nextcloud / server

lib/private/Share/Share.php

Indentation +2089 added lines, -2089 removed lines

@@ -52,2103 +52,2103 @@
  */
 class Share extends Constants {
 
-	/** CRUDS permissions (Create, Read, Update, Delete, Share) using a bitmask
-	 * Construct permissions for share() and setPermissions with Or (|) e.g.
-	 * Give user read and update permissions: PERMISSION_READ | PERMISSION_UPDATE
-	 *
-	 * Check if permission is granted with And (&) e.g. Check if delete is
-	 * granted: if ($permissions & PERMISSION_DELETE)
-	 *
-	 * Remove permissions with And (&) and Not (~) e.g. Remove the update
-	 * permission: $permissions &= ~PERMISSION_UPDATE
-	 *
-	 * Apps are required to handle permissions on their own, this class only
-	 * stores and manages the permissions of shares
-	 * @see lib/public/constants.php
-	 */
-
-	/**
-	 * Register a sharing backend class that implements OCP\Share_Backend for an item type
-	 * @param string $itemType Item type
-	 * @param string $class Backend class
-	 * @param string $collectionOf (optional) Depends on item type
-	 * @param array $supportedFileExtensions (optional) List of supported file extensions if this item type depends on files
-	 * @return boolean true if backend is registered or false if error
-	 */
-	public static function registerBackend($itemType, $class, $collectionOf = null, $supportedFileExtensions = null) {
-		if (\OC::$server->getConfig()->getAppValue('core', 'shareapi_enabled', 'yes') == 'yes') {
-			if (!isset(self::$backendTypes[$itemType])) {
-				self::$backendTypes[$itemType] = array(
-					'class' => $class,
-					'collectionOf' => $collectionOf,
-					'supportedFileExtensions' => $supportedFileExtensions
-				);
-				if(count(self::$backendTypes) === 1) {
-					Util::addScript('core', 'merged-share-backend');
-					\OC_Util::addStyle('core', 'share');
-				}
-				return true;
-			}
-			\OCP\Util::writeLog('OCP\Share',
-				'Sharing backend '.$class.' not registered, '.self::$backendTypes[$itemType]['class']
-				.' is already registered for '.$itemType,
-				\OCP\Util::WARN);
-		}
-		return false;
-	}
-
-	/**
-	 * Get the items of item type shared with the current user
-	 * @param string $itemType
-	 * @param int $format (optional) Format type must be defined by the backend
-	 * @param mixed $parameters (optional)
-	 * @param int $limit Number of items to return (optional) Returns all by default
-	 * @param boolean $includeCollections (optional)
-	 * @return mixed Return depends on format
-	 */
-	public static function getItemsSharedWith($itemType, $format = self::FORMAT_NONE,
-											  $parameters = null, $limit = -1, $includeCollections = false) {
-		return self::getItems($itemType, null, self::$shareTypeUserAndGroups, \OC_User::getUser(), null, $format,
-			$parameters, $limit, $includeCollections);
-	}
-
-	/**
-	 * Get the items of item type shared with a user
-	 * @param string $itemType
-	 * @param string $user id for which user we want the shares
-	 * @param int $format (optional) Format type must be defined by the backend
-	 * @param mixed $parameters (optional)
-	 * @param int $limit Number of items to return (optional) Returns all by default
-	 * @param boolean $includeCollections (optional)
-	 * @return mixed Return depends on format
-	 */
-	public static function getItemsSharedWithUser($itemType, $user, $format = self::FORMAT_NONE,
-												  $parameters = null, $limit = -1, $includeCollections = false) {
-		return self::getItems($itemType, null, self::$shareTypeUserAndGroups, $user, null, $format,
-			$parameters, $limit, $includeCollections);
-	}
-
-	/**
-	 * Get the item of item type shared with a given user by source
-	 * @param string $itemType
-	 * @param string $itemSource
-	 * @param string $user User to whom the item was shared
-	 * @param string $owner Owner of the share
-	 * @param int $shareType only look for a specific share type
-	 * @return array Return list of items with file_target, permissions and expiration
-	 */
-	public static function getItemSharedWithUser($itemType, $itemSource, $user, $owner = null, $shareType = null) {
-		$shares = array();
-		$fileDependent = false;
-
-		$where = 'WHERE';
-		$fileDependentWhere = '';
-		if ($itemType === 'file' || $itemType === 'folder') {
-			$fileDependent = true;
-			$column = 'file_source';
-			$fileDependentWhere = 'INNER JOIN `*PREFIX*filecache` ON `file_source` = `*PREFIX*filecache`.`fileid` ';
-			$fileDependentWhere .= 'INNER JOIN `*PREFIX*storages` ON `numeric_id` = `*PREFIX*filecache`.`storage` ';
-		} else {
-			$column = 'item_source';
-		}
-
-		$select = self::createSelectStatement(self::FORMAT_NONE, $fileDependent);
-
-		$where .= ' `' . $column . '` = ? AND `item_type` = ? ';
-		$arguments = array($itemSource, $itemType);
-		// for link shares $user === null
-		if ($user !== null) {
-			$where .= ' AND `share_with` = ? ';
-			$arguments[] = $user;
-		}
-
-		if ($shareType !== null) {
-			$where .= ' AND `share_type` = ? ';
-			$arguments[] = $shareType;
-		}
-
-		if ($owner !== null) {
-			$where .= ' AND `uid_owner` = ? ';
-			$arguments[] = $owner;
-		}
-
-		$query = \OC_DB::prepare('SELECT ' . $select . ' FROM `*PREFIX*share` '. $fileDependentWhere . $where);
-
-		$result = \OC_DB::executeAudited($query, $arguments);
-
-		while ($row = $result->fetchRow()) {
-			if ($fileDependent && !self::isFileReachable($row['path'], $row['storage_id'])) {
-				continue;
-			}
-			if ($fileDependent && (int)$row['file_parent'] === -1) {
-				// if it is a mount point we need to get the path from the mount manager
-				$mountManager = \OC\Files\Filesystem::getMountManager();
-				$mountPoint = $mountManager->findByStorageId($row['storage_id']);
-				if (!empty($mountPoint)) {
-					$path = $mountPoint[0]->getMountPoint();
-					$path = trim($path, '/');
-					$path = substr($path, strlen($owner) + 1); //normalize path to 'files/foo.txt`
-					$row['path'] = $path;
-				} else {
-					\OC::$server->getLogger()->warning(
-						'Could not resolve mount point for ' . $row['storage_id'],
-						['app' => 'OCP\Share']
-					);
-				}
-			}
-			$shares[] = $row;
-		}
-
-		//if didn't found a result than let's look for a group share.
-		if(empty($shares) && $user !== null) {
-			$userObject = \OC::$server->getUserManager()->get($user);
-			$groups = [];
-			if ($userObject) {
-				$groups = \OC::$server->getGroupManager()->getUserGroupIds($userObject);
-			}
-
-			if (!empty($groups)) {
-				$where = $fileDependentWhere . ' WHERE `' . $column . '` = ? AND `item_type` = ? AND `share_with` in (?)';
-				$arguments = array($itemSource, $itemType, $groups);
-				$types = array(null, null, IQueryBuilder::PARAM_STR_ARRAY);
-
-				if ($owner !== null) {
-					$where .= ' AND `uid_owner` = ?';
-					$arguments[] = $owner;
-					$types[] = null;
-				}
-
-				// TODO: inject connection, hopefully one day in the future when this
-				// class isn't static anymore...
-				$conn = \OC::$server->getDatabaseConnection();
-				$result = $conn->executeQuery(
-					'SELECT ' . $select . ' FROM `*PREFIX*share` ' . $where,
-					$arguments,
-					$types
-				);
-
-				while ($row = $result->fetch()) {
-					$shares[] = $row;
-				}
-			}
-		}
-
-		return $shares;
-
-	}
-
-	/**
-	 * Get the item of item type shared with the current user by source
-	 * @param string $itemType
-	 * @param string $itemSource
-	 * @param int $format (optional) Format type must be defined by the backend
-	 * @param mixed $parameters
-	 * @param boolean $includeCollections
-	 * @param string $shareWith (optional) define against which user should be checked, default: current user
-	 * @return array
-	 */
-	public static function getItemSharedWithBySource($itemType, $itemSource, $format = self::FORMAT_NONE,
-													 $parameters = null, $includeCollections = false, $shareWith = null) {
-		$shareWith = ($shareWith === null) ? \OC_User::getUser() : $shareWith;
-		return self::getItems($itemType, $itemSource, self::$shareTypeUserAndGroups, $shareWith, null, $format,
-			$parameters, 1, $includeCollections, true);
-	}
-
-	/**
-	 * Based on the given token the share information will be returned - password protected shares will be verified
-	 * @param string $token
-	 * @param bool $checkPasswordProtection
-	 * @return array|boolean false will be returned in case the token is unknown or unauthorized
-	 */
-	public static function getShareByToken($token, $checkPasswordProtection = true) {
-		$query = \OC_DB::prepare('SELECT * FROM `*PREFIX*share` WHERE `token` = ?', 1);
-		$result = $query->execute(array($token));
-		if ($result === false) {
-			\OCP\Util::writeLog('OCP\Share', \OC_DB::getErrorMessage() . ', token=' . $token, \OCP\Util::ERROR);
-		}
-		$row = $result->fetchRow();
-		if ($row === false) {
-			return false;
-		}
-		if (is_array($row) and self::expireItem($row)) {
-			return false;
-		}
-
-		// password protected shares need to be authenticated
-		if ($checkPasswordProtection && !\OC\Share\Share::checkPasswordProtectedShare($row)) {
-			return false;
-		}
-
-		return $row;
-	}
-
-	/**
-	 * resolves reshares down to the last real share
-	 * @param array $linkItem
-	 * @return array file owner
-	 */
-	public static function resolveReShare($linkItem)
-	{
-		if (isset($linkItem['parent'])) {
-			$parent = $linkItem['parent'];
-			while (isset($parent)) {
-				$query = \OC_DB::prepare('SELECT * FROM `*PREFIX*share` WHERE `id` = ?', 1);
-				$item = $query->execute(array($parent))->fetchRow();
-				if (isset($item['parent'])) {
-					$parent = $item['parent'];
-				} else {
-					return $item;
-				}
-			}
-		}
-		return $linkItem;
-	}
-
-
-	/**
-	 * Get the shared items of item type owned by the current user
-	 * @param string $itemType
-	 * @param int $format (optional) Format type must be defined by the backend
-	 * @param mixed $parameters
-	 * @param int $limit Number of items to return (optional) Returns all by default
-	 * @param boolean $includeCollections
-	 * @return mixed Return depends on format
-	 */
-	public static function getItemsShared($itemType, $format = self::FORMAT_NONE, $parameters = null,
-										  $limit = -1, $includeCollections = false) {
-		return self::getItems($itemType, null, null, null, \OC_User::getUser(), $format,
-			$parameters, $limit, $includeCollections);
-	}
-
-	/**
-	 * Get the shared item of item type owned by the current user
-	 * @param string $itemType
-	 * @param string $itemSource
-	 * @param int $format (optional) Format type must be defined by the backend
-	 * @param mixed $parameters
-	 * @param boolean $includeCollections
-	 * @return mixed Return depends on format
-	 */
-	public static function getItemShared($itemType, $itemSource, $format = self::FORMAT_NONE,
-										 $parameters = null, $includeCollections = false) {
-		return self::getItems($itemType, $itemSource, null, null, \OC_User::getUser(), $format,
-			$parameters, -1, $includeCollections);
-	}
-
-	/**
-	 * Share an item with a user, group, or via private link
-	 * @param string $itemType
-	 * @param string $itemSource
-	 * @param int $shareType SHARE_TYPE_USER, SHARE_TYPE_GROUP, or SHARE_TYPE_LINK
-	 * @param string $shareWith User or group the item is being shared with
-	 * @param int $permissions CRUDS
-	 * @param string $itemSourceName
-	 * @param \DateTime|null $expirationDate
-	 * @param bool|null $passwordChanged
-	 * @return boolean|string Returns true on success or false on failure, Returns token on success for links
-	 * @throws \OC\HintException when the share type is remote and the shareWith is invalid
-	 * @throws \Exception
-	 * @since 5.0.0 - parameter $itemSourceName was added in 6.0.0, parameter $expirationDate was added in 7.0.0, parameter $passwordChanged added in 9.0.0
-	 * TESTS ONLY
-	 */
-	public static function shareItem($itemType, $itemSource, $shareType, $shareWith, $permissions, $itemSourceName = null, \DateTime $expirationDate = null, $passwordChanged = null) {
-
-		$backend = self::getBackend($itemType);
-		$l = \OC::$server->getL10N('lib');
-
-		if ($backend->isShareTypeAllowed($shareType) === false) {
-			$message = 'Sharing %s failed, because the backend does not allow shares from type %i';
-			$message_t = $l->t('Sharing %s failed, because the backend does not allow shares from type %i', array($itemSourceName, $shareType));
-			\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareType), \OCP\Util::DEBUG);
-			throw new \Exception($message_t);
-		}
-
-		$uidOwner = \OC_User::getUser();
-		$shareWithinGroupOnly = self::shareWithGroupMembersOnly();
-
-		if (is_null($itemSourceName)) {
-			$itemSourceName = $itemSource;
-		}
-		$itemName = $itemSourceName;
-
-		// check if file can be shared
-		if ($itemType === 'file' or $itemType === 'folder') {
-			$path = \OC\Files\Filesystem::getPath($itemSource);
-			$itemName = $path;
-
-			// verify that the file exists before we try to share it
-			if (!$path) {
-				$message = 'Sharing %s failed, because the file does not exist';
-				$message_t = $l->t('Sharing %s failed, because the file does not exist', array($itemSourceName));
-				\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName), \OCP\Util::DEBUG);
-				throw new \Exception($message_t);
-			}
-			// verify that the user has share permission
-			if (!\OC\Files\Filesystem::isSharable($path) || \OCP\Util::isSharingDisabledForUser()) {
-				$message = 'You are not allowed to share %s';
-				$message_t = $l->t('You are not allowed to share %s', [$path]);
-				\OCP\Util::writeLog('OCP\Share', sprintf($message, $path), \OCP\Util::DEBUG);
-				throw new \Exception($message_t);
-			}
-		}
-
-		//verify that we don't share a folder which already contains a share mount point
-		if ($itemType === 'folder') {
-			$path = '/' . $uidOwner . '/files' . \OC\Files\Filesystem::getPath($itemSource) . '/';
-			$mountManager = \OC\Files\Filesystem::getMountManager();
-			$mounts = $mountManager->findIn($path);
-			foreach ($mounts as $mount) {
-				if ($mount->getStorage()->instanceOfStorage('\OCA\Files_Sharing\ISharedStorage')) {
-					$message = 'Sharing "' . $itemSourceName . '" failed, because it contains files shared with you!';
-					\OCP\Util::writeLog('OCP\Share', $message, \OCP\Util::DEBUG);
-					throw new \Exception($message);
-				}
-
-			}
-		}
-
-		// single file shares should never have delete permissions
-		if ($itemType === 'file') {
-			$permissions = (int)$permissions & ~\OCP\Constants::PERMISSION_DELETE;
-		}
-
-		//Validate expirationDate
-		if ($expirationDate !== null) {
-			try {
-				/*
+    /** CRUDS permissions (Create, Read, Update, Delete, Share) using a bitmask
+     * Construct permissions for share() and setPermissions with Or (|) e.g.
+     * Give user read and update permissions: PERMISSION_READ | PERMISSION_UPDATE
+     *
+     * Check if permission is granted with And (&) e.g. Check if delete is
+     * granted: if ($permissions & PERMISSION_DELETE)
+     *
+     * Remove permissions with And (&) and Not (~) e.g. Remove the update
+     * permission: $permissions &= ~PERMISSION_UPDATE
+     *
+     * Apps are required to handle permissions on their own, this class only
+     * stores and manages the permissions of shares
+     * @see lib/public/constants.php
+     */
+
+    /**
+     * Register a sharing backend class that implements OCP\Share_Backend for an item type
+     * @param string $itemType Item type
+     * @param string $class Backend class
+     * @param string $collectionOf (optional) Depends on item type
+     * @param array $supportedFileExtensions (optional) List of supported file extensions if this item type depends on files
+     * @return boolean true if backend is registered or false if error
+     */
+    public static function registerBackend($itemType, $class, $collectionOf = null, $supportedFileExtensions = null) {
+        if (\OC::$server->getConfig()->getAppValue('core', 'shareapi_enabled', 'yes') == 'yes') {
+            if (!isset(self::$backendTypes[$itemType])) {
+                self::$backendTypes[$itemType] = array(
+                    'class' => $class,
+                    'collectionOf' => $collectionOf,
+                    'supportedFileExtensions' => $supportedFileExtensions
+                );
+                if(count(self::$backendTypes) === 1) {
+                    Util::addScript('core', 'merged-share-backend');
+                    \OC_Util::addStyle('core', 'share');
+                }
+                return true;
+            }
+            \OCP\Util::writeLog('OCP\Share',
+                'Sharing backend '.$class.' not registered, '.self::$backendTypes[$itemType]['class']
+                .' is already registered for '.$itemType,
+                \OCP\Util::WARN);
+        }
+        return false;
+    }
+
+    /**
+     * Get the items of item type shared with the current user
+     * @param string $itemType
+     * @param int $format (optional) Format type must be defined by the backend
+     * @param mixed $parameters (optional)
+     * @param int $limit Number of items to return (optional) Returns all by default
+     * @param boolean $includeCollections (optional)
+     * @return mixed Return depends on format
+     */
+    public static function getItemsSharedWith($itemType, $format = self::FORMAT_NONE,
+                                                $parameters = null, $limit = -1, $includeCollections = false) {
+        return self::getItems($itemType, null, self::$shareTypeUserAndGroups, \OC_User::getUser(), null, $format,
+            $parameters, $limit, $includeCollections);
+    }
+
+    /**
+     * Get the items of item type shared with a user
+     * @param string $itemType
+     * @param string $user id for which user we want the shares
+     * @param int $format (optional) Format type must be defined by the backend
+     * @param mixed $parameters (optional)
+     * @param int $limit Number of items to return (optional) Returns all by default
+     * @param boolean $includeCollections (optional)
+     * @return mixed Return depends on format
+     */
+    public static function getItemsSharedWithUser($itemType, $user, $format = self::FORMAT_NONE,
+                                                    $parameters = null, $limit = -1, $includeCollections = false) {
+        return self::getItems($itemType, null, self::$shareTypeUserAndGroups, $user, null, $format,
+            $parameters, $limit, $includeCollections);
+    }
+
+    /**
+     * Get the item of item type shared with a given user by source
+     * @param string $itemType
+     * @param string $itemSource
+     * @param string $user User to whom the item was shared
+     * @param string $owner Owner of the share
+     * @param int $shareType only look for a specific share type
+     * @return array Return list of items with file_target, permissions and expiration
+     */
+    public static function getItemSharedWithUser($itemType, $itemSource, $user, $owner = null, $shareType = null) {
+        $shares = array();
+        $fileDependent = false;
+
+        $where = 'WHERE';
+        $fileDependentWhere = '';
+        if ($itemType === 'file' || $itemType === 'folder') {
+            $fileDependent = true;
+            $column = 'file_source';
+            $fileDependentWhere = 'INNER JOIN `*PREFIX*filecache` ON `file_source` = `*PREFIX*filecache`.`fileid` ';
+            $fileDependentWhere .= 'INNER JOIN `*PREFIX*storages` ON `numeric_id` = `*PREFIX*filecache`.`storage` ';
+        } else {
+            $column = 'item_source';
+        }
+
+        $select = self::createSelectStatement(self::FORMAT_NONE, $fileDependent);
+
+        $where .= ' `' . $column . '` = ? AND `item_type` = ? ';
+        $arguments = array($itemSource, $itemType);
+        // for link shares $user === null
+        if ($user !== null) {
+            $where .= ' AND `share_with` = ? ';
+            $arguments[] = $user;
+        }
+
+        if ($shareType !== null) {
+            $where .= ' AND `share_type` = ? ';
+            $arguments[] = $shareType;
+        }
+
+        if ($owner !== null) {
+            $where .= ' AND `uid_owner` = ? ';
+            $arguments[] = $owner;
+        }
+
+        $query = \OC_DB::prepare('SELECT ' . $select . ' FROM `*PREFIX*share` '. $fileDependentWhere . $where);
+
+        $result = \OC_DB::executeAudited($query, $arguments);
+
+        while ($row = $result->fetchRow()) {
+            if ($fileDependent && !self::isFileReachable($row['path'], $row['storage_id'])) {
+                continue;
+            }
+            if ($fileDependent && (int)$row['file_parent'] === -1) {
+                // if it is a mount point we need to get the path from the mount manager
+                $mountManager = \OC\Files\Filesystem::getMountManager();
+                $mountPoint = $mountManager->findByStorageId($row['storage_id']);
+                if (!empty($mountPoint)) {
+                    $path = $mountPoint[0]->getMountPoint();
+                    $path = trim($path, '/');
+                    $path = substr($path, strlen($owner) + 1); //normalize path to 'files/foo.txt`
+                    $row['path'] = $path;
+                } else {
+                    \OC::$server->getLogger()->warning(
+                        'Could not resolve mount point for ' . $row['storage_id'],
+                        ['app' => 'OCP\Share']
+                    );
+                }
+            }
+            $shares[] = $row;
+        }
+
+        //if didn't found a result than let's look for a group share.
+        if(empty($shares) && $user !== null) {
+            $userObject = \OC::$server->getUserManager()->get($user);
+            $groups = [];
+            if ($userObject) {
+                $groups = \OC::$server->getGroupManager()->getUserGroupIds($userObject);
+            }
+
+            if (!empty($groups)) {
+                $where = $fileDependentWhere . ' WHERE `' . $column . '` = ? AND `item_type` = ? AND `share_with` in (?)';
+                $arguments = array($itemSource, $itemType, $groups);
+                $types = array(null, null, IQueryBuilder::PARAM_STR_ARRAY);
+
+                if ($owner !== null) {
+                    $where .= ' AND `uid_owner` = ?';
+                    $arguments[] = $owner;
+                    $types[] = null;
+                }
+
+                // TODO: inject connection, hopefully one day in the future when this
+                // class isn't static anymore...
+                $conn = \OC::$server->getDatabaseConnection();
+                $result = $conn->executeQuery(
+                    'SELECT ' . $select . ' FROM `*PREFIX*share` ' . $where,
+                    $arguments,
+                    $types
+                );
+
+                while ($row = $result->fetch()) {
+                    $shares[] = $row;
+                }
+            }
+        }
+
+        return $shares;
+
+    }
+
+    /**
+     * Get the item of item type shared with the current user by source
+     * @param string $itemType
+     * @param string $itemSource
+     * @param int $format (optional) Format type must be defined by the backend
+     * @param mixed $parameters
+     * @param boolean $includeCollections
+     * @param string $shareWith (optional) define against which user should be checked, default: current user
+     * @return array
+     */
+    public static function getItemSharedWithBySource($itemType, $itemSource, $format = self::FORMAT_NONE,
+                                                        $parameters = null, $includeCollections = false, $shareWith = null) {
+        $shareWith = ($shareWith === null) ? \OC_User::getUser() : $shareWith;
+        return self::getItems($itemType, $itemSource, self::$shareTypeUserAndGroups, $shareWith, null, $format,
+            $parameters, 1, $includeCollections, true);
+    }
+
+    /**
+     * Based on the given token the share information will be returned - password protected shares will be verified
+     * @param string $token
+     * @param bool $checkPasswordProtection
+     * @return array|boolean false will be returned in case the token is unknown or unauthorized
+     */
+    public static function getShareByToken($token, $checkPasswordProtection = true) {
+        $query = \OC_DB::prepare('SELECT * FROM `*PREFIX*share` WHERE `token` = ?', 1);
+        $result = $query->execute(array($token));
+        if ($result === false) {
+            \OCP\Util::writeLog('OCP\Share', \OC_DB::getErrorMessage() . ', token=' . $token, \OCP\Util::ERROR);
+        }
+        $row = $result->fetchRow();
+        if ($row === false) {
+            return false;
+        }
+        if (is_array($row) and self::expireItem($row)) {
+            return false;
+        }
+
+        // password protected shares need to be authenticated
+        if ($checkPasswordProtection && !\OC\Share\Share::checkPasswordProtectedShare($row)) {
+            return false;
+        }
+
+        return $row;
+    }
+
+    /**
+     * resolves reshares down to the last real share
+     * @param array $linkItem
+     * @return array file owner
+     */
+    public static function resolveReShare($linkItem)
+    {
+        if (isset($linkItem['parent'])) {
+            $parent = $linkItem['parent'];
+            while (isset($parent)) {
+                $query = \OC_DB::prepare('SELECT * FROM `*PREFIX*share` WHERE `id` = ?', 1);
+                $item = $query->execute(array($parent))->fetchRow();
+                if (isset($item['parent'])) {
+                    $parent = $item['parent'];
+                } else {
+                    return $item;
+                }
+            }
+        }
+        return $linkItem;
+    }
+
+
+    /**
+     * Get the shared items of item type owned by the current user
+     * @param string $itemType
+     * @param int $format (optional) Format type must be defined by the backend
+     * @param mixed $parameters
+     * @param int $limit Number of items to return (optional) Returns all by default
+     * @param boolean $includeCollections
+     * @return mixed Return depends on format
+     */
+    public static function getItemsShared($itemType, $format = self::FORMAT_NONE, $parameters = null,
+                                            $limit = -1, $includeCollections = false) {
+        return self::getItems($itemType, null, null, null, \OC_User::getUser(), $format,
+            $parameters, $limit, $includeCollections);
+    }
+
+    /**
+     * Get the shared item of item type owned by the current user
+     * @param string $itemType
+     * @param string $itemSource
+     * @param int $format (optional) Format type must be defined by the backend
+     * @param mixed $parameters
+     * @param boolean $includeCollections
+     * @return mixed Return depends on format
+     */
+    public static function getItemShared($itemType, $itemSource, $format = self::FORMAT_NONE,
+                                            $parameters = null, $includeCollections = false) {
+        return self::getItems($itemType, $itemSource, null, null, \OC_User::getUser(), $format,
+            $parameters, -1, $includeCollections);
+    }
+
+    /**
+     * Share an item with a user, group, or via private link
+     * @param string $itemType
+     * @param string $itemSource
+     * @param int $shareType SHARE_TYPE_USER, SHARE_TYPE_GROUP, or SHARE_TYPE_LINK
+     * @param string $shareWith User or group the item is being shared with
+     * @param int $permissions CRUDS
+     * @param string $itemSourceName
+     * @param \DateTime|null $expirationDate
+     * @param bool|null $passwordChanged
+     * @return boolean|string Returns true on success or false on failure, Returns token on success for links
+     * @throws \OC\HintException when the share type is remote and the shareWith is invalid
+     * @throws \Exception
+     * @since 5.0.0 - parameter $itemSourceName was added in 6.0.0, parameter $expirationDate was added in 7.0.0, parameter $passwordChanged added in 9.0.0
+     * TESTS ONLY
+     */
+    public static function shareItem($itemType, $itemSource, $shareType, $shareWith, $permissions, $itemSourceName = null, \DateTime $expirationDate = null, $passwordChanged = null) {
+
+        $backend = self::getBackend($itemType);
+        $l = \OC::$server->getL10N('lib');
+
+        if ($backend->isShareTypeAllowed($shareType) === false) {
+            $message = 'Sharing %s failed, because the backend does not allow shares from type %i';
+            $message_t = $l->t('Sharing %s failed, because the backend does not allow shares from type %i', array($itemSourceName, $shareType));
+            \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareType), \OCP\Util::DEBUG);
+            throw new \Exception($message_t);
+        }
+
+        $uidOwner = \OC_User::getUser();
+        $shareWithinGroupOnly = self::shareWithGroupMembersOnly();
+
+        if (is_null($itemSourceName)) {
+            $itemSourceName = $itemSource;
+        }
+        $itemName = $itemSourceName;
+
+        // check if file can be shared
+        if ($itemType === 'file' or $itemType === 'folder') {
+            $path = \OC\Files\Filesystem::getPath($itemSource);
+            $itemName = $path;
+
+            // verify that the file exists before we try to share it
+            if (!$path) {
+                $message = 'Sharing %s failed, because the file does not exist';
+                $message_t = $l->t('Sharing %s failed, because the file does not exist', array($itemSourceName));
+                \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName), \OCP\Util::DEBUG);
+                throw new \Exception($message_t);
+            }
+            // verify that the user has share permission
+            if (!\OC\Files\Filesystem::isSharable($path) || \OCP\Util::isSharingDisabledForUser()) {
+                $message = 'You are not allowed to share %s';
+                $message_t = $l->t('You are not allowed to share %s', [$path]);
+                \OCP\Util::writeLog('OCP\Share', sprintf($message, $path), \OCP\Util::DEBUG);
+                throw new \Exception($message_t);
+            }
+        }
+
+        //verify that we don't share a folder which already contains a share mount point
+        if ($itemType === 'folder') {
+            $path = '/' . $uidOwner . '/files' . \OC\Files\Filesystem::getPath($itemSource) . '/';
+            $mountManager = \OC\Files\Filesystem::getMountManager();
+            $mounts = $mountManager->findIn($path);
+            foreach ($mounts as $mount) {
+                if ($mount->getStorage()->instanceOfStorage('\OCA\Files_Sharing\ISharedStorage')) {
+                    $message = 'Sharing "' . $itemSourceName . '" failed, because it contains files shared with you!';
+                    \OCP\Util::writeLog('OCP\Share', $message, \OCP\Util::DEBUG);
+                    throw new \Exception($message);
+                }
+
+            }
+        }
+
+        // single file shares should never have delete permissions
+        if ($itemType === 'file') {
+            $permissions = (int)$permissions & ~\OCP\Constants::PERMISSION_DELETE;
+        }
+
+        //Validate expirationDate
+        if ($expirationDate !== null) {
+            try {
+                /*
 				 * Reuse the validateExpireDate.
 				 * We have to pass time() since the second arg is the time
 				 * the file was shared, since it is not shared yet we just use
 				 * the current time.
 				 */
-				$expirationDate = self::validateExpireDate($expirationDate->format('Y-m-d'), time(), $itemType, $itemSource);
-			} catch (\Exception $e) {
-				throw new \OC\HintException($e->getMessage(), $e->getMessage(), 404);
-			}
-		}
-
-		// Verify share type and sharing conditions are met
-		if ($shareType === self::SHARE_TYPE_USER) {
-			if ($shareWith == $uidOwner) {
-				$message = 'Sharing %s failed, because you can not share with yourself';
-				$message_t = $l->t('Sharing %s failed, because you can not share with yourself', [$itemName]);
-				\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName), \OCP\Util::DEBUG);
-				throw new \Exception($message_t);
-			}
-			if (!\OC::$server->getUserManager()->userExists($shareWith)) {
-				$message = 'Sharing %s failed, because the user %s does not exist';
-				$message_t = $l->t('Sharing %s failed, because the user %s does not exist', array($itemSourceName, $shareWith));
-				\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareWith), \OCP\Util::DEBUG);
-				throw new \Exception($message_t);
-			}
-			if ($shareWithinGroupOnly) {
-				$userManager = \OC::$server->getUserManager();
-				$groupManager = \OC::$server->getGroupManager();
-				$userOwner = $userManager->get($uidOwner);
-				$userShareWith = $userManager->get($shareWith);
-				$groupsOwner = [];
-				$groupsShareWith = [];
-				if ($userOwner) {
-					$groupsOwner = $groupManager->getUserGroupIds($userOwner);
-				}
-				if ($userShareWith) {
-					$groupsShareWith = $groupManager->getUserGroupIds($userShareWith);
-				}
-				$inGroup = array_intersect($groupsOwner, $groupsShareWith);
-				if (empty($inGroup)) {
-					$message = 'Sharing %s failed, because the user '
-						.'%s is not a member of any groups that %s is a member of';
-					$message_t = $l->t('Sharing %s failed, because the user %s is not a member of any groups that %s is a member of', array($itemName, $shareWith, $uidOwner));
-					\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemName, $shareWith, $uidOwner), \OCP\Util::DEBUG);
-					throw new \Exception($message_t);
-				}
-			}
-			// Check if the item source is already shared with the user, either from the same owner or a different user
-			if ($checkExists = self::getItems($itemType, $itemSource, self::$shareTypeUserAndGroups,
-				$shareWith, null, self::FORMAT_NONE, null, 1, true, true)) {
-				// Only allow the same share to occur again if it is the same
-				// owner and is not a user share, this use case is for increasing
-				// permissions for a specific user
-				if ($checkExists['uid_owner'] != $uidOwner || $checkExists['share_type'] == $shareType) {
-					$message = 'Sharing %s failed, because this item is already shared with %s';
-					$message_t = $l->t('Sharing %s failed, because this item is already shared with %s', array($itemSourceName, $shareWith));
-					\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareWith), \OCP\Util::DEBUG);
-					throw new \Exception($message_t);
-				}
-			}
-			if ($checkExists = self::getItems($itemType, $itemSource, self::SHARE_TYPE_USER,
-				$shareWith, null, self::FORMAT_NONE, null, 1, true, true)) {
-				// Only allow the same share to occur again if it is the same
-				// owner and is not a user share, this use case is for increasing
-				// permissions for a specific user
-				if ($checkExists['uid_owner'] != $uidOwner || $checkExists['share_type'] == $shareType) {
-					$message = 'Sharing %s failed, because this item is already shared with user %s';
-					$message_t = $l->t('Sharing %s failed, because this item is already shared with user %s', array($itemSourceName, $shareWith));
-					\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareWith), \OCP\Util::ERROR);
-					throw new \Exception($message_t);
-				}
-			}
-		} else if ($shareType === self::SHARE_TYPE_GROUP) {
-			if (!\OC::$server->getGroupManager()->groupExists($shareWith)) {
-				$message = 'Sharing %s failed, because the group %s does not exist';
-				$message_t = $l->t('Sharing %s failed, because the group %s does not exist', array($itemSourceName, $shareWith));
-				\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareWith), \OCP\Util::DEBUG);
-				throw new \Exception($message_t);
-			}
-			if ($shareWithinGroupOnly) {
-				$group = \OC::$server->getGroupManager()->get($shareWith);
-				$user = \OC::$server->getUserManager()->get($uidOwner);
-				if (!$group || !$user || !$group->inGroup($user)) {
-					$message = 'Sharing %s failed, because '
-						. '%s is not a member of the group %s';
-					$message_t = $l->t('Sharing %s failed, because %s is not a member of the group %s', array($itemSourceName, $uidOwner, $shareWith));
-					\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $uidOwner, $shareWith), \OCP\Util::DEBUG);
-					throw new \Exception($message_t);
-				}
-			}
-			// Check if the item source is already shared with the group, either from the same owner or a different user
-			// The check for each user in the group is done inside the put() function
-			if ($checkExists = self::getItems($itemType, $itemSource, self::SHARE_TYPE_GROUP, $shareWith,
-				null, self::FORMAT_NONE, null, 1, true, true)) {
-
-				if ($checkExists['share_with'] === $shareWith && $checkExists['share_type'] === \OCP\Share::SHARE_TYPE_GROUP) {
-					$message = 'Sharing %s failed, because this item is already shared with %s';
-					$message_t = $l->t('Sharing %s failed, because this item is already shared with %s', array($itemSourceName, $shareWith));
-					\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareWith), \OCP\Util::DEBUG);
-					throw new \Exception($message_t);
-				}
-			}
-			// Convert share with into an array with the keys group and users
-			$group = $shareWith;
-			$shareWith = array();
-			$shareWith['group'] = $group;
-
-
-			$groupObject = \OC::$server->getGroupManager()->get($group);
-			$userIds = [];
-			if ($groupObject) {
-				$users = $groupObject->searchUsers('', -1, 0);
-				foreach ($users as $user) {
-					$userIds[] = $user->getUID();
-				}
-			}
-
-			$shareWith['users'] = array_diff($userIds, array($uidOwner));
-		} else if ($shareType === self::SHARE_TYPE_LINK) {
-			$updateExistingShare = false;
-			if (\OC::$server->getConfig()->getAppValue('core', 'shareapi_allow_links', 'yes') == 'yes') {
-
-				// IF the password is changed via the old ajax endpoint verify it before deleting the old share
-				if ($passwordChanged === true) {
-					self::verifyPassword($shareWith);
-				}
-
-				// when updating a link share
-				// FIXME Don't delete link if we update it
-				if ($checkExists = self::getItems($itemType, $itemSource, self::SHARE_TYPE_LINK, null,
-					$uidOwner, self::FORMAT_NONE, null, 1)) {
-					// remember old token
-					$oldToken = $checkExists['token'];
-					$oldPermissions = $checkExists['permissions'];
-					//delete the old share
-					Helper::delete($checkExists['id']);
-					$updateExistingShare = true;
-				}
-
-				if ($passwordChanged === null) {
-					// Generate hash of password - same method as user passwords
-					if (is_string($shareWith) && $shareWith !== '') {
-						self::verifyPassword($shareWith);
-						$shareWith = \OC::$server->getHasher()->hash($shareWith);
-					} else {
-						// reuse the already set password, but only if we change permissions
-						// otherwise the user disabled the password protection
-						if ($checkExists && (int)$permissions !== (int)$oldPermissions) {
-							$shareWith = $checkExists['share_with'];
-						}
-					}
-				} else {
-					if ($passwordChanged === true) {
-						if (is_string($shareWith) && $shareWith !== '') {
-							self::verifyPassword($shareWith);
-							$shareWith = \OC::$server->getHasher()->hash($shareWith);
-						}
-					} else if ($updateExistingShare) {
-						$shareWith = $checkExists['share_with'];
-					}
-				}
-
-				if (\OCP\Util::isPublicLinkPasswordRequired() && empty($shareWith)) {
-					$message = 'You need to provide a password to create a public link, only protected links are allowed';
-					$message_t = $l->t('You need to provide a password to create a public link, only protected links are allowed');
-					\OCP\Util::writeLog('OCP\Share', $message, \OCP\Util::DEBUG);
-					throw new \Exception($message_t);
-				}
-
-				if ($updateExistingShare === false &&
-					self::isDefaultExpireDateEnabled() &&
-					empty($expirationDate)) {
-					$expirationDate = Helper::calcExpireDate();
-				}
-
-				// Generate token
-				if (isset($oldToken)) {
-					$token = $oldToken;
-				} else {
-					$token = \OC::$server->getSecureRandom()->generate(self::TOKEN_LENGTH,
-						\OCP\Security\ISecureRandom::CHAR_HUMAN_READABLE
-					);
-				}
-				$result = self::put($itemType, $itemSource, $shareType, $shareWith, $uidOwner, $permissions,
-					null, $token, $itemSourceName, $expirationDate);
-				if ($result) {
-					return $token;
-				} else {
-					return false;
-				}
-			}
-			$message = 'Sharing %s failed, because sharing with links is not allowed';
-			$message_t = $l->t('Sharing %s failed, because sharing with links is not allowed', array($itemSourceName));
-			\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName), \OCP\Util::DEBUG);
-			throw new \Exception($message_t);
-		} else if ($shareType === self::SHARE_TYPE_REMOTE) {
-
-			/*
+                $expirationDate = self::validateExpireDate($expirationDate->format('Y-m-d'), time(), $itemType, $itemSource);
+            } catch (\Exception $e) {
+                throw new \OC\HintException($e->getMessage(), $e->getMessage(), 404);
+            }
+        }
+
+        // Verify share type and sharing conditions are met
+        if ($shareType === self::SHARE_TYPE_USER) {
+            if ($shareWith == $uidOwner) {
+                $message = 'Sharing %s failed, because you can not share with yourself';
+                $message_t = $l->t('Sharing %s failed, because you can not share with yourself', [$itemName]);
+                \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName), \OCP\Util::DEBUG);
+                throw new \Exception($message_t);
+            }
+            if (!\OC::$server->getUserManager()->userExists($shareWith)) {
+                $message = 'Sharing %s failed, because the user %s does not exist';
+                $message_t = $l->t('Sharing %s failed, because the user %s does not exist', array($itemSourceName, $shareWith));
+                \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareWith), \OCP\Util::DEBUG);
+                throw new \Exception($message_t);
+            }
+            if ($shareWithinGroupOnly) {
+                $userManager = \OC::$server->getUserManager();
+                $groupManager = \OC::$server->getGroupManager();
+                $userOwner = $userManager->get($uidOwner);
+                $userShareWith = $userManager->get($shareWith);
+                $groupsOwner = [];
+                $groupsShareWith = [];
+                if ($userOwner) {
+                    $groupsOwner = $groupManager->getUserGroupIds($userOwner);
+                }
+                if ($userShareWith) {
+                    $groupsShareWith = $groupManager->getUserGroupIds($userShareWith);
+                }
+                $inGroup = array_intersect($groupsOwner, $groupsShareWith);
+                if (empty($inGroup)) {
+                    $message = 'Sharing %s failed, because the user '
+                        .'%s is not a member of any groups that %s is a member of';
+                    $message_t = $l->t('Sharing %s failed, because the user %s is not a member of any groups that %s is a member of', array($itemName, $shareWith, $uidOwner));
+                    \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemName, $shareWith, $uidOwner), \OCP\Util::DEBUG);
+                    throw new \Exception($message_t);
+                }
+            }
+            // Check if the item source is already shared with the user, either from the same owner or a different user
+            if ($checkExists = self::getItems($itemType, $itemSource, self::$shareTypeUserAndGroups,
+                $shareWith, null, self::FORMAT_NONE, null, 1, true, true)) {
+                // Only allow the same share to occur again if it is the same
+                // owner and is not a user share, this use case is for increasing
+                // permissions for a specific user
+                if ($checkExists['uid_owner'] != $uidOwner || $checkExists['share_type'] == $shareType) {
+                    $message = 'Sharing %s failed, because this item is already shared with %s';
+                    $message_t = $l->t('Sharing %s failed, because this item is already shared with %s', array($itemSourceName, $shareWith));
+                    \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareWith), \OCP\Util::DEBUG);
+                    throw new \Exception($message_t);
+                }
+            }
+            if ($checkExists = self::getItems($itemType, $itemSource, self::SHARE_TYPE_USER,
+                $shareWith, null, self::FORMAT_NONE, null, 1, true, true)) {
+                // Only allow the same share to occur again if it is the same
+                // owner and is not a user share, this use case is for increasing
+                // permissions for a specific user
+                if ($checkExists['uid_owner'] != $uidOwner || $checkExists['share_type'] == $shareType) {
+                    $message = 'Sharing %s failed, because this item is already shared with user %s';
+                    $message_t = $l->t('Sharing %s failed, because this item is already shared with user %s', array($itemSourceName, $shareWith));
+                    \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareWith), \OCP\Util::ERROR);
+                    throw new \Exception($message_t);
+                }
+            }
+        } else if ($shareType === self::SHARE_TYPE_GROUP) {
+            if (!\OC::$server->getGroupManager()->groupExists($shareWith)) {
+                $message = 'Sharing %s failed, because the group %s does not exist';
+                $message_t = $l->t('Sharing %s failed, because the group %s does not exist', array($itemSourceName, $shareWith));
+                \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareWith), \OCP\Util::DEBUG);
+                throw new \Exception($message_t);
+            }
+            if ($shareWithinGroupOnly) {
+                $group = \OC::$server->getGroupManager()->get($shareWith);
+                $user = \OC::$server->getUserManager()->get($uidOwner);
+                if (!$group || !$user || !$group->inGroup($user)) {
+                    $message = 'Sharing %s failed, because '
+                        . '%s is not a member of the group %s';
+                    $message_t = $l->t('Sharing %s failed, because %s is not a member of the group %s', array($itemSourceName, $uidOwner, $shareWith));
+                    \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $uidOwner, $shareWith), \OCP\Util::DEBUG);
+                    throw new \Exception($message_t);
+                }
+            }
+            // Check if the item source is already shared with the group, either from the same owner or a different user
+            // The check for each user in the group is done inside the put() function
+            if ($checkExists = self::getItems($itemType, $itemSource, self::SHARE_TYPE_GROUP, $shareWith,
+                null, self::FORMAT_NONE, null, 1, true, true)) {
+
+                if ($checkExists['share_with'] === $shareWith && $checkExists['share_type'] === \OCP\Share::SHARE_TYPE_GROUP) {
+                    $message = 'Sharing %s failed, because this item is already shared with %s';
+                    $message_t = $l->t('Sharing %s failed, because this item is already shared with %s', array($itemSourceName, $shareWith));
+                    \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareWith), \OCP\Util::DEBUG);
+                    throw new \Exception($message_t);
+                }
+            }
+            // Convert share with into an array with the keys group and users
+            $group = $shareWith;
+            $shareWith = array();
+            $shareWith['group'] = $group;
+
+
+            $groupObject = \OC::$server->getGroupManager()->get($group);
+            $userIds = [];
+            if ($groupObject) {
+                $users = $groupObject->searchUsers('', -1, 0);
+                foreach ($users as $user) {
+                    $userIds[] = $user->getUID();
+                }
+            }
+
+            $shareWith['users'] = array_diff($userIds, array($uidOwner));
+        } else if ($shareType === self::SHARE_TYPE_LINK) {
+            $updateExistingShare = false;
+            if (\OC::$server->getConfig()->getAppValue('core', 'shareapi_allow_links', 'yes') == 'yes') {
+
+                // IF the password is changed via the old ajax endpoint verify it before deleting the old share
+                if ($passwordChanged === true) {
+                    self::verifyPassword($shareWith);
+                }
+
+                // when updating a link share
+                // FIXME Don't delete link if we update it
+                if ($checkExists = self::getItems($itemType, $itemSource, self::SHARE_TYPE_LINK, null,
+                    $uidOwner, self::FORMAT_NONE, null, 1)) {
+                    // remember old token
+                    $oldToken = $checkExists['token'];
+                    $oldPermissions = $checkExists['permissions'];
+                    //delete the old share
+                    Helper::delete($checkExists['id']);
+                    $updateExistingShare = true;
+                }
+
+                if ($passwordChanged === null) {
+                    // Generate hash of password - same method as user passwords
+                    if (is_string($shareWith) && $shareWith !== '') {
+                        self::verifyPassword($shareWith);
+                        $shareWith = \OC::$server->getHasher()->hash($shareWith);
+                    } else {
+                        // reuse the already set password, but only if we change permissions
+                        // otherwise the user disabled the password protection
+                        if ($checkExists && (int)$permissions !== (int)$oldPermissions) {
+                            $shareWith = $checkExists['share_with'];
+                        }
+                    }
+                } else {
+                    if ($passwordChanged === true) {
+                        if (is_string($shareWith) && $shareWith !== '') {
+                            self::verifyPassword($shareWith);
+                            $shareWith = \OC::$server->getHasher()->hash($shareWith);
+                        }
+                    } else if ($updateExistingShare) {
+                        $shareWith = $checkExists['share_with'];
+                    }
+                }
+
+                if (\OCP\Util::isPublicLinkPasswordRequired() && empty($shareWith)) {
+                    $message = 'You need to provide a password to create a public link, only protected links are allowed';
+                    $message_t = $l->t('You need to provide a password to create a public link, only protected links are allowed');
+                    \OCP\Util::writeLog('OCP\Share', $message, \OCP\Util::DEBUG);
+                    throw new \Exception($message_t);
+                }
+
+                if ($updateExistingShare === false &&
+                    self::isDefaultExpireDateEnabled() &&
+                    empty($expirationDate)) {
+                    $expirationDate = Helper::calcExpireDate();
+                }
+
+                // Generate token
+                if (isset($oldToken)) {
+                    $token = $oldToken;
+                } else {
+                    $token = \OC::$server->getSecureRandom()->generate(self::TOKEN_LENGTH,
+                        \OCP\Security\ISecureRandom::CHAR_HUMAN_READABLE
+                    );
+                }
+                $result = self::put($itemType, $itemSource, $shareType, $shareWith, $uidOwner, $permissions,
+                    null, $token, $itemSourceName, $expirationDate);
+                if ($result) {
+                    return $token;
+                } else {
+                    return false;
+                }
+            }
+            $message = 'Sharing %s failed, because sharing with links is not allowed';
+            $message_t = $l->t('Sharing %s failed, because sharing with links is not allowed', array($itemSourceName));
+            \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName), \OCP\Util::DEBUG);
+            throw new \Exception($message_t);
+        } else if ($shareType === self::SHARE_TYPE_REMOTE) {
+
+            /*
 			 * Check if file is not already shared with the remote user
 			 */
-			if ($checkExists = self::getItems($itemType, $itemSource, self::SHARE_TYPE_REMOTE,
-				$shareWith, $uidOwner, self::FORMAT_NONE, null, 1, true, true)) {
-					$message = 'Sharing %s failed, because this item is already shared with %s';
-					$message_t = $l->t('Sharing %s failed, because this item is already shared with %s', array($itemSourceName, $shareWith));
-					\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareWith), \OCP\Util::DEBUG);
-					throw new \Exception($message_t);
-			}
-
-			// don't allow federated shares if source and target server are the same
-			list($user, $remote) = Helper::splitUserRemote($shareWith);
-			$currentServer = self::removeProtocolFromUrl(\OC::$server->getURLGenerator()->getAbsoluteURL('/'));
-			$currentUser = \OC::$server->getUserSession()->getUser()->getUID();
-			if (Helper::isSameUserOnSameServer($user, $remote, $currentUser, $currentServer)) {
-				$message = 'Not allowed to create a federated share with the same user.';
-				$message_t = $l->t('Not allowed to create a federated share with the same user');
-				\OCP\Util::writeLog('OCP\Share', $message, \OCP\Util::DEBUG);
-				throw new \Exception($message_t);
-			}
-
-			$token = \OC::$server->getSecureRandom()->generate(self::TOKEN_LENGTH, \OCP\Security\ISecureRandom::CHAR_LOWER . \OCP\Security\ISecureRandom::CHAR_UPPER .
-				\OCP\Security\ISecureRandom::CHAR_DIGITS);
-
-			$shareWith = $user . '@' . $remote;
-			$shareId = self::put($itemType, $itemSource, $shareType, $shareWith, $uidOwner, $permissions, null, $token, $itemSourceName);
-
-			$send = false;
-			if ($shareId) {
-				$send = self::sendRemoteShare($token, $shareWith, $itemSourceName, $shareId, $uidOwner);
-			}
-
-			if ($send === false) {
-				$currentUser = \OC::$server->getUserSession()->getUser()->getUID();
-				self::unshare($itemType, $itemSource, $shareType, $shareWith, $currentUser);
-				$message_t = $l->t('Sharing %s failed, could not find %s, maybe the server is currently unreachable.', array($itemSourceName, $shareWith));
-				throw new \Exception($message_t);
-			}
-
-			return $send;
-		} else {
-			// Future share types need to include their own conditions
-			$message = 'Share type %s is not valid for %s';
-			$message_t = $l->t('Share type %s is not valid for %s', array($shareType, $itemSource));
-			\OCP\Util::writeLog('OCP\Share', sprintf($message, $shareType, $itemSource), \OCP\Util::DEBUG);
-			throw new \Exception($message_t);
-		}
-
-		// Put the item into the database
-		$result = self::put($itemType, $itemSource, $shareType, $shareWith, $uidOwner, $permissions, null, null, $itemSourceName, $expirationDate);
-
-		return $result ? true : false;
-	}
-
-	/**
-	 * Unshare an item from a user, group, or delete a private link
-	 * @param string $itemType
-	 * @param string $itemSource
-	 * @param int $shareType SHARE_TYPE_USER, SHARE_TYPE_GROUP, or SHARE_TYPE_LINK
-	 * @param string $shareWith User or group the item is being shared with
-	 * @param string $owner owner of the share, if null the current user is used
-	 * @return boolean true on success or false on failure
-	 */
-	public static function unshare($itemType, $itemSource, $shareType, $shareWith, $owner = null) {
-
-		// check if it is a valid itemType
-		self::getBackend($itemType);
-
-		$items = self::getItemSharedWithUser($itemType, $itemSource, $shareWith, $owner, $shareType);
-
-		$toDelete = array();
-		$newParent = null;
-		$currentUser = $owner ? $owner : \OC_User::getUser();
-		foreach ($items as $item) {
-			// delete the item with the expected share_type and owner
-			if ((int)$item['share_type'] === (int)$shareType && $item['uid_owner'] === $currentUser) {
-				$toDelete = $item;
-				// if there is more then one result we don't have to delete the children
-				// but update their parent. For group shares the new parent should always be
-				// the original group share and not the db entry with the unique name
-			} else if ((int)$item['share_type'] === self::$shareTypeGroupUserUnique) {
-				$newParent = $item['parent'];
-			} else {
-				$newParent = $item['id'];
-			}
-		}
-
-		if (!empty($toDelete)) {
-			self::unshareItem($toDelete, $newParent);
-			return true;
-		}
-		return false;
-	}
-
-	/**
-	 * sent status if users got informed by mail about share
-	 * @param string $itemType
-	 * @param string $itemSource
-	 * @param int $shareType SHARE_TYPE_USER, SHARE_TYPE_GROUP, or SHARE_TYPE_LINK
-	 * @param string $recipient with whom was the file shared
-	 * @param boolean $status
-	 */
-	public static function setSendMailStatus($itemType, $itemSource, $shareType, $recipient, $status) {
-		$status = $status ? 1 : 0;
-
-		$query = \OC_DB::prepare(
-			'UPDATE `*PREFIX*share`
+            if ($checkExists = self::getItems($itemType, $itemSource, self::SHARE_TYPE_REMOTE,
+                $shareWith, $uidOwner, self::FORMAT_NONE, null, 1, true, true)) {
+                    $message = 'Sharing %s failed, because this item is already shared with %s';
+                    $message_t = $l->t('Sharing %s failed, because this item is already shared with %s', array($itemSourceName, $shareWith));
+                    \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareWith), \OCP\Util::DEBUG);
+                    throw new \Exception($message_t);
+            }
+
+            // don't allow federated shares if source and target server are the same
+            list($user, $remote) = Helper::splitUserRemote($shareWith);
+            $currentServer = self::removeProtocolFromUrl(\OC::$server->getURLGenerator()->getAbsoluteURL('/'));
+            $currentUser = \OC::$server->getUserSession()->getUser()->getUID();
+            if (Helper::isSameUserOnSameServer($user, $remote, $currentUser, $currentServer)) {
+                $message = 'Not allowed to create a federated share with the same user.';
+                $message_t = $l->t('Not allowed to create a federated share with the same user');
+                \OCP\Util::writeLog('OCP\Share', $message, \OCP\Util::DEBUG);
+                throw new \Exception($message_t);
+            }
+
+            $token = \OC::$server->getSecureRandom()->generate(self::TOKEN_LENGTH, \OCP\Security\ISecureRandom::CHAR_LOWER . \OCP\Security\ISecureRandom::CHAR_UPPER .
+                \OCP\Security\ISecureRandom::CHAR_DIGITS);
+
+            $shareWith = $user . '@' . $remote;
+            $shareId = self::put($itemType, $itemSource, $shareType, $shareWith, $uidOwner, $permissions, null, $token, $itemSourceName);
+
+            $send = false;
+            if ($shareId) {
+                $send = self::sendRemoteShare($token, $shareWith, $itemSourceName, $shareId, $uidOwner);
+            }
+
+            if ($send === false) {
+                $currentUser = \OC::$server->getUserSession()->getUser()->getUID();
+                self::unshare($itemType, $itemSource, $shareType, $shareWith, $currentUser);
+                $message_t = $l->t('Sharing %s failed, could not find %s, maybe the server is currently unreachable.', array($itemSourceName, $shareWith));
+                throw new \Exception($message_t);
+            }
+
+            return $send;
+        } else {
+            // Future share types need to include their own conditions
+            $message = 'Share type %s is not valid for %s';
+            $message_t = $l->t('Share type %s is not valid for %s', array($shareType, $itemSource));
+            \OCP\Util::writeLog('OCP\Share', sprintf($message, $shareType, $itemSource), \OCP\Util::DEBUG);
+            throw new \Exception($message_t);
+        }
+
+        // Put the item into the database
+        $result = self::put($itemType, $itemSource, $shareType, $shareWith, $uidOwner, $permissions, null, null, $itemSourceName, $expirationDate);
+
+        return $result ? true : false;
+    }
+
+    /**
+     * Unshare an item from a user, group, or delete a private link
+     * @param string $itemType
+     * @param string $itemSource
+     * @param int $shareType SHARE_TYPE_USER, SHARE_TYPE_GROUP, or SHARE_TYPE_LINK
+     * @param string $shareWith User or group the item is being shared with
+     * @param string $owner owner of the share, if null the current user is used
+     * @return boolean true on success or false on failure
+     */
+    public static function unshare($itemType, $itemSource, $shareType, $shareWith, $owner = null) {
+
+        // check if it is a valid itemType
+        self::getBackend($itemType);
+
+        $items = self::getItemSharedWithUser($itemType, $itemSource, $shareWith, $owner, $shareType);
+
+        $toDelete = array();
+        $newParent = null;
+        $currentUser = $owner ? $owner : \OC_User::getUser();
+        foreach ($items as $item) {
+            // delete the item with the expected share_type and owner
+            if ((int)$item['share_type'] === (int)$shareType && $item['uid_owner'] === $currentUser) {
+                $toDelete = $item;
+                // if there is more then one result we don't have to delete the children
+                // but update their parent. For group shares the new parent should always be
+                // the original group share and not the db entry with the unique name
+            } else if ((int)$item['share_type'] === self::$shareTypeGroupUserUnique) {
+                $newParent = $item['parent'];
+            } else {
+                $newParent = $item['id'];
+            }
+        }
+
+        if (!empty($toDelete)) {
+            self::unshareItem($toDelete, $newParent);
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * sent status if users got informed by mail about share
+     * @param string $itemType
+     * @param string $itemSource
+     * @param int $shareType SHARE_TYPE_USER, SHARE_TYPE_GROUP, or SHARE_TYPE_LINK
+     * @param string $recipient with whom was the file shared
+     * @param boolean $status
+     */
+    public static function setSendMailStatus($itemType, $itemSource, $shareType, $recipient, $status) {
+        $status = $status ? 1 : 0;
+
+        $query = \OC_DB::prepare(
+            'UPDATE `*PREFIX*share`
 					SET `mail_send` = ?
 					WHERE `item_type` = ? AND `item_source` = ? AND `share_type` = ? AND `share_with` = ?');
 
-		$result = $query->execute(array($status, $itemType, $itemSource, $shareType, $recipient));
-
-		if($result === false) {
-			\OCP\Util::writeLog('OCP\Share', 'Couldn\'t set send mail status', \OCP\Util::ERROR);
-		}
-	}
-
-	/**
-	 * validate expiration date if it meets all constraints
-	 *
-	 * @param string $expireDate well formatted date string, e.g. "DD-MM-YYYY"
-	 * @param string $shareTime timestamp when the file was shared
-	 * @param string $itemType
-	 * @param string $itemSource
-	 * @return \DateTime validated date
-	 * @throws \Exception when the expire date is in the past or further in the future then the enforced date
-	 */
-	private static function validateExpireDate($expireDate, $shareTime, $itemType, $itemSource) {
-		$l = \OC::$server->getL10N('lib');
-		$date = new \DateTime($expireDate);
-		$today = new \DateTime('now');
-
-		// if the user doesn't provide a share time we need to get it from the database
-		// fall-back mode to keep API stable, because the $shareTime parameter was added later
-		$defaultExpireDateEnforced = \OCP\Util::isDefaultExpireDateEnforced();
-		if ($defaultExpireDateEnforced && $shareTime === null) {
-			$items = self::getItemShared($itemType, $itemSource);
-			$firstItem = reset($items);
-			$shareTime = (int)$firstItem['stime'];
-		}
-
-		if ($defaultExpireDateEnforced) {
-			// initialize max date with share time
-			$maxDate = new \DateTime();
-			$maxDate->setTimestamp($shareTime);
-			$maxDays = \OC::$server->getConfig()->getAppValue('core', 'shareapi_expire_after_n_days', '7');
-			$maxDate->add(new \DateInterval('P' . $maxDays . 'D'));
-			if ($date > $maxDate) {
-				$warning = 'Cannot set expiration date. Shares cannot expire later than ' . $maxDays . ' after they have been shared';
-				$warning_t = $l->t('Cannot set expiration date. Shares cannot expire later than %s after they have been shared', array($maxDays));
-				\OCP\Util::writeLog('OCP\Share', $warning, \OCP\Util::WARN);
-				throw new \Exception($warning_t);
-			}
-		}
-
-		if ($date < $today) {
-			$message = 'Cannot set expiration date. Expiration date is in the past';
-			$message_t = $l->t('Cannot set expiration date. Expiration date is in the past');
-			\OCP\Util::writeLog('OCP\Share', $message, \OCP\Util::WARN);
-			throw new \Exception($message_t);
-		}
-
-		return $date;
-	}
-
-	/**
-	 * Checks whether a share has expired, calls unshareItem() if yes.
-	 * @param array $item Share data (usually database row)
-	 * @return boolean True if item was expired, false otherwise.
-	 */
-	protected static function expireItem(array $item) {
-
-		$result = false;
-
-		// only use default expiration date for link shares
-		if ((int) $item['share_type'] === self::SHARE_TYPE_LINK) {
-
-			// calculate expiration date
-			if (!empty($item['expiration'])) {
-				$userDefinedExpire = new \DateTime($item['expiration']);
-				$expires = $userDefinedExpire->getTimestamp();
-			} else {
-				$expires = null;
-			}
-
-
-			// get default expiration settings
-			$defaultSettings = Helper::getDefaultExpireSetting();
-			$expires = Helper::calculateExpireDate($defaultSettings, $item['stime'], $expires);
-
-
-			if (is_int($expires)) {
-				$now = time();
-				if ($now > $expires) {
-					self::unshareItem($item);
-					$result = true;
-				}
-			}
-		}
-		return $result;
-	}
-
-	/**
-	 * Unshares a share given a share data array
-	 * @param array $item Share data (usually database row)
-	 * @param int $newParent parent ID
-	 * @return null
-	 */
-	protected static function unshareItem(array $item, $newParent = null) {
-
-		$shareType = (int)$item['share_type'];
-		$shareWith = null;
-		if ($shareType !== \OCP\Share::SHARE_TYPE_LINK) {
-			$shareWith = $item['share_with'];
-		}
-
-		// Pass all the vars we have for now, they may be useful
-		$hookParams = array(
-			'id'            => $item['id'],
-			'itemType'      => $item['item_type'],
-			'itemSource'    => $item['item_source'],
-			'shareType'     => $shareType,
-			'shareWith'     => $shareWith,
-			'itemParent'    => $item['parent'],
-			'uidOwner'      => $item['uid_owner'],
-		);
-		if($item['item_type'] === 'file' || $item['item_type'] === 'folder') {
-			$hookParams['fileSource'] = $item['file_source'];
-			$hookParams['fileTarget'] = $item['file_target'];
-		}
-
-		\OC_Hook::emit(\OCP\Share::class, 'pre_unshare', $hookParams);
-		$deletedShares = Helper::delete($item['id'], false, null, $newParent);
-		$deletedShares[] = $hookParams;
-		$hookParams['deletedShares'] = $deletedShares;
-		\OC_Hook::emit(\OCP\Share::class, 'post_unshare', $hookParams);
-		if ((int)$item['share_type'] === \OCP\Share::SHARE_TYPE_REMOTE && \OC::$server->getUserSession()->getUser()) {
-			list(, $remote) = Helper::splitUserRemote($item['share_with']);
-			self::sendRemoteUnshare($remote, $item['id'], $item['token']);
-		}
-	}
-
-	/**
-	 * Get the backend class for the specified item type
-	 * @param string $itemType
-	 * @throws \Exception
-	 * @return \OCP\Share_Backend
-	 */
-	public static function getBackend($itemType) {
-		$l = \OC::$server->getL10N('lib');
-		if (isset(self::$backends[$itemType])) {
-			return self::$backends[$itemType];
-		} else if (isset(self::$backendTypes[$itemType]['class'])) {
-			$class = self::$backendTypes[$itemType]['class'];
-			if (class_exists($class)) {
-				self::$backends[$itemType] = new $class;
-				if (!(self::$backends[$itemType] instanceof \OCP\Share_Backend)) {
-					$message = 'Sharing backend %s must implement the interface OCP\Share_Backend';
-					$message_t = $l->t('Sharing backend %s must implement the interface OCP\Share_Backend', array($class));
-					\OCP\Util::writeLog('OCP\Share', sprintf($message, $class), \OCP\Util::ERROR);
-					throw new \Exception($message_t);
-				}
-				return self::$backends[$itemType];
-			} else {
-				$message = 'Sharing backend %s not found';
-				$message_t = $l->t('Sharing backend %s not found', array($class));
-				\OCP\Util::writeLog('OCP\Share', sprintf($message, $class), \OCP\Util::ERROR);
-				throw new \Exception($message_t);
-			}
-		}
-		$message = 'Sharing backend for %s not found';
-		$message_t = $l->t('Sharing backend for %s not found', array($itemType));
-		\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemType), \OCP\Util::ERROR);
-		throw new \Exception($message_t);
-	}
-
-	/**
-	 * Check if resharing is allowed
-	 * @return boolean true if allowed or false
-	 *
-	 * Resharing is allowed by default if not configured
-	 */
-	public static function isResharingAllowed() {
-		if (!isset(self::$isResharingAllowed)) {
-			if (\OC::$server->getConfig()->getAppValue('core', 'shareapi_allow_resharing', 'yes') == 'yes') {
-				self::$isResharingAllowed = true;
-			} else {
-				self::$isResharingAllowed = false;
-			}
-		}
-		return self::$isResharingAllowed;
-	}
-
-	/**
-	 * Get a list of collection item types for the specified item type
-	 * @param string $itemType
-	 * @return array
-	 */
-	private static function getCollectionItemTypes($itemType) {
-		$collectionTypes = array($itemType);
-		foreach (self::$backendTypes as $type => $backend) {
-			if (in_array($backend['collectionOf'], $collectionTypes)) {
-				$collectionTypes[] = $type;
-			}
-		}
-		// TODO Add option for collections to be collection of themselves, only 'folder' does it now...
-		if (isset(self::$backendTypes[$itemType]) && (!self::getBackend($itemType) instanceof \OCP\Share_Backend_Collection || $itemType != 'folder')) {
-			unset($collectionTypes[0]);
-		}
-		// Return array if collections were found or the item type is a
-		// collection itself - collections can be inside collections
-		if (count($collectionTypes) > 0) {
-			return $collectionTypes;
-		}
-		return false;
-	}
-
-	/**
-	 * Get the owners of items shared with a user.
-	 *
-	 * @param string $user The user the items are shared with.
-	 * @param string $type The type of the items shared with the user.
-	 * @param boolean $includeCollections Include collection item types (optional)
-	 * @param boolean $includeOwner include owner in the list of users the item is shared with (optional)
-	 * @return array
-	 */
-	public static function getSharedItemsOwners($user, $type, $includeCollections = false, $includeOwner = false) {
-		// First, we find out if $type is part of a collection (and if that collection is part of
-		// another one and so on).
-		$collectionTypes = array();
-		if (!$includeCollections || !$collectionTypes = self::getCollectionItemTypes($type)) {
-			$collectionTypes[] = $type;
-		}
-
-		// Of these collection types, along with our original $type, we make a
-		// list of the ones for which a sharing backend has been registered.
-		// FIXME: Ideally, we wouldn't need to nest getItemsSharedWith in this loop but just call it
-		// with its $includeCollections parameter set to true. Unfortunately, this fails currently.
-		$allMaybeSharedItems = array();
-		foreach ($collectionTypes as $collectionType) {
-			if (isset(self::$backends[$collectionType])) {
-				$allMaybeSharedItems[$collectionType] = self::getItemsSharedWithUser(
-					$collectionType,
-					$user,
-					self::FORMAT_NONE
-				);
-			}
-		}
-
-		$owners = array();
-		if ($includeOwner) {
-			$owners[] = $user;
-		}
-
-		// We take a look at all shared items of the given $type (or of the collections it is part of)
-		// and find out their owners. Then, we gather the tags for the original $type from all owners,
-		// and return them as elements of a list that look like "Tag (owner)".
-		foreach ($allMaybeSharedItems as $collectionType => $maybeSharedItems) {
-			foreach ($maybeSharedItems as $sharedItem) {
-				if (isset($sharedItem['id'])) { //workaround for https://github.com/owncloud/core/issues/2814
-					$owners[] = $sharedItem['uid_owner'];
-				}
-			}
-		}
-
-		return $owners;
-	}
-
-	/**
-	 * Get shared items from the database
-	 * @param string $itemType
-	 * @param string $item Item source or target (optional)
-	 * @param int $shareType SHARE_TYPE_USER, SHARE_TYPE_GROUP, SHARE_TYPE_LINK, $shareTypeUserAndGroups, or $shareTypeGroupUserUnique
-	 * @param string $shareWith User or group the item is being shared with
-	 * @param string $uidOwner User that is the owner of shared items (optional)
-	 * @param int $format Format to convert items to with formatItems() (optional)
-	 * @param mixed $parameters to pass to formatItems() (optional)
-	 * @param int $limit Number of items to return, -1 to return all matches (optional)
-	 * @param boolean $includeCollections Include collection item types (optional)
-	 * @param boolean $itemShareWithBySource (optional)
-	 * @param boolean $checkExpireDate
-	 * @return array
-	 *
-	 * See public functions getItem(s)... for parameter usage
-	 *
-	 */
-	public static function getItems($itemType, $item = null, $shareType = null, $shareWith = null,
-									$uidOwner = null, $format = self::FORMAT_NONE, $parameters = null, $limit = -1,
-									$includeCollections = false, $itemShareWithBySource = false, $checkExpireDate  = true) {
-		if (\OC::$server->getConfig()->getAppValue('core', 'shareapi_enabled', 'yes') != 'yes') {
-			return array();
-		}
-		$backend = self::getBackend($itemType);
-		$collectionTypes = false;
-		// Get filesystem root to add it to the file target and remove from the
-		// file source, match file_source with the file cache
-		if ($itemType == 'file' || $itemType == 'folder') {
-			if(!is_null($uidOwner)) {
-				$root = \OC\Files\Filesystem::getRoot();
-			} else {
-				$root = '';
-			}
-			$where = 'INNER JOIN `*PREFIX*filecache` ON `file_source` = `*PREFIX*filecache`.`fileid` ';
-			if (!isset($item)) {
-				$where .= ' AND `file_target` IS NOT NULL ';
-			}
-			$where .= 'INNER JOIN `*PREFIX*storages` ON `numeric_id` = `*PREFIX*filecache`.`storage` ';
-			$fileDependent = true;
-			$queryArgs = array();
-		} else {
-			$fileDependent = false;
-			$root = '';
-			$collectionTypes = self::getCollectionItemTypes($itemType);
-			if ($includeCollections && !isset($item) && $collectionTypes) {
-				// If includeCollections is true, find collections of this item type, e.g. a music album contains songs
-				if (!in_array($itemType, $collectionTypes)) {
-					$itemTypes = array_merge(array($itemType), $collectionTypes);
-				} else {
-					$itemTypes = $collectionTypes;
-				}
-				$placeholders = implode(',', array_fill(0, count($itemTypes), '?'));
-				$where = ' WHERE `item_type` IN ('.$placeholders.'))';
-				$queryArgs = $itemTypes;
-			} else {
-				$where = ' WHERE `item_type` = ?';
-				$queryArgs = array($itemType);
-			}
-		}
-		if (\OC::$server->getConfig()->getAppValue('core', 'shareapi_allow_links', 'yes') !== 'yes') {
-			$where .= ' AND `share_type` != ?';
-			$queryArgs[] = self::SHARE_TYPE_LINK;
-		}
-		if (isset($shareType)) {
-			// Include all user and group items
-			if ($shareType == self::$shareTypeUserAndGroups && isset($shareWith)) {
-				$where .= ' AND ((`share_type` in (?, ?) AND `share_with` = ?) ';
-				$queryArgs[] = self::SHARE_TYPE_USER;
-				$queryArgs[] = self::$shareTypeGroupUserUnique;
-				$queryArgs[] = $shareWith;
-
-				$user = \OC::$server->getUserManager()->get($shareWith);
-				$groups = [];
-				if ($user) {
-					$groups = \OC::$server->getGroupManager()->getUserGroupIds($user);
-				}
-				if (!empty($groups)) {
-					$placeholders = implode(',', array_fill(0, count($groups), '?'));
-					$where .= ' OR (`share_type` = ? AND `share_with` IN ('.$placeholders.')) ';
-					$queryArgs[] = self::SHARE_TYPE_GROUP;
-					$queryArgs = array_merge($queryArgs, $groups);
-				}
-				$where .= ')';
-				// Don't include own group shares
-				$where .= ' AND `uid_owner` != ?';
-				$queryArgs[] = $shareWith;
-			} else {
-				$where .= ' AND `share_type` = ?';
-				$queryArgs[] = $shareType;
-				if (isset($shareWith)) {
-					$where .= ' AND `share_with` = ?';
-					$queryArgs[] = $shareWith;
-				}
-			}
-		}
-		if (isset($uidOwner)) {
-			$where .= ' AND `uid_owner` = ?';
-			$queryArgs[] = $uidOwner;
-			if (!isset($shareType)) {
-				// Prevent unique user targets for group shares from being selected
-				$where .= ' AND `share_type` != ?';
-				$queryArgs[] = self::$shareTypeGroupUserUnique;
-			}
-			if ($fileDependent) {
-				$column = 'file_source';
-			} else {
-				$column = 'item_source';
-			}
-		} else {
-			if ($fileDependent) {
-				$column = 'file_target';
-			} else {
-				$column = 'item_target';
-			}
-		}
-		if (isset($item)) {
-			$collectionTypes = self::getCollectionItemTypes($itemType);
-			if ($includeCollections && $collectionTypes && !in_array('folder', $collectionTypes)) {
-				$where .= ' AND (';
-			} else {
-				$where .= ' AND';
-			}
-			// If looking for own shared items, check item_source else check item_target
-			if (isset($uidOwner) || $itemShareWithBySource) {
-				// If item type is a file, file source needs to be checked in case the item was converted
-				if ($fileDependent) {
-					$where .= ' `file_source` = ?';
-					$column = 'file_source';
-				} else {
-					$where .= ' `item_source` = ?';
-					$column = 'item_source';
-				}
-			} else {
-				if ($fileDependent) {
-					$where .= ' `file_target` = ?';
-					$item = \OC\Files\Filesystem::normalizePath($item);
-				} else {
-					$where .= ' `item_target` = ?';
-				}
-			}
-			$queryArgs[] = $item;
-			if ($includeCollections && $collectionTypes && !in_array('folder', $collectionTypes)) {
-				$placeholders = implode(',', array_fill(0, count($collectionTypes), '?'));
-				$where .= ' OR `item_type` IN ('.$placeholders.'))';
-				$queryArgs = array_merge($queryArgs, $collectionTypes);
-			}
-		}
-
-		if ($shareType == self::$shareTypeUserAndGroups && $limit === 1) {
-			// Make sure the unique user target is returned if it exists,
-			// unique targets should follow the group share in the database
-			// If the limit is not 1, the filtering can be done later
-			$where .= ' ORDER BY `*PREFIX*share`.`id` DESC';
-		} else {
-			$where .= ' ORDER BY `*PREFIX*share`.`id` ASC';
-		}
-
-		if ($limit != -1 && !$includeCollections) {
-			// The limit must be at least 3, because filtering needs to be done
-			if ($limit < 3) {
-				$queryLimit = 3;
-			} else {
-				$queryLimit = $limit;
-			}
-		} else {
-			$queryLimit = null;
-		}
-		$select = self::createSelectStatement($format, $fileDependent, $uidOwner);
-		$root = strlen($root);
-		$query = \OC_DB::prepare('SELECT '.$select.' FROM `*PREFIX*share` '.$where, $queryLimit);
-		$result = $query->execute($queryArgs);
-		if ($result === false) {
-			\OCP\Util::writeLog('OCP\Share',
-				\OC_DB::getErrorMessage() . ', select=' . $select . ' where=',
-				\OCP\Util::ERROR);
-		}
-		$items = array();
-		$targets = array();
-		$switchedItems = array();
-		$mounts = array();
-		while ($row = $result->fetchRow()) {
-			self::transformDBResults($row);
-			// Filter out duplicate group shares for users with unique targets
-			if ($fileDependent && !self::isFileReachable($row['path'], $row['storage_id'])) {
-				continue;
-			}
-			if ($row['share_type'] == self::$shareTypeGroupUserUnique && isset($items[$row['parent']])) {
-				$row['share_type'] = self::SHARE_TYPE_GROUP;
-				$row['unique_name'] = true; // remember that we use a unique name for this user
-				$row['share_with'] = $items[$row['parent']]['share_with'];
-				// if the group share was unshared from the user we keep the permission, otherwise
-				// we take the permission from the parent because this is always the up-to-date
-				// permission for the group share
-				if ($row['permissions'] > 0) {
-					$row['permissions'] = $items[$row['parent']]['permissions'];
-				}
-				// Remove the parent group share
-				unset($items[$row['parent']]);
-				if ($row['permissions'] == 0) {
-					continue;
-				}
-			} else if (!isset($uidOwner)) {
-				// Check if the same target already exists
-				if (isset($targets[$row['id']])) {
-					// Check if the same owner shared with the user twice
-					// through a group and user share - this is allowed
-					$id = $targets[$row['id']];
-					if (isset($items[$id]) && $items[$id]['uid_owner'] == $row['uid_owner']) {
-						// Switch to group share type to ensure resharing conditions aren't bypassed
-						if ($items[$id]['share_type'] != self::SHARE_TYPE_GROUP) {
-							$items[$id]['share_type'] = self::SHARE_TYPE_GROUP;
-							$items[$id]['share_with'] = $row['share_with'];
-						}
-						// Switch ids if sharing permission is granted on only
-						// one share to ensure correct parent is used if resharing
-						if (~(int)$items[$id]['permissions'] & \OCP\Constants::PERMISSION_SHARE
-							&& (int)$row['permissions'] & \OCP\Constants::PERMISSION_SHARE) {
-							$items[$row['id']] = $items[$id];
-							$switchedItems[$id] = $row['id'];
-							unset($items[$id]);
-							$id = $row['id'];
-						}
-						$items[$id]['permissions'] |= (int)$row['permissions'];
-
-					}
-					continue;
-				} elseif (!empty($row['parent'])) {
-					$targets[$row['parent']] = $row['id'];
-				}
-			}
-			// Remove root from file source paths if retrieving own shared items
-			if (isset($uidOwner) && isset($row['path'])) {
-				if (isset($row['parent'])) {
-					$query = \OC_DB::prepare('SELECT `file_target` FROM `*PREFIX*share` WHERE `id` = ?');
-					$parentResult = $query->execute(array($row['parent']));
-					if ($result === false) {
-						\OCP\Util::writeLog('OCP\Share', 'Can\'t select parent: ' .
-							\OC_DB::getErrorMessage() . ', select=' . $select . ' where=' . $where,
-							\OCP\Util::ERROR);
-					} else {
-						$parentRow = $parentResult->fetchRow();
-						$tmpPath = $parentRow['file_target'];
-						// find the right position where the row path continues from the target path
-						$pos = strrpos($row['path'], $parentRow['file_target']);
-						$subPath = substr($row['path'], $pos);
-						$splitPath = explode('/', $subPath);
-						foreach (array_slice($splitPath, 2) as $pathPart) {
-							$tmpPath = $tmpPath . '/' . $pathPart;
-						}
-						$row['path'] = $tmpPath;
-					}
-				} else {
-					if (!isset($mounts[$row['storage']])) {
-						$mountPoints = \OC\Files\Filesystem::getMountByNumericId($row['storage']);
-						if (is_array($mountPoints) && !empty($mountPoints)) {
-							$mounts[$row['storage']] = current($mountPoints);
-						}
-					}
-					if (!empty($mounts[$row['storage']])) {
-						$path = $mounts[$row['storage']]->getMountPoint().$row['path'];
-						$relPath = substr($path, $root); // path relative to data/user
-						$row['path'] = rtrim($relPath, '/');
-					}
-				}
-			}
-
-			if($checkExpireDate) {
-				if (self::expireItem($row)) {
-					continue;
-				}
-			}
-			// Check if resharing is allowed, if not remove share permission
-			if (isset($row['permissions']) && (!self::isResharingAllowed() | \OCP\Util::isSharingDisabledForUser())) {
-				$row['permissions'] &= ~\OCP\Constants::PERMISSION_SHARE;
-			}
-			// Add display names to result
-			$row['share_with_displayname'] = $row['share_with'];
-			if ( isset($row['share_with']) && $row['share_with'] != '' &&
-				$row['share_type'] === self::SHARE_TYPE_USER) {
-				$row['share_with_displayname'] = \OCP\User::getDisplayName($row['share_with']);
-			} else if(isset($row['share_with']) && $row['share_with'] != '' &&
-				$row['share_type'] === self::SHARE_TYPE_REMOTE) {
-				$addressBookEntries = \OC::$server->getContactsManager()->search($row['share_with'], ['CLOUD']);
-				foreach ($addressBookEntries as $entry) {
-					foreach ($entry['CLOUD'] as $cloudID) {
-						if ($cloudID === $row['share_with']) {
-							$row['share_with_displayname'] = $entry['FN'];
-						}
-					}
-				}
-			}
-			if ( isset($row['uid_owner']) && $row['uid_owner'] != '') {
-				$row['displayname_owner'] = \OCP\User::getDisplayName($row['uid_owner']);
-			}
-
-			if ($row['permissions'] > 0) {
-				$items[$row['id']] = $row;
-			}
-
-		}
-
-		// group items if we are looking for items shared with the current user
-		if (isset($shareWith) && $shareWith === \OCP\User::getUser()) {
-			$items = self::groupItems($items, $itemType);
-		}
-
-		if (!empty($items)) {
-			$collectionItems = array();
-			foreach ($items as &$row) {
-				// Return only the item instead of a 2-dimensional array
-				if ($limit == 1 && $row[$column] == $item && ($row['item_type'] == $itemType || $itemType == 'file')) {
-					if ($format == self::FORMAT_NONE) {
-						return $row;
-					} else {
-						break;
-					}
-				}
-				// Check if this is a collection of the requested item type
-				if ($includeCollections && $collectionTypes && $row['item_type'] !== 'folder' && in_array($row['item_type'], $collectionTypes)) {
-					if (($collectionBackend = self::getBackend($row['item_type']))
-						&& $collectionBackend instanceof \OCP\Share_Backend_Collection) {
-						// Collections can be inside collections, check if the item is a collection
-						if (isset($item) && $row['item_type'] == $itemType && $row[$column] == $item) {
-							$collectionItems[] = $row;
-						} else {
-							$collection = array();
-							$collection['item_type'] = $row['item_type'];
-							if ($row['item_type'] == 'file' || $row['item_type'] == 'folder') {
-								$collection['path'] = basename($row['path']);
-							}
-							$row['collection'] = $collection;
-							// Fetch all of the children sources
-							$children = $collectionBackend->getChildren($row[$column]);
-							foreach ($children as $child) {
-								$childItem = $row;
-								$childItem['item_type'] = $itemType;
-								if ($row['item_type'] != 'file' && $row['item_type'] != 'folder') {
-									$childItem['item_source'] = $child['source'];
-									$childItem['item_target'] = $child['target'];
-								}
-								if ($backend instanceof \OCP\Share_Backend_File_Dependent) {
-									if ($row['item_type'] == 'file' || $row['item_type'] == 'folder') {
-										$childItem['file_source'] = $child['source'];
-									} else { // TODO is this really needed if we already know that we use the file backend?
-										$meta = \OC\Files\Filesystem::getFileInfo($child['file_path']);
-										$childItem['file_source'] = $meta['fileid'];
-									}
-									$childItem['file_target'] =
-										\OC\Files\Filesystem::normalizePath($child['file_path']);
-								}
-								if (isset($item)) {
-									if ($childItem[$column] == $item) {
-										// Return only the item instead of a 2-dimensional array
-										if ($limit == 1) {
-											if ($format == self::FORMAT_NONE) {
-												return $childItem;
-											} else {
-												// Unset the items array and break out of both loops
-												$items = array();
-												$items[] = $childItem;
-												break 2;
-											}
-										} else {
-											$collectionItems[] = $childItem;
-										}
-									}
-								} else {
-									$collectionItems[] = $childItem;
-								}
-							}
-						}
-					}
-					// Remove collection item
-					$toRemove = $row['id'];
-					if (array_key_exists($toRemove, $switchedItems)) {
-						$toRemove = $switchedItems[$toRemove];
-					}
-					unset($items[$toRemove]);
-				} elseif ($includeCollections && $collectionTypes && in_array($row['item_type'], $collectionTypes)) {
-					// FIXME: Thats a dirty hack to improve file sharing performance,
-					// see github issue #10588 for more details
-					// Need to find a solution which works for all back-ends
-					$collectionBackend = self::getBackend($row['item_type']);
-					$sharedParents = $collectionBackend->getParents($row['item_source']);
-					foreach ($sharedParents as $parent) {
-						$collectionItems[] = $parent;
-					}
-				}
-			}
-			if (!empty($collectionItems)) {
-				$collectionItems = array_unique($collectionItems, SORT_REGULAR);
-				$items = array_merge($items, $collectionItems);
-			}
-
-			// filter out invalid items, these can appear when subshare entries exist
-			// for a group in which the requested user isn't a member any more
-			$items = array_filter($items, function($item) {
-				return $item['share_type'] !== self::$shareTypeGroupUserUnique;
-			});
-
-			return self::formatResult($items, $column, $backend, $format, $parameters);
-		} elseif ($includeCollections && $collectionTypes && in_array('folder', $collectionTypes)) {
-			// FIXME: Thats a dirty hack to improve file sharing performance,
-			// see github issue #10588 for more details
-			// Need to find a solution which works for all back-ends
-			$collectionItems = array();
-			$collectionBackend = self::getBackend('folder');
-			$sharedParents = $collectionBackend->getParents($item, $shareWith, $uidOwner);
-			foreach ($sharedParents as $parent) {
-				$collectionItems[] = $parent;
-			}
-			if ($limit === 1) {
-				return reset($collectionItems);
-			}
-			return self::formatResult($collectionItems, $column, $backend, $format, $parameters);
-		}
-
-		return array();
-	}
-
-	/**
-	 * group items with link to the same source
-	 *
-	 * @param array $items
-	 * @param string $itemType
-	 * @return array of grouped items
-	 */
-	protected static function groupItems($items, $itemType) {
-
-		$fileSharing = $itemType === 'file' || $itemType === 'folder';
-
-		$result = array();
-
-		foreach ($items as $item) {
-			$grouped = false;
-			foreach ($result as $key => $r) {
-				// for file/folder shares we need to compare file_source, otherwise we compare item_source
-				// only group shares if they already point to the same target, otherwise the file where shared
-				// before grouping of shares was added. In this case we don't group them toi avoid confusions
-				if (( $fileSharing && $item['file_source'] === $r['file_source'] && $item['file_target'] === $r['file_target']) ||
-					(!$fileSharing && $item['item_source'] === $r['item_source'] && $item['item_target'] === $r['item_target'])) {
-					// add the first item to the list of grouped shares
-					if (!isset($result[$key]['grouped'])) {
-						$result[$key]['grouped'][] = $result[$key];
-					}
-					$result[$key]['permissions'] = (int) $item['permissions'] | (int) $r['permissions'];
-					$result[$key]['grouped'][] = $item;
-					$grouped = true;
-					break;
-				}
-			}
-
-			if (!$grouped) {
-				$result[] = $item;
-			}
-
-		}
-
-		return $result;
-	}
-
-	/**
-	 * Put shared item into the database
-	 * @param string $itemType Item type
-	 * @param string $itemSource Item source
-	 * @param int $shareType SHARE_TYPE_USER, SHARE_TYPE_GROUP, or SHARE_TYPE_LINK
-	 * @param string $shareWith User or group the item is being shared with
-	 * @param string $uidOwner User that is the owner of shared item
-	 * @param int $permissions CRUDS permissions
-	 * @param boolean|array $parentFolder Parent folder target (optional)
-	 * @param string $token (optional)
-	 * @param string $itemSourceName name of the source item (optional)
-	 * @param \DateTime $expirationDate (optional)
-	 * @throws \Exception
-	 * @return mixed id of the new share or false
-	 */
-	private static function put($itemType, $itemSource, $shareType, $shareWith, $uidOwner,
-								$permissions, $parentFolder = null, $token = null, $itemSourceName = null, \DateTime $expirationDate = null) {
-
-		$queriesToExecute = array();
-		$suggestedItemTarget = null;
-		$groupFileTarget = $fileTarget = $suggestedFileTarget = $filePath = '';
-		$groupItemTarget = $itemTarget = $fileSource = $parent = 0;
-
-		$result = self::checkReshare($itemType, $itemSource, $shareType, $shareWith, $uidOwner, $permissions, $itemSourceName, $expirationDate);
-		if(!empty($result)) {
-			$parent = $result['parent'];
-			$itemSource = $result['itemSource'];
-			$fileSource = $result['fileSource'];
-			$suggestedItemTarget = $result['suggestedItemTarget'];
-			$suggestedFileTarget = $result['suggestedFileTarget'];
-			$filePath = $result['filePath'];
-		}
-
-		$isGroupShare = false;
-		if ($shareType == self::SHARE_TYPE_GROUP) {
-			$isGroupShare = true;
-			if (isset($shareWith['users'])) {
-				$users = $shareWith['users'];
-			} else {
-				$group = \OC::$server->getGroupManager()->get($shareWith['group']);
-				if ($group) {
-					$users = $group->searchUsers('', -1, 0);
-					$userIds = [];
-					foreach ($users as $user) {
-						$userIds[] = $user->getUID();
-					}
-					$users = $userIds;
-				} else {
-					$users = [];
-				}
-			}
-			// remove current user from list
-			if (in_array(\OCP\User::getUser(), $users)) {
-				unset($users[array_search(\OCP\User::getUser(), $users)]);
-			}
-			$groupItemTarget = Helper::generateTarget($itemType, $itemSource,
-				$shareType, $shareWith['group'], $uidOwner, $suggestedItemTarget);
-			$groupFileTarget = Helper::generateTarget($itemType, $itemSource,
-				$shareType, $shareWith['group'], $uidOwner, $filePath);
-
-			// add group share to table and remember the id as parent
-			$queriesToExecute['groupShare'] = array(
-				'itemType'			=> $itemType,
-				'itemSource'		=> $itemSource,
-				'itemTarget'		=> $groupItemTarget,
-				'shareType'			=> $shareType,
-				'shareWith'			=> $shareWith['group'],
-				'uidOwner'			=> $uidOwner,
-				'permissions'		=> $permissions,
-				'shareTime'			=> time(),
-				'fileSource'		=> $fileSource,
-				'fileTarget'		=> $groupFileTarget,
-				'token'				=> $token,
-				'parent'			=> $parent,
-				'expiration'		=> $expirationDate,
-			);
-
-		} else {
-			$users = array($shareWith);
-			$itemTarget = Helper::generateTarget($itemType, $itemSource, $shareType, $shareWith, $uidOwner,
-				$suggestedItemTarget);
-		}
-
-		$run = true;
-		$error = '';
-		$preHookData = array(
-			'itemType' => $itemType,
-			'itemSource' => $itemSource,
-			'shareType' => $shareType,
-			'uidOwner' => $uidOwner,
-			'permissions' => $permissions,
-			'fileSource' => $fileSource,
-			'expiration' => $expirationDate,
-			'token' => $token,
-			'run' => &$run,
-			'error' => &$error
-		);
-
-		$preHookData['itemTarget'] = $isGroupShare ? $groupItemTarget : $itemTarget;
-		$preHookData['shareWith'] = $isGroupShare ? $shareWith['group'] : $shareWith;
-
-		\OC_Hook::emit(\OCP\Share::class, 'pre_shared', $preHookData);
-
-		if ($run === false) {
-			throw new \Exception($error);
-		}
-
-		foreach ($users as $user) {
-			$sourceId = ($itemType === 'file' || $itemType === 'folder') ? $fileSource : $itemSource;
-			$sourceExists = self::getItemSharedWithBySource($itemType, $sourceId, self::FORMAT_NONE, null, true, $user);
-
-			$userShareType = $isGroupShare ? self::$shareTypeGroupUserUnique : $shareType;
-
-			if ($sourceExists && $sourceExists['item_source'] === $itemSource) {
-				$fileTarget = $sourceExists['file_target'];
-				$itemTarget = $sourceExists['item_target'];
-
-				// for group shares we don't need a additional entry if the target is the same
-				if($isGroupShare && $groupItemTarget === $itemTarget) {
-					continue;
-				}
-
-			} elseif(!$sourceExists && !$isGroupShare)  {
-
-				$itemTarget = Helper::generateTarget($itemType, $itemSource, $userShareType, $user,
-					$uidOwner, $suggestedItemTarget, $parent);
-				if (isset($fileSource)) {
-					if ($parentFolder) {
-						if ($parentFolder === true) {
-							$fileTarget = Helper::generateTarget('file', $filePath, $userShareType, $user,
-								$uidOwner, $suggestedFileTarget, $parent);
-							if ($fileTarget != $groupFileTarget) {
-								$parentFolders[$user]['folder'] = $fileTarget;
-							}
-						} else if (isset($parentFolder[$user])) {
-							$fileTarget = $parentFolder[$user]['folder'].$itemSource;
-							$parent = $parentFolder[$user]['id'];
-						}
-					} else {
-						$fileTarget = Helper::generateTarget('file', $filePath, $userShareType,
-							$user, $uidOwner, $suggestedFileTarget, $parent);
-					}
-				} else {
-					$fileTarget = null;
-				}
-
-			} else {
-
-				// group share which doesn't exists until now, check if we need a unique target for this user
-
-				$itemTarget = Helper::generateTarget($itemType, $itemSource, self::SHARE_TYPE_USER, $user,
-					$uidOwner, $suggestedItemTarget, $parent);
-
-				// do we also need a file target
-				if (isset($fileSource)) {
-					$fileTarget = Helper::generateTarget('file', $filePath, self::SHARE_TYPE_USER, $user,
-						$uidOwner, $suggestedFileTarget, $parent);
-				} else {
-					$fileTarget = null;
-				}
-
-				if (($itemTarget === $groupItemTarget) &&
-					(!isset($fileSource) || $fileTarget === $groupFileTarget)) {
-					continue;
-				}
-			}
-
-			$queriesToExecute[] = array(
-				'itemType'			=> $itemType,
-				'itemSource'		=> $itemSource,
-				'itemTarget'		=> $itemTarget,
-				'shareType'			=> $userShareType,
-				'shareWith'			=> $user,
-				'uidOwner'			=> $uidOwner,
-				'permissions'		=> $permissions,
-				'shareTime'			=> time(),
-				'fileSource'		=> $fileSource,
-				'fileTarget'		=> $fileTarget,
-				'token'				=> $token,
-				'parent'			=> $parent,
-				'expiration'		=> $expirationDate,
-			);
-
-		}
-
-		$id = false;
-		if ($isGroupShare) {
-			$id = self::insertShare($queriesToExecute['groupShare']);
-			// Save this id, any extra rows for this group share will need to reference it
-			$parent = \OC::$server->getDatabaseConnection()->lastInsertId('*PREFIX*share');
-			unset($queriesToExecute['groupShare']);
-		}
-
-		foreach ($queriesToExecute as $shareQuery) {
-			$shareQuery['parent'] = $parent;
-			$id = self::insertShare($shareQuery);
-		}
-
-		$postHookData = array(
-			'itemType' => $itemType,
-			'itemSource' => $itemSource,
-			'parent' => $parent,
-			'shareType' => $shareType,
-			'uidOwner' => $uidOwner,
-			'permissions' => $permissions,
-			'fileSource' => $fileSource,
-			'id' => $parent,
-			'token' => $token,
-			'expirationDate' => $expirationDate,
-		);
-
-		$postHookData['shareWith'] = $isGroupShare ? $shareWith['group'] : $shareWith;
-		$postHookData['itemTarget'] = $isGroupShare ? $groupItemTarget : $itemTarget;
-		$postHookData['fileTarget'] = $isGroupShare ? $groupFileTarget : $fileTarget;
-
-		\OC_Hook::emit(\OCP\Share::class, 'post_shared', $postHookData);
-
-
-		return $id ? $id : false;
-	}
-
-	/**
-	 * @param string $itemType
-	 * @param string $itemSource
-	 * @param int $shareType
-	 * @param string $shareWith
-	 * @param string $uidOwner
-	 * @param int $permissions
-	 * @param string|null $itemSourceName
-	 * @param null|\DateTime $expirationDate
-	 */
-	private static function checkReshare($itemType, $itemSource, $shareType, $shareWith, $uidOwner, $permissions, $itemSourceName, $expirationDate) {
-		$backend = self::getBackend($itemType);
-
-		$l = \OC::$server->getL10N('lib');
-		$result = array();
-
-		$column = ($itemType === 'file' || $itemType === 'folder') ? 'file_source' : 'item_source';
-
-		$checkReshare = self::getItemSharedWithBySource($itemType, $itemSource, self::FORMAT_NONE, null, true);
-		if ($checkReshare) {
-			// Check if attempting to share back to owner
-			if ($checkReshare['uid_owner'] == $shareWith && $shareType == self::SHARE_TYPE_USER) {
-				$message = 'Sharing %s failed, because the user %s is the original sharer';
-				$message_t = $l->t('Sharing failed, because the user %s is the original sharer', [$shareWith]);
-
-				\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareWith), \OCP\Util::DEBUG);
-				throw new \Exception($message_t);
-			}
-		}
-
-		if ($checkReshare && $checkReshare['uid_owner'] !== \OC_User::getUser()) {
-			// Check if share permissions is granted
-			if (self::isResharingAllowed() && (int)$checkReshare['permissions'] & \OCP\Constants::PERMISSION_SHARE) {
-				if (~(int)$checkReshare['permissions'] & $permissions) {
-					$message = 'Sharing %s failed, because the permissions exceed permissions granted to %s';
-					$message_t = $l->t('Sharing %s failed, because the permissions exceed permissions granted to %s', array($itemSourceName, $uidOwner));
-
-					\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $uidOwner), \OCP\Util::DEBUG);
-					throw new \Exception($message_t);
-				} else {
-					// TODO Don't check if inside folder
-					$result['parent'] = $checkReshare['id'];
-
-					$result['expirationDate'] = $expirationDate;
-					// $checkReshare['expiration'] could be null and then is always less than any value
-					if(isset($checkReshare['expiration']) && $checkReshare['expiration'] < $expirationDate) {
-						$result['expirationDate'] = $checkReshare['expiration'];
-					}
-
-					// only suggest the same name as new target if it is a reshare of the
-					// same file/folder and not the reshare of a child
-					if ($checkReshare[$column] === $itemSource) {
-						$result['filePath'] = $checkReshare['file_target'];
-						$result['itemSource'] = $checkReshare['item_source'];
-						$result['fileSource'] = $checkReshare['file_source'];
-						$result['suggestedItemTarget'] = $checkReshare['item_target'];
-						$result['suggestedFileTarget'] = $checkReshare['file_target'];
-					} else {
-						$result['filePath'] = ($backend instanceof \OCP\Share_Backend_File_Dependent) ? $backend->getFilePath($itemSource, $uidOwner) : null;
-						$result['suggestedItemTarget'] = null;
-						$result['suggestedFileTarget'] = null;
-						$result['itemSource'] = $itemSource;
-						$result['fileSource'] = ($backend instanceof \OCP\Share_Backend_File_Dependent) ? $itemSource : null;
-					}
-				}
-			} else {
-				$message = 'Sharing %s failed, because resharing is not allowed';
-				$message_t = $l->t('Sharing %s failed, because resharing is not allowed', array($itemSourceName));
-
-				\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName), \OCP\Util::DEBUG);
-				throw new \Exception($message_t);
-			}
-		} else {
-			$result['parent'] = null;
-			$result['suggestedItemTarget'] = null;
-			$result['suggestedFileTarget'] = null;
-			$result['itemSource'] = $itemSource;
-			$result['expirationDate'] = $expirationDate;
-			if (!$backend->isValidSource($itemSource, $uidOwner)) {
-				$message = 'Sharing %s failed, because the sharing backend for '
-					.'%s could not find its source';
-				$message_t = $l->t('Sharing %s failed, because the sharing backend for %s could not find its source', array($itemSource, $itemType));
-				\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSource, $itemType), \OCP\Util::DEBUG);
-				throw new \Exception($message_t);
-			}
-			if ($backend instanceof \OCP\Share_Backend_File_Dependent) {
-				$result['filePath'] = $backend->getFilePath($itemSource, $uidOwner);
-				if ($itemType == 'file' || $itemType == 'folder') {
-					$result['fileSource'] = $itemSource;
-				} else {
-					$meta = \OC\Files\Filesystem::getFileInfo($result['filePath']);
-					$result['fileSource'] = $meta['fileid'];
-				}
-				if ($result['fileSource'] == -1) {
-					$message = 'Sharing %s failed, because the file could not be found in the file cache';
-					$message_t = $l->t('Sharing %s failed, because the file could not be found in the file cache', array($itemSource));
-
-					\OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSource), \OCP\Util::DEBUG);
-					throw new \Exception($message_t);
-				}
-			} else {
-				$result['filePath'] = null;
-				$result['fileSource'] = null;
-			}
-		}
-
-		return $result;
-	}
-
-	/**
-	 *
-	 * @param array $shareData
-	 * @return mixed false in case of a failure or the id of the new share
-	 */
-	private static function insertShare(array $shareData) {
-
-		$query = \OC_DB::prepare('INSERT INTO `*PREFIX*share` ('
-			.' `item_type`, `item_source`, `item_target`, `share_type`,'
-			.' `share_with`, `uid_owner`, `permissions`, `stime`, `file_source`,'
-			.' `file_target`, `token`, `parent`, `expiration`) VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?)');
-		$query->bindValue(1, $shareData['itemType']);
-		$query->bindValue(2, $shareData['itemSource']);
-		$query->bindValue(3, $shareData['itemTarget']);
-		$query->bindValue(4, $shareData['shareType']);
-		$query->bindValue(5, $shareData['shareWith']);
-		$query->bindValue(6, $shareData['uidOwner']);
-		$query->bindValue(7, $shareData['permissions']);
-		$query->bindValue(8, $shareData['shareTime']);
-		$query->bindValue(9, $shareData['fileSource']);
-		$query->bindValue(10, $shareData['fileTarget']);
-		$query->bindValue(11, $shareData['token']);
-		$query->bindValue(12, $shareData['parent']);
-		$query->bindValue(13, $shareData['expiration'], 'datetime');
-		$result = $query->execute();
-
-		$id = false;
-		if ($result) {
-			$id =  \OC::$server->getDatabaseConnection()->lastInsertId('*PREFIX*share');
-		}
-
-		return $id;
-
-	}
-
-	/**
-	 * In case a password protected link is not yet authenticated this function will return false
-	 *
-	 * @param array $linkItem
-	 * @return boolean
-	 */
-	public static function checkPasswordProtectedShare(array $linkItem) {
-		if (!isset($linkItem['share_with'])) {
-			return true;
-		}
-		if (!isset($linkItem['share_type'])) {
-			return true;
-		}
-		if (!isset($linkItem['id'])) {
-			return true;
-		}
-
-		if ($linkItem['share_type'] != \OCP\Share::SHARE_TYPE_LINK) {
-			return true;
-		}
-
-		if ( \OC::$server->getSession()->exists('public_link_authenticated')
-			&& \OC::$server->getSession()->get('public_link_authenticated') === (string)$linkItem['id'] ) {
-			return true;
-		}
-
-		return false;
-	}
-
-	/**
-	 * construct select statement
-	 * @param int $format
-	 * @param boolean $fileDependent ist it a file/folder share or a generla share
-	 * @param string $uidOwner
-	 * @return string select statement
-	 */
-	private static function createSelectStatement($format, $fileDependent, $uidOwner = null) {
-		$select = '*';
-		if ($format == self::FORMAT_STATUSES) {
-			if ($fileDependent) {
-				$select = '`*PREFIX*share`.`id`, `*PREFIX*share`.`parent`, `share_type`, `path`, `storage`, '
-					. '`share_with`, `uid_owner` , `file_source`, `stime`, `*PREFIX*share`.`permissions`, '
-					. '`*PREFIX*storages`.`id` AS `storage_id`, `*PREFIX*filecache`.`parent` as `file_parent`, '
-					. '`uid_initiator`';
-			} else {
-				$select = '`id`, `parent`, `share_type`, `share_with`, `uid_owner`, `item_source`, `stime`, `*PREFIX*share`.`permissions`';
-			}
-		} else {
-			if (isset($uidOwner)) {
-				if ($fileDependent) {
-					$select = '`*PREFIX*share`.`id`, `item_type`, `item_source`, `*PREFIX*share`.`parent`,'
-						. ' `share_type`, `share_with`, `file_source`, `file_target`, `path`, `*PREFIX*share`.`permissions`, `stime`,'
-						. ' `expiration`, `token`, `storage`, `mail_send`, `uid_owner`, '
-						. '`*PREFIX*storages`.`id` AS `storage_id`, `*PREFIX*filecache`.`parent` as `file_parent`';
-				} else {
-					$select = '`id`, `item_type`, `item_source`, `parent`, `share_type`, `share_with`, `*PREFIX*share`.`permissions`,'
-						. ' `stime`, `file_source`, `expiration`, `token`, `mail_send`, `uid_owner`';
-				}
-			} else {
-				if ($fileDependent) {
-					if ($format == \OCA\Files_Sharing\ShareBackend\File::FORMAT_GET_FOLDER_CONTENTS || $format == \OCA\Files_Sharing\ShareBackend\File::FORMAT_FILE_APP_ROOT) {
-						$select = '`*PREFIX*share`.`id`, `item_type`, `item_source`, `*PREFIX*share`.`parent`, `uid_owner`, '
-							. '`share_type`, `share_with`, `file_source`, `path`, `file_target`, `stime`, '
-							. '`*PREFIX*share`.`permissions`, `expiration`, `storage`, `*PREFIX*filecache`.`parent` as `file_parent`, '
-							. '`name`, `mtime`, `mimetype`, `mimepart`, `size`, `encrypted`, `etag`, `mail_send`';
-					} else {
-						$select = '`*PREFIX*share`.`id`, `item_type`, `item_source`, `item_target`,'
-							. '`*PREFIX*share`.`parent`, `share_type`, `share_with`, `uid_owner`,'
-							. '`file_source`, `path`, `file_target`, `*PREFIX*share`.`permissions`,'
-						    . '`stime`, `expiration`, `token`, `storage`, `mail_send`,'
-							. '`*PREFIX*storages`.`id` AS `storage_id`, `*PREFIX*filecache`.`parent` as `file_parent`';
-					}
-				}
-			}
-		}
-		return $select;
-	}
-
-
-	/**
-	 * transform db results
-	 * @param array $row result
-	 */
-	private static function transformDBResults(&$row) {
-		if (isset($row['id'])) {
-			$row['id'] = (int) $row['id'];
-		}
-		if (isset($row['share_type'])) {
-			$row['share_type'] = (int) $row['share_type'];
-		}
-		if (isset($row['parent'])) {
-			$row['parent'] = (int) $row['parent'];
-		}
-		if (isset($row['file_parent'])) {
-			$row['file_parent'] = (int) $row['file_parent'];
-		}
-		if (isset($row['file_source'])) {
-			$row['file_source'] = (int) $row['file_source'];
-		}
-		if (isset($row['permissions'])) {
-			$row['permissions'] = (int) $row['permissions'];
-		}
-		if (isset($row['storage'])) {
-			$row['storage'] = (int) $row['storage'];
-		}
-		if (isset($row['stime'])) {
-			$row['stime'] = (int) $row['stime'];
-		}
-		if (isset($row['expiration']) && $row['share_type'] !== self::SHARE_TYPE_LINK) {
-			// discard expiration date for non-link shares, which might have been
-			// set by ancient bugs
-			$row['expiration'] = null;
-		}
-	}
-
-	/**
-	 * format result
-	 * @param array $items result
-	 * @param string $column is it a file share or a general share ('file_target' or 'item_target')
-	 * @param \OCP\Share_Backend $backend sharing backend
-	 * @param int $format
-	 * @param array $parameters additional format parameters
-	 * @return array format result
-	 */
-	private static function formatResult($items, $column, $backend, $format = self::FORMAT_NONE , $parameters = null) {
-		if ($format === self::FORMAT_NONE) {
-			return $items;
-		} else if ($format === self::FORMAT_STATUSES) {
-			$statuses = array();
-			foreach ($items as $item) {
-				if ($item['share_type'] === self::SHARE_TYPE_LINK) {
-					if ($item['uid_initiator'] !== \OC::$server->getUserSession()->getUser()->getUID()) {
-						continue;
-					}
-					$statuses[$item[$column]]['link'] = true;
-				} else if (!isset($statuses[$item[$column]])) {
-					$statuses[$item[$column]]['link'] = false;
-				}
-				if (!empty($item['file_target'])) {
-					$statuses[$item[$column]]['path'] = $item['path'];
-				}
-			}
-			return $statuses;
-		} else {
-			return $backend->formatItems($items, $format, $parameters);
-		}
-	}
-
-	/**
-	 * remove protocol from URL
-	 *
-	 * @param string $url
-	 * @return string
-	 */
-	public static function removeProtocolFromUrl($url) {
-		if (strpos($url, 'https://') === 0) {
-			return substr($url, strlen('https://'));
-		} else if (strpos($url, 'http://') === 0) {
-			return substr($url, strlen('http://'));
-		}
-
-		return $url;
-	}
-
-	/**
-	 * try http post first with https and then with http as a fallback
-	 *
-	 * @param string $remoteDomain
-	 * @param string $urlSuffix
-	 * @param array $fields post parameters
-	 * @return array
-	 */
-	private static function tryHttpPostToShareEndpoint($remoteDomain, $urlSuffix, array $fields) {
-		$protocol = 'https://';
-		$result = [
-			'success' => false,
-			'result' => '',
-		];
-		$try = 0;
-		$discoveryService = \OC::$server->query(\OCP\OCS\IDiscoveryService::class);
-		while ($result['success'] === false && $try < 2) {
-			$federationEndpoints = $discoveryService->discover($protocol . $remoteDomain, 'FEDERATED_SHARING');
-			$endpoint = isset($federationEndpoints['share']) ? $federationEndpoints['share'] : '/ocs/v2.php/cloud/shares';
-			$client = \OC::$server->getHTTPClientService()->newClient();
-
-			try {
-				$response = $client->post(
-					$protocol . $remoteDomain . $endpoint . $urlSuffix . '?format=' . self::RESPONSE_FORMAT,
-					[
-						'body' => $fields,
-						'connect_timeout' => 10,
-					]
-				);
-
-				$result = ['success' => true, 'result' => $response->getBody()];
-			} catch (\Exception $e) {
-				$result = ['success' => false, 'result' => $e->getMessage()];
-			}
-
-			$try++;
-			$protocol = 'http://';
-		}
-
-		return $result;
-	}
-
-	/**
-	 * send server-to-server share to remote server
-	 *
-	 * @param string $token
-	 * @param string $shareWith
-	 * @param string $name
-	 * @param int $remote_id
-	 * @param string $owner
-	 * @return bool
-	 */
-	private static function sendRemoteShare($token, $shareWith, $name, $remote_id, $owner) {
-
-		list($user, $remote) = Helper::splitUserRemote($shareWith);
-
-		if ($user && $remote) {
-			$url = $remote;
-
-			$local = \OC::$server->getURLGenerator()->getAbsoluteURL('/');
-
-			$fields = array(
-				'shareWith' => $user,
-				'token' => $token,
-				'name' => $name,
-				'remoteId' => $remote_id,
-				'owner' => $owner,
-				'remote' => $local,
-			);
-
-			$url = self::removeProtocolFromUrl($url);
-			$result = self::tryHttpPostToShareEndpoint($url, '', $fields);
-			$status = json_decode($result['result'], true);
-
-			if ($result['success'] && ($status['ocs']['meta']['statuscode'] === 100 || $status['ocs']['meta']['statuscode'] === 200)) {
-				\OC_Hook::emit(\OCP\Share::class, 'federated_share_added', ['server' => $remote]);
-				return true;
-			}
-
-		}
-
-		return false;
-	}
-
-	/**
-	 * send server-to-server unshare to remote server
-	 *
-	 * @param string $remote url
-	 * @param int $id share id
-	 * @param string $token
-	 * @return bool
-	 */
-	private static function sendRemoteUnshare($remote, $id, $token) {
-		$url = rtrim($remote, '/');
-		$fields = array('token' => $token, 'format' => 'json');
-		$url = self::removeProtocolFromUrl($url);
-		$result = self::tryHttpPostToShareEndpoint($url, '/'.$id.'/unshare', $fields);
-		$status = json_decode($result['result'], true);
-
-		return ($result['success'] && ($status['ocs']['meta']['statuscode'] === 100 || $status['ocs']['meta']['statuscode'] === 200));
-	}
-
-	/**
-	 * check if user can only share with group members
-	 * @return bool
-	 */
-	public static function shareWithGroupMembersOnly() {
-		$value = \OC::$server->getConfig()->getAppValue('core', 'shareapi_only_share_with_group_members', 'no');
-		return $value === 'yes';
-	}
-
-	/**
-	 * @return bool
-	 */
-	public static function isDefaultExpireDateEnabled() {
-		$defaultExpireDateEnabled = \OC::$server->getConfig()->getAppValue('core', 'shareapi_default_expire_date', 'no');
-		return $defaultExpireDateEnabled === 'yes';
-	}
-
-	/**
-	 * @return int
-	 */
-	public static function getExpireInterval() {
-		return (int)\OC::$server->getConfig()->getAppValue('core', 'shareapi_expire_after_n_days', '7');
-	}
-
-	/**
-	 * Checks whether the given path is reachable for the given owner
-	 *
-	 * @param string $path path relative to files
-	 * @param string $ownerStorageId storage id of the owner
-	 *
-	 * @return boolean true if file is reachable, false otherwise
-	 */
-	private static function isFileReachable($path, $ownerStorageId) {
-		// if outside the home storage, file is always considered reachable
-		if (!(substr($ownerStorageId, 0, 6) === 'home::' ||
-			substr($ownerStorageId, 0, 13) === 'object::user:'
-		)) {
-			return true;
-		}
-
-		// if inside the home storage, the file has to be under "/files/"
-		$path = ltrim($path, '/');
-		if (substr($path, 0, 6) === 'files/') {
-			return true;
-		}
-
-		return false;
-	}
-
-	/**
-	 * @param IConfig $config
-	 * @return bool
-	 */
-	public static function enforcePassword(IConfig $config) {
-		$enforcePassword = $config->getAppValue('core', 'shareapi_enforce_links_password', 'no');
-		return $enforcePassword === 'yes';
-	}
-
-	/**
-	 * @param string $password
-	 * @throws \Exception
-	 */
-	private static function verifyPassword($password) {
-
-		$accepted = true;
-		$message = '';
-		\OCP\Util::emitHook('\OC\Share', 'verifyPassword', [
-			'password' => $password,
-			'accepted' => &$accepted,
-			'message' => &$message
-		]);
-
-		if (!$accepted) {
-			throw new \Exception($message);
-		}
-	}
+        $result = $query->execute(array($status, $itemType, $itemSource, $shareType, $recipient));
+
+        if($result === false) {
+            \OCP\Util::writeLog('OCP\Share', 'Couldn\'t set send mail status', \OCP\Util::ERROR);
+        }
+    }
+
+    /**
+     * validate expiration date if it meets all constraints
+     *
+     * @param string $expireDate well formatted date string, e.g. "DD-MM-YYYY"
+     * @param string $shareTime timestamp when the file was shared
+     * @param string $itemType
+     * @param string $itemSource
+     * @return \DateTime validated date
+     * @throws \Exception when the expire date is in the past or further in the future then the enforced date
+     */
+    private static function validateExpireDate($expireDate, $shareTime, $itemType, $itemSource) {
+        $l = \OC::$server->getL10N('lib');
+        $date = new \DateTime($expireDate);
+        $today = new \DateTime('now');
+
+        // if the user doesn't provide a share time we need to get it from the database
+        // fall-back mode to keep API stable, because the $shareTime parameter was added later
+        $defaultExpireDateEnforced = \OCP\Util::isDefaultExpireDateEnforced();
+        if ($defaultExpireDateEnforced && $shareTime === null) {
+            $items = self::getItemShared($itemType, $itemSource);
+            $firstItem = reset($items);
+            $shareTime = (int)$firstItem['stime'];
+        }
+
+        if ($defaultExpireDateEnforced) {
+            // initialize max date with share time
+            $maxDate = new \DateTime();
+            $maxDate->setTimestamp($shareTime);
+            $maxDays = \OC::$server->getConfig()->getAppValue('core', 'shareapi_expire_after_n_days', '7');
+            $maxDate->add(new \DateInterval('P' . $maxDays . 'D'));
+            if ($date > $maxDate) {
+                $warning = 'Cannot set expiration date. Shares cannot expire later than ' . $maxDays . ' after they have been shared';
+                $warning_t = $l->t('Cannot set expiration date. Shares cannot expire later than %s after they have been shared', array($maxDays));
+                \OCP\Util::writeLog('OCP\Share', $warning, \OCP\Util::WARN);
+                throw new \Exception($warning_t);
+            }
+        }
+
+        if ($date < $today) {
+            $message = 'Cannot set expiration date. Expiration date is in the past';
+            $message_t = $l->t('Cannot set expiration date. Expiration date is in the past');
+            \OCP\Util::writeLog('OCP\Share', $message, \OCP\Util::WARN);
+            throw new \Exception($message_t);
+        }
+
+        return $date;
+    }
+
+    /**
+     * Checks whether a share has expired, calls unshareItem() if yes.
+     * @param array $item Share data (usually database row)
+     * @return boolean True if item was expired, false otherwise.
+     */
+    protected static function expireItem(array $item) {
+
+        $result = false;
+
+        // only use default expiration date for link shares
+        if ((int) $item['share_type'] === self::SHARE_TYPE_LINK) {
+
+            // calculate expiration date
+            if (!empty($item['expiration'])) {
+                $userDefinedExpire = new \DateTime($item['expiration']);
+                $expires = $userDefinedExpire->getTimestamp();
+            } else {
+                $expires = null;
+            }
+
+
+            // get default expiration settings
+            $defaultSettings = Helper::getDefaultExpireSetting();
+            $expires = Helper::calculateExpireDate($defaultSettings, $item['stime'], $expires);
+
+
+            if (is_int($expires)) {
+                $now = time();
+                if ($now > $expires) {
+                    self::unshareItem($item);
+                    $result = true;
+                }
+            }
+        }
+        return $result;
+    }
+
+    /**
+     * Unshares a share given a share data array
+     * @param array $item Share data (usually database row)
+     * @param int $newParent parent ID
+     * @return null
+     */
+    protected static function unshareItem(array $item, $newParent = null) {
+
+        $shareType = (int)$item['share_type'];
+        $shareWith = null;
+        if ($shareType !== \OCP\Share::SHARE_TYPE_LINK) {
+            $shareWith = $item['share_with'];
+        }
+
+        // Pass all the vars we have for now, they may be useful
+        $hookParams = array(
+            'id'            => $item['id'],
+            'itemType'      => $item['item_type'],
+            'itemSource'    => $item['item_source'],
+            'shareType'     => $shareType,
+            'shareWith'     => $shareWith,
+            'itemParent'    => $item['parent'],
+            'uidOwner'      => $item['uid_owner'],
+        );
+        if($item['item_type'] === 'file' || $item['item_type'] === 'folder') {
+            $hookParams['fileSource'] = $item['file_source'];
+            $hookParams['fileTarget'] = $item['file_target'];
+        }
+
+        \OC_Hook::emit(\OCP\Share::class, 'pre_unshare', $hookParams);
+        $deletedShares = Helper::delete($item['id'], false, null, $newParent);
+        $deletedShares[] = $hookParams;
+        $hookParams['deletedShares'] = $deletedShares;
+        \OC_Hook::emit(\OCP\Share::class, 'post_unshare', $hookParams);
+        if ((int)$item['share_type'] === \OCP\Share::SHARE_TYPE_REMOTE && \OC::$server->getUserSession()->getUser()) {
+            list(, $remote) = Helper::splitUserRemote($item['share_with']);
+            self::sendRemoteUnshare($remote, $item['id'], $item['token']);
+        }
+    }
+
+    /**
+     * Get the backend class for the specified item type
+     * @param string $itemType
+     * @throws \Exception
+     * @return \OCP\Share_Backend
+     */
+    public static function getBackend($itemType) {
+        $l = \OC::$server->getL10N('lib');
+        if (isset(self::$backends[$itemType])) {
+            return self::$backends[$itemType];
+        } else if (isset(self::$backendTypes[$itemType]['class'])) {
+            $class = self::$backendTypes[$itemType]['class'];
+            if (class_exists($class)) {
+                self::$backends[$itemType] = new $class;
+                if (!(self::$backends[$itemType] instanceof \OCP\Share_Backend)) {
+                    $message = 'Sharing backend %s must implement the interface OCP\Share_Backend';
+                    $message_t = $l->t('Sharing backend %s must implement the interface OCP\Share_Backend', array($class));
+                    \OCP\Util::writeLog('OCP\Share', sprintf($message, $class), \OCP\Util::ERROR);
+                    throw new \Exception($message_t);
+                }
+                return self::$backends[$itemType];
+            } else {
+                $message = 'Sharing backend %s not found';
+                $message_t = $l->t('Sharing backend %s not found', array($class));
+                \OCP\Util::writeLog('OCP\Share', sprintf($message, $class), \OCP\Util::ERROR);
+                throw new \Exception($message_t);
+            }
+        }
+        $message = 'Sharing backend for %s not found';
+        $message_t = $l->t('Sharing backend for %s not found', array($itemType));
+        \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemType), \OCP\Util::ERROR);
+        throw new \Exception($message_t);
+    }
+
+    /**
+     * Check if resharing is allowed
+     * @return boolean true if allowed or false
+     *
+     * Resharing is allowed by default if not configured
+     */
+    public static function isResharingAllowed() {
+        if (!isset(self::$isResharingAllowed)) {
+            if (\OC::$server->getConfig()->getAppValue('core', 'shareapi_allow_resharing', 'yes') == 'yes') {
+                self::$isResharingAllowed = true;
+            } else {
+                self::$isResharingAllowed = false;
+            }
+        }
+        return self::$isResharingAllowed;
+    }
+
+    /**
+     * Get a list of collection item types for the specified item type
+     * @param string $itemType
+     * @return array
+     */
+    private static function getCollectionItemTypes($itemType) {
+        $collectionTypes = array($itemType);
+        foreach (self::$backendTypes as $type => $backend) {
+            if (in_array($backend['collectionOf'], $collectionTypes)) {
+                $collectionTypes[] = $type;
+            }
+        }
+        // TODO Add option for collections to be collection of themselves, only 'folder' does it now...
+        if (isset(self::$backendTypes[$itemType]) && (!self::getBackend($itemType) instanceof \OCP\Share_Backend_Collection || $itemType != 'folder')) {
+            unset($collectionTypes[0]);
+        }
+        // Return array if collections were found or the item type is a
+        // collection itself - collections can be inside collections
+        if (count($collectionTypes) > 0) {
+            return $collectionTypes;
+        }
+        return false;
+    }
+
+    /**
+     * Get the owners of items shared with a user.
+     *
+     * @param string $user The user the items are shared with.
+     * @param string $type The type of the items shared with the user.
+     * @param boolean $includeCollections Include collection item types (optional)
+     * @param boolean $includeOwner include owner in the list of users the item is shared with (optional)
+     * @return array
+     */
+    public static function getSharedItemsOwners($user, $type, $includeCollections = false, $includeOwner = false) {
+        // First, we find out if $type is part of a collection (and if that collection is part of
+        // another one and so on).
+        $collectionTypes = array();
+        if (!$includeCollections || !$collectionTypes = self::getCollectionItemTypes($type)) {
+            $collectionTypes[] = $type;
+        }
+
+        // Of these collection types, along with our original $type, we make a
+        // list of the ones for which a sharing backend has been registered.
+        // FIXME: Ideally, we wouldn't need to nest getItemsSharedWith in this loop but just call it
+        // with its $includeCollections parameter set to true. Unfortunately, this fails currently.
+        $allMaybeSharedItems = array();
+        foreach ($collectionTypes as $collectionType) {
+            if (isset(self::$backends[$collectionType])) {
+                $allMaybeSharedItems[$collectionType] = self::getItemsSharedWithUser(
+                    $collectionType,
+                    $user,
+                    self::FORMAT_NONE
+                );
+            }
+        }
+
+        $owners = array();
+        if ($includeOwner) {
+            $owners[] = $user;
+        }
+
+        // We take a look at all shared items of the given $type (or of the collections it is part of)
+        // and find out their owners. Then, we gather the tags for the original $type from all owners,
+        // and return them as elements of a list that look like "Tag (owner)".
+        foreach ($allMaybeSharedItems as $collectionType => $maybeSharedItems) {
+            foreach ($maybeSharedItems as $sharedItem) {
+                if (isset($sharedItem['id'])) { //workaround for https://github.com/owncloud/core/issues/2814
+                    $owners[] = $sharedItem['uid_owner'];
+                }
+            }
+        }
+
+        return $owners;
+    }
+
+    /**
+     * Get shared items from the database
+     * @param string $itemType
+     * @param string $item Item source or target (optional)
+     * @param int $shareType SHARE_TYPE_USER, SHARE_TYPE_GROUP, SHARE_TYPE_LINK, $shareTypeUserAndGroups, or $shareTypeGroupUserUnique
+     * @param string $shareWith User or group the item is being shared with
+     * @param string $uidOwner User that is the owner of shared items (optional)
+     * @param int $format Format to convert items to with formatItems() (optional)
+     * @param mixed $parameters to pass to formatItems() (optional)
+     * @param int $limit Number of items to return, -1 to return all matches (optional)
+     * @param boolean $includeCollections Include collection item types (optional)
+     * @param boolean $itemShareWithBySource (optional)
+     * @param boolean $checkExpireDate
+     * @return array
+     *
+     * See public functions getItem(s)... for parameter usage
+     *
+     */
+    public static function getItems($itemType, $item = null, $shareType = null, $shareWith = null,
+                                    $uidOwner = null, $format = self::FORMAT_NONE, $parameters = null, $limit = -1,
+                                    $includeCollections = false, $itemShareWithBySource = false, $checkExpireDate  = true) {
+        if (\OC::$server->getConfig()->getAppValue('core', 'shareapi_enabled', 'yes') != 'yes') {
+            return array();
+        }
+        $backend = self::getBackend($itemType);
+        $collectionTypes = false;
+        // Get filesystem root to add it to the file target and remove from the
+        // file source, match file_source with the file cache
+        if ($itemType == 'file' || $itemType == 'folder') {
+            if(!is_null($uidOwner)) {
+                $root = \OC\Files\Filesystem::getRoot();
+            } else {
+                $root = '';
+            }
+            $where = 'INNER JOIN `*PREFIX*filecache` ON `file_source` = `*PREFIX*filecache`.`fileid` ';
+            if (!isset($item)) {
+                $where .= ' AND `file_target` IS NOT NULL ';
+            }
+            $where .= 'INNER JOIN `*PREFIX*storages` ON `numeric_id` = `*PREFIX*filecache`.`storage` ';
+            $fileDependent = true;
+            $queryArgs = array();
+        } else {
+            $fileDependent = false;
+            $root = '';
+            $collectionTypes = self::getCollectionItemTypes($itemType);
+            if ($includeCollections && !isset($item) && $collectionTypes) {
+                // If includeCollections is true, find collections of this item type, e.g. a music album contains songs
+                if (!in_array($itemType, $collectionTypes)) {
+                    $itemTypes = array_merge(array($itemType), $collectionTypes);
+                } else {
+                    $itemTypes = $collectionTypes;
+                }
+                $placeholders = implode(',', array_fill(0, count($itemTypes), '?'));
+                $where = ' WHERE `item_type` IN ('.$placeholders.'))';
+                $queryArgs = $itemTypes;
+            } else {
+                $where = ' WHERE `item_type` = ?';
+                $queryArgs = array($itemType);
+            }
+        }
+        if (\OC::$server->getConfig()->getAppValue('core', 'shareapi_allow_links', 'yes') !== 'yes') {
+            $where .= ' AND `share_type` != ?';
+            $queryArgs[] = self::SHARE_TYPE_LINK;
+        }
+        if (isset($shareType)) {
+            // Include all user and group items
+            if ($shareType == self::$shareTypeUserAndGroups && isset($shareWith)) {
+                $where .= ' AND ((`share_type` in (?, ?) AND `share_with` = ?) ';
+                $queryArgs[] = self::SHARE_TYPE_USER;
+                $queryArgs[] = self::$shareTypeGroupUserUnique;
+                $queryArgs[] = $shareWith;
+
+                $user = \OC::$server->getUserManager()->get($shareWith);
+                $groups = [];
+                if ($user) {
+                    $groups = \OC::$server->getGroupManager()->getUserGroupIds($user);
+                }
+                if (!empty($groups)) {
+                    $placeholders = implode(',', array_fill(0, count($groups), '?'));
+                    $where .= ' OR (`share_type` = ? AND `share_with` IN ('.$placeholders.')) ';
+                    $queryArgs[] = self::SHARE_TYPE_GROUP;
+                    $queryArgs = array_merge($queryArgs, $groups);
+                }
+                $where .= ')';
+                // Don't include own group shares
+                $where .= ' AND `uid_owner` != ?';
+                $queryArgs[] = $shareWith;
+            } else {
+                $where .= ' AND `share_type` = ?';
+                $queryArgs[] = $shareType;
+                if (isset($shareWith)) {
+                    $where .= ' AND `share_with` = ?';
+                    $queryArgs[] = $shareWith;
+                }
+            }
+        }
+        if (isset($uidOwner)) {
+            $where .= ' AND `uid_owner` = ?';
+            $queryArgs[] = $uidOwner;
+            if (!isset($shareType)) {
+                // Prevent unique user targets for group shares from being selected
+                $where .= ' AND `share_type` != ?';
+                $queryArgs[] = self::$shareTypeGroupUserUnique;
+            }
+            if ($fileDependent) {
+                $column = 'file_source';
+            } else {
+                $column = 'item_source';
+            }
+        } else {
+            if ($fileDependent) {
+                $column = 'file_target';
+            } else {
+                $column = 'item_target';
+            }
+        }
+        if (isset($item)) {
+            $collectionTypes = self::getCollectionItemTypes($itemType);
+            if ($includeCollections && $collectionTypes && !in_array('folder', $collectionTypes)) {
+                $where .= ' AND (';
+            } else {
+                $where .= ' AND';
+            }
+            // If looking for own shared items, check item_source else check item_target
+            if (isset($uidOwner) || $itemShareWithBySource) {
+                // If item type is a file, file source needs to be checked in case the item was converted
+                if ($fileDependent) {
+                    $where .= ' `file_source` = ?';
+                    $column = 'file_source';
+                } else {
+                    $where .= ' `item_source` = ?';
+                    $column = 'item_source';
+                }
+            } else {
+                if ($fileDependent) {
+                    $where .= ' `file_target` = ?';
+                    $item = \OC\Files\Filesystem::normalizePath($item);
+                } else {
+                    $where .= ' `item_target` = ?';
+                }
+            }
+            $queryArgs[] = $item;
+            if ($includeCollections && $collectionTypes && !in_array('folder', $collectionTypes)) {
+                $placeholders = implode(',', array_fill(0, count($collectionTypes), '?'));
+                $where .= ' OR `item_type` IN ('.$placeholders.'))';
+                $queryArgs = array_merge($queryArgs, $collectionTypes);
+            }
+        }
+
+        if ($shareType == self::$shareTypeUserAndGroups && $limit === 1) {
+            // Make sure the unique user target is returned if it exists,
+            // unique targets should follow the group share in the database
+            // If the limit is not 1, the filtering can be done later
+            $where .= ' ORDER BY `*PREFIX*share`.`id` DESC';
+        } else {
+            $where .= ' ORDER BY `*PREFIX*share`.`id` ASC';
+        }
+
+        if ($limit != -1 && !$includeCollections) {
+            // The limit must be at least 3, because filtering needs to be done
+            if ($limit < 3) {
+                $queryLimit = 3;
+            } else {
+                $queryLimit = $limit;
+            }
+        } else {
+            $queryLimit = null;
+        }
+        $select = self::createSelectStatement($format, $fileDependent, $uidOwner);
+        $root = strlen($root);
+        $query = \OC_DB::prepare('SELECT '.$select.' FROM `*PREFIX*share` '.$where, $queryLimit);
+        $result = $query->execute($queryArgs);
+        if ($result === false) {
+            \OCP\Util::writeLog('OCP\Share',
+                \OC_DB::getErrorMessage() . ', select=' . $select . ' where=',
+                \OCP\Util::ERROR);
+        }
+        $items = array();
+        $targets = array();
+        $switchedItems = array();
+        $mounts = array();
+        while ($row = $result->fetchRow()) {
+            self::transformDBResults($row);
+            // Filter out duplicate group shares for users with unique targets
+            if ($fileDependent && !self::isFileReachable($row['path'], $row['storage_id'])) {
+                continue;
+            }
+            if ($row['share_type'] == self::$shareTypeGroupUserUnique && isset($items[$row['parent']])) {
+                $row['share_type'] = self::SHARE_TYPE_GROUP;
+                $row['unique_name'] = true; // remember that we use a unique name for this user
+                $row['share_with'] = $items[$row['parent']]['share_with'];
+                // if the group share was unshared from the user we keep the permission, otherwise
+                // we take the permission from the parent because this is always the up-to-date
+                // permission for the group share
+                if ($row['permissions'] > 0) {
+                    $row['permissions'] = $items[$row['parent']]['permissions'];
+                }
+                // Remove the parent group share
+                unset($items[$row['parent']]);
+                if ($row['permissions'] == 0) {
+                    continue;
+                }
+            } else if (!isset($uidOwner)) {
+                // Check if the same target already exists
+                if (isset($targets[$row['id']])) {
+                    // Check if the same owner shared with the user twice
+                    // through a group and user share - this is allowed
+                    $id = $targets[$row['id']];
+                    if (isset($items[$id]) && $items[$id]['uid_owner'] == $row['uid_owner']) {
+                        // Switch to group share type to ensure resharing conditions aren't bypassed
+                        if ($items[$id]['share_type'] != self::SHARE_TYPE_GROUP) {
+                            $items[$id]['share_type'] = self::SHARE_TYPE_GROUP;
+                            $items[$id]['share_with'] = $row['share_with'];
+                        }
+                        // Switch ids if sharing permission is granted on only
+                        // one share to ensure correct parent is used if resharing
+                        if (~(int)$items[$id]['permissions'] & \OCP\Constants::PERMISSION_SHARE
+                            && (int)$row['permissions'] & \OCP\Constants::PERMISSION_SHARE) {
+                            $items[$row['id']] = $items[$id];
+                            $switchedItems[$id] = $row['id'];
+                            unset($items[$id]);
+                            $id = $row['id'];
+                        }
+                        $items[$id]['permissions'] |= (int)$row['permissions'];
+
+                    }
+                    continue;
+                } elseif (!empty($row['parent'])) {
+                    $targets[$row['parent']] = $row['id'];
+                }
+            }
+            // Remove root from file source paths if retrieving own shared items
+            if (isset($uidOwner) && isset($row['path'])) {
+                if (isset($row['parent'])) {
+                    $query = \OC_DB::prepare('SELECT `file_target` FROM `*PREFIX*share` WHERE `id` = ?');
+                    $parentResult = $query->execute(array($row['parent']));
+                    if ($result === false) {
+                        \OCP\Util::writeLog('OCP\Share', 'Can\'t select parent: ' .
+                            \OC_DB::getErrorMessage() . ', select=' . $select . ' where=' . $where,
+                            \OCP\Util::ERROR);
+                    } else {
+                        $parentRow = $parentResult->fetchRow();
+                        $tmpPath = $parentRow['file_target'];
+                        // find the right position where the row path continues from the target path
+                        $pos = strrpos($row['path'], $parentRow['file_target']);
+                        $subPath = substr($row['path'], $pos);
+                        $splitPath = explode('/', $subPath);
+                        foreach (array_slice($splitPath, 2) as $pathPart) {
+                            $tmpPath = $tmpPath . '/' . $pathPart;
+                        }
+                        $row['path'] = $tmpPath;
+                    }
+                } else {
+                    if (!isset($mounts[$row['storage']])) {
+                        $mountPoints = \OC\Files\Filesystem::getMountByNumericId($row['storage']);
+                        if (is_array($mountPoints) && !empty($mountPoints)) {
+                            $mounts[$row['storage']] = current($mountPoints);
+                        }
+                    }
+                    if (!empty($mounts[$row['storage']])) {
+                        $path = $mounts[$row['storage']]->getMountPoint().$row['path'];
+                        $relPath = substr($path, $root); // path relative to data/user
+                        $row['path'] = rtrim($relPath, '/');
+                    }
+                }
+            }
+
+            if($checkExpireDate) {
+                if (self::expireItem($row)) {
+                    continue;
+                }
+            }
+            // Check if resharing is allowed, if not remove share permission
+            if (isset($row['permissions']) && (!self::isResharingAllowed() | \OCP\Util::isSharingDisabledForUser())) {
+                $row['permissions'] &= ~\OCP\Constants::PERMISSION_SHARE;
+            }
+            // Add display names to result
+            $row['share_with_displayname'] = $row['share_with'];
+            if ( isset($row['share_with']) && $row['share_with'] != '' &&
+                $row['share_type'] === self::SHARE_TYPE_USER) {
+                $row['share_with_displayname'] = \OCP\User::getDisplayName($row['share_with']);
+            } else if(isset($row['share_with']) && $row['share_with'] != '' &&
+                $row['share_type'] === self::SHARE_TYPE_REMOTE) {
+                $addressBookEntries = \OC::$server->getContactsManager()->search($row['share_with'], ['CLOUD']);
+                foreach ($addressBookEntries as $entry) {
+                    foreach ($entry['CLOUD'] as $cloudID) {
+                        if ($cloudID === $row['share_with']) {
+                            $row['share_with_displayname'] = $entry['FN'];
+                        }
+                    }
+                }
+            }
+            if ( isset($row['uid_owner']) && $row['uid_owner'] != '') {
+                $row['displayname_owner'] = \OCP\User::getDisplayName($row['uid_owner']);
+            }
+
+            if ($row['permissions'] > 0) {
+                $items[$row['id']] = $row;
+            }
+
+        }
+
+        // group items if we are looking for items shared with the current user
+        if (isset($shareWith) && $shareWith === \OCP\User::getUser()) {
+            $items = self::groupItems($items, $itemType);
+        }
+
+        if (!empty($items)) {
+            $collectionItems = array();
+            foreach ($items as &$row) {
+                // Return only the item instead of a 2-dimensional array
+                if ($limit == 1 && $row[$column] == $item && ($row['item_type'] == $itemType || $itemType == 'file')) {
+                    if ($format == self::FORMAT_NONE) {
+                        return $row;
+                    } else {
+                        break;
+                    }
+                }
+                // Check if this is a collection of the requested item type
+                if ($includeCollections && $collectionTypes && $row['item_type'] !== 'folder' && in_array($row['item_type'], $collectionTypes)) {
+                    if (($collectionBackend = self::getBackend($row['item_type']))
+                        && $collectionBackend instanceof \OCP\Share_Backend_Collection) {
+                        // Collections can be inside collections, check if the item is a collection
+                        if (isset($item) && $row['item_type'] == $itemType && $row[$column] == $item) {
+                            $collectionItems[] = $row;
+                        } else {
+                            $collection = array();
+                            $collection['item_type'] = $row['item_type'];
+                            if ($row['item_type'] == 'file' || $row['item_type'] == 'folder') {
+                                $collection['path'] = basename($row['path']);
+                            }
+                            $row['collection'] = $collection;
+                            // Fetch all of the children sources
+                            $children = $collectionBackend->getChildren($row[$column]);
+                            foreach ($children as $child) {
+                                $childItem = $row;
+                                $childItem['item_type'] = $itemType;
+                                if ($row['item_type'] != 'file' && $row['item_type'] != 'folder') {
+                                    $childItem['item_source'] = $child['source'];
+                                    $childItem['item_target'] = $child['target'];
+                                }
+                                if ($backend instanceof \OCP\Share_Backend_File_Dependent) {
+                                    if ($row['item_type'] == 'file' || $row['item_type'] == 'folder') {
+                                        $childItem['file_source'] = $child['source'];
+                                    } else { // TODO is this really needed if we already know that we use the file backend?
+                                        $meta = \OC\Files\Filesystem::getFileInfo($child['file_path']);
+                                        $childItem['file_source'] = $meta['fileid'];
+                                    }
+                                    $childItem['file_target'] =
+                                        \OC\Files\Filesystem::normalizePath($child['file_path']);
+                                }
+                                if (isset($item)) {
+                                    if ($childItem[$column] == $item) {
+                                        // Return only the item instead of a 2-dimensional array
+                                        if ($limit == 1) {
+                                            if ($format == self::FORMAT_NONE) {
+                                                return $childItem;
+                                            } else {
+                                                // Unset the items array and break out of both loops
+                                                $items = array();
+                                                $items[] = $childItem;
+                                                break 2;
+                                            }
+                                        } else {
+                                            $collectionItems[] = $childItem;
+                                        }
+                                    }
+                                } else {
+                                    $collectionItems[] = $childItem;
+                                }
+                            }
+                        }
+                    }
+                    // Remove collection item
+                    $toRemove = $row['id'];
+                    if (array_key_exists($toRemove, $switchedItems)) {
+                        $toRemove = $switchedItems[$toRemove];
+                    }
+                    unset($items[$toRemove]);
+                } elseif ($includeCollections && $collectionTypes && in_array($row['item_type'], $collectionTypes)) {
+                    // FIXME: Thats a dirty hack to improve file sharing performance,
+                    // see github issue #10588 for more details
+                    // Need to find a solution which works for all back-ends
+                    $collectionBackend = self::getBackend($row['item_type']);
+                    $sharedParents = $collectionBackend->getParents($row['item_source']);
+                    foreach ($sharedParents as $parent) {
+                        $collectionItems[] = $parent;
+                    }
+                }
+            }
+            if (!empty($collectionItems)) {
+                $collectionItems = array_unique($collectionItems, SORT_REGULAR);
+                $items = array_merge($items, $collectionItems);
+            }
+
+            // filter out invalid items, these can appear when subshare entries exist
+            // for a group in which the requested user isn't a member any more
+            $items = array_filter($items, function($item) {
+                return $item['share_type'] !== self::$shareTypeGroupUserUnique;
+            });
+
+            return self::formatResult($items, $column, $backend, $format, $parameters);
+        } elseif ($includeCollections && $collectionTypes && in_array('folder', $collectionTypes)) {
+            // FIXME: Thats a dirty hack to improve file sharing performance,
+            // see github issue #10588 for more details
+            // Need to find a solution which works for all back-ends
+            $collectionItems = array();
+            $collectionBackend = self::getBackend('folder');
+            $sharedParents = $collectionBackend->getParents($item, $shareWith, $uidOwner);
+            foreach ($sharedParents as $parent) {
+                $collectionItems[] = $parent;
+            }
+            if ($limit === 1) {
+                return reset($collectionItems);
+            }
+            return self::formatResult($collectionItems, $column, $backend, $format, $parameters);
+        }
+
+        return array();
+    }
+
+    /**
+     * group items with link to the same source
+     *
+     * @param array $items
+     * @param string $itemType
+     * @return array of grouped items
+     */
+    protected static function groupItems($items, $itemType) {
+
+        $fileSharing = $itemType === 'file' || $itemType === 'folder';
+
+        $result = array();
+
+        foreach ($items as $item) {
+            $grouped = false;
+            foreach ($result as $key => $r) {
+                // for file/folder shares we need to compare file_source, otherwise we compare item_source
+                // only group shares if they already point to the same target, otherwise the file where shared
+                // before grouping of shares was added. In this case we don't group them toi avoid confusions
+                if (( $fileSharing && $item['file_source'] === $r['file_source'] && $item['file_target'] === $r['file_target']) ||
+                    (!$fileSharing && $item['item_source'] === $r['item_source'] && $item['item_target'] === $r['item_target'])) {
+                    // add the first item to the list of grouped shares
+                    if (!isset($result[$key]['grouped'])) {
+                        $result[$key]['grouped'][] = $result[$key];
+                    }
+                    $result[$key]['permissions'] = (int) $item['permissions'] | (int) $r['permissions'];
+                    $result[$key]['grouped'][] = $item;
+                    $grouped = true;
+                    break;
+                }
+            }
+
+            if (!$grouped) {
+                $result[] = $item;
+            }
+
+        }
+
+        return $result;
+    }
+
+    /**
+     * Put shared item into the database
+     * @param string $itemType Item type
+     * @param string $itemSource Item source
+     * @param int $shareType SHARE_TYPE_USER, SHARE_TYPE_GROUP, or SHARE_TYPE_LINK
+     * @param string $shareWith User or group the item is being shared with
+     * @param string $uidOwner User that is the owner of shared item
+     * @param int $permissions CRUDS permissions
+     * @param boolean|array $parentFolder Parent folder target (optional)
+     * @param string $token (optional)
+     * @param string $itemSourceName name of the source item (optional)
+     * @param \DateTime $expirationDate (optional)
+     * @throws \Exception
+     * @return mixed id of the new share or false
+     */
+    private static function put($itemType, $itemSource, $shareType, $shareWith, $uidOwner,
+                                $permissions, $parentFolder = null, $token = null, $itemSourceName = null, \DateTime $expirationDate = null) {
+
+        $queriesToExecute = array();
+        $suggestedItemTarget = null;
+        $groupFileTarget = $fileTarget = $suggestedFileTarget = $filePath = '';
+        $groupItemTarget = $itemTarget = $fileSource = $parent = 0;
+
+        $result = self::checkReshare($itemType, $itemSource, $shareType, $shareWith, $uidOwner, $permissions, $itemSourceName, $expirationDate);
+        if(!empty($result)) {
+            $parent = $result['parent'];
+            $itemSource = $result['itemSource'];
+            $fileSource = $result['fileSource'];
+            $suggestedItemTarget = $result['suggestedItemTarget'];
+            $suggestedFileTarget = $result['suggestedFileTarget'];
+            $filePath = $result['filePath'];
+        }
+
+        $isGroupShare = false;
+        if ($shareType == self::SHARE_TYPE_GROUP) {
+            $isGroupShare = true;
+            if (isset($shareWith['users'])) {
+                $users = $shareWith['users'];
+            } else {
+                $group = \OC::$server->getGroupManager()->get($shareWith['group']);
+                if ($group) {
+                    $users = $group->searchUsers('', -1, 0);
+                    $userIds = [];
+                    foreach ($users as $user) {
+                        $userIds[] = $user->getUID();
+                    }
+                    $users = $userIds;
+                } else {
+                    $users = [];
+                }
+            }
+            // remove current user from list
+            if (in_array(\OCP\User::getUser(), $users)) {
+                unset($users[array_search(\OCP\User::getUser(), $users)]);
+            }
+            $groupItemTarget = Helper::generateTarget($itemType, $itemSource,
+                $shareType, $shareWith['group'], $uidOwner, $suggestedItemTarget);
+            $groupFileTarget = Helper::generateTarget($itemType, $itemSource,
+                $shareType, $shareWith['group'], $uidOwner, $filePath);
+
+            // add group share to table and remember the id as parent
+            $queriesToExecute['groupShare'] = array(
+                'itemType'			=> $itemType,
+                'itemSource'		=> $itemSource,
+                'itemTarget'		=> $groupItemTarget,
+                'shareType'			=> $shareType,
+                'shareWith'			=> $shareWith['group'],
+                'uidOwner'			=> $uidOwner,
+                'permissions'		=> $permissions,
+                'shareTime'			=> time(),
+                'fileSource'		=> $fileSource,
+                'fileTarget'		=> $groupFileTarget,
+                'token'				=> $token,
+                'parent'			=> $parent,
+                'expiration'		=> $expirationDate,
+            );
+
+        } else {
+            $users = array($shareWith);
+            $itemTarget = Helper::generateTarget($itemType, $itemSource, $shareType, $shareWith, $uidOwner,
+                $suggestedItemTarget);
+        }
+
+        $run = true;
+        $error = '';
+        $preHookData = array(
+            'itemType' => $itemType,
+            'itemSource' => $itemSource,
+            'shareType' => $shareType,
+            'uidOwner' => $uidOwner,
+            'permissions' => $permissions,
+            'fileSource' => $fileSource,
+            'expiration' => $expirationDate,
+            'token' => $token,
+            'run' => &$run,
+            'error' => &$error
+        );
+
+        $preHookData['itemTarget'] = $isGroupShare ? $groupItemTarget : $itemTarget;
+        $preHookData['shareWith'] = $isGroupShare ? $shareWith['group'] : $shareWith;
+
+        \OC_Hook::emit(\OCP\Share::class, 'pre_shared', $preHookData);
+
+        if ($run === false) {
+            throw new \Exception($error);
+        }
+
+        foreach ($users as $user) {
+            $sourceId = ($itemType === 'file' || $itemType === 'folder') ? $fileSource : $itemSource;
+            $sourceExists = self::getItemSharedWithBySource($itemType, $sourceId, self::FORMAT_NONE, null, true, $user);
+
+            $userShareType = $isGroupShare ? self::$shareTypeGroupUserUnique : $shareType;
+
+            if ($sourceExists && $sourceExists['item_source'] === $itemSource) {
+                $fileTarget = $sourceExists['file_target'];
+                $itemTarget = $sourceExists['item_target'];
+
+                // for group shares we don't need a additional entry if the target is the same
+                if($isGroupShare && $groupItemTarget === $itemTarget) {
+                    continue;
+                }
+
+            } elseif(!$sourceExists && !$isGroupShare)  {
+
+                $itemTarget = Helper::generateTarget($itemType, $itemSource, $userShareType, $user,
+                    $uidOwner, $suggestedItemTarget, $parent);
+                if (isset($fileSource)) {
+                    if ($parentFolder) {
+                        if ($parentFolder === true) {
+                            $fileTarget = Helper::generateTarget('file', $filePath, $userShareType, $user,
+                                $uidOwner, $suggestedFileTarget, $parent);
+                            if ($fileTarget != $groupFileTarget) {
+                                $parentFolders[$user]['folder'] = $fileTarget;
+                            }
+                        } else if (isset($parentFolder[$user])) {
+                            $fileTarget = $parentFolder[$user]['folder'].$itemSource;
+                            $parent = $parentFolder[$user]['id'];
+                        }
+                    } else {
+                        $fileTarget = Helper::generateTarget('file', $filePath, $userShareType,
+                            $user, $uidOwner, $suggestedFileTarget, $parent);
+                    }
+                } else {
+                    $fileTarget = null;
+                }
+
+            } else {
+
+                // group share which doesn't exists until now, check if we need a unique target for this user
+
+                $itemTarget = Helper::generateTarget($itemType, $itemSource, self::SHARE_TYPE_USER, $user,
+                    $uidOwner, $suggestedItemTarget, $parent);
+
+                // do we also need a file target
+                if (isset($fileSource)) {
+                    $fileTarget = Helper::generateTarget('file', $filePath, self::SHARE_TYPE_USER, $user,
+                        $uidOwner, $suggestedFileTarget, $parent);
+                } else {
+                    $fileTarget = null;
+                }
+
+                if (($itemTarget === $groupItemTarget) &&
+                    (!isset($fileSource) || $fileTarget === $groupFileTarget)) {
+                    continue;
+                }
+            }
+
+            $queriesToExecute[] = array(
+                'itemType'			=> $itemType,
+                'itemSource'		=> $itemSource,
+                'itemTarget'		=> $itemTarget,
+                'shareType'			=> $userShareType,
+                'shareWith'			=> $user,
+                'uidOwner'			=> $uidOwner,
+                'permissions'		=> $permissions,
+                'shareTime'			=> time(),
+                'fileSource'		=> $fileSource,
+                'fileTarget'		=> $fileTarget,
+                'token'				=> $token,
+                'parent'			=> $parent,
+                'expiration'		=> $expirationDate,
+            );
+
+        }
+
+        $id = false;
+        if ($isGroupShare) {
+            $id = self::insertShare($queriesToExecute['groupShare']);
+            // Save this id, any extra rows for this group share will need to reference it
+            $parent = \OC::$server->getDatabaseConnection()->lastInsertId('*PREFIX*share');
+            unset($queriesToExecute['groupShare']);
+        }
+
+        foreach ($queriesToExecute as $shareQuery) {
+            $shareQuery['parent'] = $parent;
+            $id = self::insertShare($shareQuery);
+        }
+
+        $postHookData = array(
+            'itemType' => $itemType,
+            'itemSource' => $itemSource,
+            'parent' => $parent,
+            'shareType' => $shareType,
+            'uidOwner' => $uidOwner,
+            'permissions' => $permissions,
+            'fileSource' => $fileSource,
+            'id' => $parent,
+            'token' => $token,
+            'expirationDate' => $expirationDate,
+        );
+
+        $postHookData['shareWith'] = $isGroupShare ? $shareWith['group'] : $shareWith;
+        $postHookData['itemTarget'] = $isGroupShare ? $groupItemTarget : $itemTarget;
+        $postHookData['fileTarget'] = $isGroupShare ? $groupFileTarget : $fileTarget;
+
+        \OC_Hook::emit(\OCP\Share::class, 'post_shared', $postHookData);
+
+
+        return $id ? $id : false;
+    }
+
+    /**
+     * @param string $itemType
+     * @param string $itemSource
+     * @param int $shareType
+     * @param string $shareWith
+     * @param string $uidOwner
+     * @param int $permissions
+     * @param string|null $itemSourceName
+     * @param null|\DateTime $expirationDate
+     */
+    private static function checkReshare($itemType, $itemSource, $shareType, $shareWith, $uidOwner, $permissions, $itemSourceName, $expirationDate) {
+        $backend = self::getBackend($itemType);
+
+        $l = \OC::$server->getL10N('lib');
+        $result = array();
+
+        $column = ($itemType === 'file' || $itemType === 'folder') ? 'file_source' : 'item_source';
+
+        $checkReshare = self::getItemSharedWithBySource($itemType, $itemSource, self::FORMAT_NONE, null, true);
+        if ($checkReshare) {
+            // Check if attempting to share back to owner
+            if ($checkReshare['uid_owner'] == $shareWith && $shareType == self::SHARE_TYPE_USER) {
+                $message = 'Sharing %s failed, because the user %s is the original sharer';
+                $message_t = $l->t('Sharing failed, because the user %s is the original sharer', [$shareWith]);
+
+                \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $shareWith), \OCP\Util::DEBUG);
+                throw new \Exception($message_t);
+            }
+        }
+
+        if ($checkReshare && $checkReshare['uid_owner'] !== \OC_User::getUser()) {
+            // Check if share permissions is granted
+            if (self::isResharingAllowed() && (int)$checkReshare['permissions'] & \OCP\Constants::PERMISSION_SHARE) {
+                if (~(int)$checkReshare['permissions'] & $permissions) {
+                    $message = 'Sharing %s failed, because the permissions exceed permissions granted to %s';
+                    $message_t = $l->t('Sharing %s failed, because the permissions exceed permissions granted to %s', array($itemSourceName, $uidOwner));
+
+                    \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName, $uidOwner), \OCP\Util::DEBUG);
+                    throw new \Exception($message_t);
+                } else {
+                    // TODO Don't check if inside folder
+                    $result['parent'] = $checkReshare['id'];
+
+                    $result['expirationDate'] = $expirationDate;
+                    // $checkReshare['expiration'] could be null and then is always less than any value
+                    if(isset($checkReshare['expiration']) && $checkReshare['expiration'] < $expirationDate) {
+                        $result['expirationDate'] = $checkReshare['expiration'];
+                    }
+
+                    // only suggest the same name as new target if it is a reshare of the
+                    // same file/folder and not the reshare of a child
+                    if ($checkReshare[$column] === $itemSource) {
+                        $result['filePath'] = $checkReshare['file_target'];
+                        $result['itemSource'] = $checkReshare['item_source'];
+                        $result['fileSource'] = $checkReshare['file_source'];
+                        $result['suggestedItemTarget'] = $checkReshare['item_target'];
+                        $result['suggestedFileTarget'] = $checkReshare['file_target'];
+                    } else {
+                        $result['filePath'] = ($backend instanceof \OCP\Share_Backend_File_Dependent) ? $backend->getFilePath($itemSource, $uidOwner) : null;
+                        $result['suggestedItemTarget'] = null;
+                        $result['suggestedFileTarget'] = null;
+                        $result['itemSource'] = $itemSource;
+                        $result['fileSource'] = ($backend instanceof \OCP\Share_Backend_File_Dependent) ? $itemSource : null;
+                    }
+                }
+            } else {
+                $message = 'Sharing %s failed, because resharing is not allowed';
+                $message_t = $l->t('Sharing %s failed, because resharing is not allowed', array($itemSourceName));
+
+                \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSourceName), \OCP\Util::DEBUG);
+                throw new \Exception($message_t);
+            }
+        } else {
+            $result['parent'] = null;
+            $result['suggestedItemTarget'] = null;
+            $result['suggestedFileTarget'] = null;
+            $result['itemSource'] = $itemSource;
+            $result['expirationDate'] = $expirationDate;
+            if (!$backend->isValidSource($itemSource, $uidOwner)) {
+                $message = 'Sharing %s failed, because the sharing backend for '
+                    .'%s could not find its source';
+                $message_t = $l->t('Sharing %s failed, because the sharing backend for %s could not find its source', array($itemSource, $itemType));
+                \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSource, $itemType), \OCP\Util::DEBUG);
+                throw new \Exception($message_t);
+            }
+            if ($backend instanceof \OCP\Share_Backend_File_Dependent) {
+                $result['filePath'] = $backend->getFilePath($itemSource, $uidOwner);
+                if ($itemType == 'file' || $itemType == 'folder') {
+                    $result['fileSource'] = $itemSource;
+                } else {
+                    $meta = \OC\Files\Filesystem::getFileInfo($result['filePath']);
+                    $result['fileSource'] = $meta['fileid'];
+                }
+                if ($result['fileSource'] == -1) {
+                    $message = 'Sharing %s failed, because the file could not be found in the file cache';
+                    $message_t = $l->t('Sharing %s failed, because the file could not be found in the file cache', array($itemSource));
+
+                    \OCP\Util::writeLog('OCP\Share', sprintf($message, $itemSource), \OCP\Util::DEBUG);
+                    throw new \Exception($message_t);
+                }
+            } else {
+                $result['filePath'] = null;
+                $result['fileSource'] = null;
+            }
+        }
+
+        return $result;
+    }
+
+    /**
+     *
+     * @param array $shareData
+     * @return mixed false in case of a failure or the id of the new share
+     */
+    private static function insertShare(array $shareData) {
+
+        $query = \OC_DB::prepare('INSERT INTO `*PREFIX*share` ('
+            .' `item_type`, `item_source`, `item_target`, `share_type`,'
+            .' `share_with`, `uid_owner`, `permissions`, `stime`, `file_source`,'
+            .' `file_target`, `token`, `parent`, `expiration`) VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?)');
+        $query->bindValue(1, $shareData['itemType']);
+        $query->bindValue(2, $shareData['itemSource']);
+        $query->bindValue(3, $shareData['itemTarget']);
+        $query->bindValue(4, $shareData['shareType']);
+        $query->bindValue(5, $shareData['shareWith']);
+        $query->bindValue(6, $shareData['uidOwner']);
+        $query->bindValue(7, $shareData['permissions']);
+        $query->bindValue(8, $shareData['shareTime']);
+        $query->bindValue(9, $shareData['fileSource']);
+        $query->bindValue(10, $shareData['fileTarget']);
+        $query->bindValue(11, $shareData['token']);
+        $query->bindValue(12, $shareData['parent']);
+        $query->bindValue(13, $shareData['expiration'], 'datetime');
+        $result = $query->execute();
+
+        $id = false;
+        if ($result) {
+            $id =  \OC::$server->getDatabaseConnection()->lastInsertId('*PREFIX*share');
+        }
+
+        return $id;
+
+    }
+
+    /**
+     * In case a password protected link is not yet authenticated this function will return false
+     *
+     * @param array $linkItem
+     * @return boolean
+     */
+    public static function checkPasswordProtectedShare(array $linkItem) {
+        if (!isset($linkItem['share_with'])) {
+            return true;
+        }
+        if (!isset($linkItem['share_type'])) {
+            return true;
+        }
+        if (!isset($linkItem['id'])) {
+            return true;
+        }
+
+        if ($linkItem['share_type'] != \OCP\Share::SHARE_TYPE_LINK) {
+            return true;
+        }
+
+        if ( \OC::$server->getSession()->exists('public_link_authenticated')
+            && \OC::$server->getSession()->get('public_link_authenticated') === (string)$linkItem['id'] ) {
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * construct select statement
+     * @param int $format
+     * @param boolean $fileDependent ist it a file/folder share or a generla share
+     * @param string $uidOwner
+     * @return string select statement
+     */
+    private static function createSelectStatement($format, $fileDependent, $uidOwner = null) {
+        $select = '*';
+        if ($format == self::FORMAT_STATUSES) {
+            if ($fileDependent) {
+                $select = '`*PREFIX*share`.`id`, `*PREFIX*share`.`parent`, `share_type`, `path`, `storage`, '
+                    . '`share_with`, `uid_owner` , `file_source`, `stime`, `*PREFIX*share`.`permissions`, '
+                    . '`*PREFIX*storages`.`id` AS `storage_id`, `*PREFIX*filecache`.`parent` as `file_parent`, '
+                    . '`uid_initiator`';
+            } else {
+                $select = '`id`, `parent`, `share_type`, `share_with`, `uid_owner`, `item_source`, `stime`, `*PREFIX*share`.`permissions`';
+            }
+        } else {
+            if (isset($uidOwner)) {
+                if ($fileDependent) {
+                    $select = '`*PREFIX*share`.`id`, `item_type`, `item_source`, `*PREFIX*share`.`parent`,'
+                        . ' `share_type`, `share_with`, `file_source`, `file_target`, `path`, `*PREFIX*share`.`permissions`, `stime`,'
+                        . ' `expiration`, `token`, `storage`, `mail_send`, `uid_owner`, '
+                        . '`*PREFIX*storages`.`id` AS `storage_id`, `*PREFIX*filecache`.`parent` as `file_parent`';
+                } else {
+                    $select = '`id`, `item_type`, `item_source`, `parent`, `share_type`, `share_with`, `*PREFIX*share`.`permissions`,'
+                        . ' `stime`, `file_source`, `expiration`, `token`, `mail_send`, `uid_owner`';
+                }
+            } else {
+                if ($fileDependent) {
+                    if ($format == \OCA\Files_Sharing\ShareBackend\File::FORMAT_GET_FOLDER_CONTENTS || $format == \OCA\Files_Sharing\ShareBackend\File::FORMAT_FILE_APP_ROOT) {
+                        $select = '`*PREFIX*share`.`id`, `item_type`, `item_source`, `*PREFIX*share`.`parent`, `uid_owner`, '
+                            . '`share_type`, `share_with`, `file_source`, `path`, `file_target`, `stime`, '
+                            . '`*PREFIX*share`.`permissions`, `expiration`, `storage`, `*PREFIX*filecache`.`parent` as `file_parent`, '
+                            . '`name`, `mtime`, `mimetype`, `mimepart`, `size`, `encrypted`, `etag`, `mail_send`';
+                    } else {
+                        $select = '`*PREFIX*share`.`id`, `item_type`, `item_source`, `item_target`,'
+                            . '`*PREFIX*share`.`parent`, `share_type`, `share_with`, `uid_owner`,'
+                            . '`file_source`, `path`, `file_target`, `*PREFIX*share`.`permissions`,'
+                            . '`stime`, `expiration`, `token`, `storage`, `mail_send`,'
+                            . '`*PREFIX*storages`.`id` AS `storage_id`, `*PREFIX*filecache`.`parent` as `file_parent`';
+                    }
+                }
+            }
+        }
+        return $select;
+    }
+
+
+    /**
+     * transform db results
+     * @param array $row result
+     */
+    private static function transformDBResults(&$row) {
+        if (isset($row['id'])) {
+            $row['id'] = (int) $row['id'];
+        }
+        if (isset($row['share_type'])) {
+            $row['share_type'] = (int) $row['share_type'];
+        }
+        if (isset($row['parent'])) {
+            $row['parent'] = (int) $row['parent'];
+        }
+        if (isset($row['file_parent'])) {
+            $row['file_parent'] = (int) $row['file_parent'];
+        }
+        if (isset($row['file_source'])) {
+            $row['file_source'] = (int) $row['file_source'];
+        }
+        if (isset($row['permissions'])) {
+            $row['permissions'] = (int) $row['permissions'];
+        }
+        if (isset($row['storage'])) {
+            $row['storage'] = (int) $row['storage'];
+        }
+        if (isset($row['stime'])) {
+            $row['stime'] = (int) $row['stime'];
+        }
+        if (isset($row['expiration']) && $row['share_type'] !== self::SHARE_TYPE_LINK) {
+            // discard expiration date for non-link shares, which might have been
+            // set by ancient bugs
+            $row['expiration'] = null;
+        }
+    }
+
+    /**
+     * format result
+     * @param array $items result
+     * @param string $column is it a file share or a general share ('file_target' or 'item_target')
+     * @param \OCP\Share_Backend $backend sharing backend
+     * @param int $format
+     * @param array $parameters additional format parameters
+     * @return array format result
+     */
+    private static function formatResult($items, $column, $backend, $format = self::FORMAT_NONE , $parameters = null) {
+        if ($format === self::FORMAT_NONE) {
+            return $items;
+        } else if ($format === self::FORMAT_STATUSES) {
+            $statuses = array();
+            foreach ($items as $item) {
+                if ($item['share_type'] === self::SHARE_TYPE_LINK) {
+                    if ($item['uid_initiator'] !== \OC::$server->getUserSession()->getUser()->getUID()) {
+                        continue;
+                    }
+                    $statuses[$item[$column]]['link'] = true;
+                } else if (!isset($statuses[$item[$column]])) {
+                    $statuses[$item[$column]]['link'] = false;
+                }
+                if (!empty($item['file_target'])) {
+                    $statuses[$item[$column]]['path'] = $item['path'];
+                }
+            }
+            return $statuses;
+        } else {
+            return $backend->formatItems($items, $format, $parameters);
+        }
+    }
+
+    /**
+     * remove protocol from URL
+     *
+     * @param string $url
+     * @return string
+     */
+    public static function removeProtocolFromUrl($url) {
+        if (strpos($url, 'https://') === 0) {
+            return substr($url, strlen('https://'));
+        } else if (strpos($url, 'http://') === 0) {
+            return substr($url, strlen('http://'));
+        }
+
+        return $url;
+    }
+
+    /**
+     * try http post first with https and then with http as a fallback
+     *
+     * @param string $remoteDomain
+     * @param string $urlSuffix
+     * @param array $fields post parameters
+     * @return array
+     */
+    private static function tryHttpPostToShareEndpoint($remoteDomain, $urlSuffix, array $fields) {
+        $protocol = 'https://';
+        $result = [
+            'success' => false,
+            'result' => '',
+        ];
+        $try = 0;
+        $discoveryService = \OC::$server->query(\OCP\OCS\IDiscoveryService::class);
+        while ($result['success'] === false && $try < 2) {
+            $federationEndpoints = $discoveryService->discover($protocol . $remoteDomain, 'FEDERATED_SHARING');
+            $endpoint = isset($federationEndpoints['share']) ? $federationEndpoints['share'] : '/ocs/v2.php/cloud/shares';
+            $client = \OC::$server->getHTTPClientService()->newClient();
+
+            try {
+                $response = $client->post(
+                    $protocol . $remoteDomain . $endpoint . $urlSuffix . '?format=' . self::RESPONSE_FORMAT,
+                    [
+                        'body' => $fields,
+                        'connect_timeout' => 10,
+                    ]
+                );
+
+                $result = ['success' => true, 'result' => $response->getBody()];
+            } catch (\Exception $e) {
+                $result = ['success' => false, 'result' => $e->getMessage()];
+            }
+
+            $try++;
+            $protocol = 'http://';
+        }
+
+        return $result;
+    }
+
+    /**
+     * send server-to-server share to remote server
+     *
+     * @param string $token
+     * @param string $shareWith
+     * @param string $name
+     * @param int $remote_id
+     * @param string $owner
+     * @return bool
+     */
+    private static function sendRemoteShare($token, $shareWith, $name, $remote_id, $owner) {
+
+        list($user, $remote) = Helper::splitUserRemote($shareWith);
+
+        if ($user && $remote) {
+            $url = $remote;
+
+            $local = \OC::$server->getURLGenerator()->getAbsoluteURL('/');
+
+            $fields = array(
+                'shareWith' => $user,
+                'token' => $token,
+                'name' => $name,
+                'remoteId' => $remote_id,
+                'owner' => $owner,
+                'remote' => $local,
+            );
+
+            $url = self::removeProtocolFromUrl($url);
+            $result = self::tryHttpPostToShareEndpoint($url, '', $fields);
+            $status = json_decode($result['result'], true);
+
+            if ($result['success'] && ($status['ocs']['meta']['statuscode'] === 100 || $status['ocs']['meta']['statuscode'] === 200)) {
+                \OC_Hook::emit(\OCP\Share::class, 'federated_share_added', ['server' => $remote]);
+                return true;
+            }
+
+        }
+
+        return false;
+    }
+
+    /**
+     * send server-to-server unshare to remote server
+     *
+     * @param string $remote url
+     * @param int $id share id
+     * @param string $token
+     * @return bool
+     */
+    private static function sendRemoteUnshare($remote, $id, $token) {
+        $url = rtrim($remote, '/');
+        $fields = array('token' => $token, 'format' => 'json');
+        $url = self::removeProtocolFromUrl($url);
+        $result = self::tryHttpPostToShareEndpoint($url, '/'.$id.'/unshare', $fields);
+        $status = json_decode($result['result'], true);
+
+        return ($result['success'] && ($status['ocs']['meta']['statuscode'] === 100 || $status['ocs']['meta']['statuscode'] === 200));
+    }
+
+    /**
+     * check if user can only share with group members
+     * @return bool
+     */
+    public static function shareWithGroupMembersOnly() {
+        $value = \OC::$server->getConfig()->getAppValue('core', 'shareapi_only_share_with_group_members', 'no');
+        return $value === 'yes';
+    }
+
+    /**
+     * @return bool
+     */
+    public static function isDefaultExpireDateEnabled() {
+        $defaultExpireDateEnabled = \OC::$server->getConfig()->getAppValue('core', 'shareapi_default_expire_date', 'no');
+        return $defaultExpireDateEnabled === 'yes';
+    }
+
+    /**
+     * @return int
+     */
+    public static function getExpireInterval() {
+        return (int)\OC::$server->getConfig()->getAppValue('core', 'shareapi_expire_after_n_days', '7');
+    }
+
+    /**
+     * Checks whether the given path is reachable for the given owner
+     *
+     * @param string $path path relative to files
+     * @param string $ownerStorageId storage id of the owner
+     *
+     * @return boolean true if file is reachable, false otherwise
+     */
+    private static function isFileReachable($path, $ownerStorageId) {
+        // if outside the home storage, file is always considered reachable
+        if (!(substr($ownerStorageId, 0, 6) === 'home::' ||
+            substr($ownerStorageId, 0, 13) === 'object::user:'
+        )) {
+            return true;
+        }
+
+        // if inside the home storage, the file has to be under "/files/"
+        $path = ltrim($path, '/');
+        if (substr($path, 0, 6) === 'files/') {
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * @param IConfig $config
+     * @return bool
+     */
+    public static function enforcePassword(IConfig $config) {
+        $enforcePassword = $config->getAppValue('core', 'shareapi_enforce_links_password', 'no');
+        return $enforcePassword === 'yes';
+    }
+
+    /**
+     * @param string $password
+     * @throws \Exception
+     */
+    private static function verifyPassword($password) {
+
+        $accepted = true;
+        $message = '';
+        \OCP\Util::emitHook('\OC\Share', 'verifyPassword', [
+            'password' => $password,
+            'accepted' => &$accepted,
+            'message' => &$message
+        ]);
+
+        if (!$accepted) {
+            throw new \Exception($message);
+        }
+    }
 }