nextcloud / server

apps/dav/lib/CalDAV/CalDavBackend.php

Indentation +2652 added lines, -2652 removed lines

@@ -77,2656 +77,2656 @@
  * @package OCA\DAV\CalDAV
  */
 class CalDavBackend extends AbstractBackend implements SyncSupport, SubscriptionSupport, SchedulingSupport {
-	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
-	 * Add your own properties by simply adding on to this array.
-	 *
-	 * Note that only string-based properties are supported here.
-	 *
-	 * @var array
-	 */
-	public $propertyMap = [
-		'{DAV:}displayname'                          => 'displayname',
-		'{urn:ietf:params:xml:ns:caldav}calendar-description' => 'description',
-		'{urn:ietf:params:xml:ns:caldav}calendar-timezone'    => 'timezone',
-		'{http://apple.com/ns/ical/}calendar-order'  => 'calendarorder',
-		'{http://apple.com/ns/ical/}calendar-color'  => 'calendarcolor',
-	];
-
-	/**
-	 * List of subscription properties, and how they map to database field names.
-	 *
-	 * @var array
-	 */
-	public $subscriptionPropertyMap = [
-		'{DAV:}displayname'                                           => 'displayname',
-		'{http://apple.com/ns/ical/}refreshrate'                      => 'refreshrate',
-		'{http://apple.com/ns/ical/}calendar-order'                   => 'calendarorder',
-		'{http://apple.com/ns/ical/}calendar-color'                   => 'calendarcolor',
-		'{http://calendarserver.org/ns/}subscribed-strip-todos'       => 'striptodos',
-		'{http://calendarserver.org/ns/}subscribed-strip-alarms'      => 'stripalarms',
-		'{http://calendarserver.org/ns/}subscribed-strip-attachments' => 'stripattachments',
-	];
-
-	/** @var array properties to index */
-	public static $indexProperties = ['CATEGORIES', 'COMMENT', 'DESCRIPTION',
-		'LOCATION', 'RESOURCES', 'STATUS', 'SUMMARY', 'ATTENDEE', 'CONTACT',
-		'ORGANIZER'];
-
-	/** @var array parameters to index */
-	public static $indexParameters = [
-		'ATTENDEE' => ['CN'],
-		'ORGANIZER' => ['CN'],
-	];
-
-	/**
-	 * @var string[] Map of uid => display name
-	 */
-	protected $userDisplayNames;
-
-	/** @var IDBConnection */
-	private $db;
-
-	/** @var Backend */
-	private $calendarSharingBackend;
-
-	/** @var Principal */
-	private $principalBackend;
-
-	/** @var IUserManager */
-	private $userManager;
-
-	/** @var ISecureRandom */
-	private $random;
-
-	/** @var ILogger */
-	private $logger;
-
-	/** @var EventDispatcherInterface */
-	private $dispatcher;
-
-	/** @var bool */
-	private $legacyEndpoint;
-
-	/** @var string */
-	private $dbObjectPropertiesTable = 'calendarobjects_props';
-
-	/**
-	 * CalDavBackend constructor.
-	 *
-	 * @param IDBConnection $db
-	 * @param Principal $principalBackend
-	 * @param IUserManager $userManager
-	 * @param IGroupManager $groupManager
-	 * @param ISecureRandom $random
-	 * @param ILogger $logger
-	 * @param EventDispatcherInterface $dispatcher
-	 * @param bool $legacyEndpoint
-	 */
-	public function __construct(IDBConnection $db,
-								Principal $principalBackend,
-								IUserManager $userManager,
-								IGroupManager $groupManager,
-								ISecureRandom $random,
-								ILogger $logger,
-								EventDispatcherInterface $dispatcher,
-								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->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')
-			->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)));
-
-		if ($excludeBirthday) {
-			$query->andWhere($query->expr()->neq('uri', $query->createNamedParameter(BirthdayService::BIRTHDAY_CALENDAR_URI)));
-		}
-
-		return (int)$query->execute()->fetchColumn();
-	}
-
-	/**
-	 * 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);
-		$fields = array_values($this->propertyMap);
-		$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->execute();
-
-		$calendars = [];
-		while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
-			$components = [];
-			if ($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, !$this->legacyEndpoint),
-			];
-
-			foreach ($this->propertyMap as $xmlName=>$dbName) {
-				$calendar[$xmlName] = $row[$dbName];
-			}
-
-			$this->addOwnerPrincipal($calendar);
-
-			if (!isset($calendars[$calendar['id']])) {
-				$calendars[$calendar['id']] = $calendar;
-			}
-		}
-
-		$stmt->closeCursor();
-
-		// query for shared calendars
-		$principals = $this->principalBackend->getGroupMembership($principalUriOriginal, true);
-		$principals = array_merge($principals, $this->principalBackend->getCircleMembership($principalUriOriginal));
-
-		$principals = array_map(function ($principal) {
-			return urldecode($principal);
-		}, $principals);
-		$principals[]= $principalUri;
-
-		$fields = array_values($this->propertyMap);
-		$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();
-		$result = $query->select($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)
-			->execute();
-
-		$readOnlyPropertyName = '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}read-only';
-		while ($row = $result->fetch()) {
-			if ($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;
-				}
-			}
-
-			list(, $name) = Uri\split($row['principaluri']);
-			$uri = $row['uri'] . '_shared_by_' . $name;
-			$row['displayname'] = $row['displayname'] . ' (' . $this->getUserDisplayName($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 => $readOnly,
-			];
-
-			foreach ($this->propertyMap as $xmlName=>$dbName) {
-				$calendar[$xmlName] = $row[$dbName];
-			}
-
-			$this->addOwnerPrincipal($calendar);
-
-			$calendars[$calendar['id']] = $calendar;
-		}
-		$result->closeCursor();
-
-		return array_values($calendars);
-	}
-
-	/**
-	 * @param $principalUri
-	 * @return array
-	 */
-	public function getUsersOwnCalendars($principalUri) {
-		$principalUri = $this->convertPrincipal($principalUri, true);
-		$fields = array_values($this->propertyMap);
-		$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->execute();
-		$calendars = [];
-		while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
-			$components = [];
-			if ($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'),
-			];
-			foreach ($this->propertyMap as $xmlName=>$dbName) {
-				$calendar[$xmlName] = $row[$dbName];
-			}
-
-			$this->addOwnerPrincipal($calendar);
-
-			if (!isset($calendars[$calendar['id']])) {
-				$calendars[$calendar['id']] = $calendar;
-			}
-		}
-		$stmt->closeCursor();
-		return array_values($calendars);
-	}
-
-
-	/**
-	 * @param $uid
-	 * @return string
-	 */
-	private function getUserDisplayName($uid) {
-		if (!isset($this->userDisplayNames[$uid])) {
-			$user = $this->userManager->get($uid);
-
-			if ($user instanceof IUser) {
-				$this->userDisplayNames[$uid] = $user->getDisplayName();
-			} else {
-				$this->userDisplayNames[$uid] = $uid;
-			}
-		}
-
-		return $this->userDisplayNames[$uid];
-	}
-
-	/**
-	 * @return array
-	 */
-	public function getPublicCalendars() {
-		$fields = array_values($this->propertyMap);
-		$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', $query->createNamedParameter('calendar')))
-			->execute();
-
-		while ($row = $result->fetch()) {
-			list(, $name) = Uri\split($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)$row['access'] === self::ACCESS_PUBLIC,
-			];
-
-			foreach ($this->propertyMap as $xmlName=>$dbName) {
-				$calendar[$xmlName] = $row[$dbName];
-			}
-
-			$this->addOwnerPrincipal($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) {
-		$fields = array_values($this->propertyMap);
-		$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)))
-			->execute();
-
-		$row = $result->fetch(\PDO::FETCH_ASSOC);
-
-		$result->closeCursor();
-
-		if ($row === false) {
-			throw new NotFound('Node with name \'' . $uri . '\' could not be found');
-		}
-
-		list(, $name) = Uri\split($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)$row['access'] === self::ACCESS_PUBLIC,
-		];
-
-		foreach ($this->propertyMap as $xmlName=>$dbName) {
-			$calendar[$xmlName] = $row[$dbName];
-		}
-
-		$this->addOwnerPrincipal($calendar);
-
-		return $calendar;
-	}
-
-	/**
-	 * @param string $principal
-	 * @param string $uri
-	 * @return array|null
-	 */
-	public function getCalendarByUri($principal, $uri) {
-		$fields = array_values($this->propertyMap);
-		$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->execute();
-
-		$row = $stmt->fetch(\PDO::FETCH_ASSOC);
-		$stmt->closeCursor();
-		if ($row === false) {
-			return null;
-		}
-
-		$components = [];
-		if ($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'),
-		];
-
-		foreach ($this->propertyMap as $xmlName=>$dbName) {
-			$calendar[$xmlName] = $row[$dbName];
-		}
-
-		$this->addOwnerPrincipal($calendar);
-
-		return $calendar;
-	}
-
-	/**
-	 * @param $calendarId
-	 * @return array|null
-	 */
-	public function getCalendarById($calendarId) {
-		$fields = array_values($this->propertyMap);
-		$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->execute();
-
-		$row = $stmt->fetch(\PDO::FETCH_ASSOC);
-		$stmt->closeCursor();
-		if ($row === false) {
-			return null;
-		}
-
-		$components = [];
-		if ($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'),
-		];
-
-		foreach ($this->propertyMap as $xmlName=>$dbName) {
-			$calendar[$xmlName] = $row[$dbName];
-		}
-
-		$this->addOwnerPrincipal($calendar);
-
-		return $calendar;
-	}
-
-	/**
-	 * @param $subscriptionId
-	 */
-	public function getSubscriptionById($subscriptionId) {
-		$fields = array_values($this->subscriptionPropertyMap);
-		$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->execute();
-
-		$row = $stmt->fetch(\PDO::FETCH_ASSOC);
-		$stmt->closeCursor();
-		if ($row === false) {
-			return null;
-		}
-
-		$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',
-		];
-
-		foreach ($this->subscriptionPropertyMap as $xmlName=>$dbName) {
-			if (!is_null($row[$dbName])) {
-				$subscription[$xmlName] = $row[$dbName];
-			}
-		}
-
-		return $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 $properties
-	 * @return int
-	 * @suppress SqlInjectionChecker
-	 */
-	public function createCalendar($principalUri, $calendarUri, array $properties) {
-		$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) {
-			if (isset($properties[$xmlName])) {
-				$values[$dbName] = $properties[$xmlName];
-			}
-		}
-
-		$query = $this->db->getQueryBuilder();
-		$query->insert('calendars');
-		foreach ($values as $column => $value) {
-			$query->setValue($column, $query->createNamedParameter($value));
-		}
-		$query->execute();
-		$calendarId = $query->getLastInsertId();
-
-		$this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::createCalendar', new GenericEvent(
-			'\OCA\DAV\CalDAV\CalDavBackend::createCalendar',
-			[
-				'calendarId' => $calendarId,
-				'calendarData' => $this->getCalendarById($calendarId),
-			]));
-
-		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';
-
-		/**
-		 * @suppress SqlInjectionChecker
-		 */
-		$propPatch->handle($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];
-						$newValues[$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->execute();
-
-			$this->addChange($calendarId, "", 2);
-
-			$this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::updateCalendar', new GenericEvent(
-				'\OCA\DAV\CalDAV\CalDavBackend::updateCalendar',
-				[
-					'calendarId' => $calendarId,
-					'calendarData' => $this->getCalendarById($calendarId),
-					'shares' => $this->getShares($calendarId),
-					'propertyMutations' => $mutations,
-				]));
-
-			return true;
-		});
-	}
-
-	/**
-	 * Delete a calendar and all it's objects
-	 *
-	 * @param mixed $calendarId
-	 * @return void
-	 */
-	public function deleteCalendar($calendarId) {
-		$this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::deleteCalendar', new GenericEvent(
-			'\OCA\DAV\CalDAV\CalDavBackend::deleteCalendar',
-			[
-				'calendarId' => $calendarId,
-				'calendarData' => $this->getCalendarById($calendarId),
-				'shares' => $this->getShares($calendarId),
-			]));
-
-		$stmt = $this->db->prepare('DELETE FROM `*PREFIX*calendarobjects` WHERE `calendarid` = ? AND `calendartype` = ?');
-		$stmt->execute([$calendarId, self::CALENDAR_TYPE_CALENDAR]);
-
-		$stmt = $this->db->prepare('DELETE FROM `*PREFIX*calendars` WHERE `id` = ?');
-		$stmt->execute([$calendarId]);
-
-		$stmt = $this->db->prepare('DELETE FROM `*PREFIX*calendarchanges` WHERE `calendarid` = ? AND `calendartype` = ?');
-		$stmt->execute([$calendarId, self::CALENDAR_TYPE_CALENDAR]);
-
-		$this->calendarSharingBackend->deleteAllShares($calendarId);
-
-		$query = $this->db->getQueryBuilder();
-		$query->delete($this->dbObjectPropertiesTable)
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)))
-			->execute();
-	}
-
-	/**
-	 * 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 $id
-	 * @param int $calendarType
-	 * @return array
-	 */
-	public function getCalendarObjects($id, $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', $query->createNamedParameter($id)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)));
-		$stmt = $query->execute();
-
-		$result = [];
-		foreach ($stmt->fetchAll(\PDO::FETCH_ASSOC) 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']
-			];
-		}
-
-		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 $id
-	 * @param string $objectUri
-	 * @param int $calendarType
-	 * @return array|null
-	 */
-	public function getCalendarObject($id, $objectUri, $calendarType=self::CALENDAR_TYPE_CALENDAR) {
-		$query = $this->db->getQueryBuilder();
-		$query->select(['id', 'uri', 'lastmodified', 'etag', 'calendarid', 'size', 'calendardata', 'componenttype', 'classification'])
-			->from('calendarobjects')
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($id)))
-			->andWhere($query->expr()->eq('uri', $query->createNamedParameter($objectUri)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)));
-		$stmt = $query->execute();
-		$row = $stmt->fetch(\PDO::FETCH_ASSOC);
-
-		if (!$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']
-		];
-	}
-
-	/**
-	 * 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 $calendarType
-	 * @return array
-	 */
-	public function getMultipleCalendarObjects($id, 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', $query->createNamedParameter($id)))
-			->andWhere($query->expr()->in('uri', $query->createParameter('uri')))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)));
-
-		foreach ($chunks as $uris) {
-			$query->setParameter('uri', $uris, IQueryBuilder::PARAM_STR_ARRAY);
-			$result = $query->execute();
-
-			while ($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);
-
-		$q = $this->db->getQueryBuilder();
-		$q->select($q->func()->count('*'))
-			->from('calendarobjects')
-			->where($q->expr()->eq('calendarid', $q->createNamedParameter($calendarId)))
-			->andWhere($q->expr()->eq('uid', $q->createNamedParameter($extraData['uid'])))
-			->andWhere($q->expr()->eq('calendartype', $q->createNamedParameter($calendarType)));
-
-		$result = $q->execute();
-		$count = (int) $result->fetchColumn();
-		$result->closeCursor();
-
-		if ($count !== 0) {
-			throw new \Sabre\DAV\Exception\BadRequest('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),
-			])
-			->execute();
-
-		$this->updateProperties($calendarId, $objectUri, $calendarData, $calendarType);
-
-		if ($calendarType === self::CALENDAR_TYPE_CALENDAR) {
-			$this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::createCalendarObject', new GenericEvent(
-				'\OCA\DAV\CalDAV\CalDavBackend::createCalendarObject',
-				[
-					'calendarId' => $calendarId,
-					'calendarData' => $this->getCalendarById($calendarId),
-					'shares' => $this->getShares($calendarId),
-					'objectData' => $this->getCalendarObject($calendarId, $objectUri),
-				]
-			));
-		} else {
-			$this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::createCachedCalendarObject', new GenericEvent(
-				'\OCA\DAV\CalDAV\CalDavBackend::createCachedCalendarObject',
-				[
-					'subscriptionId' => $calendarId,
-					'calendarData' => $this->getCalendarById($calendarId),
-					'shares' => $this->getShares($calendarId),
-					'objectData' => $this->getCalendarObject($calendarId, $objectUri),
-				]
-			));
-		}
-		$this->addChange($calendarId, $objectUri, 1, $calendarType);
-
-		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)))
-			->execute();
-
-		$this->updateProperties($calendarId, $objectUri, $calendarData, $calendarType);
-
-		$data = $this->getCalendarObject($calendarId, $objectUri);
-		if (is_array($data)) {
-			if ($calendarType === self::CALENDAR_TYPE_CALENDAR) {
-				$this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::updateCalendarObject', new GenericEvent(
-					'\OCA\DAV\CalDAV\CalDavBackend::updateCalendarObject',
-					[
-						'calendarId' => $calendarId,
-						'calendarData' => $this->getCalendarById($calendarId),
-						'shares' => $this->getShares($calendarId),
-						'objectData' => $data,
-					]
-				));
-			} else {
-				$this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::updateCachedCalendarObject', new GenericEvent(
-					'\OCA\DAV\CalDAV\CalDavBackend::updateCachedCalendarObject',
-					[
-						'subscriptionId' => $calendarId,
-						'calendarData' => $this->getCalendarById($calendarId),
-						'shares' => $this->getShares($calendarId),
-						'objectData' => $data,
-					]
-				));
-			}
-		}
-		$this->addChange($calendarId, $objectUri, 2, $calendarType);
-
-		return '"' . $extraData['etag'] . '"';
-	}
-
-	/**
-	 * @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)))
-			->execute();
-	}
-
-	/**
-	 * 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 $calendarType
-	 * @return void
-	 */
-	public function deleteCalendarObject($calendarId, $objectUri, $calendarType=self::CALENDAR_TYPE_CALENDAR) {
-		$data = $this->getCalendarObject($calendarId, $objectUri, $calendarType);
-		if (is_array($data)) {
-			if ($calendarType === self::CALENDAR_TYPE_CALENDAR) {
-				$this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::deleteCalendarObject', new GenericEvent(
-					'\OCA\DAV\CalDAV\CalDavBackend::deleteCalendarObject',
-					[
-						'calendarId' => $calendarId,
-						'calendarData' => $this->getCalendarById($calendarId),
-						'shares' => $this->getShares($calendarId),
-						'objectData' => $data,
-					]
-				));
-			} else {
-				$this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::deleteCachedCalendarObject', new GenericEvent(
-					'\OCA\DAV\CalDAV\CalDavBackend::deleteCachedCalendarObject',
-					[
-						'subscriptionId' => $calendarId,
-						'calendarData' => $this->getCalendarById($calendarId),
-						'shares' => $this->getShares($calendarId),
-						'objectData' => $data,
-					]
-				));
-			}
-		}
-
-		$stmt = $this->db->prepare('DELETE FROM `*PREFIX*calendarobjects` WHERE `calendarid` = ? AND `uri` = ? AND `calendartype` = ?');
-		$stmt->execute([$calendarId, $objectUri, $calendarType]);
-
-		if (is_array($data)) {
-			$this->purgeProperties($calendarId, $data['id'], $calendarType);
-		}
-
-		$this->addChange($calendarId, $objectUri, 3, $calendarType);
-	}
-
-	/**
-	 * 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 interprete 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 $id
-	 * @param array $filters
-	 * @param int $calendarType
-	 * @return array
-	 */
-	public function calendarQuery($id, 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'])) {
-				$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', $query->createNamedParameter($id)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)));
-
-		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->execute();
-
-		$result = [];
-		while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
-			if ($requirePostFilter) {
-				// validateFilterForObject will parse the calendar data
-				// catch parsing errors
-				try {
-					$matches = $this->validateFilterForObject($row, $filters);
-				} catch (ParseException $ex) {
-					$this->logger->logException($ex, [
-						'app' => 'dav',
-						'message' => 'Caught parsing exception for calendar data. This usually indicates invalid calendar data. calendar-id:'.$id.' uri:'.$row['uri']
-					]);
-					continue;
-				} catch (InvalidDataException $ex) {
-					$this->logger->logException($ex, [
-						'app' => 'dav',
-						'message' => 'Caught invalid data exception for calendar data. This usually indicates invalid calendar data. calendar-id:'.$id.' uri:'.$row['uri']
-					]);
-					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($filters['search-term']).'%')));
-
-		if ($offset) {
-			$query->setFirstResult($offset);
-		}
-		if ($limit) {
-			$query->setMaxResults($limit);
-		}
-
-		$stmt = $query->execute();
-
-		$result = [];
-		while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
-			$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',
-				$outerQuery->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)));
-
-		// only return public items for shared calendars for now
-		if ($calendarInfo['principaluri'] !== $calendarInfo['{http://owncloud.org/ns}owner-principal']) {
-			$innerQuery->andWhere($innerQuery->expr()->eq('c.classification',
-				$outerQuery->createNamedParameter(self::CLASSIFICATION_PUBLIC)));
-		}
-
-		$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) . '%')));
-		}
-
-		$outerQuery->select('c.id', 'c.calendardata', 'c.componenttype', 'c.uid', 'c.uri')
-			->from('calendarobjects', 'c');
-
-		if (isset($options['timerange'])) {
-			if (isset($options['timerange']['start']) && $options['timerange']['start'] instanceof DateTime) {
-				$outerQuery->andWhere($outerQuery->expr()->gt('lastoccurence',
-					$outerQuery->createNamedParameter($options['timerange']['start']->getTimeStamp())));
-			}
-			if (isset($options['timerange']['end']) && $options['timerange']['end'] instanceof DateTime) {
-				$outerQuery->andWhere($outerQuery->expr()->lt('firstoccurence',
-					$outerQuery->createNamedParameter($options['timerange']['end']->getTimeStamp())));
-			}
-		}
-
-		if (isset($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->execute();
-		$calendarObjects = $result->fetchAll();
-
-		return array_map(function ($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', $calendarObjectIdQuery->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)));
-
-			// If it's shared, limit search to public events
-			if ($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', $calendarObjectIdQuery->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)));
-
-			// If it's shared, limit search to public events
-			if ($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)));
-
-			$searchOr->add($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);
-
-		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->execute();
-		$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->execute();
-		$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)));
-
-		$stmt = $query->execute();
-
-		if ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
-			return $row['calendaruri'] . '/' . $row['objecturi'];
-		}
-
-		return 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 $limit
-	 * @param int $calendarType
-	 * @return array
-	 */
-	public function getChangesForCalendar($calendarId, $syncToken, $syncLevel, $limit = null, $calendarType=self::CALENDAR_TYPE_CALENDAR) {
-		// Current synctoken
-		$stmt = $this->db->prepare('SELECT `synctoken` FROM `*PREFIX*calendars` WHERE `id` = ?');
-		$stmt->execute([ $calendarId ]);
-		$currentToken = $stmt->fetchColumn(0);
-
-		if (is_null($currentToken)) {
-			return null;
-		}
-
-		$result = [
-			'syncToken' => $currentToken,
-			'added'     => [],
-			'modified'  => [],
-			'deleted'   => [],
-		];
-
-		if ($syncToken) {
-			$query = "SELECT `uri`, `operation` FROM `*PREFIX*calendarchanges` WHERE `synctoken` >= ? AND `synctoken` < ? AND `calendarid` = ? AND `calendartype` = ? ORDER BY `synctoken`";
-			if ($limit>0) {
-				$query.= " LIMIT " . (int)$limit;
-			}
-
-			// Fetching all changes
-			$stmt = $this->db->prepare($query);
-			$stmt->execute([$syncToken, $currentToken, $calendarId, $calendarType]);
-
-			$changes = [];
-
-			// This loop ensures that any duplicates are overwritten, only the
-			// last change on a node is relevant.
-			while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
-				$changes[$row['uri']] = $row['operation'];
-			}
-
-			foreach ($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.
-			$query = "SELECT `uri` FROM `*PREFIX*calendarobjects` WHERE `calendarid` = ? AND `calendartype` = ?";
-			$stmt = $this->db->prepare($query);
-			$stmt->execute([$calendarId, $calendarType]);
-
-			$result['added'] = $stmt->fetchAll(\PDO::FETCH_COLUMN);
-		}
-		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) {
-		$fields = array_values($this->subscriptionPropertyMap);
-		$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->execute();
-
-		$subscriptions = [];
-		while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
-			$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',
-			];
-
-			foreach ($this->subscriptionPropertyMap as $xmlName=>$dbName) {
-				if (!is_null($row[$dbName])) {
-					$subscription[$xmlName] = $row[$dbName];
-				}
-			}
-
-			$subscriptions[] = $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) {
-			if (array_key_exists($xmlName, $properties)) {
-				$values[$dbName] = $properties[$xmlName];
-				if (in_array($dbName, $propertiesBoolean)) {
-					$values[$dbName] = true;
-				}
-			}
-		}
-
-		$valuesToInsert = [];
-
-		$query = $this->db->getQueryBuilder();
-
-		foreach (array_keys($values) as $name) {
-			$valuesToInsert[$name] = $query->createNamedParameter($values[$name]);
-		}
-
-		$query->insert('calendarsubscriptions')
-			->values($valuesToInsert)
-			->execute();
-
-		$subscriptionId = $this->db->lastInsertId('*PREFIX*calendarsubscriptions');
-
-		$this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::createSubscription', new GenericEvent(
-			'\OCA\DAV\CalDAV\CalDavBackend::createSubscription',
-			[
-				'subscriptionId' => $subscriptionId,
-				'subscriptionData' => $this->getSubscriptionById($subscriptionId),
-			]));
-
-		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';
-
-		/**
-		 * @suppress SqlInjectionChecker
-		 */
-		$propPatch->handle($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];
-					$newValues[$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)))
-				->execute();
-
-			$this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::updateSubscription', new GenericEvent(
-				'\OCA\DAV\CalDAV\CalDavBackend::updateSubscription',
-				[
-					'subscriptionId' => $subscriptionId,
-					'subscriptionData' => $this->getSubscriptionById($subscriptionId),
-					'propertyMutations' => $mutations,
-				]));
-
-			return true;
-		});
-	}
-
-	/**
-	 * Deletes a subscription.
-	 *
-	 * @param mixed $subscriptionId
-	 * @return void
-	 */
-	public function deleteSubscription($subscriptionId) {
-		$this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::deleteSubscription', new GenericEvent(
-			'\OCA\DAV\CalDAV\CalDavBackend::deleteSubscription',
-			[
-				'subscriptionId' => $subscriptionId,
-				'subscriptionData' => $this->getSubscriptionById($subscriptionId),
-			]));
-
-		$query = $this->db->getQueryBuilder();
-		$query->delete('calendarsubscriptions')
-			->where($query->expr()->eq('id', $query->createNamedParameter($subscriptionId)))
-			->execute();
-
-		$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)))
-			->execute();
-
-		$query->delete('calendarchanges')
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
-			->execute();
-
-		$query->delete($this->dbObjectPropertiesTable)
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
-			->execute();
-	}
-
-	/**
-	 * 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)))
-			->execute();
-
-		$row = $stmt->fetch(\PDO::FETCH_ASSOC);
-
-		if (!$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)))
-				->execute();
-
-		$result = [];
-		foreach ($stmt->fetchAll(\PDO::FETCH_ASSOC) as $row) {
-			$result[] = [
-				'calendardata' => $row['calendardata'],
-				'uri'          => $row['uri'],
-				'lastmodified' => $row['lastmodified'],
-				'etag'         => '"' . $row['etag'] . '"',
-				'size'         => (int)$row['size'],
-			];
-		}
-
-		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)))
-				->execute();
-	}
-
-	/**
-	 * 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))
-			])
-			->execute();
-	}
-
-	/**
-	 * 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)));
-		$syncToken = (int)$query->execute()->fetchColumn();
-
-		$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),
-			])
-			->execute();
-
-		$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);
-		$componentType = null;
-		$component = null;
-		$firstOccurrence = null;
-		$lastOccurrence = null;
-		$uid = null;
-		$classification = self::CLASSIFICATION_PUBLIC;
-		foreach ($vObject->getComponents() as $component) {
-			if ($component->name!=='VTIMEZONE') {
-				$componentType = $component->name;
-				$uid = (string)$component->UID;
-				break;
-			}
-		}
-		if (!$componentType) {
-			throw new \Sabre\DAV\Exception\BadRequest('Calendar objects must have a VJOURNAL, VEVENT or VTODO component');
-		}
-		if ($componentType === 'VEVENT' && $component->DTSTART) {
-			$firstOccurrence = $component->DTSTART->getDateTime()->getTimeStamp();
-			// Finding the last occurrence is a bit harder
-			if (!isset($component->RRULE)) {
-				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 {
-				$it = new EventIterator($vObject, (string)$component->UID);
-				$maxDate = new DateTime(self::MAX_DATE);
-				if ($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 IShareable $shareable
-	 * @param array $add
-	 * @param array $remove
-	 */
-	public function updateShares($shareable, $add, $remove) {
-		$calendarId = $shareable->getResourceId();
-		$this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::updateShares', new GenericEvent(
-			'\OCA\DAV\CalDAV\CalDavBackend::updateShares',
-			[
-				'calendarId' => $calendarId,
-				'calendarData' => $this->getCalendarById($calendarId),
-				'shares' => $this->getShares($calendarId),
-				'add' => $add,
-				'remove' => $remove,
-			]));
-		$this->calendarSharingBackend->updateShares($shareable, $add, $remove);
-	}
-
-	/**
-	 * @param int $resourceId
-	 * @param int $calendarType
-	 * @return array
-	 */
-	public function getShares($resourceId, $calendarType=self::CALENDAR_TYPE_CALENDAR) {
-		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();
-		$this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::publishCalendar', new GenericEvent(
-			'\OCA\DAV\CalDAV\CalDavBackend::updateShares',
-			[
-				'calendarId' => $calendarId,
-				'calendarData' => $this->getCalendarById($calendarId),
-				'public' => $value,
-			]));
-
-		$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->execute();
-			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->execute();
-		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)))
-			->execute();
-
-		$row = $result->fetch();
-		$result->closeCursor();
-		return $row ? reset($row) : false;
-	}
-
-	/**
-	 * @param int $resourceId
-	 * @param array $acl
-	 * @return array
-	 */
-	public function applyShareAcl($resourceId, $acl) {
-		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::$indexProperties)) {
-					$value = $property->getValue();
-					// is this a shitty db?
-					if (!$this->db->supports4ByteText()) {
-						$value = preg_replace('/[\x{10000}-\x{10FFFF}]/u', "\xEF\xBF\xBD", $value);
-					}
-					$value = mb_substr($value, 0, 254);
-
-					$query->setParameter('name', $property->name);
-					$query->setParameter('parameter', null);
-					$query->setParameter('value', $value);
-					$query->execute();
-				}
-
-				if (array_key_exists($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);
-							$query->setParameter('parameter', mb_substr($key, 0, 254));
-							$query->setParameter('value', mb_substr($value, 0, 254));
-							$query->execute();
-						}
-					}
-				}
-			}
-		}
-	}
-
-	/**
-	 * 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)))
-			->execute();
-
-		$ids = $result->fetchAll();
-		foreach ($ids as $id) {
-			$this->deleteCalendar($id['id']);
-		}
-	}
-
-	/**
-	 * @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->execute();
-
-		$uris = [];
-		foreach ($stmt->fetchAll(\PDO::FETCH_ASSOC) 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)))
-			->execute();
-
-		$query->delete('calendarchanges')
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
-			->execute();
-
-		$query->delete($this->dbObjectPropertiesTable)
-			->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
-			->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
-			->execute();
-
-		foreach ($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 $uriDestination
-	 */
-	public function moveCalendar($uriName, $uriOrigin, $uriDestination) {
-		$query = $this->db->getQueryBuilder();
-		$query->update('calendars')
-			->set('principaluri', $query->createNamedParameter($uriDestination))
-			->where($query->expr()->eq('principaluri', $query->createNamedParameter($uriOrigin)))
-			->andWhere($query->expr()->eq('uri', $query->createNamedParameter($uriName)))
-			->execute();
-	}
-
-	/**
-	 * 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->execute();
-	}
-
-	/**
-	 * 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->execute();
-		$objectIds = $result->fetch();
-		$result->closeCursor();
-
-		if (!isset($objectIds['id'])) {
-			throw new \InvalidArgumentException('Calendarobject does not exists: ' . $uri);
-		}
-
-		return (int)$objectIds['id'];
-	}
-
-	/**
-	 * 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') {
-			list(, $name) = Uri\split($principalUri);
-			if ($toV2 === true) {
-				return "principals/users/$name";
-			}
-			return "principals/$name";
-		}
-		return $principalUri;
-	}
-
-	/**
-	 * adds information about an owner to the calendar data
-	 *
-	 * @param $calendarInfo
-	 */
-	private function addOwnerPrincipal(&$calendarInfo) {
-		$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'];
-		}
-	}
+    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
+     * Add your own properties by simply adding on to this array.
+     *
+     * Note that only string-based properties are supported here.
+     *
+     * @var array
+     */
+    public $propertyMap = [
+        '{DAV:}displayname'                          => 'displayname',
+        '{urn:ietf:params:xml:ns:caldav}calendar-description' => 'description',
+        '{urn:ietf:params:xml:ns:caldav}calendar-timezone'    => 'timezone',
+        '{http://apple.com/ns/ical/}calendar-order'  => 'calendarorder',
+        '{http://apple.com/ns/ical/}calendar-color'  => 'calendarcolor',
+    ];
+
+    /**
+     * List of subscription properties, and how they map to database field names.
+     *
+     * @var array
+     */
+    public $subscriptionPropertyMap = [
+        '{DAV:}displayname'                                           => 'displayname',
+        '{http://apple.com/ns/ical/}refreshrate'                      => 'refreshrate',
+        '{http://apple.com/ns/ical/}calendar-order'                   => 'calendarorder',
+        '{http://apple.com/ns/ical/}calendar-color'                   => 'calendarcolor',
+        '{http://calendarserver.org/ns/}subscribed-strip-todos'       => 'striptodos',
+        '{http://calendarserver.org/ns/}subscribed-strip-alarms'      => 'stripalarms',
+        '{http://calendarserver.org/ns/}subscribed-strip-attachments' => 'stripattachments',
+    ];
+
+    /** @var array properties to index */
+    public static $indexProperties = ['CATEGORIES', 'COMMENT', 'DESCRIPTION',
+        'LOCATION', 'RESOURCES', 'STATUS', 'SUMMARY', 'ATTENDEE', 'CONTACT',
+        'ORGANIZER'];
+
+    /** @var array parameters to index */
+    public static $indexParameters = [
+        'ATTENDEE' => ['CN'],
+        'ORGANIZER' => ['CN'],
+    ];
+
+    /**
+     * @var string[] Map of uid => display name
+     */
+    protected $userDisplayNames;
+
+    /** @var IDBConnection */
+    private $db;
+
+    /** @var Backend */
+    private $calendarSharingBackend;
+
+    /** @var Principal */
+    private $principalBackend;
+
+    /** @var IUserManager */
+    private $userManager;
+
+    /** @var ISecureRandom */
+    private $random;
+
+    /** @var ILogger */
+    private $logger;
+
+    /** @var EventDispatcherInterface */
+    private $dispatcher;
+
+    /** @var bool */
+    private $legacyEndpoint;
+
+    /** @var string */
+    private $dbObjectPropertiesTable = 'calendarobjects_props';
+
+    /**
+     * CalDavBackend constructor.
+     *
+     * @param IDBConnection $db
+     * @param Principal $principalBackend
+     * @param IUserManager $userManager
+     * @param IGroupManager $groupManager
+     * @param ISecureRandom $random
+     * @param ILogger $logger
+     * @param EventDispatcherInterface $dispatcher
+     * @param bool $legacyEndpoint
+     */
+    public function __construct(IDBConnection $db,
+                                Principal $principalBackend,
+                                IUserManager $userManager,
+                                IGroupManager $groupManager,
+                                ISecureRandom $random,
+                                ILogger $logger,
+                                EventDispatcherInterface $dispatcher,
+                                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->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')
+            ->where($query->expr()->eq('principaluri', $query->createNamedParameter($principalUri)));
+
+        if ($excludeBirthday) {
+            $query->andWhere($query->expr()->neq('uri', $query->createNamedParameter(BirthdayService::BIRTHDAY_CALENDAR_URI)));
+        }
+
+        return (int)$query->execute()->fetchColumn();
+    }
+
+    /**
+     * 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);
+        $fields = array_values($this->propertyMap);
+        $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->execute();
+
+        $calendars = [];
+        while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
+            $components = [];
+            if ($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, !$this->legacyEndpoint),
+            ];
+
+            foreach ($this->propertyMap as $xmlName=>$dbName) {
+                $calendar[$xmlName] = $row[$dbName];
+            }
+
+            $this->addOwnerPrincipal($calendar);
+
+            if (!isset($calendars[$calendar['id']])) {
+                $calendars[$calendar['id']] = $calendar;
+            }
+        }
+
+        $stmt->closeCursor();
+
+        // query for shared calendars
+        $principals = $this->principalBackend->getGroupMembership($principalUriOriginal, true);
+        $principals = array_merge($principals, $this->principalBackend->getCircleMembership($principalUriOriginal));
+
+        $principals = array_map(function ($principal) {
+            return urldecode($principal);
+        }, $principals);
+        $principals[]= $principalUri;
+
+        $fields = array_values($this->propertyMap);
+        $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();
+        $result = $query->select($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)
+            ->execute();
+
+        $readOnlyPropertyName = '{' . \OCA\DAV\DAV\Sharing\Plugin::NS_OWNCLOUD . '}read-only';
+        while ($row = $result->fetch()) {
+            if ($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;
+                }
+            }
+
+            list(, $name) = Uri\split($row['principaluri']);
+            $uri = $row['uri'] . '_shared_by_' . $name;
+            $row['displayname'] = $row['displayname'] . ' (' . $this->getUserDisplayName($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 => $readOnly,
+            ];
+
+            foreach ($this->propertyMap as $xmlName=>$dbName) {
+                $calendar[$xmlName] = $row[$dbName];
+            }
+
+            $this->addOwnerPrincipal($calendar);
+
+            $calendars[$calendar['id']] = $calendar;
+        }
+        $result->closeCursor();
+
+        return array_values($calendars);
+    }
+
+    /**
+     * @param $principalUri
+     * @return array
+     */
+    public function getUsersOwnCalendars($principalUri) {
+        $principalUri = $this->convertPrincipal($principalUri, true);
+        $fields = array_values($this->propertyMap);
+        $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->execute();
+        $calendars = [];
+        while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
+            $components = [];
+            if ($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'),
+            ];
+            foreach ($this->propertyMap as $xmlName=>$dbName) {
+                $calendar[$xmlName] = $row[$dbName];
+            }
+
+            $this->addOwnerPrincipal($calendar);
+
+            if (!isset($calendars[$calendar['id']])) {
+                $calendars[$calendar['id']] = $calendar;
+            }
+        }
+        $stmt->closeCursor();
+        return array_values($calendars);
+    }
+
+
+    /**
+     * @param $uid
+     * @return string
+     */
+    private function getUserDisplayName($uid) {
+        if (!isset($this->userDisplayNames[$uid])) {
+            $user = $this->userManager->get($uid);
+
+            if ($user instanceof IUser) {
+                $this->userDisplayNames[$uid] = $user->getDisplayName();
+            } else {
+                $this->userDisplayNames[$uid] = $uid;
+            }
+        }
+
+        return $this->userDisplayNames[$uid];
+    }
+
+    /**
+     * @return array
+     */
+    public function getPublicCalendars() {
+        $fields = array_values($this->propertyMap);
+        $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', $query->createNamedParameter('calendar')))
+            ->execute();
+
+        while ($row = $result->fetch()) {
+            list(, $name) = Uri\split($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)$row['access'] === self::ACCESS_PUBLIC,
+            ];
+
+            foreach ($this->propertyMap as $xmlName=>$dbName) {
+                $calendar[$xmlName] = $row[$dbName];
+            }
+
+            $this->addOwnerPrincipal($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) {
+        $fields = array_values($this->propertyMap);
+        $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)))
+            ->execute();
+
+        $row = $result->fetch(\PDO::FETCH_ASSOC);
+
+        $result->closeCursor();
+
+        if ($row === false) {
+            throw new NotFound('Node with name \'' . $uri . '\' could not be found');
+        }
+
+        list(, $name) = Uri\split($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)$row['access'] === self::ACCESS_PUBLIC,
+        ];
+
+        foreach ($this->propertyMap as $xmlName=>$dbName) {
+            $calendar[$xmlName] = $row[$dbName];
+        }
+
+        $this->addOwnerPrincipal($calendar);
+
+        return $calendar;
+    }
+
+    /**
+     * @param string $principal
+     * @param string $uri
+     * @return array|null
+     */
+    public function getCalendarByUri($principal, $uri) {
+        $fields = array_values($this->propertyMap);
+        $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->execute();
+
+        $row = $stmt->fetch(\PDO::FETCH_ASSOC);
+        $stmt->closeCursor();
+        if ($row === false) {
+            return null;
+        }
+
+        $components = [];
+        if ($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'),
+        ];
+
+        foreach ($this->propertyMap as $xmlName=>$dbName) {
+            $calendar[$xmlName] = $row[$dbName];
+        }
+
+        $this->addOwnerPrincipal($calendar);
+
+        return $calendar;
+    }
+
+    /**
+     * @param $calendarId
+     * @return array|null
+     */
+    public function getCalendarById($calendarId) {
+        $fields = array_values($this->propertyMap);
+        $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->execute();
+
+        $row = $stmt->fetch(\PDO::FETCH_ASSOC);
+        $stmt->closeCursor();
+        if ($row === false) {
+            return null;
+        }
+
+        $components = [];
+        if ($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'),
+        ];
+
+        foreach ($this->propertyMap as $xmlName=>$dbName) {
+            $calendar[$xmlName] = $row[$dbName];
+        }
+
+        $this->addOwnerPrincipal($calendar);
+
+        return $calendar;
+    }
+
+    /**
+     * @param $subscriptionId
+     */
+    public function getSubscriptionById($subscriptionId) {
+        $fields = array_values($this->subscriptionPropertyMap);
+        $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->execute();
+
+        $row = $stmt->fetch(\PDO::FETCH_ASSOC);
+        $stmt->closeCursor();
+        if ($row === false) {
+            return null;
+        }
+
+        $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',
+        ];
+
+        foreach ($this->subscriptionPropertyMap as $xmlName=>$dbName) {
+            if (!is_null($row[$dbName])) {
+                $subscription[$xmlName] = $row[$dbName];
+            }
+        }
+
+        return $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 $properties
+     * @return int
+     * @suppress SqlInjectionChecker
+     */
+    public function createCalendar($principalUri, $calendarUri, array $properties) {
+        $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) {
+            if (isset($properties[$xmlName])) {
+                $values[$dbName] = $properties[$xmlName];
+            }
+        }
+
+        $query = $this->db->getQueryBuilder();
+        $query->insert('calendars');
+        foreach ($values as $column => $value) {
+            $query->setValue($column, $query->createNamedParameter($value));
+        }
+        $query->execute();
+        $calendarId = $query->getLastInsertId();
+
+        $this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::createCalendar', new GenericEvent(
+            '\OCA\DAV\CalDAV\CalDavBackend::createCalendar',
+            [
+                'calendarId' => $calendarId,
+                'calendarData' => $this->getCalendarById($calendarId),
+            ]));
+
+        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';
+
+        /**
+         * @suppress SqlInjectionChecker
+         */
+        $propPatch->handle($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];
+                        $newValues[$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->execute();
+
+            $this->addChange($calendarId, "", 2);
+
+            $this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::updateCalendar', new GenericEvent(
+                '\OCA\DAV\CalDAV\CalDavBackend::updateCalendar',
+                [
+                    'calendarId' => $calendarId,
+                    'calendarData' => $this->getCalendarById($calendarId),
+                    'shares' => $this->getShares($calendarId),
+                    'propertyMutations' => $mutations,
+                ]));
+
+            return true;
+        });
+    }
+
+    /**
+     * Delete a calendar and all it's objects
+     *
+     * @param mixed $calendarId
+     * @return void
+     */
+    public function deleteCalendar($calendarId) {
+        $this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::deleteCalendar', new GenericEvent(
+            '\OCA\DAV\CalDAV\CalDavBackend::deleteCalendar',
+            [
+                'calendarId' => $calendarId,
+                'calendarData' => $this->getCalendarById($calendarId),
+                'shares' => $this->getShares($calendarId),
+            ]));
+
+        $stmt = $this->db->prepare('DELETE FROM `*PREFIX*calendarobjects` WHERE `calendarid` = ? AND `calendartype` = ?');
+        $stmt->execute([$calendarId, self::CALENDAR_TYPE_CALENDAR]);
+
+        $stmt = $this->db->prepare('DELETE FROM `*PREFIX*calendars` WHERE `id` = ?');
+        $stmt->execute([$calendarId]);
+
+        $stmt = $this->db->prepare('DELETE FROM `*PREFIX*calendarchanges` WHERE `calendarid` = ? AND `calendartype` = ?');
+        $stmt->execute([$calendarId, self::CALENDAR_TYPE_CALENDAR]);
+
+        $this->calendarSharingBackend->deleteAllShares($calendarId);
+
+        $query = $this->db->getQueryBuilder();
+        $query->delete($this->dbObjectPropertiesTable)
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($calendarId)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)))
+            ->execute();
+    }
+
+    /**
+     * 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 $id
+     * @param int $calendarType
+     * @return array
+     */
+    public function getCalendarObjects($id, $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', $query->createNamedParameter($id)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)));
+        $stmt = $query->execute();
+
+        $result = [];
+        foreach ($stmt->fetchAll(\PDO::FETCH_ASSOC) 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']
+            ];
+        }
+
+        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 $id
+     * @param string $objectUri
+     * @param int $calendarType
+     * @return array|null
+     */
+    public function getCalendarObject($id, $objectUri, $calendarType=self::CALENDAR_TYPE_CALENDAR) {
+        $query = $this->db->getQueryBuilder();
+        $query->select(['id', 'uri', 'lastmodified', 'etag', 'calendarid', 'size', 'calendardata', 'componenttype', 'classification'])
+            ->from('calendarobjects')
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($id)))
+            ->andWhere($query->expr()->eq('uri', $query->createNamedParameter($objectUri)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)));
+        $stmt = $query->execute();
+        $row = $stmt->fetch(\PDO::FETCH_ASSOC);
+
+        if (!$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']
+        ];
+    }
+
+    /**
+     * 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 $calendarType
+     * @return array
+     */
+    public function getMultipleCalendarObjects($id, 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', $query->createNamedParameter($id)))
+            ->andWhere($query->expr()->in('uri', $query->createParameter('uri')))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)));
+
+        foreach ($chunks as $uris) {
+            $query->setParameter('uri', $uris, IQueryBuilder::PARAM_STR_ARRAY);
+            $result = $query->execute();
+
+            while ($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);
+
+        $q = $this->db->getQueryBuilder();
+        $q->select($q->func()->count('*'))
+            ->from('calendarobjects')
+            ->where($q->expr()->eq('calendarid', $q->createNamedParameter($calendarId)))
+            ->andWhere($q->expr()->eq('uid', $q->createNamedParameter($extraData['uid'])))
+            ->andWhere($q->expr()->eq('calendartype', $q->createNamedParameter($calendarType)));
+
+        $result = $q->execute();
+        $count = (int) $result->fetchColumn();
+        $result->closeCursor();
+
+        if ($count !== 0) {
+            throw new \Sabre\DAV\Exception\BadRequest('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),
+            ])
+            ->execute();
+
+        $this->updateProperties($calendarId, $objectUri, $calendarData, $calendarType);
+
+        if ($calendarType === self::CALENDAR_TYPE_CALENDAR) {
+            $this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::createCalendarObject', new GenericEvent(
+                '\OCA\DAV\CalDAV\CalDavBackend::createCalendarObject',
+                [
+                    'calendarId' => $calendarId,
+                    'calendarData' => $this->getCalendarById($calendarId),
+                    'shares' => $this->getShares($calendarId),
+                    'objectData' => $this->getCalendarObject($calendarId, $objectUri),
+                ]
+            ));
+        } else {
+            $this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::createCachedCalendarObject', new GenericEvent(
+                '\OCA\DAV\CalDAV\CalDavBackend::createCachedCalendarObject',
+                [
+                    'subscriptionId' => $calendarId,
+                    'calendarData' => $this->getCalendarById($calendarId),
+                    'shares' => $this->getShares($calendarId),
+                    'objectData' => $this->getCalendarObject($calendarId, $objectUri),
+                ]
+            ));
+        }
+        $this->addChange($calendarId, $objectUri, 1, $calendarType);
+
+        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)))
+            ->execute();
+
+        $this->updateProperties($calendarId, $objectUri, $calendarData, $calendarType);
+
+        $data = $this->getCalendarObject($calendarId, $objectUri);
+        if (is_array($data)) {
+            if ($calendarType === self::CALENDAR_TYPE_CALENDAR) {
+                $this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::updateCalendarObject', new GenericEvent(
+                    '\OCA\DAV\CalDAV\CalDavBackend::updateCalendarObject',
+                    [
+                        'calendarId' => $calendarId,
+                        'calendarData' => $this->getCalendarById($calendarId),
+                        'shares' => $this->getShares($calendarId),
+                        'objectData' => $data,
+                    ]
+                ));
+            } else {
+                $this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::updateCachedCalendarObject', new GenericEvent(
+                    '\OCA\DAV\CalDAV\CalDavBackend::updateCachedCalendarObject',
+                    [
+                        'subscriptionId' => $calendarId,
+                        'calendarData' => $this->getCalendarById($calendarId),
+                        'shares' => $this->getShares($calendarId),
+                        'objectData' => $data,
+                    ]
+                ));
+            }
+        }
+        $this->addChange($calendarId, $objectUri, 2, $calendarType);
+
+        return '"' . $extraData['etag'] . '"';
+    }
+
+    /**
+     * @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)))
+            ->execute();
+    }
+
+    /**
+     * 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 $calendarType
+     * @return void
+     */
+    public function deleteCalendarObject($calendarId, $objectUri, $calendarType=self::CALENDAR_TYPE_CALENDAR) {
+        $data = $this->getCalendarObject($calendarId, $objectUri, $calendarType);
+        if (is_array($data)) {
+            if ($calendarType === self::CALENDAR_TYPE_CALENDAR) {
+                $this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::deleteCalendarObject', new GenericEvent(
+                    '\OCA\DAV\CalDAV\CalDavBackend::deleteCalendarObject',
+                    [
+                        'calendarId' => $calendarId,
+                        'calendarData' => $this->getCalendarById($calendarId),
+                        'shares' => $this->getShares($calendarId),
+                        'objectData' => $data,
+                    ]
+                ));
+            } else {
+                $this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::deleteCachedCalendarObject', new GenericEvent(
+                    '\OCA\DAV\CalDAV\CalDavBackend::deleteCachedCalendarObject',
+                    [
+                        'subscriptionId' => $calendarId,
+                        'calendarData' => $this->getCalendarById($calendarId),
+                        'shares' => $this->getShares($calendarId),
+                        'objectData' => $data,
+                    ]
+                ));
+            }
+        }
+
+        $stmt = $this->db->prepare('DELETE FROM `*PREFIX*calendarobjects` WHERE `calendarid` = ? AND `uri` = ? AND `calendartype` = ?');
+        $stmt->execute([$calendarId, $objectUri, $calendarType]);
+
+        if (is_array($data)) {
+            $this->purgeProperties($calendarId, $data['id'], $calendarType);
+        }
+
+        $this->addChange($calendarId, $objectUri, 3, $calendarType);
+    }
+
+    /**
+     * 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 interprete 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 $id
+     * @param array $filters
+     * @param int $calendarType
+     * @return array
+     */
+    public function calendarQuery($id, 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'])) {
+                $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', $query->createNamedParameter($id)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter($calendarType)));
+
+        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->execute();
+
+        $result = [];
+        while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
+            if ($requirePostFilter) {
+                // validateFilterForObject will parse the calendar data
+                // catch parsing errors
+                try {
+                    $matches = $this->validateFilterForObject($row, $filters);
+                } catch (ParseException $ex) {
+                    $this->logger->logException($ex, [
+                        'app' => 'dav',
+                        'message' => 'Caught parsing exception for calendar data. This usually indicates invalid calendar data. calendar-id:'.$id.' uri:'.$row['uri']
+                    ]);
+                    continue;
+                } catch (InvalidDataException $ex) {
+                    $this->logger->logException($ex, [
+                        'app' => 'dav',
+                        'message' => 'Caught invalid data exception for calendar data. This usually indicates invalid calendar data. calendar-id:'.$id.' uri:'.$row['uri']
+                    ]);
+                    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($filters['search-term']).'%')));
+
+        if ($offset) {
+            $query->setFirstResult($offset);
+        }
+        if ($limit) {
+            $query->setMaxResults($limit);
+        }
+
+        $stmt = $query->execute();
+
+        $result = [];
+        while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
+            $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',
+                $outerQuery->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)));
+
+        // only return public items for shared calendars for now
+        if ($calendarInfo['principaluri'] !== $calendarInfo['{http://owncloud.org/ns}owner-principal']) {
+            $innerQuery->andWhere($innerQuery->expr()->eq('c.classification',
+                $outerQuery->createNamedParameter(self::CLASSIFICATION_PUBLIC)));
+        }
+
+        $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) . '%')));
+        }
+
+        $outerQuery->select('c.id', 'c.calendardata', 'c.componenttype', 'c.uid', 'c.uri')
+            ->from('calendarobjects', 'c');
+
+        if (isset($options['timerange'])) {
+            if (isset($options['timerange']['start']) && $options['timerange']['start'] instanceof DateTime) {
+                $outerQuery->andWhere($outerQuery->expr()->gt('lastoccurence',
+                    $outerQuery->createNamedParameter($options['timerange']['start']->getTimeStamp())));
+            }
+            if (isset($options['timerange']['end']) && $options['timerange']['end'] instanceof DateTime) {
+                $outerQuery->andWhere($outerQuery->expr()->lt('firstoccurence',
+                    $outerQuery->createNamedParameter($options['timerange']['end']->getTimeStamp())));
+            }
+        }
+
+        if (isset($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->execute();
+        $calendarObjects = $result->fetchAll();
+
+        return array_map(function ($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', $calendarObjectIdQuery->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)));
+
+            // If it's shared, limit search to public events
+            if ($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', $calendarObjectIdQuery->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)));
+
+            // If it's shared, limit search to public events
+            if ($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)));
+
+            $searchOr->add($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);
+
+        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->execute();
+        $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->execute();
+        $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)));
+
+        $stmt = $query->execute();
+
+        if ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
+            return $row['calendaruri'] . '/' . $row['objecturi'];
+        }
+
+        return 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 $limit
+     * @param int $calendarType
+     * @return array
+     */
+    public function getChangesForCalendar($calendarId, $syncToken, $syncLevel, $limit = null, $calendarType=self::CALENDAR_TYPE_CALENDAR) {
+        // Current synctoken
+        $stmt = $this->db->prepare('SELECT `synctoken` FROM `*PREFIX*calendars` WHERE `id` = ?');
+        $stmt->execute([ $calendarId ]);
+        $currentToken = $stmt->fetchColumn(0);
+
+        if (is_null($currentToken)) {
+            return null;
+        }
+
+        $result = [
+            'syncToken' => $currentToken,
+            'added'     => [],
+            'modified'  => [],
+            'deleted'   => [],
+        ];
+
+        if ($syncToken) {
+            $query = "SELECT `uri`, `operation` FROM `*PREFIX*calendarchanges` WHERE `synctoken` >= ? AND `synctoken` < ? AND `calendarid` = ? AND `calendartype` = ? ORDER BY `synctoken`";
+            if ($limit>0) {
+                $query.= " LIMIT " . (int)$limit;
+            }
+
+            // Fetching all changes
+            $stmt = $this->db->prepare($query);
+            $stmt->execute([$syncToken, $currentToken, $calendarId, $calendarType]);
+
+            $changes = [];
+
+            // This loop ensures that any duplicates are overwritten, only the
+            // last change on a node is relevant.
+            while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
+                $changes[$row['uri']] = $row['operation'];
+            }
+
+            foreach ($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.
+            $query = "SELECT `uri` FROM `*PREFIX*calendarobjects` WHERE `calendarid` = ? AND `calendartype` = ?";
+            $stmt = $this->db->prepare($query);
+            $stmt->execute([$calendarId, $calendarType]);
+
+            $result['added'] = $stmt->fetchAll(\PDO::FETCH_COLUMN);
+        }
+        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) {
+        $fields = array_values($this->subscriptionPropertyMap);
+        $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->execute();
+
+        $subscriptions = [];
+        while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
+            $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',
+            ];
+
+            foreach ($this->subscriptionPropertyMap as $xmlName=>$dbName) {
+                if (!is_null($row[$dbName])) {
+                    $subscription[$xmlName] = $row[$dbName];
+                }
+            }
+
+            $subscriptions[] = $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) {
+            if (array_key_exists($xmlName, $properties)) {
+                $values[$dbName] = $properties[$xmlName];
+                if (in_array($dbName, $propertiesBoolean)) {
+                    $values[$dbName] = true;
+                }
+            }
+        }
+
+        $valuesToInsert = [];
+
+        $query = $this->db->getQueryBuilder();
+
+        foreach (array_keys($values) as $name) {
+            $valuesToInsert[$name] = $query->createNamedParameter($values[$name]);
+        }
+
+        $query->insert('calendarsubscriptions')
+            ->values($valuesToInsert)
+            ->execute();
+
+        $subscriptionId = $this->db->lastInsertId('*PREFIX*calendarsubscriptions');
+
+        $this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::createSubscription', new GenericEvent(
+            '\OCA\DAV\CalDAV\CalDavBackend::createSubscription',
+            [
+                'subscriptionId' => $subscriptionId,
+                'subscriptionData' => $this->getSubscriptionById($subscriptionId),
+            ]));
+
+        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';
+
+        /**
+         * @suppress SqlInjectionChecker
+         */
+        $propPatch->handle($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];
+                    $newValues[$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)))
+                ->execute();
+
+            $this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::updateSubscription', new GenericEvent(
+                '\OCA\DAV\CalDAV\CalDavBackend::updateSubscription',
+                [
+                    'subscriptionId' => $subscriptionId,
+                    'subscriptionData' => $this->getSubscriptionById($subscriptionId),
+                    'propertyMutations' => $mutations,
+                ]));
+
+            return true;
+        });
+    }
+
+    /**
+     * Deletes a subscription.
+     *
+     * @param mixed $subscriptionId
+     * @return void
+     */
+    public function deleteSubscription($subscriptionId) {
+        $this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::deleteSubscription', new GenericEvent(
+            '\OCA\DAV\CalDAV\CalDavBackend::deleteSubscription',
+            [
+                'subscriptionId' => $subscriptionId,
+                'subscriptionData' => $this->getSubscriptionById($subscriptionId),
+            ]));
+
+        $query = $this->db->getQueryBuilder();
+        $query->delete('calendarsubscriptions')
+            ->where($query->expr()->eq('id', $query->createNamedParameter($subscriptionId)))
+            ->execute();
+
+        $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)))
+            ->execute();
+
+        $query->delete('calendarchanges')
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
+            ->execute();
+
+        $query->delete($this->dbObjectPropertiesTable)
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
+            ->execute();
+    }
+
+    /**
+     * 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)))
+            ->execute();
+
+        $row = $stmt->fetch(\PDO::FETCH_ASSOC);
+
+        if (!$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)))
+                ->execute();
+
+        $result = [];
+        foreach ($stmt->fetchAll(\PDO::FETCH_ASSOC) as $row) {
+            $result[] = [
+                'calendardata' => $row['calendardata'],
+                'uri'          => $row['uri'],
+                'lastmodified' => $row['lastmodified'],
+                'etag'         => '"' . $row['etag'] . '"',
+                'size'         => (int)$row['size'],
+            ];
+        }
+
+        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)))
+                ->execute();
+    }
+
+    /**
+     * 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))
+            ])
+            ->execute();
+    }
+
+    /**
+     * 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)));
+        $syncToken = (int)$query->execute()->fetchColumn();
+
+        $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),
+            ])
+            ->execute();
+
+        $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);
+        $componentType = null;
+        $component = null;
+        $firstOccurrence = null;
+        $lastOccurrence = null;
+        $uid = null;
+        $classification = self::CLASSIFICATION_PUBLIC;
+        foreach ($vObject->getComponents() as $component) {
+            if ($component->name!=='VTIMEZONE') {
+                $componentType = $component->name;
+                $uid = (string)$component->UID;
+                break;
+            }
+        }
+        if (!$componentType) {
+            throw new \Sabre\DAV\Exception\BadRequest('Calendar objects must have a VJOURNAL, VEVENT or VTODO component');
+        }
+        if ($componentType === 'VEVENT' && $component->DTSTART) {
+            $firstOccurrence = $component->DTSTART->getDateTime()->getTimeStamp();
+            // Finding the last occurrence is a bit harder
+            if (!isset($component->RRULE)) {
+                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 {
+                $it = new EventIterator($vObject, (string)$component->UID);
+                $maxDate = new DateTime(self::MAX_DATE);
+                if ($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 IShareable $shareable
+     * @param array $add
+     * @param array $remove
+     */
+    public function updateShares($shareable, $add, $remove) {
+        $calendarId = $shareable->getResourceId();
+        $this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::updateShares', new GenericEvent(
+            '\OCA\DAV\CalDAV\CalDavBackend::updateShares',
+            [
+                'calendarId' => $calendarId,
+                'calendarData' => $this->getCalendarById($calendarId),
+                'shares' => $this->getShares($calendarId),
+                'add' => $add,
+                'remove' => $remove,
+            ]));
+        $this->calendarSharingBackend->updateShares($shareable, $add, $remove);
+    }
+
+    /**
+     * @param int $resourceId
+     * @param int $calendarType
+     * @return array
+     */
+    public function getShares($resourceId, $calendarType=self::CALENDAR_TYPE_CALENDAR) {
+        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();
+        $this->dispatcher->dispatch('\OCA\DAV\CalDAV\CalDavBackend::publishCalendar', new GenericEvent(
+            '\OCA\DAV\CalDAV\CalDavBackend::updateShares',
+            [
+                'calendarId' => $calendarId,
+                'calendarData' => $this->getCalendarById($calendarId),
+                'public' => $value,
+            ]));
+
+        $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->execute();
+            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->execute();
+        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)))
+            ->execute();
+
+        $row = $result->fetch();
+        $result->closeCursor();
+        return $row ? reset($row) : false;
+    }
+
+    /**
+     * @param int $resourceId
+     * @param array $acl
+     * @return array
+     */
+    public function applyShareAcl($resourceId, $acl) {
+        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::$indexProperties)) {
+                    $value = $property->getValue();
+                    // is this a shitty db?
+                    if (!$this->db->supports4ByteText()) {
+                        $value = preg_replace('/[\x{10000}-\x{10FFFF}]/u', "\xEF\xBF\xBD", $value);
+                    }
+                    $value = mb_substr($value, 0, 254);
+
+                    $query->setParameter('name', $property->name);
+                    $query->setParameter('parameter', null);
+                    $query->setParameter('value', $value);
+                    $query->execute();
+                }
+
+                if (array_key_exists($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);
+                            $query->setParameter('parameter', mb_substr($key, 0, 254));
+                            $query->setParameter('value', mb_substr($value, 0, 254));
+                            $query->execute();
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    /**
+     * 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)))
+            ->execute();
+
+        $ids = $result->fetchAll();
+        foreach ($ids as $id) {
+            $this->deleteCalendar($id['id']);
+        }
+    }
+
+    /**
+     * @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->execute();
+
+        $uris = [];
+        foreach ($stmt->fetchAll(\PDO::FETCH_ASSOC) 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)))
+            ->execute();
+
+        $query->delete('calendarchanges')
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
+            ->execute();
+
+        $query->delete($this->dbObjectPropertiesTable)
+            ->where($query->expr()->eq('calendarid', $query->createNamedParameter($subscriptionId)))
+            ->andWhere($query->expr()->eq('calendartype', $query->createNamedParameter(self::CALENDAR_TYPE_SUBSCRIPTION)))
+            ->execute();
+
+        foreach ($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 $uriDestination
+     */
+    public function moveCalendar($uriName, $uriOrigin, $uriDestination) {
+        $query = $this->db->getQueryBuilder();
+        $query->update('calendars')
+            ->set('principaluri', $query->createNamedParameter($uriDestination))
+            ->where($query->expr()->eq('principaluri', $query->createNamedParameter($uriOrigin)))
+            ->andWhere($query->expr()->eq('uri', $query->createNamedParameter($uriName)))
+            ->execute();
+    }
+
+    /**
+     * 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->execute();
+    }
+
+    /**
+     * 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->execute();
+        $objectIds = $result->fetch();
+        $result->closeCursor();
+
+        if (!isset($objectIds['id'])) {
+            throw new \InvalidArgumentException('Calendarobject does not exists: ' . $uri);
+        }
+
+        return (int)$objectIds['id'];
+    }
+
+    /**
+     * 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') {
+            list(, $name) = Uri\split($principalUri);
+            if ($toV2 === true) {
+                return "principals/users/$name";
+            }
+            return "principals/$name";
+        }
+        return $principalUri;
+    }
+
+    /**
+     * adds information about an owner to the calendar data
+     *
+     * @param $calendarInfo
+     */
+    private function addOwnerPrincipal(&$calendarInfo) {
+        $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'];
+        }
+    }
 }