nextcloud/apps/files_trashbin/lib/trash.php

<?php
/**
 * ownCloud - trash bin
 *
 * @author Bjoern Schiessle
 * @copyright 2013 Bjoern Schiessle schiessle@owncloud.com
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU AFFERO GENERAL PUBLIC LICENSE for more details.
 *
 * You should have received a copy of the GNU Affero General Public
 * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

namespace OCA\Files_Trashbin;

class Trashbin {
	// how long do we keep files in the trash bin if no other value is defined in the config file (unit: days)

	const DEFAULT_RETENTION_OBLIGATION = 180;

	// unit: percentage; 50% of available disk space/quota
	const DEFAULTMAXSIZE = 50;

	public static function getUidAndFilename($filename) {
		$uid = \OC\Files\Filesystem::getOwner($filename);
		\OC\Files\Filesystem::initMountPoints($uid);
		if ($uid != \OCP\User::getUser()) {
			$info = \OC\Files\Filesystem::getFileInfo($filename);
			$ownerView = new \OC\Files\View('/' . $uid . '/files');
			$filename = $ownerView->getPath($info['fileid']);
		}
		return array($uid, $filename);
	}

	/**
	 * move file to the trash bin
	 *
	 * @param $file_path path to the deleted file/directory relative to the files root directory
	 */
	public static function move2trash($file_path) {
		$user = \OCP\User::getUser();
		$view = new \OC\Files\View('/' . $user);
		if (!$view->is_dir('files_trashbin')) {
			$view->mkdir('files_trashbin');
		}
		if (!$view->is_dir('files_trashbin/files')) {
			$view->mkdir('files_trashbin/files');
		}
		if (!$view->is_dir('files_trashbin/versions')) {
			$view->mkdir('files_trashbin/versions');
		}
		if (!$view->is_dir('files_trashbin/keyfiles')) {
			$view->mkdir('files_trashbin/keyfiles');
		}
		if (!$view->is_dir('files_trashbin/share-keys')) {
			$view->mkdir('files_trashbin/share-keys');
		}
		$path_parts = pathinfo($file_path);

		$filename = $path_parts['basename'];
		$location = $path_parts['dirname'];
		$timestamp = time();
		$mime = $view->getMimeType('files' . $file_path);

		if ($view->is_dir('files' . $file_path)) {
			$type = 'dir';
		} else {
			$type = 'file';
		}

		$trashbinSize = self::getTrashbinSize($user);
		if ($trashbinSize === false || $trashbinSize < 0) {
			$trashbinSize = self::calculateSize(new \OC\Files\View('/' . $user . '/files_trashbin'));
		}

		// disable proxy to prevent recursive calls
		$proxyStatus = \OC_FileProxy::$enabled;
		\OC_FileProxy::$enabled = false;
		$sizeOfAddedFiles = self::copy_recursive($file_path, 'files_trashbin/files/' . $filename . '.d' . $timestamp, $view);
		\OC_FileProxy::$enabled = $proxyStatus;

		if ($view->file_exists('files_trashbin/files/' . $filename . '.d' . $timestamp)) {
			$trashbinSize += $sizeOfAddedFiles;
			$query = \OC_DB::prepare("INSERT INTO `*PREFIX*files_trash` (`id`,`timestamp`,`location`,`type`,`mime`,`user`) VALUES (?,?,?,?,?,?)");
			$result = $query->execute(array($filename, $timestamp, $location, $type, $mime, $user));
			if (!$result) { // if file couldn't be added to the database than also don't store it in the trash bin.
				$view->deleteAll('files_trashbin/files/' . $filename . '.d' . $timestamp);
				\OC_Log::write('files_trashbin', 'trash bin database couldn\'t be updated', \OC_log::ERROR);
				return;
			}
			\OCP\Util::emitHook('\OCA\Files_Trashbin\Trashbin', 'post_moveToTrash', array('filePath' => \OC\Files\Filesystem::normalizePath($file_path),
				'trashPath' => \OC\Files\Filesystem::normalizePath($filename . '.d' . $timestamp)));

			$trashbinSize += self::retainVersions($view, $file_path, $filename, $timestamp);
			$trashbinSize += self::retainEncryptionKeys($view, $file_path, $filename, $timestamp);
		} else {
			\OC_Log::write('files_trashbin', 'Couldn\'t move ' . $file_path . ' to the trash bin', \OC_log::ERROR);
		}

		$trashbinSize -= self::expire($trashbinSize);

		self::setTrashbinSize($user, $trashbinSize);
	}

	/**
	 * Move file versions to trash so that they can be restored later
	 *
	 * @param \OC\Files\View $view
	 * @param $file_path path to original file
	 * @param $filename of deleted file
	 * @param $timestamp when the file was deleted
	 *
	 * @return size of stored versions
	 */
	private static function retainVersions($view, $file_path, $filename, $timestamp) {
		$size = 0;
		if (\OCP\App::isEnabled('files_versions')) {

			// disable proxy to prevent recursive calls
			$proxyStatus = \OC_FileProxy::$enabled;
			\OC_FileProxy::$enabled = false;

			$user = \OCP\User::getUser();
			$rootView = new \OC\Files\View('/');

			list($owner, $ownerPath) = self::getUidAndFilename($file_path);

			if ($rootView->is_dir($owner . '/files_versions/' . $ownerPath)) {
				$size += self::calculateSize(new \OC\Files\View('/' . $owner . '/files_versions/' . $ownerPath));
				$rootView->rename($owner . '/files_versions/' . $ownerPath, $user . '/files_trashbin/versions/' . $filename . '.d' . $timestamp);
			} else if ($versions = \OCA\Files_Versions\Storage::getVersions($owner, $ownerPath)) {
				foreach ($versions as $v) {
					$size += $rootView->filesize($owner . '/files_versions' . $v['path'] . '.v' . $v['version']);
					$rootView->rename($owner . '/files_versions' . $v['path'] . '.v' . $v['version'], $user . '/files_trashbin/versions/' . $filename . '.v' . $v['version'] . '.d' . $timestamp);
				}
			}

			// enable proxy
			\OC_FileProxy::$enabled = $proxyStatus;
		}

		return $size;
	}

	/**
	 * Move encryption keys to trash so that they can be restored later
	 *
	 * @param \OC\Files\View $view
	 * @param $file_path path to original file
	 * @param $filename of deleted file
	 * @param $timestamp when the file was deleted
	 *
	 * @return size of encryption keys
	 */
	private static function retainEncryptionKeys($view, $file_path, $filename, $timestamp) {
		$size = 0;

		if (\OCP\App::isEnabled('files_encryption')) {

			$user = \OCP\User::getUser();
			$rootView = new \OC\Files\View('/');

			list($owner, $ownerPath) = self::getUidAndFilename($file_path);


			// disable proxy to prevent recursive calls
			$proxyStatus = \OC_FileProxy::$enabled;
			\OC_FileProxy::$enabled = false;

			// retain key files
			$keyfile = \OC\Files\Filesystem::normalizePath($owner . '/files_encryption/keyfiles/' . $ownerPath);

			if ($rootView->is_dir($keyfile) || $rootView->file_exists($keyfile . '.key')) {
				// move keyfiles
				if ($rootView->is_dir($keyfile)) {
					$size += self::calculateSize(new \OC\Files\View($keyfile));
					$rootView->rename($keyfile, $user . '/files_trashbin/keyfiles/' . $filename . '.d' . $timestamp);
				} else {
					$size += $rootView->filesize($keyfile . '.key');
					$rootView->rename($keyfile . '.key', $user . '/files_trashbin/keyfiles/' . $filename . '.key.d' . $timestamp);
				}
			}

			// retain share keys
			$sharekeys = \OC\Files\Filesystem::normalizePath($owner . '/files_encryption/share-keys/' . $ownerPath);

			if ($rootView->is_dir($sharekeys)) {
				$size += self::calculateSize(new \OC\Files\View($sharekeys));
				$rootView->rename($sharekeys, $user . '/files_trashbin/share-keys/' . $filename . '.d' . $timestamp);
			} else {
				// get local path to share-keys
				$localShareKeysPath = $rootView->getLocalFile($sharekeys);
				$escapedLocalShareKeysPath = preg_replace('/(\*|\?|\[)/', '[$1]', $localShareKeysPath);

				// handle share-keys
				$matches = glob($escapedLocalShareKeysPath . '*.shareKey');
				foreach ($matches as $src) {
					// get source file parts
					$pathinfo = pathinfo($src);

					// we only want to keep the owners key so we can access the private key
					$ownerShareKey = $filename . '.' . $user . '.shareKey';

					// if we found the share-key for the owner, we need to move it to files_trashbin
					if ($pathinfo['basename'] == $ownerShareKey) {

						// calculate size
						$size += $rootView->filesize($sharekeys . '.' . $user . '.shareKey');

						// move file
						$rootView->rename($sharekeys . '.' . $user . '.shareKey', $user . '/files_trashbin/share-keys/' . $ownerShareKey . '.d' . $timestamp);
					} else {

						// calculate size
						$size += filesize($src);

						// don't keep other share-keys
						unlink($src);
					}
				}
			}

			// enable proxy
			\OC_FileProxy::$enabled = $proxyStatus;
		}
		return $size;
	}

	/**
	 * restore files from trash bin
	 * @param $file path to the deleted file
	 * @param $filename name of the file
	 * @param $timestamp time when the file was deleted
	 *
	 * @return bool
	 */
	public static function restore($file, $filename, $timestamp) {

		$user = \OCP\User::getUser();
		$view = new \OC\Files\View('/' . $user);

		$trashbinSize = self::getTrashbinSize($user);
		if ($trashbinSize === false || $trashbinSize < 0) {
			$trashbinSize = self::calculateSize(new \OC\Files\View('/' . $user . '/files_trashbin'));
		}
		if ($timestamp) {
			$query = \OC_DB::prepare('SELECT `location`,`type` FROM `*PREFIX*files_trash`'
					. ' WHERE `user`=? AND `id`=? AND `timestamp`=?');
			$result = $query->execute(array($user, $filename, $timestamp))->fetchAll();
			if (count($result) != 1) {
				\OC_Log::write('files_trashbin', 'trash bin database inconsistent!', \OC_Log::ERROR);
				return false;
			}

			// if location no longer exists, restore file in the root directory
			$location = $result[0]['location'];
			if ($result[0]['location'] != '/' &&
				(!$view->is_dir('files' . $result[0]['location']) ||
				!$view->isUpdatable('files' . $result[0]['location']))) {
				$location = '';
			}
		} else {
			$path_parts = pathinfo($file);
			$result[] = array(
				'location' => $path_parts['dirname'],
				'type' => $view->is_dir('/files_trashbin/files/' . $file) ? 'dir' : 'files',
			);
			$location = '';
		}

		$source = \OC\Files\Filesystem::normalizePath('files_trashbin/files/' . $file);
		$target = \OC\Files\Filesystem::normalizePath('files/' . $location . '/' . $filename);

		// we need a  extension in case a file/dir with the same name already exists
		$ext = self::getUniqueExtension($location, $filename, $view);
		$mtime = $view->filemtime($source);

		// disable proxy to prevent recursive calls
		$proxyStatus = \OC_FileProxy::$enabled;
		\OC_FileProxy::$enabled = false;

		// restore file
		$restoreResult = $view->rename($source, $target . $ext);

		// handle the restore result
		if ($restoreResult) {
			$fakeRoot = $view->getRoot();
			$view->chroot('/' . $user . '/files');
			$view->touch('/' . $location . '/' . $filename . $ext, $mtime);
			$view->chroot($fakeRoot);
			\OCP\Util::emitHook('\OCA\Files_Trashbin\Trashbin', 'post_restore', array('filePath' => \OC\Files\Filesystem::normalizePath('/' . $location . '/' . $filename . $ext),
				'trashPath' => \OC\Files\Filesystem::normalizePath($file)));
			if ($view->is_dir($target . $ext)) {
				$trashbinSize -= self::calculateSize(new \OC\Files\View('/' . $user . '/' . $target . $ext));
			} else {
				$trashbinSize -= $view->filesize($target . $ext);
			}

			$trashbinSize -= self::restoreVersions($view, $file, $filename, $ext, $location, $timestamp);
			$trashbinSize -= self::restoreEncryptionKeys($view, $file, $filename, $ext, $location, $timestamp);

			if ($timestamp) {
				$query = \OC_DB::prepare('DELETE FROM `*PREFIX*files_trash` WHERE `user`=? AND `id`=? AND `timestamp`=?');
				$query->execute(array($user, $filename, $timestamp));
			}

			self::setTrashbinSize($user, $trashbinSize);

			// enable proxy
			\OC_FileProxy::$enabled = $proxyStatus;

			return true;
		}

		// enable proxy
		\OC_FileProxy::$enabled = $proxyStatus;

		return false;
	}

	/**
	 * @brief restore versions from trash bin
	 *
	 * @param \OC\Files\View $view file view
	 * @param $file complete path to file
	 * @param $filename name of file
	 * @param $ext file extension in case a file with the same $filename already exists
	 * @param $location location if file
	 * @param $timestamp deleteion time
	 *
	 * @return size of restored versions
	 */
	private static function restoreVersions($view, $file, $filename, $ext, $location, $timestamp) {
		$size = 0;
		if (\OCP\App::isEnabled('files_versions')) {
			// disable proxy to prevent recursive calls
			$proxyStatus = \OC_FileProxy::$enabled;
			\OC_FileProxy::$enabled = false;

			$user = \OCP\User::getUser();
			$rootView = new \OC\Files\View('/');

			$target = \OC\Files\Filesystem::normalizePath('/' . $location . '/' . $filename . $ext);

			list($owner, $ownerPath) = self::getUidAndFilename($target);

			if ($timestamp) {
				$versionedFile = $filename;
			} else {
				$versionedFile = $file;
			}

			if ($view->is_dir('/files_trashbin/versions/' . $file)) {
				$size += self::calculateSize(new \OC\Files\View('/' . $user . '/' . 'files_trashbin/versions/' . $file));
				$rootView->rename(\OC\Files\Filesystem::normalizePath($user . '/files_trashbin/versions/' . $file), \OC\Files\Filesystem::normalizePath($owner . '/files_versions/' . $ownerPath));
			} else if ($versions = self::getVersionsFromTrash($versionedFile, $timestamp)) {
				foreach ($versions as $v) {
					if ($timestamp) {
						$size += $view->filesize('files_trashbin/versions/' . $versionedFile . '.v' . $v . '.d' . $timestamp);
						$rootView->rename($user . '/files_trashbin/versions/' . $versionedFile . '.v' . $v . '.d' . $timestamp, $owner . '/files_versions/' . $ownerPath . '.v' . $v);
					} else {
						$size += $view->filesize('files_trashbin/versions/' . $versionedFile . '.v' . $v);
						$rootView->rename($user . '/files_trashbin/versions/' . $versionedFile . '.v' . $v, $owner . '/files_versions/' . $ownerPath . '.v' . $v);
					}
				}
			}

			// enable proxy
			\OC_FileProxy::$enabled = $proxyStatus;
		}
		return $size;
	}

	/**
	 * @brief restore encryption keys from trash bin
	 *
	 * @param \OC\Files\View $view
	 * @param $file complete path to file
	 * @param $filename name of file
	 * @param $ext file extension in case a file with the same $filename already exists
	 * @param $location location of file
	 * @param $timestamp deleteion time
	 *
	 * @return size of restored encrypted file
	 */
	private static function restoreEncryptionKeys($view, $file, $filename, $ext, $location, $timestamp) {
		// Take care of encryption keys TODO! Get '.key' in file between file name and delete date (also for permanent delete!)
		$size = 0;
		if (\OCP\App::isEnabled('files_encryption')) {
			$user = \OCP\User::getUser();
			$rootView = new \OC\Files\View('/');

			$target = \OC\Files\Filesystem::normalizePath('/' . $location . '/' . $filename . $ext);

			list($owner, $ownerPath) = self::getUidAndFilename($target);

			$path_parts = pathinfo($file);
			$source_location = $path_parts['dirname'];

			if ($view->is_dir('/files_trashbin/keyfiles/' . $file)) {
				if ($source_location != '.') {
					$keyfile = \OC\Files\Filesystem::normalizePath($user . '/files_trashbin/keyfiles/' . $source_location . '/' . $filename);
					$sharekey = \OC\Files\Filesystem::normalizePath($user . '/files_trashbin/share-keys/' . $source_location . '/' . $filename);
				} else {
					$keyfile = \OC\Files\Filesystem::normalizePath($user . '/files_trashbin/keyfiles/' . $filename);
					$sharekey = \OC\Files\Filesystem::normalizePath($user . '/files_trashbin/share-keys/' . $filename);
				}
			} else {
				$keyfile = \OC\Files\Filesystem::normalizePath($user . '/files_trashbin/keyfiles/' . $source_location . '/' . $filename . '.key');
			}

			if ($timestamp) {
				$keyfile .= '.d' . $timestamp;
			}

			// disable proxy to prevent recursive calls
			$proxyStatus = \OC_FileProxy::$enabled;
			\OC_FileProxy::$enabled = false;

			if ($rootView->file_exists($keyfile)) {
				// handle directory
				if ($rootView->is_dir($keyfile)) {

					// handle keyfiles
					$size += self::calculateSize(new \OC\Files\View($keyfile));
					$rootView->rename($keyfile, $owner . '/files_encryption/keyfiles/' . $ownerPath);

					// handle share-keys
					if ($timestamp) {
						$sharekey .= '.d' . $timestamp;
					}
					$size += self::calculateSize(new \OC\Files\View($sharekey));
					$rootView->rename($sharekey, $owner . '/files_encryption/share-keys/' . $ownerPath);
				} else {
					// handle keyfiles
					$size += $rootView->filesize($keyfile);
					$rootView->rename($keyfile, $owner . '/files_encryption/keyfiles/' . $ownerPath . '.key');

					// handle share-keys
					$ownerShareKey = \OC\Files\Filesystem::normalizePath($user . '/files_trashbin/share-keys/' . $source_location . '/' . $filename . '.' . $user . '.shareKey');
					if ($timestamp) {
						$ownerShareKey .= '.d' . $timestamp;
					}

					$size += $rootView->filesize($ownerShareKey);

					// move only owners key
					$rootView->rename($ownerShareKey, $owner . '/files_encryption/share-keys/' . $ownerPath . '.' . $user . '.shareKey');

					// try to re-share if file is shared
					$filesystemView = new \OC_FilesystemView('/');
					$session = new \OCA\Encryption\Session($filesystemView);
					$util = new \OCA\Encryption\Util($filesystemView, $user);

					// fix the file size
					$absolutePath = \OC\Files\Filesystem::normalizePath('/' . $owner . '/files/' . $ownerPath);
					$util->fixFileSize($absolutePath);

					// get current sharing state
					$sharingEnabled = \OCP\Share::isEnabled();

					// get the final filename
					$target = \OC\Files\Filesystem::normalizePath($location . '/' . $filename);

					// get users sharing this file
					$usersSharing = $util->getSharingUsersArray($sharingEnabled, $target . $ext, $user);

					// Attempt to set shareKey
					$util->setSharedFileKeyfiles($session, $usersSharing, $target . $ext);
				}
			}

			// enable proxy
			\OC_FileProxy::$enabled = $proxyStatus;
		}
		return $size;
	}

	/**
	 * @brief delete file from trash bin permanently
	 *
	 * @param $filename path to the file
	 * @param $timestamp of deletion time
	 *
	 * @return size of deleted files
	 */
	public static function delete($filename, $timestamp = null) {
		$user = \OCP\User::getUser();
		$view = new \OC\Files\View('/' . $user);
		$size = 0;

		$trashbinSize = self::getTrashbinSize($user);
		if ($trashbinSize === false || $trashbinSize < 0) {
			$trashbinSize = self::calculateSize(new \OC\Files\View('/' . $user . '/files_trashbin'));
		}

		if ($timestamp) {
			$query = \OC_DB::prepare('DELETE FROM `*PREFIX*files_trash` WHERE `user`=? AND `id`=? AND `timestamp`=?');
			$query->execute(array($user, $filename, $timestamp));
			$file = $filename . '.d' . $timestamp;
		} else {
			$file = $filename;
		}

		$size += self::deleteVersions($view, $file, $filename, $timestamp);
		$size += self::deleteEncryptionKeys($view, $file, $filename, $timestamp);

		if ($view->is_dir('/files_trashbin/files/' . $file)) {
			$size += self::calculateSize(new \OC\Files\View('/' . $user . '/files_trashbin/files/' . $file));
		} else {
			$size += $view->filesize('/files_trashbin/files/' . $file);
		}
		$view->unlink('/files_trashbin/files/' . $file);
		$trashbinSize -= $size;
		self::setTrashbinSize($user, $trashbinSize);

		return $size;
	}

	private static function deleteVersions($view, $file, $filename, $timestamp) {
		$size = 0;
		if (\OCP\App::isEnabled('files_versions')) {
			$user = \OCP\User::getUser();
			if ($view->is_dir('files_trashbin/versions/' . $file)) {
				$size += self::calculateSize(new \OC\Files\view('/' . $user . '/files_trashbin/versions/' . $file));
				$view->unlink('files_trashbin/versions/' . $file);
			} else if ($versions = self::getVersionsFromTrash($filename, $timestamp)) {
				foreach ($versions as $v) {
					if ($timestamp) {
						$size += $view->filesize('/files_trashbin/versions/' . $filename . '.v' . $v . '.d' . $timestamp);
						$view->unlink('/files_trashbin/versions/' . $filename . '.v' . $v . '.d' . $timestamp);
					} else {
						$size += $view->filesize('/files_trashbin/versions/' . $filename . '.v' . $v);
						$view->unlink('/files_trashbin/versions/' . $filename . '.v' . $v);
					}
				}
			}
		}
		return $size;
	}

	private static function deleteEncryptionKeys($view, $file, $filename, $timestamp) {
		$size = 0;
		if (\OCP\App::isEnabled('files_encryption')) {
			$user = \OCP\User::getUser();

			if ($view->is_dir('/files_trashbin/files/' . $file)) {
				$keyfile = \OC\Files\Filesystem::normalizePath('files_trashbin/keyfiles/' . $filename);
				$sharekeys = \OC\Files\Filesystem::normalizePath('files_trashbin/share-keys/' . $filename);
			} else {
				$keyfile = \OC\Files\Filesystem::normalizePath('files_trashbin/keyfiles/' . $filename . '.key');
				$sharekeys = \OC\Files\Filesystem::normalizePath('files_trashbin/share-keys/' . $filename . '.' . $user . '.shareKey');
			}
			if ($timestamp) {
				$keyfile .= '.d' . $timestamp;
				$sharekeys .= '.d' . $timestamp;
			}
			if ($view->file_exists($keyfile)) {
				if ($view->is_dir($keyfile)) {
					$size += self::calculateSize(new \OC\Files\View('/' . $user . '/' . $keyfile));
					$size += self::calculateSize(new \OC\Files\View('/' . $user . '/' . $sharekeys));
				} else {
					$size += $view->filesize($keyfile);
					$size += $view->filesize($sharekeys);
				}
				$view->unlink($keyfile);
				$view->unlink($sharekeys);
			}
		}
		return $size;
	}

	/**
	 * check to see whether a file exists in trashbin
	 * @param $filename path to the file
	 * @param $timestamp of deletion time
	 * @return true if file exists, otherwise false
	 */
	public static function file_exists($filename, $timestamp = null) {
		$user = \OCP\User::getUser();
		$view = new \OC\Files\View('/' . $user);

		if ($timestamp) {
			$filename = $filename . '.d' . $timestamp;
		} else {
			$filename = $filename;
		}

		$target = \OC\Files\Filesystem::normalizePath('files_trashbin/files/' . $filename);
		return $view->file_exists($target);
	}

	/**
	 * @brief deletes used space for trash bin in db if user was deleted
	 *
	 * @param type $uid id of deleted user
	 * @return result of db delete operation
	 */
	public static function deleteUser($uid) {
		$query = \OC_DB::prepare('DELETE FROM `*PREFIX*files_trash` WHERE `user`=?');
		$result = $query->execute(array($uid));
		if ($result) {
			$query = \OC_DB::prepare('DELETE FROM `*PREFIX*files_trashsize` WHERE `user`=?');
			return $query->execute(array($uid));
		}
		return false;
	}

	/**
	 * calculate remaining free space for trash bin
	 *
	 * @param $trashbinSize current size of the trash bin
	 * @return available free space for trash bin
	 */
	private static function calculateFreeSpace($trashbinSize) {
		$softQuota = true;
		$user = \OCP\User::getUser();
		$quota = \OC_Preferences::getValue($user, 'files', 'quota');
		$view = new \OC\Files\View('/' . $user);
		if ($quota === null || $quota === 'default') {
			$quota = \OC_Appconfig::getValue('files', 'default_quota');
		}
		if ($quota === null || $quota === 'none') {
			$quota = \OC\Files\Filesystem::free_space('/');
			$softQuota = false;
		} else {
			$quota = \OCP\Util::computerFileSize($quota);
		}

		// calculate available space for trash bin
		// subtract size of files and current trash bin size from quota
		if ($softQuota) {
			$rootInfo = $view->getFileInfo('/files/');
			$free = $quota - $rootInfo['size']; // remaining free space for user
			if ($free > 0) {
				$availableSpace = ($free * self::DEFAULTMAXSIZE / 100) - $trashbinSize; // how much space can be used for versions
			} else {
				$availableSpace = $free - $trashbinSize;
			}
		} else {
			$availableSpace = $quota;
		}

		return $availableSpace;
	}

	/**
	 * clean up the trash bin
	 * @param current size of the trash bin
	 */
	private static function expire($trashbinSize) {

		$user = \OCP\User::getUser();
		$view = new \OC\Files\View('/' . $user);
		$availableSpace = self::calculateFreeSpace($trashbinSize);
		$size = 0;

		$query = \OC_DB::prepare('SELECT `location`,`type`,`id`,`timestamp` FROM `*PREFIX*files_trash` WHERE `user`=?');
		$result = $query->execute(array($user))->fetchAll();

		$retention_obligation = \OC_Config::getValue('trashbin_retention_obligation', self::DEFAULT_RETENTION_OBLIGATION);

		$limit = time() - ($retention_obligation * 86400);

		foreach ($result as $r) {
			$timestamp = $r['timestamp'];
			$filename = $r['id'];
			if ($r['timestamp'] < $limit) {
				$size += self::delete($filename, $timestamp);
				\OC_Log::write('files_trashbin', 'remove "' . $filename . '" fom trash bin because it is older than ' . $retention_obligation, \OC_log::INFO);
			}
		}
		$availableSpace = $availableSpace + $size;
		// if size limit for trash bin reached, delete oldest files in trash bin
		if ($availableSpace < 0) {
			$query = \OC_DB::prepare('SELECT `location`,`type`,`id`,`timestamp` FROM `*PREFIX*files_trash`'
					. ' WHERE `user`=? ORDER BY `timestamp` ASC');
			$result = $query->execute(array($user))->fetchAll();
			$length = count($result);
			$i = 0;
			while ($i < $length && $availableSpace < 0) {
				$tmp = self::delete($result[$i]['id'], $result[$i]['timestamp']);
				\OC_Log::write('files_trashbin', 'remove "' . $result[$i]['id'] . '" (' . $tmp . 'B) to meet the limit of trash bin size (50% of available quota)', \OC_log::INFO);
				$availableSpace += $tmp;
				$size += $tmp;
				$i++;
			}
		}

		return $size;
	}

	/**
	 * recursive copy to copy a whole directory
	 *
	 * @param $source source path, relative to the users files directory
	 * @param $destination destination path relative to the users root directoy
	 * @param $view file view for the users root directory
	 */
	private static function copy_recursive($source, $destination, $view) {
		$size = 0;
		if ($view->is_dir('files' . $source)) {
			$view->mkdir($destination);
			$view->touch($destination, $view->filemtime('files' . $source));
			foreach (\OC_Files::getDirectoryContent($source) as $i) {
				$pathDir = $source . '/' . $i['name'];
				if ($view->is_dir('files' . $pathDir)) {
					$size += self::copy_recursive($pathDir, $destination . '/' . $i['name'], $view);
				} else {
					$size += $view->filesize('files' . $pathDir);
					$view->copy('files' . $pathDir, $destination . '/' . $i['name']);
					$view->touch($destination . '/' . $i['name'], $view->filemtime('files' . $pathDir));
				}
			}
		} else {
			$size += $view->filesize('files' . $source);
			$view->copy('files' . $source, $destination);
			$view->touch($destination, $view->filemtime('files' . $source));
		}
		return $size;
	}

	/**
	 * find all versions which belong to the file we want to restore
	 * @param $filename name of the file which should be restored
	 * @param $timestamp timestamp when the file was deleted
	 */
	private static function getVersionsFromTrash($filename, $timestamp) {
		$view = new \OC\Files\View('/' . \OCP\User::getUser() . '/files_trashbin/versions');
		$versionsName = $view->getLocalFile($filename) . '.v';
		$escapedVersionsName = preg_replace('/(\*|\?|\[)/', '[$1]', $versionsName);
		$versions = array();
		if ($timestamp) {
			// fetch for old versions
			$matches = glob($escapedVersionsName . '*.d' . $timestamp);
			$offset = -strlen($timestamp) - 2;
		} else {
			$matches = glob($escapedVersionsName . '*');
		}

		foreach ($matches as $ma) {
			if ($timestamp) {
				$parts = explode('.v', substr($ma, 0, $offset));
				$versions[] = ( end($parts) );
			} else {
				$parts = explode('.v', $ma);
				$versions[] = ( end($parts) );
			}
		}
		return $versions;
	}

	/**
	 * find unique extension for restored file if a file with the same name already exists
	 * @param $location where the file should be restored
	 * @param $filename name of the file
	 * @param $view filesystem view relative to users root directory
	 * @return string with unique extension
	 */
	private static function getUniqueExtension($location, $filename, $view) {
		$ext = '';
		if ($view->file_exists('files' . $location . '/' . $filename)) {
			$tmpext = '.restored';
			$ext = $tmpext;
			$i = 1;
			while ($view->file_exists('files' . $location . '/' . $filename . $ext)) {
				$ext = $tmpext . $i;
				$i++;
			}
		}
		return $ext;
	}

	/**
	 * @brief get the size from a given root folder
	 * @param $view file view on the root folder
	 * @return size of the folder
	 */
	private static function calculateSize($view) {
		$root = \OCP\Config::getSystemValue('datadirectory') . $view->getAbsolutePath('');
		if (!file_exists($root)) {
			return 0;
		}
		$iterator = new \RecursiveIteratorIterator(new \RecursiveDirectoryIterator($root), \RecursiveIteratorIterator::CHILD_FIRST);
		$size = 0;

		foreach ($iterator as $path) {
			$relpath = substr($path, strlen($root) - 1);
			if (!$view->is_dir($relpath)) {
				$size += $view->filesize($relpath);
			}
		}
		return $size;
	}

	/**
	 * get current size of trash bin from a given user
	 *
	 * @param $user user who owns the trash bin
	 * @return mixed trash bin size or false if no trash bin size is stored
	 */
	private static function getTrashbinSize($user) {
		$query = \OC_DB::prepare('SELECT `size` FROM `*PREFIX*files_trashsize` WHERE `user`=?');
		$result = $query->execute(array($user))->fetchAll();

		if ($result) {
			return $result[0]['size'];
		}
		return false;
	}

	/**
	 * write to the database how much space is in use for the trash bin
	 *
	 * @param $user owner of the trash bin
	 * @param $size size of the trash bin
	 */
	private static function setTrashbinSize($user, $size) {
		if (self::getTrashbinSize($user) === false) {
			$query = \OC_DB::prepare('INSERT INTO `*PREFIX*files_trashsize` (`size`, `user`) VALUES (?, ?)');
		} else {
			$query = \OC_DB::prepare('UPDATE `*PREFIX*files_trashsize` SET `size`=? WHERE `user`=?');
		}
		$query->execute(array($size, $user));
	}

	/**
	 * register hooks
	 */
	public static function registerHooks() {
		//Listen to delete file signal
		\OCP\Util::connectHook('OC_Filesystem', 'delete', "OCA\Files_Trashbin\Hooks", "remove_hook");
		//Listen to delete user signal
		\OCP\Util::connectHook('OC_User', 'pre_deleteUser', "OCA\Files_Trashbin\Hooks", "deleteUser_hook");
	}

}