparent']?'transparent':'opaque'),
+        ];
+
+        $calendar = $this->rowToCalendar($row, $calendar);
+        $calendar = $this->addOwnerPrincipalToCalendar($calendar);
+        $calendar = $this->addResourceTypeToCalendar($row, $calendar);
+
+        return $calendar;
+    }
+
+    /**
+     * @param $subscriptionId
+     */
+    public function getSubscriptionById($subscriptionId) {
+        $fields = array_column($this->subscriptionPropertyMap, 0);
+        $fields[] = 'id';
+        $fields[] = 'uri';
+        $fields[] = 'source';
+        $fields[] = 'synctoken';
+        $fields[] = 'principaluri';
+        $fields[] = 'lastmodified';
+
+        $query = $this->db->getQueryBuilder();
+        $query->select($fields)
+            ->from('calendarsubscriptions')
+            ->where($query->expr()->eq('id', $query->createNamedParameter($subscriptionId)))
+            ->orderBy('calendarorder', 'asc');
+        $stmt = $query->executeQuery();
+
+        $row = $stmt->fetch();
+        $stmt->closeCursor();
+        if ($row === false) {
+            return null;
+        }
+
+        $row['principaluri'] = (string) $row['principaluri'];
+        $subscription = [
+            'id' => $row['id'],
+            'uri' => $row['uri'],
+            'principaluri' => $row['principaluri'],
+            'source' => $row['source'],
+            'lastmodified' => $row['lastmodified'],
+            '{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet(['VTODO', 'VEVENT']),
+            '{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
+        ];
+
+        return $this->rowToSubscription($row, $subscription);
+    }
+
+    /**
+     * Creates a new calendar for a principal.
+     *
+     * If the creation was a success, an id must be returned that can be used to reference
+     * this calendar in other methods, such as updateCalendar.
+     *
+     * @param string $principalUri
+     * @param string $calendarUri
+     * @param array $properties
+     * @return int
+     *
+     * @throws CalendarException
+     */
+    public function createCalendar($principalUri, $calendarUri, array $properties) {
+        if (strlen($calendarUri) > 255) {
+            throw new CalendarException('URI too long. Calendar not created');
+        }
+
+        $values = [
+            'principaluri' => $this->convertPrincipal($principalUri, true),
+            'uri' => $calendarUri,
+            'synctoken' => 1,
+            'transparent' => 0,
+            'components' => 'VEVENT,VTODO',
+            'displayname' => $calendarUri
+        ];
+
+        // Default value
+        $sccs = '{urn:ietf:params:xml:ns:caldav}supported-calendar-component-set';
+        if (isset($properties[$sccs])) {
+            if (!($properties[$sccs] instanceof SupportedCalendarComponentSet)) {
+                throw new DAV\Exception('The ' . $sccs . ' property must be of type: \Sabre\CalDAV\Property\SupportedCalendarComponentSet');
+            }
+            $values['components'] = implode(',', $properties[$sccs]->getValue());
+        } elseif (isset($properties['components'])) {
+            // Allow to provide components internally without having
+            // to create a SupportedCalendarComponentSet object
+            $values['components'] = $properties['components'];
+        }
+
+        $transp = '{' . Plugin::NS_CALDAV . '}schedule-calendar-transp';
+        if (isset($properties[$transp])) {
+            $values['transparent'] = (int) ($properties[$transp]->getValue() === 'transparent');
+        }
+
+        foreach ($this->propertyMap as $xmlName => [$dbName, $type]) {
+            if (isset($properties[$xmlName])) {
+                $values[$dbName] = $properties[$xmlName];
+            }
+        }
+
+        [$calendarId, $calendarData] = $this->atomic(function () use ($values) {
+            $query = $this->db->getQueryBuilder();
+            $query->insert('calendars');
+            foreach ($values as $column => $value) {
+                $query->setValue($column, $query->createNamedParameter($value));
+            }
+            $query->executeStatement();
+            $calendarId = $query->getLastInsertId();
+
+            $calendarData = $this->getCalendarById($calendarId);
+            return [$calendarId, $calendarData];
+        }, $this->db);
+
+        $this->dispatcher->dispatchTyped(new CalendarCreatedEvent((int)$calendarId, $calendarData));
+
+        return $calendarId;
+    }
+
+    /**
+     * Updates properties for a calendar.
+     *
+     * The list of mutations is stored in a Sabre\DAV\PropPatch object.
+     * To do the actual updates, you must tell this object which properties
+     * you're going to process with the handle() method.
+     *
+     * Calling the handle method is like telling the PropPatch object "I
+     * promise I can handle updating this property".
+     *
+     * Read the PropPatch documentation for more info and examples.
+     *
+     * @param mixed $calendarId
+     * @param PropPatch $propPatch
+     * @return void
+     */
+    public function updateCalendar($calendarId, PropPatch $propPatch) {
+        $supportedProperties = array_keys($this->propertyMap);
+        $supportedProperties[] = '{' . Plugin::NS_CALDAV . '}schedule-calendar-transp';
+
+        $propPatch->handle($supportedProperties, function ($mutations) use ($calendarId) {
+            $newValues = [];
+            foreach ($mutations as $propertyName => $propertyValue) {
+                switch ($propertyName) {
+                    case '{' . Plugin::NS_CALDAV . '}schedule-calendar-transp':
+                        $fieldName = 'transparent';
+                        $newValues[$fieldName] = (int) ($propertyValue->getValue() === 'transparent');
+                        break;
+                    default:
+                        $fieldName = $this->propertyMap[$propertyName][0];
+                        $newValues[$fieldName] = $propertyValue;
+                        break;
+                }
+            }
+            $query = $this->db->getQueryBuilder();
+            $query->update('calendars');
+            foreach ($newValues as $fieldName => $value) {
+                $query->set($fieldName, $query->createNamedParameter($value));
+            }
+            $query->where($query->expr()->eq('id', $query->createNamedParameter($calendarId)));
+            $query->executeStatement();
+
+            $this->addChange($calendarId, "", 2);
+
+            $calendarData = $this->getCalendarById($calendarId);
+            $shares = $this->getShares($calendarId);
+            $this->dispatcher->dispatchTyped(new CalendarUpdatedEvent($calendarId, $calendarData, $shares, $mutations));
+
+            return true;
+        });
+    }
+
+    /**
+     * Delete a calendar and all it's objects
+     *
+     * @param mixed $calendarId
+     * @return void
+     */
+    public function deleteCalendar($calendarId, bool $forceDeletePermanently = false) {
+        // The calendar is deleted right away if this is either enforced by the caller
+        // or the special contacts birthday calendar or when the preference of an empty
+        // retention (0 seconds) is set, which signals a disabled trashbin.
+        $calendarData = $this->getCalendarById($calendarId);
+        $isBirthdayCalendar = isset($calendarData['uri']) && $calendarData['uri'] === BirthdayService::BIRTHDAY_CALENDAR_URI;
+        $trashbinDisabled = $this->config->getAppValue(Application::APP_ID, RetentionService::RETENTION_CONFIG_KEY) === '0';
+        if ($forceDeletePermanently || $isBirthdayCalendar || $trashbinDisabled) {
+            $calendarData = $this->getCalendarById($calendarId);
+            $shares = $this->getShares($calendarId);
+
+            $qbDeleteCalendarObjectProps = $this->db->getQueryBuilder();
+            $qbDeleteCalendarObjectProps->delete($this->dbObjectPropertiesTable)
+                ->where($qbDeleteCalendarObjectProps->expr()->eq('calendarid', $qbDeleteCalendarObjectProps->createNamedParameter($calendarId)))
+                ->andWhere($qbDeleteCalendarObjectProps->expr()->eq('calendartype', $qbDeleteCalendarObjectProps->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)))
+                ->executeStatement();
+
+            $qbDeleteCalendarObjects = $this->db->getQueryBuilder();
+            $qbDeleteCalendarObjects->delete('calendarobjects')
+                ->where($qbDeleteCalendarObjects->expr()->eq('calendarid', $qbDeleteCalendarObjects->createNamedParameter($calendarId)))
+                ->andWhere($qbDeleteCalendarObjects->expr()->eq('calendartype', $qbDeleteCalendarObjects->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)))
+                ->executeStatement();
+
+            $qbDeleteCalendarChanges = $this->db->getQueryBuilder();
+            $qbDeleteCalendarChanges->delete('calendarchanges')
+                ->where($qbDeleteCalendarChanges->expr()->eq('calendarid', $qbDeleteCalendarChanges->createNamedParameter($calendarId)))
+                ->andWhere($qbDeleteCalendarChanges->expr()->eq('calendartype', $qbDeleteCalendarChanges->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)))
+                ->executeStatement();
+
+            $this->calendarSharingBackend->deleteAllShares($calendarId);
+
+            $qbDeleteCalendar = $this->db->getQueryBuilder();
+            $qbDeleteCalendar->delete('calendars')
+                ->where($qbDeleteCalendar->expr()->eq('id', $qbDeleteCalendar->createNamedParameter($calendarId)))
+                ->executeStatement();
+
+            // Only dispatch if we actually deleted anything
+            if ($calendarData) {
+                $this->dispatcher->dispatchTyped(new CalendarDeletedEvent($calendarId, $calendarData, $shares));
+            }
+        } else {
+            $qbMarkCalendarDeleted = $this->db->getQueryBuilder();
+            $qbMarkCalendarDeleted->update('calendars')
+                ->set('deleted_at', $qbMarkCalendarDeleted->createNamedParameter(time()))
+                ->where($qbMarkCalendarDeleted->expr()->eq('id', $qbMarkCalendarDeleted->createNamedParameter($calendarId)))
+                ->executeStatement();
+
+            $calendarData = $this->getCalendarById($calendarId);
+            $shares = $this->getShares($calendarId);
+            if ($calendarData) {
+                $this->dispatcher->dispatchTyped(new CalendarMovedToTrashEvent(
+                    $calendarId,
+                    $calendarData,
+                    $shares
+                ));
+            }
+        }
+    }
+
+    public function restoreCalendar(int $id): void {
+        $qb = $this->db->getQueryBuilder();
+        $update = $qb->update('calendars')
+            ->set('deleted_at', $qb->createNamedParameter(null))
+            ->where($qb->expr()->eq('id', $qb->createNamedParameter($id, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT));
+        $update->executeStatement();
+
+        $calendarData = $this->getCalendarById($id);
+        $shares = $this->getShares($id);
+        if ($calendarData === null) {
+            throw new RuntimeException('Calendar data that was just written can\'t be read back. Check your database configuration.');
+        }
+        $this->dispatcher->dispatchTyped(new CalendarRestoredEvent(
+            $id,
+            $calendarData,
+            $shares
+        ));
+    }
+
+    /**
+     * Delete all of an user's shares
+     *
+     * @param string $principaluri
+     * @return void
+     */
+    public function deleteAllSharesByUser($principaluri) {
+        $this->calendarSharingBackend->deleteAllSharesByUser($principaluri);
+    }
+
+    /**
+     * Returns all calendar objects within a calendar.
+     *
+     * Every item contains an array with the following keys:
+     *   * calendardata - The iCalendar-compatible calendar data
+     *   * uri - a unique key which will be used to construct the uri. This can
+     *     be any arbitrary string, but making sure it ends with '.ics' is a
+     *     good idea. This is only the basename, or filename, not the full
+     *     path.
+     *   * lastmodified - a timestamp of the last modification time
+     *   * etag - An arbitrary string, surrounded by double-quotes. (e.g.:
+     *   '"abcdef"')
+     *   * size - The size of the calendar objects, in bytes.
+     *   * component - optional, a string containing the type of object, such
+     *     as 'vevent' or 'vtodo'. If specified, this will be used to populate
+     *     the Content-Type header.
+     *
+     * Note that the etag is optional, but it's highly encouraged to return for
+     * speed reasons.
+     *
+     * The calendardata is also optional. If it's not returned
+     * 'getCalendarObject' will be called later, which *is* expected to return
+     * calendardata.
+     *
+     * If neither etag or size are specified, the calendardata will be
+     * used/fetched to determine these numbers. If both are specified the
+     * amount of times this is needed is reduced by a great degree.
+     *
+     * @param mixed $calendarId
+     * @param int $calendarType
+     * @return array
+     */
+    public function getCalendarObjects($calendarId, $calendarType = self::CALENDAR_TYPE_CALENDAR):array {
+        $query = $this->db->getQueryBuilder();
+        $query->select(['id', 'uri', 'lastmodified', 'etag', 'calendarid', 'size', 'componenttype', 'classification'])
+            ->from('calendarobjects')
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)))
+            ->andWhere($query->expr()->isNull('deleted_at'));
+        $stmt = $query->executeQuery();
+
+        $result = [];
+        foreach ($stmt->fetchAll() as $row) {
+            $result[] = [
+                'id' => $row['id'],
+                'uri' => $row['uri'],
+                'lastmodified' => $row['lastmodified'],
+                'etag' => '"' . $row['etag'] . '"',
+                'calendarid' => $row['calendarid'],
+                'size' => (int)$row['size'],
+                'component' => strtolower($row['componenttype']),
+                'classification' => (int)$row['classification']
+            ];
+        }
+        $stmt->closeCursor();
+
+        return $result;
+    }
+
+    public function getDeletedCalendarObjects(int $deletedBefore): array {
+        $query = $this->db->getQueryBuilder();
+        $query->select(['co.id', 'co.uri', 'co.lastmodified', 'co.etag', 'co.calendarid', 'co.calendartype', 'co.size', 'co.componenttype', 'co.classification', 'co.deleted_at'])
+            ->from('calendarobjects', 'co')
+            ->join('co', 'calendars', 'c', $query->expr()->eq('c.id', 'co.calendarid', IQueryBuilder::PARAM_INT))
+            ->where($query->expr()->isNotNull('co.deleted_at'))
+            ->andWhere($query->expr()->lt('co.deleted_at', $query->createNamedParameter($deletedBefore)));
+        $stmt = $query->executeQuery();
+
+        $result = [];
+        foreach ($stmt->fetchAll() as $row) {
+            $result[] = [
+                'id' => $row['id'],
+                'uri' => $row['uri'],
+                'lastmodified' => $row['lastmodified'],
+                'etag' => '"' . $row['etag'] . '"',
+                'calendarid' => (int) $row['calendarid'],
+                'calendartype' => (int) $row['calendartype'],
+                'size' => (int) $row['size'],
+                'component' => strtolower($row['componenttype']),
+                'classification' => (int) $row['classification'],
+                '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_NEXTCLOUD . '}deleted-at' => $row['deleted_at'] === null ? $row['deleted_at'] : (int) $row['deleted_at'],
+            ];
+        }
+        $stmt->closeCursor();
+
+        return $result;
+    }
+
+    /**
+     * Return all deleted calendar objects by the given principal that are not
+     * in deleted calendars.
+     *
+     * @param string $principalUri
+     * @return array
+     * @throws Exception
+     */
+    public function getDeletedCalendarObjectsByPrincipal(string $principalUri): array {
+        $query = $this->db->getQueryBuilder();
+        $query->select(['co.id', 'co.uri', 'co.lastmodified', 'co.etag', 'co.calendarid', 'co.size', 'co.componenttype', 'co.classification', 'co.deleted_at'])
+            ->selectAlias('c.uri', 'calendaruri')
+            ->from('calendarobjects', 'co')
+            ->join('co', 'calendars', 'c', $query->expr()->eq('c.id', 'co.calendarid', IQueryBuilder::PARAM_INT))
+            ->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)))
+            ->andWhere($query->expr()->isNotNull('co.deleted_at'))
+            ->andWhere($query->expr()->isNull('c.deleted_at'));
+        $stmt = $query->executeQuery();
+
+        $result = [];
+        while ($row = $stmt->fetch()) {
+            $result[] = [
+                'id' => $row['id'],
+                'uri' => $row['uri'],
+                'lastmodified' => $row['lastmodified'],
+                'etag' => '"' . $row['etag'] . '"',
+                'calendarid' => $row['calendarid'],
+                'calendaruri' => $row['calendaruri'],
+                'size' => (int)$row['size'],
+                'component' => strtolower($row['componenttype']),
+                'classification' => (int)$row['classification'],
+                '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_NEXTCLOUD . '}deleted-at' => $row['deleted_at'] === null ? $row['deleted_at'] : (int) $row['deleted_at'],
+            ];
+        }
+        $stmt->closeCursor();
+
+        return $result;
+    }
+
+    /**
+     * Returns information from a single calendar object, based on it's object
+     * uri.
+     *
+     * The object uri is only the basename, or filename and not a full path.
+     *
+     * The returned array must have the same keys as getCalendarObjects. The
+     * 'calendardata' object is required here though, while it's not required
+     * for getCalendarObjects.
+     *
+     * This method must return null if the object did not exist.
+     *
+     * @param mixed $calendarId
+     * @param string $objectUri
+     * @param int $calendarType
+     * @return array|null
+     */
+    public function getCalendarObject($calendarId, $objectUri, int $calendarType = self::CALENDAR_TYPE_CALENDAR) {
+        $query = $this->db->getQueryBuilder();
+        $query->select(['id', 'uri', 'lastmodified', 'etag', 'calendarid', 'size', 'calendardata', 'componenttype', 'classification', 'deleted_at'])
+            ->from('calendarobjects')
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)))
+            ->andWhere($query->expr()->eq('uri', $query->createNamedParameter($objectUri)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)));
+        $stmt = $query->executeQuery();
+        $row = $stmt->fetch();
+        $stmt->closeCursor();
+
+        if (!$row) {
+            return null;
+        }
+
+        return [
+            'id' => $row['id'],
+            'uri' => $row['uri'],
+            'lastmodified' => $row['lastmodified'],
+            'etag' => '"' . $row['etag'] . '"',
+            'calendarid' => $row['calendarid'],
+            'size' => (int)$row['size'],
+            'calendardata' => $this->readBlob($row['calendardata']),
+            'component' => strtolower($row['componenttype']),
+            'classification' => (int)$row['classification'],
+            '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_NEXTCLOUD . '}deleted-at' => $row['deleted_at'] === null ? $row['deleted_at'] : (int) $row['deleted_at'],
+        ];
+    }
+
+    /**
+     * Returns a list of calendar objects.
+     *
+     * This method should work identical to getCalendarObject, but instead
+     * return all the calendar objects in the list as an array.
+     *
+     * If the backend supports this, it may allow for some speed-ups.
+     *
+     * @param mixed $calendarId
+     * @param string[] $uris
+     * @param int $calendarType
+     * @return array
+     */
+    public function getMultipleCalendarObjects($calendarId, array $uris, $calendarType = self::CALENDAR_TYPE_CALENDAR):array {
+        if (empty($uris)) {
+            return [];
+        }
+
+        $chunks = array_chunk($uris, 100);
+        $objects = [];
+
+        $query = $this->db->getQueryBuilder();
+        $query->select(['id', 'uri', 'lastmodified', 'etag', 'calendarid', 'size', 'calendardata', 'componenttype', 'classification'])
+            ->from('calendarobjects')
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)))
+            ->andWhere($query->expr()->in('uri', $query->createParameter('uri')))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)))
+            ->andWhere($query->expr()->isNull('deleted_at'));
+
+        foreach ($chunks as $uris) {
+            $query->setParameter('uri', $uris, IQueryBuilder::PARAM_STR_ARRAY);
+            $result = $query->executeQuery();
+
+            while ($row = $result->fetch()) {
+                $objects[] = [
+                    'id' => $row['id'],
+                    'uri' => $row['uri'],
+                    'lastmodified' => $row['lastmodified'],
+                    'etag' => '"' . $row['etag'] . '"',
+                    'calendarid' => $row['calendarid'],
+                    'size' => (int)$row['size'],
+                    'calendardata' => $this->readBlob($row['calendardata']),
+                    'component' => strtolower($row['componenttype']),
+                    'classification' => (int)$row['classification']
+                ];
+            }
+            $result->closeCursor();
+        }
+
+        return $objects;
+    }
+
+    /**
+     * Creates a new calendar object.
+     *
+     * The object uri is only the basename, or filename and not a full path.
+     *
+     * It is possible return an etag from this function, which will be used in
+     * the response to this PUT request. Note that the ETag must be surrounded
+     * by double-quotes.
+     *
+     * However, you should only really return this ETag if you don't mangle the
+     * calendar-data. If the result of a subsequent GET to this object is not
+     * the exact same as this request body, you should omit the ETag.
+     *
+     * @param mixed $calendarId
+     * @param string $objectUri
+     * @param string $calendarData
+     * @param int $calendarType
+     * @return string
+     */
+    public function createCalendarObject($calendarId, $objectUri, $calendarData, $calendarType = self::CALENDAR_TYPE_CALENDAR) {
+        $extraData = $this->getDenormalizedData($calendarData);
+
+        // Try to detect duplicates
+        $qb = $this->db->getQueryBuilder();
+        $qb->select($qb->func()->count('*'))
+            ->from('calendarobjects')
+            ->where($qb->expr()->eq('calendarid', $qb->createNamedParameter($calendarId)))
+            ->andWhere($qb->expr()->eq('uid', $qb->createNamedParameter($extraData['uid'])))
+            ->andWhere($qb->expr()->eq('calendartype', $qb->createNamedParameter($calendarType)))
+            ->andWhere($qb->expr()->isNull('deleted_at'));
+        $result = $qb->executeQuery();
+        $count = (int) $result->fetchOne();
+        $result->closeCursor();
+
+        if ($count !== 0) {
+            throw new BadRequest('Calendar object with uid already exists in this calendar collection.');
+        }
+        // For a more specific error message we also try to explicitly look up the UID but as a deleted entry
+        $qbDel = $this->db->getQueryBuilder();
+        $qbDel->select($qb->func()->count('*'))
+            ->from('calendarobjects')
+            ->where($qbDel->expr()->eq('calendarid', $qbDel->createNamedParameter($calendarId)))
+            ->andWhere($qbDel->expr()->eq('uid', $qbDel->createNamedParameter($extraData['uid'])))
+            ->andWhere($qbDel->expr()->eq('calendartype', $qbDel->createNamedParameter($calendarType)))
+            ->andWhere($qbDel->expr()->isNotNull('deleted_at'));
+        $result = $qbDel->executeQuery();
+        $count = (int) $result->fetchOne();
+        $result->closeCursor();
+        if ($count !== 0) {
+            throw new BadRequest('Deleted calendar object with uid already exists in this calendar collection.');
+        }
+
+        $query = $this->db->getQueryBuilder();
+        $query->insert('calendarobjects')
+            ->values([
+                'calendarid' => $query->createNamedParameter($calendarId),
+                'uri' => $query->createNamedParameter($objectUri),
+                'calendardata' => $query->createNamedParameter($calendarData, IQueryBuilder::PARAM_LOB),
+                'lastmodified' => $query->createNamedParameter(time()),
+                'etag' => $query->createNamedParameter($extraData['etag']),
+                'size' => $query->createNamedParameter($extraData['size']),
+                'componenttype' => $query->createNamedParameter($extraData['componentType']),
+                'firstoccurence' => $query->createNamedParameter($extraData['firstOccurence']),
+                'lastoccurence' => $query->createNamedParameter($extraData['lastOccurence']),
+                'classification' => $query->createNamedParameter($extraData['classification']),
+                'uid' => $query->createNamedParameter($extraData['uid']),
+                'calendartype' => $query->createNamedParameter($calendarType),
+            ])
+            ->executeStatement();
+
+        $this->updateProperties($calendarId, $objectUri, $calendarData, $calendarType);
+        $this->addChange($calendarId, $objectUri, 1, $calendarType);
+
+        $objectRow = $this->getCalendarObject($calendarId, $objectUri, $calendarType);
+        assert($objectRow !== null);
+
+        if ($calendarType === self::CALENDAR_TYPE_CALENDAR) {
+            $calendarRow = $this->getCalendarById($calendarId);
+            $shares = $this->getShares($calendarId);
+
+            $this->dispatcher->dispatchTyped(new CalendarObjectCreatedEvent($calendarId, $calendarRow, $shares, $objectRow));
+        } else {
+            $subscriptionRow = $this->getSubscriptionById($calendarId);
+
+            $this->dispatcher->dispatchTyped(new CachedCalendarObjectCreatedEvent($calendarId, $subscriptionRow, [], $objectRow));
+        }
+
+        return '"' . $extraData['etag'] . '"';
+    }
+
+    /**
+     * Updates an existing calendarobject, based on it's uri.
+     *
+     * The object uri is only the basename, or filename and not a full path.
+     *
+     * It is possible return an etag from this function, which will be used in
+     * the response to this PUT request. Note that the ETag must be surrounded
+     * by double-quotes.
+     *
+     * However, you should only really return this ETag if you don't mangle the
+     * calendar-data. If the result of a subsequent GET to this object is not
+     * the exact same as this request body, you should omit the ETag.
+     *
+     * @param mixed $calendarId
+     * @param string $objectUri
+     * @param string $calendarData
+     * @param int $calendarType
+     * @return string
+     */
+    public function updateCalendarObject($calendarId, $objectUri, $calendarData, $calendarType = self::CALENDAR_TYPE_CALENDAR) {
+        $extraData = $this->getDenormalizedData($calendarData);
+        $query = $this->db->getQueryBuilder();
+        $query->update('calendarobjects')
+                ->set('calendardata', $query->createNamedParameter($calendarData, IQueryBuilder::PARAM_LOB))
+                ->set('lastmodified', $query->createNamedParameter(time()))
+                ->set('etag', $query->createNamedParameter($extraData['etag']))
+                ->set('size', $query->createNamedParameter($extraData['size']))
+                ->set('componenttype', $query->createNamedParameter($extraData['componentType']))
+                ->set('firstoccurence', $query->createNamedParameter($extraData['firstOccurence']))
+                ->set('lastoccurence', $query->createNamedParameter($extraData['lastOccurence']))
+                ->set('classification', $query->createNamedParameter($extraData['classification']))
+                ->set('uid', $query->createNamedParameter($extraData['uid']))
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)))
+            ->andWhere($query->expr()->eq('uri', $query->createNamedParameter($objectUri)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)))
+            ->executeStatement();
+
+        $this->updateProperties($calendarId, $objectUri, $calendarData, $calendarType);
+        $this->addChange($calendarId, $objectUri, 2, $calendarType);
+
+        $objectRow = $this->getCalendarObject($calendarId, $objectUri, $calendarType);
+        if (is_array($objectRow)) {
+            if ($calendarType === self::CALENDAR_TYPE_CALENDAR) {
+                $calendarRow = $this->getCalendarById($calendarId);
+                $shares = $this->getShares($calendarId);
+
+                $this->dispatcher->dispatchTyped(new CalendarObjectUpdatedEvent($calendarId, $calendarRow, $shares, $objectRow));
+            } else {
+                $subscriptionRow = $this->getSubscriptionById($calendarId);
+
+                $this->dispatcher->dispatchTyped(new CachedCalendarObjectUpdatedEvent($calendarId, $subscriptionRow, [], $objectRow));
+            }
+        }
+
+        return '"' . $extraData['etag'] . '"';
+    }
+
+    /**
+     * Moves a calendar object from calendar to calendar.
+     *
+     * @param int $sourceCalendarId
+     * @param int $targetCalendarId
+     * @param int $objectId
+     * @param string $oldPrincipalUri
+     * @param string $newPrincipalUri
+     * @param int $calendarType
+     * @return bool
+     * @throws Exception
+     */
+    public function moveCalendarObject(int $sourceCalendarId, int $targetCalendarId, int $objectId, string $oldPrincipalUri, string $newPrincipalUri, int $calendarType = self::CALENDAR_TYPE_CALENDAR): bool {
+        $object = $this->getCalendarObjectById($oldPrincipalUri, $objectId);
+        if (empty($object)) {
+            return false;
+        }
+
+        $query = $this->db->getQueryBuilder();
+        $query->update('calendarobjects')
+            ->set('calendarid', $query->createNamedParameter($targetCalendarId, IQueryBuilder::PARAM_INT))
+            ->where($query->expr()->eq('id', $query->createNamedParameter($objectId, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT))
+            ->executeStatement();
+
+        $this->purgeProperties($sourceCalendarId, $objectId);
+        $this->updateProperties($targetCalendarId, $object['uri'], $object['calendardata'], $calendarType);
+
+        $this->addChange($sourceCalendarId, $object['uri'], 1, $calendarType);
+        $this->addChange($targetCalendarId, $object['uri'], 3, $calendarType);
+
+        $object = $this->getCalendarObjectById($newPrincipalUri, $objectId);
+        // Calendar Object wasn't found - possibly because it was deleted in the meantime by a different client
+        if (empty($object)) {
+            return false;
+        }
+
+        $targetCalendarRow = $this->getCalendarById($targetCalendarId);
+        // the calendar this event is being moved to does not exist any longer
+        if (empty($targetCalendarRow)) {
+            return false;
+        }
+
+        if ($calendarType === self::CALENDAR_TYPE_CALENDAR) {
+            $sourceShares = $this->getShares($sourceCalendarId);
+            $targetShares = $this->getShares($targetCalendarId);
+            $sourceCalendarRow = $this->getCalendarById($sourceCalendarId);
+            $this->dispatcher->dispatchTyped(new CalendarObjectMovedEvent($sourceCalendarId, $sourceCalendarRow, $targetCalendarId, $targetCalendarRow, $sourceShares, $targetShares, $object));
+        }
+        return true;
+    }
+
+
+    /**
+     * @param int $calendarObjectId
+     * @param int $classification
+     */
+    public function setClassification($calendarObjectId, $classification) {
+        if (!in_array($classification, [
+            self::CLASSIFICATION_PUBLIC, self::CLASSIFICATION_PRIVATE, self::CLASSIFICATION_CONFIDENTIAL
+        ])) {
+            throw new \InvalidArgumentException();
+        }
+        $query = $this->db->getQueryBuilder();
+        $query->update('calendarobjects')
+            ->set('classification', $query->createNamedParameter($classification))
+            ->where($query->expr()->eq('id', $query->createNamedParameter($calendarObjectId)))
+            ->executeStatement();
+    }
+
+    /**
+     * Deletes an existing calendar object.
+     *
+     * The object uri is only the basename, or filename and not a full path.
+     *
+     * @param mixed $calendarId
+     * @param string $objectUri
+     * @param int $calendarType
+     * @param bool $forceDeletePermanently
+     * @return void
+     */
+    public function deleteCalendarObject($calendarId, $objectUri, $calendarType = self::CALENDAR_TYPE_CALENDAR, bool $forceDeletePermanently = false) {
+        $data = $this->getCalendarObject($calendarId, $objectUri, $calendarType);
+
+        if ($data === null) {
+            // Nothing to delete
+            return;
+        }
+
+        if ($forceDeletePermanently || $this->config->getAppValue(Application::APP_ID, RetentionService::RETENTION_CONFIG_KEY) === '0') {
+            $stmt = $this->db->prepare('DELETE FROM `*PREFIX*calendarobjects` WHERE `calendarid` = ? AND `uri` = ? AND `calendartype` = ?');
+            $stmt->execute([$calendarId, $objectUri, $calendarType]);
+
+            $this->purgeProperties($calendarId, $data['id']);
+
+            if ($calendarType === self::CALENDAR_TYPE_CALENDAR) {
+                $calendarRow = $this->getCalendarById($calendarId);
+                $shares = $this->getShares($calendarId);
+
+                $this->dispatcher->dispatchTyped(new CalendarObjectDeletedEvent($calendarId, $calendarRow, $shares, $data));
+            } else {
+                $subscriptionRow = $this->getSubscriptionById($calendarId);
+
+                $this->dispatcher->dispatchTyped(new CachedCalendarObjectDeletedEvent($calendarId, $subscriptionRow, [], $data));
+            }
+        } else {
+            $pathInfo = pathinfo($data['uri']);
+            if (!empty($pathInfo['extension'])) {
+                // Append a suffix to "free" the old URI for recreation
+                $newUri = sprintf(
+                    "%s-deleted.%s",
+                    $pathInfo['filename'],
+                    $pathInfo['extension']
+                );
+            } else {
+                $newUri = sprintf(
+                    "%s-deleted",
+                    $pathInfo['filename']
+                );
+            }
+
+            // Try to detect conflicts before the DB does
+            // As unlikely as it seems, this can happen when the user imports, then deletes, imports and deletes again
+            $newObject = $this->getCalendarObject($calendarId, $newUri, $calendarType);
+            if ($newObject !== null) {
+                throw new Forbidden("A calendar object with URI $newUri already exists in calendar $calendarId, therefore this object can't be moved into the trashbin");
+            }
+
+            $qb = $this->db->getQueryBuilder();
+            $markObjectDeletedQuery = $qb->update('calendarobjects')
+                ->set('deleted_at', $qb->createNamedParameter(time(), IQueryBuilder::PARAM_INT))
+                ->set('uri', $qb->createNamedParameter($newUri))
+                ->where(
+                    $qb->expr()->eq('calendarid', $qb->createNamedParameter($calendarId)),
+                    $qb->expr()->eq('calendartype', $qb->createNamedParameter($calendarType, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT),
+                    $qb->expr()->eq('uri', $qb->createNamedParameter($objectUri))
+                );
+            $markObjectDeletedQuery->executeStatement();
+
+            $calendarData = $this->getCalendarById($calendarId);
+            if ($calendarData !== null) {
+                $this->dispatcher->dispatchTyped(
+                    new CalendarObjectMovedToTrashEvent(
+                        $calendarId,
+                        $calendarData,
+                        $this->getShares($calendarId),
+                        $data
+                    )
+                );
+            }
+        }
+
+        $this->addChange($calendarId, $objectUri, 3, $calendarType);
+    }
+
+    /**
+     * @param mixed $objectData
+     *
+     * @throws Forbidden
+     */
+    public function restoreCalendarObject(array $objectData): void {
+        $id = (int) $objectData['id'];
+        $restoreUri = str_replace("-deleted.ics", ".ics", $objectData['uri']);
+        $targetObject = $this->getCalendarObject(
+            $objectData['calendarid'],
+            $restoreUri
+        );
+        if ($targetObject !== null) {
+            throw new Forbidden("Can not restore calendar $id because a calendar object with the URI $restoreUri already exists");
+        }
+
+        $qb = $this->db->getQueryBuilder();
+        $update = $qb->update('calendarobjects')
+            ->set('uri', $qb->createNamedParameter($restoreUri))
+            ->set('deleted_at', $qb->createNamedParameter(null))
+            ->where($qb->expr()->eq('id', $qb->createNamedParameter($id, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT));
+        $update->executeStatement();
+
+        // Make sure this change is tracked in the changes table
+        $qb2 = $this->db->getQueryBuilder();
+        $selectObject = $qb2->select('calendardata', 'uri', 'calendarid', 'calendartype')
+            ->selectAlias('componenttype', 'component')
+            ->from('calendarobjects')
+            ->where($qb2->expr()->eq('id', $qb2->createNamedParameter($id, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT));
+        $result = $selectObject->executeQuery();
+        $row = $result->fetch();
+        $result->closeCursor();
+        if ($row === false) {
+            // Welp, this should possibly not have happened, but let's ignore
+            return;
+        }
+        $this->addChange($row['calendarid'], $row['uri'], 1, (int) $row['calendartype']);
+
+        $calendarRow = $this->getCalendarById((int) $row['calendarid']);
+        if ($calendarRow === null) {
+            throw new RuntimeException('Calendar object data that was just written can\'t be read back. Check your database configuration.');
+        }
+        $this->dispatcher->dispatchTyped(
+            new CalendarObjectRestoredEvent(
+                (int) $objectData['calendarid'],
+                $calendarRow,
+                $this->getShares((int) $row['calendarid']),
+                $row
+            )
+        );
+    }
+
+    /**
+     * Performs a calendar-query on the contents of this calendar.
+     *
+     * The calendar-query is defined in RFC4791 : CalDAV. Using the
+     * calendar-query it is possible for a client to request a specific set of
+     * object, based on contents of iCalendar properties, date-ranges and
+     * iCalendar component types (VTODO, VEVENT).
+     *
+     * This method should just return a list of (relative) urls that match this
+     * query.
+     *
+     * The list of filters are specified as an array. The exact array is
+     * documented by Sabre\CalDAV\CalendarQueryParser.
+     *
+     * Note that it is extremely likely that getCalendarObject for every path
+     * returned from this method will be called almost immediately after. You
+     * may want to anticipate this to speed up these requests.
+     *
+     * This method provides a default implementation, which parses *all* the
+     * iCalendar objects in the specified calendar.
+     *
+     * This default may well be good enough for personal use, and calendars
+     * that aren't very large. But if you anticipate high usage, big calendars
+     * or high loads, you are strongly advised to optimize certain paths.
+     *
+     * The best way to do so is override this method and to optimize
+     * specifically for 'common filters'.
+     *
+     * Requests that are extremely common are:
+     *   * requests for just VEVENTS
+     *   * requests for just VTODO
+     *   * requests with a time-range-filter on either VEVENT or VTODO.
+     *
+     * ..and combinations of these requests. It may not be worth it to try to
+     * handle every possible situation and just rely on the (relatively
+     * easy to use) CalendarQueryValidator to handle the rest.
+     *
+     * Note that especially time-range-filters may be difficult to parse. A
+     * time-range filter specified on a VEVENT must for instance also handle
+     * recurrence rules correctly.
+     * A good example of how to interpret all these filters can also simply
+     * be found in Sabre\CalDAV\CalendarQueryFilter. This class is as correct
+     * as possible, so it gives you a good idea on what type of stuff you need
+     * to think of.
+     *
+     * @param mixed $calendarId
+     * @param array $filters
+     * @param int $calendarType
+     * @return array
+     */
+    public function calendarQuery($calendarId, array $filters, $calendarType = self::CALENDAR_TYPE_CALENDAR):array {
+        $componentType = null;
+        $requirePostFilter = true;
+        $timeRange = null;
+
+        // if no filters were specified, we don't need to filter after a query
+        if (!$filters['prop-filters'] && !$filters['comp-filters']) {
+            $requirePostFilter = false;
+        }
+
+        // Figuring out if there's a component filter
+        if (count($filters['comp-filters']) > 0 && !$filters['comp-filters'][0]['is-not-defined']) {
+            $componentType = $filters['comp-filters'][0]['name'];
+
+            // Checking if we need post-filters
+            if (!$filters['prop-filters'] && !$filters['comp-filters'][0]['comp-filters'] && !$filters['comp-filters'][0]['time-range'] && !$filters['comp-filters'][0]['prop-filters']) {
+                $requirePostFilter = false;
+            }
+            // There was a time-range filter
+            if ($componentType === 'VEVENT' && isset($filters['comp-filters'][0]['time-range']) && is_array($filters['comp-filters'][0]['time-range'])) {
+                $timeRange = $filters['comp-filters'][0]['time-range'];
+
+                // If start time OR the end time is not specified, we can do a
+                // 100% accurate mysql query.
+                if (!$filters['prop-filters'] && !$filters['comp-filters'][0]['comp-filters'] && !$filters['comp-filters'][0]['prop-filters'] && (!$timeRange['start'] || !$timeRange['end'])) {
+                    $requirePostFilter = false;
+                }
+            }
+        }
+        $columns = ['uri'];
+        if ($requirePostFilter) {
+            $columns = ['uri', 'calendardata'];
+        }
+        $query = $this->db->getQueryBuilder();
+        $query->select($columns)
+            ->from('calendarobjects')
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)))
+            ->andWhere($query->expr()->isNull('deleted_at'));
+
+        if ($componentType) {
+            $query->andWhere($query->expr()->eq('componenttype', $query->createNamedParameter($componentType)));
+        }
+
+        if ($timeRange && $timeRange['start']) {
+            $query->andWhere($query->expr()->gt('lastoccurence', $query->createNamedParameter($timeRange['start']->getTimeStamp())));
+        }
+        if ($timeRange && $timeRange['end']) {
+            $query->andWhere($query->expr()->lt('firstoccurence', $query->createNamedParameter($timeRange['end']->getTimeStamp())));
+        }
+
+        $stmt = $query->executeQuery();
+
+        $result = [];
+        while ($row = $stmt->fetch()) {
+            if ($requirePostFilter) {
+                // validateFilterForObject will parse the calendar data
+                // catch parsing errors
+                try {
+                    $matches = $this->validateFilterForObject($row, $filters);
+                } catch (ParseException $ex) {
+                    $this->logger->error('Caught parsing exception for calendar data. This usually indicates invalid calendar data. calendar-id:'.$calendarId.' uri:'.$row['uri'], [
+                        'app' => 'dav',
+                        'exception' => $ex,
+                    ]);
+                    continue;
+                } catch (InvalidDataException $ex) {
+                    $this->logger->error('Caught invalid data exception for calendar data. This usually indicates invalid calendar data. calendar-id:'.$calendarId.' uri:'.$row['uri'], [
+                        'app' => 'dav',
+                        'exception' => $ex,
+                    ]);
+                    continue;
+                }
+
+                if (!$matches) {
+                    continue;
+                }
+            }
+            $result[] = $row['uri'];
+        }
+
+        return $result;
+    }
+
+    /**
+     * custom Nextcloud search extension for CalDAV
+     *
+     * TODO - this should optionally cover cached calendar objects as well
+     *
+     * @param string $principalUri
+     * @param array $filters
+     * @param integer|null $limit
+     * @param integer|null $offset
+     * @return array
+     */
+    public function calendarSearch($principalUri, array $filters, $limit = null, $offset = null) {
+        $calendars = $this->getCalendarsForUser($principalUri);
+        $ownCalendars = [];
+        $sharedCalendars = [];
+
+        $uriMapper = [];
+
+        foreach ($calendars as $calendar) {
+            if ($calendar['{http://owncloud.org/ns}owner-principal'] === $principalUri) {
+                $ownCalendars[] = $calendar['id'];
+            } else {
+                $sharedCalendars[] = $calendar['id'];
+            }
+            $uriMapper[$calendar['id']] = $calendar['uri'];
+        }
+        if (count($ownCalendars) === 0 && count($sharedCalendars) === 0) {
+            return [];
+        }
+
+        $query = $this->db->getQueryBuilder();
+        // Calendar id expressions
+        $calendarExpressions = [];
+        foreach ($ownCalendars as $id) {
+            $calendarExpressions[] = $query->expr()->andX(
+                $query->expr()->eq('c.calendarid',
+                    $query->createNamedParameter($id)),
+                $query->expr()->eq('c.calendartype',
+                    $query->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)));
+        }
+        foreach ($sharedCalendars as $id) {
+            $calendarExpressions[] = $query->expr()->andX(
+                $query->expr()->eq('c.calendarid',
+                    $query->createNamedParameter($id)),
+                $query->expr()->eq('c.classification',
+                    $query->createNamedParameter(self::CLASSIFICATION_PUBLIC)),
+                $query->expr()->eq('c.calendartype',
+                    $query->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)));
+        }
+
+        if (count($calendarExpressions) === 1) {
+            $calExpr = $calendarExpressions[0];
+        } else {
+            $calExpr = call_user_func_array([$query->expr(), 'orX'], $calendarExpressions);
+        }
+
+        // Component expressions
+        $compExpressions = [];
+        foreach ($filters['comps'] as $comp) {
+            $compExpressions[] = $query->expr()
+                ->eq('c.componenttype', $query->createNamedParameter($comp));
+        }
+
+        if (count($compExpressions) === 1) {
+            $compExpr = $compExpressions[0];
+        } else {
+            $compExpr = call_user_func_array([$query->expr(), 'orX'], $compExpressions);
+        }
+
+        if (!isset($filters['props'])) {
+            $filters['props'] = [];
+        }
+        if (!isset($filters['params'])) {
+            $filters['params'] = [];
+        }
+
+        $propParamExpressions = [];
+        foreach ($filters['props'] as $prop) {
+            $propParamExpressions[] = $query->expr()->andX(
+                $query->expr()->eq('i.name', $query->createNamedParameter($prop)),
+                $query->expr()->isNull('i.parameter')
+            );
+        }
+        foreach ($filters['params'] as $param) {
+            $propParamExpressions[] = $query->expr()->andX(
+                $query->expr()->eq('i.name', $query->createNamedParameter($param['property'])),
+                $query->expr()->eq('i.parameter', $query->createNamedParameter($param['parameter']))
+            );
+        }
+
+        if (count($propParamExpressions) === 1) {
+            $propParamExpr = $propParamExpressions[0];
+        } else {
+            $propParamExpr = call_user_func_array([$query->expr(), 'orX'], $propParamExpressions);
+        }
+
+        $query->select(['c.calendarid', 'c.uri'])
+            ->from($this->dbObjectPropertiesTable, 'i')
+            ->join('i', 'calendarobjects', 'c', $query->expr()->eq('i.objectid', 'c.id'))
+            ->where($calExpr)
+            ->andWhere($compExpr)
+            ->andWhere($propParamExpr)
+            ->andWhere($query->expr()->iLike('i.value',
+                $query->createNamedParameter('%'.$this->db->escapeLikeParameter($filters['search-term']).'%')))
+            ->andWhere($query->expr()->isNull('deleted_at'));
+
+        if ($offset) {
+            $query->setFirstResult($offset);
+        }
+        if ($limit) {
+            $query->setMaxResults($limit);
+        }
+
+        $stmt = $query->executeQuery();
+
+        $result = [];
+        while ($row = $stmt->fetch()) {
+            $path = $uriMapper[$row['calendarid']] . '/' . $row['uri'];
+            if (!in_array($path, $result)) {
+                $result[] = $path;
+            }
+        }
+
+        return $result;
+    }
+
+    /**
+     * used for Nextcloud's calendar API
+     *
+     * @param array $calendarInfo
+     * @param string $pattern
+     * @param array $searchProperties
+     * @param array $options
+     * @param integer|null $limit
+     * @param integer|null $offset
+     *
+     * @return array
+     */
+    public function search(array $calendarInfo, $pattern, array $searchProperties,
+                            array $options, $limit, $offset) {
+        $outerQuery = $this->db->getQueryBuilder();
+        $innerQuery = $this->db->getQueryBuilder();
+
+        $innerQuery->selectDistinct('op.objectid')
+            ->from($this->dbObjectPropertiesTable, 'op')
+            ->andWhere($innerQuery->expr()->eq('op.calendarid',
+                $outerQuery->createNamedParameter($calendarInfo['id'])))
+            ->andWhere($innerQuery->expr()->eq('op.calendartype',
+                $outerQuery->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)));
+
+        // only return public items for shared calendars for now
+        if (isset($calendarInfo['{http://owncloud.org/ns}owner-principal']) === false || $calendarInfo['principaluri'] !== $calendarInfo['{http://owncloud.org/ns}owner-principal']) {
+            $innerQuery->andWhere($innerQuery->expr()->eq('c.classification',
+                $outerQuery->createNamedParameter(self::CLASSIFICATION_PUBLIC)));
+        }
+
+        if (!empty($searchProperties)) {
+            $or = $innerQuery->expr()->orX();
+            foreach ($searchProperties as $searchProperty) {
+                $or->add($innerQuery->expr()->eq('op.name',
+                    $outerQuery->createNamedParameter($searchProperty)));
+            }
+            $innerQuery->andWhere($or);
+        }
+
+        if ($pattern !== '') {
+            $innerQuery->andWhere($innerQuery->expr()->iLike('op.value',
+                $outerQuery->createNamedParameter('%' .
+                    $this->db->escapeLikeParameter($pattern) . '%')));
+        }
+
+        $outerQuery->select('c.id', 'c.calendardata', 'c.componenttype', 'c.uid', 'c.uri')
+            ->from('calendarobjects', 'c')
+            ->where($outerQuery->expr()->isNull('deleted_at'));
+
+        if (isset($options['timerange'])) {
+            if (isset($options['timerange']['start']) && $options['timerange']['start'] instanceof DateTimeInterface) {
+                $outerQuery->andWhere($outerQuery->expr()->gt('lastoccurence',
+                    $outerQuery->createNamedParameter($options['timerange']['start']->getTimeStamp())));
+            }
+            if (isset($options['timerange']['end']) && $options['timerange']['end'] instanceof DateTimeInterface) {
+                $outerQuery->andWhere($outerQuery->expr()->lt('firstoccurence',
+                    $outerQuery->createNamedParameter($options['timerange']['end']->getTimeStamp())));
+            }
+        }
+
+        if (isset($options['uid'])) {
+            $outerQuery->andWhere($outerQuery->expr()->eq('uid', $outerQuery->createNamedParameter($options['uid'])));
+        }
+
+        if (!empty($options['types'])) {
+            $or = $outerQuery->expr()->orX();
+            foreach ($options['types'] as $type) {
+                $or->add($outerQuery->expr()->eq('componenttype',
+                    $outerQuery->createNamedParameter($type)));
+            }
+            $outerQuery->andWhere($or);
+        }
+
+        $outerQuery->andWhere($outerQuery->expr()->in('c.id', $outerQuery->createFunction($innerQuery->getSQL())));
+
+        if ($offset) {
+            $outerQuery->setFirstResult($offset);
+        }
+        if ($limit) {
+            $outerQuery->setMaxResults($limit);
+        }
+
+        $result = $outerQuery->executeQuery();
+        $calendarObjects = array_filter($result->fetchAll(), function (array $row) use ($options) {
+            $start = $options['timerange']['start'] ?? null;
+            $end = $options['timerange']['end'] ?? null;
+
+            if ($start === null || !($start instanceof DateTimeInterface) || $end === null || !($end instanceof DateTimeInterface)) {
+                // No filter required
+                return true;
+            }
+
+            $isValid = $this->validateFilterForObject($row, [
+                'name' => 'VCALENDAR',
+                'comp-filters' => [
+                    [
+                        'name' => 'VEVENT',
+                        'comp-filters' => [],
+                        'prop-filters' => [],
+                        'is-not-defined' => false,
+                        'time-range' => [
+                            'start' => $start,
+                            'end' => $end,
+                        ],
+                    ],
+                ],
+                'prop-filters' => [],
+                'is-not-defined' => false,
+                'time-range' => null,
+            ]);
+            if (is_resource($row['calendardata'])) {
+                // Put the stream back to the beginning so it can be read another time
+                rewind($row['calendardata']);
+            }
+            return $isValid;
+        });
+        $result->closeCursor();
+
+        return array_map(function ($o) {
+            $calendarData = Reader::read($o['calendardata']);
+            $comps = $calendarData->getComponents();
+            $objects = [];
+            $timezones = [];
+            foreach ($comps as $comp) {
+                if ($comp instanceof VTimeZone) {
+                    $timezones[] = $comp;
+                } else {
+                    $objects[] = $comp;
+                }
+            }
+
+            return [
+                'id' => $o['id'],
+                'type' => $o['componenttype'],
+                'uid' => $o['uid'],
+                'uri' => $o['uri'],
+                'objects' => array_map(function ($c) {
+                    return $this->transformSearchData($c);
+                }, $objects),
+                'timezones' => array_map(function ($c) {
+                    return $this->transformSearchData($c);
+                }, $timezones),
+            ];
+        }, $calendarObjects);
+    }
+
+    /**
+     * @param Component $comp
+     * @return array
+     */
+    private function transformSearchData(Component $comp) {
+        $data = [];
+        /** @var Component[] $subComponents */
+        $subComponents = $comp->getComponents();
+        /** @var Property[] $properties */
+        $properties = array_filter($comp->children(), function ($c) {
+            return $c instanceof Property;
+        });
+        $validationRules = $comp->getValidationRules();
+
+        foreach ($subComponents as $subComponent) {
+            $name = $subComponent->name;
+            if (!isset($data[$name])) {
+                $data[$name] = [];
+            }
+            $data[$name][] = $this->transformSearchData($subComponent);
+        }
+
+        foreach ($properties as $property) {
+            $name = $property->name;
+            if (!isset($validationRules[$name])) {
+                $validationRules[$name] = '*';
+            }
+
+            $rule = $validationRules[$property->name];
+            if ($rule === '+' || $rule === '*') { // multiple
+                if (!isset($data[$name])) {
+                    $data[$name] = [];
+                }
+
+                $data[$name][] = $this->transformSearchProperty($property);
+            } else { // once
+                $data[$name] = $this->transformSearchProperty($property);
+            }
+        }
+
+        return $data;
+    }
+
+    /**
+     * @param Property $prop
+     * @return array
+     */
+    private function transformSearchProperty(Property $prop) {
+        // No need to check Date, as it extends DateTime
+        if ($prop instanceof Property\ICalendar\DateTime) {
+            $value = $prop->getDateTime();
+        } else {
+            $value = $prop->getValue();
+        }
+
+        return [
+            $value,
+            $prop->parameters()
+        ];
+    }
+
+    /**
+     * @param string $principalUri
+     * @param string $pattern
+     * @param array $componentTypes
+     * @param array $searchProperties
+     * @param array $searchParameters
+     * @param array $options
+     * @return array
+     */
+    public function searchPrincipalUri(string $principalUri,
+                                        string $pattern,
+                                        array $componentTypes,
+                                        array $searchProperties,
+                                        array $searchParameters,
+                                        array $options = []): array {
+        $escapePattern = !\array_key_exists('escape_like_param', $options) || $options['escape_like_param'] !== false;
+
+        $calendarObjectIdQuery = $this->db->getQueryBuilder();
+        $calendarOr = $calendarObjectIdQuery->expr()->orX();
+        $searchOr = $calendarObjectIdQuery->expr()->orX();
+
+        // Fetch calendars and subscription
+        $calendars = $this->getCalendarsForUser($principalUri);
+        $subscriptions = $this->getSubscriptionsForUser($principalUri);
+        foreach ($calendars as $calendar) {
+            $calendarAnd = $calendarObjectIdQuery->expr()->andX();
+            $calendarAnd->add($calendarObjectIdQuery->expr()->eq('cob.calendarid', $calendarObjectIdQuery->createNamedParameter((int)$calendar['id'])));
+            $calendarAnd->add($calendarObjectIdQuery->expr()->eq('cob.calendartype', $calendarObjectIdQuery->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)));
+
+            // If it's shared, limit search to public events
+            if (isset($calendar['{http://owncloud.org/ns}owner-principal'])
+                && $calendar['principaluri'] !== $calendar['{http://owncloud.org/ns}owner-principal']) {
+                $calendarAnd->add($calendarObjectIdQuery->expr()->eq('co.classification', $calendarObjectIdQuery->createNamedParameter(self::CLASSIFICATION_PUBLIC)));
+            }
+
+            $calendarOr->add($calendarAnd);
+        }
+        foreach ($subscriptions as $subscription) {
+            $subscriptionAnd = $calendarObjectIdQuery->expr()->andX();
+            $subscriptionAnd->add($calendarObjectIdQuery->expr()->eq('cob.calendarid', $calendarObjectIdQuery->createNamedParameter((int)$subscription['id'])));
+            $subscriptionAnd->add($calendarObjectIdQuery->expr()->eq('cob.calendartype', $calendarObjectIdQuery->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)));
+
+            // If it's shared, limit search to public events
+            if (isset($subscription['{http://owncloud.org/ns}owner-principal'])
+                && $subscription['principaluri'] !== $subscription['{http://owncloud.org/ns}owner-principal']) {
+                $subscriptionAnd->add($calendarObjectIdQuery->expr()->eq('co.classification', $calendarObjectIdQuery->createNamedParameter(self::CLASSIFICATION_PUBLIC)));
+            }
+
+            $calendarOr->add($subscriptionAnd);
+        }
+
+        foreach ($searchProperties as $property) {
+            $propertyAnd = $calendarObjectIdQuery->expr()->andX();
+            $propertyAnd->add($calendarObjectIdQuery->expr()->eq('cob.name', $calendarObjectIdQuery->createNamedParameter($property, IQueryBuilder::PARAM_STR)));
+            $propertyAnd->add($calendarObjectIdQuery->expr()->isNull('cob.parameter'));
+
+            $searchOr->add($propertyAnd);
+        }
+        foreach ($searchParameters as $property => $parameter) {
+            $parameterAnd = $calendarObjectIdQuery->expr()->andX();
+            $parameterAnd->add($calendarObjectIdQuery->expr()->eq('cob.name', $calendarObjectIdQuery->createNamedParameter($property, IQueryBuilder::PARAM_STR)));
+            $parameterAnd->add($calendarObjectIdQuery->expr()->eq('cob.parameter', $calendarObjectIdQuery->createNamedParameter($parameter, IQueryBuilder::PARAM_STR_ARRAY)));
+
+            $searchOr->add($parameterAnd);
+        }
+
+        if ($calendarOr->count() === 0) {
+            return [];
+        }
+        if ($searchOr->count() === 0) {
+            return [];
+        }
+
+        $calendarObjectIdQuery->selectDistinct('cob.objectid')
+            ->from($this->dbObjectPropertiesTable, 'cob')
+            ->leftJoin('cob', 'calendarobjects', 'co', $calendarObjectIdQuery->expr()->eq('co.id', 'cob.objectid'))
+            ->andWhere($calendarObjectIdQuery->expr()->in('co.componenttype', $calendarObjectIdQuery->createNamedParameter($componentTypes, IQueryBuilder::PARAM_STR_ARRAY)))
+            ->andWhere($calendarOr)
+            ->andWhere($searchOr)
+            ->andWhere($calendarObjectIdQuery->expr()->isNull('deleted_at'));
+
+        if ('' !== $pattern) {
+            if (!$escapePattern) {
+                $calendarObjectIdQuery->andWhere($calendarObjectIdQuery->expr()->ilike('cob.value', $calendarObjectIdQuery->createNamedParameter($pattern)));
+            } else {
+                $calendarObjectIdQuery->andWhere($calendarObjectIdQuery->expr()->ilike('cob.value', $calendarObjectIdQuery->createNamedParameter('%' . $this->db->escapeLikeParameter($pattern) . '%')));
+            }
+        }
+
+        if (isset($options['limit'])) {
+            $calendarObjectIdQuery->setMaxResults($options['limit']);
+        }
+        if (isset($options['offset'])) {
+            $calendarObjectIdQuery->setFirstResult($options['offset']);
+        }
+
+        $result = $calendarObjectIdQuery->executeQuery();
+        $matches = $result->fetchAll();
+        $result->closeCursor();
+        $matches = array_map(static function (array $match):int {
+            return (int) $match['objectid'];
+        }, $matches);
+
+        $query = $this->db->getQueryBuilder();
+        $query->select('calendardata', 'uri', 'calendarid', 'calendartype')
+            ->from('calendarobjects')
+            ->where($query->expr()->in('id', $query->createNamedParameter($matches, IQueryBuilder::PARAM_INT_ARRAY)));
+
+        $result = $query->executeQuery();
+        $calendarObjects = $result->fetchAll();
+        $result->closeCursor();
+
+        return array_map(function (array $array): array {
+            $array['calendarid'] = (int)$array['calendarid'];
+            $array['calendartype'] = (int)$array['calendartype'];
+            $array['calendardata'] = $this->readBlob($array['calendardata']);
+
+            return $array;
+        }, $calendarObjects);
+    }
+
+    /**
+     * Searches through all of a users calendars and calendar objects to find
+     * an object with a specific UID.
+     *
+     * This method should return the path to this object, relative to the
+     * calendar home, so this path usually only contains two parts:
+     *
+     * calendarpath/objectpath.ics
+     *
+     * If the uid is not found, return null.
+     *
+     * This method should only consider * objects that the principal owns, so
+     * any calendars owned by other principals that also appear in this
+     * collection should be ignored.
+     *
+     * @param string $principalUri
+     * @param string $uid
+     * @return string|null
+     */
+    public function getCalendarObjectByUID($principalUri, $uid) {
+        $query = $this->db->getQueryBuilder();
+        $query->selectAlias('c.uri', 'calendaruri')->selectAlias('co.uri', 'objecturi')
+            ->from('calendarobjects', 'co')
+            ->leftJoin('co', 'calendars', 'c', $query->expr()->eq('co.calendarid', 'c.id'))
+            ->where($query->expr()->eq('c.principaluri', $query->createNamedParameter($principalUri)))
+            ->andWhere($query->expr()->eq('co.uid', $query->createNamedParameter($uid)))
+            ->andWhere($query->expr()->isNull('co.deleted_at'));
+        $stmt = $query->executeQuery();
+        $row = $stmt->fetch();
+        $stmt->closeCursor();
+        if ($row) {
+            return $row['calendaruri'] . '/' . $row['objecturi'];
+        }
+
+        return null;
+    }
+
+    public function getCalendarObjectById(string $principalUri, int $id): ?array {
+        $query = $this->db->getQueryBuilder();
+        $query->select(['co.id', 'co.uri', 'co.lastmodified', 'co.etag', 'co.calendarid', 'co.size', 'co.calendardata', 'co.componenttype', 'co.classification', 'co.deleted_at'])
+            ->selectAlias('c.uri', 'calendaruri')
+            ->from('calendarobjects', 'co')
+            ->join('co', 'calendars', 'c', $query->expr()->eq('c.id', 'co.calendarid', IQueryBuilder::PARAM_INT))
+            ->where($query->expr()->eq('c.principaluri', $query->createNamedParameter($principalUri)))
+            ->andWhere($query->expr()->eq('co.id', $query->createNamedParameter($id, IQueryBuilder::PARAM_INT), IQueryBuilder::PARAM_INT));
+        $stmt = $query->executeQuery();
+        $row = $stmt->fetch();
+        $stmt->closeCursor();
+
+        if (!$row) {
+            return null;
+        }
+
+        return [
+            'id' => $row['id'],
+            'uri' => $row['uri'],
+            'lastmodified' => $row['lastmodified'],
+            'etag' => '"' . $row['etag'] . '"',
+            'calendarid' => $row['calendarid'],
+            'calendaruri' => $row['calendaruri'],
+            'size' => (int)$row['size'],
+            'calendardata' => $this->readBlob($row['calendardata']),
+            'component' => strtolower($row['componenttype']),
+            'classification' => (int)$row['classification'],
+            'deleted_at' => isset($row['deleted_at']) ? ((int) $row['deleted_at']) : null,
+        ];
+    }
+
+    /**
+     * The getChanges method returns all the changes that have happened, since
+     * the specified syncToken in the specified calendar.
+     *
+     * This function should return an array, such as the following:
+     *
+     * [
+     *   'syncToken' => 'The current synctoken',
+     *   'added'   => [
+     *      'new.txt',
+     *   ],
+     *   'modified'   => [
+     *      'modified.txt',
+     *   ],
+     *   'deleted' => [
+     *      'foo.php.bak',
+     *      'old.txt'
+     *   ]
+     * );
+     *
+     * The returned syncToken property should reflect the *current* syncToken
+     * of the calendar, as reported in the {http://sabredav.org/ns}sync-token
+     * property This is * needed here too, to ensure the operation is atomic.
+     *
+     * If the $syncToken argument is specified as null, this is an initial
+     * sync, and all members should be reported.
+     *
+     * The modified property is an array of nodenames that have changed since
+     * the last token.
+     *
+     * The deleted property is an array with nodenames, that have been deleted
+     * from collection.
+     *
+     * The $syncLevel argument is basically the 'depth' of the report. If it's
+     * 1, you only have to report changes that happened only directly in
+     * immediate descendants. If it's 2, it should also include changes from
+     * the nodes below the child collections. (grandchildren)
+     *
+     * The $limit argument allows a client to specify how many results should
+     * be returned at most. If the limit is not specified, it should be treated
+     * as infinite.
+     *
+     * If the limit (infinite or not) is higher than you're willing to return,
+     * you should throw a Sabre\DAV\Exception\TooMuchMatches() exception.
+     *
+     * If the syncToken is expired (due to data cleanup) or unknown, you must
+     * return null.
+     *
+     * The limit is 'suggestive'. You are free to ignore it.
+     *
+     * @param string $calendarId
+     * @param string $syncToken
+     * @param int $syncLevel
+     * @param int|null $limit
+     * @param int $calendarType
+     * @return array
+     */
+    public function getChangesForCalendar($calendarId, $syncToken, $syncLevel, $limit = null, $calendarType = self::CALENDAR_TYPE_CALENDAR) {
+        // Current synctoken
+        $qb = $this->db->getQueryBuilder();
+        $qb->select('synctoken')
+            ->from('calendars')
+            ->where(
+                $qb->expr()->eq('id', $qb->createNamedParameter($calendarId))
+            );
+        $stmt = $qb->executeQuery();
+        $currentToken = $stmt->fetchOne();
+
+        if ($currentToken === false) {
+            return null;
+        }
+
+        $result = [
+            'syncToken' => $currentToken,
+            'added' => [],
+            'modified' => [],
+            'deleted' => [],
+        ];
+
+        if ($syncToken) {
+            $qb = $this->db->getQueryBuilder();
+
+            $qb->select('uri', 'operation')
+                ->from('calendarchanges')
+                ->where(
+                    $qb->expr()->andX(
+                        $qb->expr()->gte('synctoken', $qb->createNamedParameter($syncToken)),
+                        $qb->expr()->lt('synctoken', $qb->createNamedParameter($currentToken)),
+                        $qb->expr()->eq('calendarid', $qb->createNamedParameter($calendarId)),
+                        $qb->expr()->eq('calendartype', $qb->createNamedParameter($calendarType))
+                    )
+                )->orderBy('synctoken');
+            if (is_int($limit) && $limit > 0) {
+                $qb->setMaxResults($limit);
+            }
+
+            // Fetching all changes
+            $stmt = $qb->executeQuery();
+            $changes = [];
+
+            // This loop ensures that any duplicates are overwritten, only the
+            // last change on a node is relevant.
+            while ($row = $stmt->fetch()) {
+                $changes[$row['uri']] = $row['operation'];
+            }
+            $stmt->closeCursor();
+
+            foreach ($changes as $uri => $operation) {
+                switch ($operation) {
+                    case 1:
+                        $result['added'][] = $uri;
+                        break;
+                    case 2:
+                        $result['modified'][] = $uri;
+                        break;
+                    case 3:
+                        $result['deleted'][] = $uri;
+                        break;
+                }
+            }
+        } else {
+            // No synctoken supplied, this is the initial sync.
+            $qb = $this->db->getQueryBuilder();
+            $qb->select('uri')
+                ->from('calendarobjects')
+                ->where(
+                    $qb->expr()->andX(
+                        $qb->expr()->eq('calendarid', $qb->createNamedParameter($calendarId)),
+                        $qb->expr()->eq('calendartype', $qb->createNamedParameter($calendarType))
+                    )
+                );
+            $stmt = $qb->executeQuery();
+            $result['added'] = $stmt->fetchAll(\PDO::FETCH_COLUMN);
+            $stmt->closeCursor();
+        }
+        return $result;
+    }
+
+    /**
+     * Returns a list of subscriptions for a principal.
+     *
+     * Every subscription is an array with the following keys:
+     *  * id, a unique id that will be used by other functions to modify the
+     *    subscription. This can be the same as the uri or a database key.
+     *  * uri. This is just the 'base uri' or 'filename' of the subscription.
+     *  * principaluri. The owner of the subscription. Almost always the same as
+     *    principalUri passed to this method.
+     *
+     * Furthermore, all the subscription info must be returned too:
+     *
+     * 1. {DAV:}displayname
+     * 2. {http://apple.com/ns/ical/}refreshrate
+     * 3. {http://calendarserver.org/ns/}subscribed-strip-todos (omit if todos
+     *    should not be stripped).
+     * 4. {http://calendarserver.org/ns/}subscribed-strip-alarms (omit if alarms
+     *    should not be stripped).
+     * 5. {http://calendarserver.org/ns/}subscribed-strip-attachments (omit if
+     *    attachments should not be stripped).
+     * 6. {http://calendarserver.org/ns/}source (Must be a
+     *     Sabre\DAV\Property\Href).
+     * 7. {http://apple.com/ns/ical/}calendar-color
+     * 8. {http://apple.com/ns/ical/}calendar-order
+     * 9. {urn:ietf:params:xml:ns:caldav}supported-calendar-component-set
+     *    (should just be an instance of
+     *    Sabre\CalDAV\Property\SupportedCalendarComponentSet, with a bunch of
+     *    default components).
+     *
+     * @param string $principalUri
+     * @return array
+     */
+    public function getSubscriptionsForUser($principalUri) {
+        $fields = array_column($this->subscriptionPropertyMap, 0);
+        $fields[] = 'id';
+        $fields[] = 'uri';
+        $fields[] = 'source';
+        $fields[] = 'principaluri';
+        $fields[] = 'lastmodified';
+        $fields[] = 'synctoken';
+
+        $query = $this->db->getQueryBuilder();
+        $query->select($fields)
+            ->from('calendarsubscriptions')
+            ->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)))
+            ->orderBy('calendarorder', 'asc');
+        $stmt = $query->executeQuery();
+
+        $subscriptions = [];
+        while ($row = $stmt->fetch()) {
+            $subscription = [
+                'id' => $row['id'],
+                'uri' => $row['uri'],
+                'principaluri' => $row['principaluri'],
+                'source' => $row['source'],
+                'lastmodified' => $row['lastmodified'],
+
+                '{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet(['VTODO', 'VEVENT']),
+                '{http://sabredav.org/ns}sync-token' => $row['synctoken']?$row['synctoken']:'0',
+            ];
+
+            $subscriptions[] = $this->rowToSubscription($row, $subscription);
+        }
+
+        return $subscriptions;
+    }
+
+    /**
+     * Creates a new subscription for a principal.
+     *
+     * If the creation was a success, an id must be returned that can be used to reference
+     * this subscription in other methods, such as updateSubscription.
+     *
+     * @param string $principalUri
+     * @param string $uri
+     * @param array $properties
+     * @return mixed
+     */
+    public function createSubscription($principalUri, $uri, array $properties) {
+        if (!isset($properties['{http://calendarserver.org/ns/}source'])) {
+            throw new Forbidden('The {http://calendarserver.org/ns/}source property is required when creating subscriptions');
+        }
+
+        $values = [
+            'principaluri' => $principalUri,
+            'uri' => $uri,
+            'source' => $properties['{http://calendarserver.org/ns/}source']->getHref(),
+            'lastmodified' => time(),
+        ];
+
+        $propertiesBoolean = ['striptodos', 'stripalarms', 'stripattachments'];
+
+        foreach ($this->subscriptionPropertyMap as $xmlName => [$dbName, $type]) {
+            if (array_key_exists($xmlName, $properties)) {
+                $values[$dbName] = $properties[$xmlName];
+                if (in_array($dbName, $propertiesBoolean)) {
+                    $values[$dbName] = true;
+                }
+            }
+        }
+
+        [$subscriptionId, $subscriptionRow] = $this->atomic(function () use ($values) {
+            $valuesToInsert = [];
+            $query = $this->db->getQueryBuilder();
+            foreach (array_keys($values) as $name) {
+                $valuesToInsert[$name] = $query->createNamedParameter($values[$name]);
+            }
+            $query->insert('calendarsubscriptions')
+                ->values($valuesToInsert)
+                ->executeStatement();
+
+            $subscriptionId = $query->getLastInsertId();
+
+            $subscriptionRow = $this->getSubscriptionById($subscriptionId);
+            return [$subscriptionId, $subscriptionRow];
+        }, $this->db);
+
+        $this->dispatcher->dispatchTyped(new SubscriptionCreatedEvent($subscriptionId, $subscriptionRow));
+
+        return $subscriptionId;
+    }
+
+    /**
+     * Updates a subscription
+     *
+     * The list of mutations is stored in a Sabre\DAV\PropPatch object.
+     * To do the actual updates, you must tell this object which properties
+     * you're going to process with the handle() method.
+     *
+     * Calling the handle method is like telling the PropPatch object "I
+     * promise I can handle updating this property".
+     *
+     * Read the PropPatch documentation for more info and examples.
+     *
+     * @param mixed $subscriptionId
+     * @param PropPatch $propPatch
+     * @return void
+     */
+    public function updateSubscription($subscriptionId, PropPatch $propPatch) {
+        $supportedProperties = array_keys($this->subscriptionPropertyMap);
+        $supportedProperties[] = '{http://calendarserver.org/ns/}source';
+
+        $propPatch->handle($supportedProperties, function ($mutations) use ($subscriptionId) {
+            $newValues = [];
+
+            foreach ($mutations as $propertyName => $propertyValue) {
+                if ($propertyName === '{http://calendarserver.org/ns/}source') {
+                    $newValues['source'] = $propertyValue->getHref();
+                } else {
+                    $fieldName = $this->subscriptionPropertyMap[$propertyName][0];
+                    $newValues[$fieldName] = $propertyValue;
+                }
+            }
+
+            $query = $this->db->getQueryBuilder();
+            $query->update('calendarsubscriptions')
+                ->set('lastmodified', $query->createNamedParameter(time()));
+            foreach ($newValues as $fieldName => $value) {
+                $query->set($fieldName, $query->createNamedParameter($value));
+            }
+            $query->where($query->expr()->eq('id', $query->createNamedParameter($subscriptionId)))
+                ->executeStatement();
+
+            $subscriptionRow = $this->getSubscriptionById($subscriptionId);
+            $this->dispatcher->dispatchTyped(new SubscriptionUpdatedEvent((int)$subscriptionId, $subscriptionRow, [], $mutations));
+
+            return true;
+        });
+    }
+
+    /**
+     * Deletes a subscription.
+     *
+     * @param mixed $subscriptionId
+     * @return void
+     */
+    public function deleteSubscription($subscriptionId) {
+        $subscriptionRow = $this->getSubscriptionById($subscriptionId);
+
+        $query = $this->db->getQueryBuilder();
+        $query->delete('calendarsubscriptions')
+            ->where($query->expr()->eq('id', $query->createNamedParameter($subscriptionId)))
+            ->executeStatement();
+
+        $query = $this->db->getQueryBuilder();
+        $query->delete('calendarobjects')
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
+            ->executeStatement();
+
+        $query->delete('calendarchanges')
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
+            ->executeStatement();
+
+        $query->delete($this->dbObjectPropertiesTable)
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
+            ->executeStatement();
+
+        if ($subscriptionRow) {
+            $this->dispatcher->dispatchTyped(new SubscriptionDeletedEvent((int)$subscriptionId, $subscriptionRow, []));
+        }
+    }
+
+    /**
+     * Returns a single scheduling object for the inbox collection.
+     *
+     * The returned array should contain the following elements:
+     *   * uri - A unique basename for the object. This will be used to
+     *           construct a full uri.
+     *   * calendardata - The iCalendar object
+     *   * lastmodified - The last modification date. Can be an int for a unix
+     *                    timestamp, or a PHP DateTime object.
+     *   * etag - A unique token that must change if the object changed.
+     *   * size - The size of the object, in bytes.
+     *
+     * @param string $principalUri
+     * @param string $objectUri
+     * @return array
+     */
+    public function getSchedulingObject($principalUri, $objectUri) {
+        $query = $this->db->getQueryBuilder();
+        $stmt = $query->select(['uri', 'calendardata', 'lastmodified', 'etag', 'size'])
+            ->from('schedulingobjects')
+            ->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)))
+            ->andWhere($query->expr()->eq('uri', $query->createNamedParameter($objectUri)))
+            ->executeQuery();
+
+        $row = $stmt->fetch();
+
+        if (!$row) {
+            return null;
+        }
+
+        return [
+            'uri' => $row['uri'],
+            'calendardata' => $row['calendardata'],
+            'lastmodified' => $row['lastmodified'],
+            'etag' => '"' . $row['etag'] . '"',
+            'size' => (int)$row['size'],
+        ];
+    }
+
+    /**
+     * Returns all scheduling objects for the inbox collection.
+     *
+     * These objects should be returned as an array. Every item in the array
+     * should follow the same structure as returned from getSchedulingObject.
+     *
+     * The main difference is that 'calendardata' is optional.
+     *
+     * @param string $principalUri
+     * @return array
+     */
+    public function getSchedulingObjects($principalUri) {
+        $query = $this->db->getQueryBuilder();
+        $stmt = $query->select(['uri', 'calendardata', 'lastmodified', 'etag', 'size'])
+                ->from('schedulingobjects')
+                ->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)))
+                ->executeQuery();
+
+        $result = [];
+        foreach ($stmt->fetchAll() as $row) {
+            $result[] = [
+                'calendardata' => $row['calendardata'],
+                'uri' => $row['uri'],
+                'lastmodified' => $row['lastmodified'],
+                'etag' => '"' . $row['etag'] . '"',
+                'size' => (int)$row['size'],
+            ];
+        }
+        $stmt->closeCursor();
+
+        return $result;
+    }
+
+    /**
+     * Deletes a scheduling object from the inbox collection.
+     *
+     * @param string $principalUri
+     * @param string $objectUri
+     * @return void
+     */
+    public function deleteSchedulingObject($principalUri, $objectUri) {
+        $query = $this->db->getQueryBuilder();
+        $query->delete('schedulingobjects')
+                ->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)))
+                ->andWhere($query->expr()->eq('uri', $query->createNamedParameter($objectUri)))
+                ->executeStatement();
+    }
+
+    /**
+     * Creates a new scheduling object. This should land in a users' inbox.
+     *
+     * @param string $principalUri
+     * @param string $objectUri
+     * @param string $objectData
+     * @return void
+     */
+    public function createSchedulingObject($principalUri, $objectUri, $objectData) {
+        $query = $this->db->getQueryBuilder();
+        $query->insert('schedulingobjects')
+            ->values([
+                'principaluri' => $query->createNamedParameter($principalUri),
+                'calendardata' => $query->createNamedParameter($objectData, IQueryBuilder::PARAM_LOB),
+                'uri' => $query->createNamedParameter($objectUri),
+                'lastmodified' => $query->createNamedParameter(time()),
+                'etag' => $query->createNamedParameter(md5($objectData)),
+                'size' => $query->createNamedParameter(strlen($objectData))
+            ])
+            ->executeStatement();
+    }
+
+    /**
+     * Adds a change record to the calendarchanges table.
+     *
+     * @param mixed $calendarId
+     * @param string $objectUri
+     * @param int $operation 1 = add, 2 = modify, 3 = delete.
+     * @param int $calendarType
+     * @return void
+     */
+    protected function addChange($calendarId, $objectUri, $operation, $calendarType = self::CALENDAR_TYPE_CALENDAR) {
+        $table = $calendarType === self::CALENDAR_TYPE_CALENDAR ? 'calendars': 'calendarsubscriptions';
+
+        $query = $this->db->getQueryBuilder();
+        $query->select('synctoken')
+            ->from($table)
+            ->where($query->expr()->eq('id', $query->createNamedParameter($calendarId)));
+        $result = $query->executeQuery();
+        $syncToken = (int)$result->fetchOne();
+        $result->closeCursor();
+
+        $query = $this->db->getQueryBuilder();
+        $query->insert('calendarchanges')
+            ->values([
+                'uri' => $query->createNamedParameter($objectUri),
+                'synctoken' => $query->createNamedParameter($syncToken),
+                'calendarid' => $query->createNamedParameter($calendarId),
+                'operation' => $query->createNamedParameter($operation),
+                'calendartype' => $query->createNamedParameter($calendarType),
+            ])
+            ->executeStatement();
+
+        $stmt = $this->db->prepare("UPDATE `*PREFIX*$table` SET `synctoken` = `synctoken` + 1 WHERE `id` = ?");
+        $stmt->execute([
+            $calendarId
+        ]);
+    }
+
+    /**
+     * Parses some information from calendar objects, used for optimized
+     * calendar-queries.
+     *
+     * Returns an array with the following keys:
+     *   * etag - An md5 checksum of the object without the quotes.
+     *   * size - Size of the object in bytes
+     *   * componentType - VEVENT, VTODO or VJOURNAL
+     *   * firstOccurence
+     *   * lastOccurence
+     *   * uid - value of the UID property
+     *
+     * @param string $calendarData
+     * @return array
+     */
+    public function getDenormalizedData($calendarData) {
+        $vObject = Reader::read($calendarData);
+        $vEvents = [];
+        $componentType = null;
+        $component = null;
+        $firstOccurrence = null;
+        $lastOccurrence = null;
+        $uid = null;
+        $classification = self::CLASSIFICATION_PUBLIC;
+        $hasDTSTART = false;
+        foreach ($vObject->getComponents() as $component) {
+            if ($component->name !== 'VTIMEZONE') {
+                // Finding all VEVENTs, and track them
+                if ($component->name === 'VEVENT') {
+                    array_push($vEvents, $component);
+                    if ($component->DTSTART) {
+                        $hasDTSTART = true;
+                    }
+                }
+                // Track first component type and uid
+                if ($uid === null) {
+                    $componentType = $component->name;
+                    $uid = (string)$component->UID;
+                }
+            }
+        }
+        if (!$componentType) {
+            throw new BadRequest('Calendar objects must have a VJOURNAL, VEVENT or VTODO component');
+        }
+
+        if ($hasDTSTART) {
+            $component = $vEvents[0];
+
+            // Finding the last occurrence is a bit harder
+            if (!isset($component->RRULE) && count($vEvents) === 1) {
+                $firstOccurrence = $component->DTSTART->getDateTime()->getTimeStamp();
+                if (isset($component->DTEND)) {
+                    $lastOccurrence = $component->DTEND->getDateTime()->getTimeStamp();
+                } elseif (isset($component->DURATION)) {
+                    $endDate = clone $component->DTSTART->getDateTime();
+                    $endDate->add(DateTimeParser::parse($component->DURATION->getValue()));
+                    $lastOccurrence = $endDate->getTimeStamp();
+                } elseif (!$component->DTSTART->hasTime()) {
+                    $endDate = clone $component->DTSTART->getDateTime();
+                    $endDate->modify('+1 day');
+                    $lastOccurrence = $endDate->getTimeStamp();
+                } else {
+                    $lastOccurrence = $firstOccurrence;
+                }
+            } else {
+                $it = new EventIterator($vEvents);
+                $maxDate = new DateTime(self::MAX_DATE);
+                $firstOccurrence = $it->getDtStart()->getTimestamp();
+                if ($it->isInfinite()) {
+                    $lastOccurrence = $maxDate->getTimestamp();
+                } else {
+                    $end = $it->getDtEnd();
+                    while ($it->valid() && $end < $maxDate) {
+                        $end = $it->getDtEnd();
+                        $it->next();
+                    }
+                    $lastOccurrence = $end->getTimestamp();
+                }
+            }
+        }
+
+        if ($component->CLASS) {
+            $classification = CalDavBackend::CLASSIFICATION_PRIVATE;
+            switch ($component->CLASS->getValue()) {
+                case 'PUBLIC':
+                    $classification = CalDavBackend::CLASSIFICATION_PUBLIC;
+                    break;
+                case 'CONFIDENTIAL':
+                    $classification = CalDavBackend::CLASSIFICATION_CONFIDENTIAL;
+                    break;
+            }
+        }
+        return [
+            'etag' => md5($calendarData),
+            'size' => strlen($calendarData),
+            'componentType' => $componentType,
+            'firstOccurence' => is_null($firstOccurrence) ? null : max(0, $firstOccurrence),
+            'lastOccurence' => $lastOccurrence,
+            'uid' => $uid,
+            'classification' => $classification
+        ];
+    }
+
+    /**
+     * @param $cardData
+     * @return bool|string
+     */
+    private function readBlob($cardData) {
+        if (is_resource($cardData)) {
+            return stream_get_contents($cardData);
+        }
+
+        return $cardData;
+    }
+
+    /**
+     * @param list<array{href: string, commonName: string, readOnly: bool}> $add
+     * @param list<string> $remove
+     */
+    public function updateShares(IShareable $shareable, array $add, array $remove): void {
+        $calendarId = $shareable->getResourceId();
+        $calendarRow = $this->getCalendarById($calendarId);
+        if ($calendarRow === null) {
+            throw new \RuntimeException('Trying to update shares for innexistant calendar: ' . $calendarId);
+        }
+        $oldShares = $this->getShares($calendarId);
+
+        $this->calendarSharingBackend->updateShares($shareable, $add, $remove);
+
+        $this->dispatcher->dispatchTyped(new CalendarShareUpdatedEvent($calendarId, $calendarRow, $oldShares, $add, $remove));
+    }
+
+    /**
+     * @return list<array{href: string, commonName: string, status: int, readOnly: bool, '{http://owncloud.org/ns}principal': string, '{http://owncloud.org/ns}group-share': bool}>
+     */
+    public function getShares(int $resourceId): array {
+        return $this->calendarSharingBackend->getShares($resourceId);
+    }
+
+    /**
+     * @param boolean $value
+     * @param \OCA\DAV\CalDAV\Calendar $calendar
+     * @return string|null
+     */
+    public function setPublishStatus($value, $calendar) {
+        $calendarId = $calendar->getResourceId();
+        $calendarData = $this->getCalendarById($calendarId);
+
+        $query = $this->db->getQueryBuilder();
+        if ($value) {
+            $publicUri = $this->random->generate(16, ISecureRandom::CHAR_HUMAN_READABLE);
+            $query->insert('dav_shares')
+                ->values([
+                    'principaluri' => $query->createNamedParameter($calendar->getPrincipalURI()),
+                    'type' => $query->createNamedParameter('calendar'),
+                    'access' => $query->createNamedParameter(self::ACCESS_PUBLIC),
+                    'resourceid' => $query->createNamedParameter($calendar->getResourceId()),
+                    'publicuri' => $query->createNamedParameter($publicUri)
+                ]);
+            $query->executeStatement();
+
+            $this->dispatcher->dispatchTyped(new CalendarPublishedEvent($calendarId, $calendarData, $publicUri));
+            return $publicUri;
+        }
+        $query->delete('dav_shares')
+            ->where($query->expr()->eq('resourceid', $query->createNamedParameter($calendar->getResourceId())))
+            ->andWhere($query->expr()->eq('access', $query->createNamedParameter(self::ACCESS_PUBLIC)));
+        $query->executeStatement();
+
+        $this->dispatcher->dispatchTyped(new CalendarUnpublishedEvent($calendarId, $calendarData));
+        return null;
+    }
+
+    /**
+     * @param \OCA\DAV\CalDAV\Calendar $calendar
+     * @return mixed
+     */
+    public function getPublishStatus($calendar) {
+        $query = $this->db->getQueryBuilder();
+        $result = $query->select('publicuri')
+            ->from('dav_shares')
+            ->where($query->expr()->eq('resourceid', $query->createNamedParameter($calendar->getResourceId())))
+            ->andWhere($query->expr()->eq('access', $query->createNamedParameter(self::ACCESS_PUBLIC)))
+            ->executeQuery();
+
+        $row = $result->fetch();
+        $result->closeCursor();
+        return $row ? reset($row) : false;
+    }
+
+    /**
+     * @param int $resourceId
+     * @param list<array{privilege: string, principal: string, protected: bool}> $acl
+     * @return list<array{privilege: string, principal: string, protected: bool}>
+     */
+    public function applyShareAcl(int $resourceId, array $acl): array {
+        return $this->calendarSharingBackend->applyShareAcl($resourceId, $acl);
+    }
+
+    /**
+     * update properties table
+     *
+     * @param int $calendarId
+     * @param string $objectUri
+     * @param string $calendarData
+     * @param int $calendarType
+     */
+    public function updateProperties($calendarId, $objectUri, $calendarData, $calendarType = self::CALENDAR_TYPE_CALENDAR) {
+        $objectId = $this->getCalendarObjectId($calendarId, $objectUri, $calendarType);
+
+        try {
+            $vCalendar = $this->readCalendarData($calendarData);
+        } catch (\Exception $ex) {
+            return;
+        }
+
+        $this->purgeProperties($calendarId, $objectId);
+
+        $query = $this->db->getQueryBuilder();
+        $query->insert($this->dbObjectPropertiesTable)
+            ->values(
+                [
+                    'calendarid' => $query->createNamedParameter($calendarId),
+                    'calendartype' => $query->createNamedParameter($calendarType),
+                    'objectid' => $query->createNamedParameter($objectId),
+                    'name' => $query->createParameter('name'),
+                    'parameter' => $query->createParameter('parameter'),
+                    'value' => $query->createParameter('value'),
+                ]
+            );
+
+        $indexComponents = ['VEVENT', 'VJOURNAL', 'VTODO'];
+        foreach ($vCalendar->getComponents() as $component) {
+            if (!in_array($component->name, $indexComponents)) {
+                continue;
+            }
+
+            foreach ($component->children() as $property) {
+                if (in_array($property->name, self::INDEXED_PROPERTIES, true)) {
+                    $value = $property->getValue();
+                    // is this a shitty db?
+                    if (!$this->db->supports4ByteText()) {
+                        $value = preg_replace('/[\x{10000}-\x{10FFFF}]/u', "\xEF\xBF\xBD", $value);
+                    }
+                    $value = mb_strcut($value, 0, 254);
+
+                    $query->setParameter('name', $property->name);
+                    $query->setParameter('parameter', null);
+                    $query->setParameter('value', $value);
+                    $query->executeStatement();
+                }
+
+                if (array_key_exists($property->name, self::$indexParameters)) {
+                    $parameters = $property->parameters();
+                    $indexedParametersForProperty = self::$indexParameters[$property->name];
+
+                    foreach ($parameters as $key => $value) {
+                        if (in_array($key, $indexedParametersForProperty)) {
+                            // is this a shitty db?
+                            if ($this->db->supports4ByteText()) {
+                                $value = preg_replace('/[\x{10000}-\x{10FFFF}]/u', "\xEF\xBF\xBD", $value);
+                            }
+
+                            $query->setParameter('name', $property->name);
+                            $query->setParameter('parameter', mb_strcut($key, 0, 254));
+                            $query->setParameter('value', mb_strcut($value, 0, 254));
+                            $query->executeStatement();
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    /**
+     * deletes all birthday calendars
+     */
+    public function deleteAllBirthdayCalendars() {
+        $query = $this->db->getQueryBuilder();
+        $result = $query->select(['id'])->from('calendars')
+            ->where($query->expr()->eq('uri', $query->createNamedParameter(BirthdayService::BIRTHDAY_CALENDAR_URI)))
+            ->executeQuery();
+
+        $ids = $result->fetchAll();
+        $result->closeCursor();
+        foreach ($ids as $id) {
+            $this->deleteCalendar(
+                $id['id'],
+                true // No data to keep in the trashbin, if the user re-enables then we regenerate
+            );
+        }
+    }
+
+    /**
+     * @param $subscriptionId
+     */
+    public function purgeAllCachedEventsForSubscription($subscriptionId) {
+        $query = $this->db->getQueryBuilder();
+        $query->select('uri')
+            ->from('calendarobjects')
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)));
+        $stmt = $query->executeQuery();
+
+        $uris = [];
+        foreach ($stmt->fetchAll() as $row) {
+            $uris[] = $row['uri'];
+        }
+        $stmt->closeCursor();
+
+        $query = $this->db->getQueryBuilder();
+        $query->delete('calendarobjects')
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
+            ->executeStatement();
+
+        $query->delete('calendarchanges')
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
+            ->executeStatement();
+
+        $query->delete($this->dbObjectPropertiesTable)
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
+            ->executeStatement();
+
+        foreach ($uris as $uri) {
+            $this->addChange($subscriptionId, $uri, 3, self::CALENDAR_TYPE_SUBSCRIPTION);
+        }
+    }
+
+    /**
+     * Move a calendar from one user to another
+     *
+     * @param string $uriName
+     * @param string $uriOrigin
+     * @param string $uriDestination
+     * @param string $newUriName (optional) the new uriName
+     */
+    public function moveCalendar($uriName, $uriOrigin, $uriDestination, $newUriName = null) {
+        $query = $this->db->getQueryBuilder();
+        $query->update('calendars')
+            ->set('principaluri', $query->createNamedParameter($uriDestination))
+            ->set('uri', $query->createNamedParameter($newUriName ?: $uriName))
+            ->where($query->expr()->eq('principaluri', $query->createNamedParameter($uriOrigin)))
+            ->andWhere($query->expr()->eq('uri', $query->createNamedParameter($uriName)))
+            ->executeStatement();
+    }
+
+    /**
+     * read VCalendar data into a VCalendar object
+     *
+     * @param string $objectData
+     * @return VCalendar
+     */
+    protected function readCalendarData($objectData) {
+        return Reader::read($objectData);
+    }
+
+    /**
+     * delete all properties from a given calendar object
+     *
+     * @param int $calendarId
+     * @param int $objectId
+     */
+    protected function purgeProperties($calendarId, $objectId) {
+        $query = $this->db->getQueryBuilder();
+        $query->delete($this->dbObjectPropertiesTable)
+            ->where($query->expr()->eq('objectid', $query->createNamedParameter($objectId)))
+            ->andWhere($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)));
+        $query->executeStatement();
+    }
+
+    /**
+     * get ID from a given calendar object
+     *
+     * @param int $calendarId
+     * @param string $uri
+     * @param int $calendarType
+     * @return int
+     */
+    protected function getCalendarObjectId($calendarId, $uri, $calendarType):int {
+        $query = $this->db->getQueryBuilder();
+        $query->select('id')
+            ->from('calendarobjects')
+            ->where($query->expr()->eq('uri', $query->createNamedParameter($uri)))
+            ->andWhere($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)));
+
+        $result = $query->executeQuery();
+        $objectIds = $result->fetch();
+        $result->closeCursor();
+
+        if (!isset($objectIds['id'])) {
+            throw new \InvalidArgumentException('Calendarobject does not exists: ' . $uri);
+        }
+
+        return (int)$objectIds['id'];
+    }
+
+    /**
+     * @throws \InvalidArgumentException
+     */
+    public function pruneOutdatedSyncTokens(int $keep = 10_000): int {
+        if ($keep < 0) {
+            throw new \InvalidArgumentException();
+        }
+        $query = $this->db->getQueryBuilder();
+        $query->delete('calendarchanges')
+            ->orderBy('id', 'DESC')
+            ->setFirstResult($keep);
+        return $query->executeStatement();
+    }
+
+    /**
+     * return legacy endpoint principal name to new principal name
+     *
+     * @param $principalUri
+     * @param $toV2
+     * @return string
+     */
+    private function convertPrincipal($principalUri, $toV2) {
+        if ($this->principalBackend->getPrincipalPrefix() === 'principals') {
+            [, $name] = Uri\split($principalUri);
+            if ($toV2 === true) {
+                return "principals/users/$name";
+            }
+            return "principals/$name";
+        }
+        return $principalUri;
+    }
+
+    /**
+     * adds information about an owner to the calendar data
+     *
+     */
+    private function addOwnerPrincipalToCalendar(array $calendarInfo): array {
+        $ownerPrincipalKey = '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}owner-principal';
+        $displaynameKey = '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_NEXTCLOUD . '}owner-displayname';
+        if (isset($calendarInfo[$ownerPrincipalKey])) {
+            $uri = $calendarInfo[$ownerPrincipalKey];
+        } else {
+            $uri = $calendarInfo['principaluri'];
+        }
+
+        $principalInformation = $this->principalBackend->getPrincipalByPath($uri);
+        if (isset($principalInformation['{DAV:}displayname'])) {
+            $calendarInfo[$displaynameKey] = $principalInformation['{DAV:}displayname'];
+        }
+        return $calendarInfo;
+    }
+
+    private function addResourceTypeToCalendar(array $row, array $calendar): array {
+        if (isset($row['deleted_at'])) {
+            // Columns is set and not null -> this is a deleted calendar
+            // we send a custom resourcetype to hide the deleted calendar
+            // from ordinary DAV clients, but the Calendar app will know
+            // how to handle this special resource.
+            $calendar['{DAV:}resourcetype'] = new DAV\Xml\Property\ResourceType([
+                '{DAV:}collection',
+                sprintf('{%s}deleted-calendar', \OCA\DAV\DAV\Sharing\Plugin::NS_NEXTCLOUD),
+            ]);
+        }
+        return $calendar;
+    }
+
+    /**
+     * Amend the calendar info with database row data
+     *
+     * @param array $row
+     * @param array $calendar
+     *
+     * @return array
+     */
+    private function rowToCalendar($row, array $calendar): array {
+        foreach ($this->propertyMap as $xmlName => [$dbName, $type]) {
+            $value = $row[$dbName];
+            if ($value !== null) {
+                settype($value, $type);
+            }
+            $calendar[$xmlName] = $value;
+        }
+        return $calendar;
+    }
+
+    /**
+     * Amend the subscription info with database row data
+     *
+     * @param array $row
+     * @param array $subscription
+     *
+     * @return array
+     */
+    private function rowToSubscription($row, array $subscription): array {
+        foreach ($this->subscriptionPropertyMap as $xmlName => [$dbName, $type]) {
+            $value = $row[$dbName];
+            if ($value !== null) {
+                settype($value, $type);
+            }
+            $subscription[$xmlName] = $value;
+        }
+        return $subscription;
+    }
 }