<?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 = 30;

  
  	// 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);
  	}

  	private static function setUpTrash($user) {
  		$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');
  		}
  	}

  	/**
  	 * copy file to owners trash
  	 * @param string $sourcePath
  	 * @param string $owner
  	 * @param string $ownerPath
  	 * @param integer $timestamp
  	 */
  	private static function copyFilesToOwner($sourcePath, $owner, $ownerPath, $timestamp) {

  		self::setUpTrash($owner);
  
  		$ownerFilename = basename($ownerPath);
  		$ownerLocation = dirname($ownerPath);
  
  		$sourceFilename = basename($sourcePath);
  
  		$view = new \OC\Files\View('/');

  		$source = \OCP\User::getUser() . '/files_trashbin/files/' . $sourceFilename . '.d' . $timestamp;
  		$target = $owner . '/files_trashbin/files/' . $ownerFilename . '.d' . $timestamp;

  		self::copy_recursive($source, $target, $view);
  
  
  		if ($view->file_exists($target)) {

  			$query = \OC_DB::prepare("INSERT INTO `*PREFIX*files_trash` (`id`,`timestamp`,`location`,`user`) VALUES (?,?,?,?)");
  			$result = $query->execute(array($ownerFilename, $timestamp, $ownerLocation, $owner));
  			if (!$result) {

  				\OC_Log::write('files_trashbin', 'trash bin database couldn\'t be updated for the files owner', \OC_log::ERROR);

  			}
  		}
  	}

  	/**
  	 * move file to the trash bin
  	 *

  	 * @param string $file_path path to the deleted file/directory relative to the files root directory

  	 */
  	public static function move2trash($file_path) {
  		$user = \OCP\User::getUser();

  		$size = 0;
  		list($owner, $ownerPath) = self::getUidAndFilename($file_path);
  		self::setUpTrash($user);

  		$view = new \OC\Files\View('/' . $user);

  		$path_parts = pathinfo($file_path);
  
  		$filename = $path_parts['basename'];
  		$location = $path_parts['dirname'];
  		$timestamp = time();

  		$userTrashSize = self::getTrashbinSize($user);

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

  		$trashPath = '/files_trashbin/files/' . $filename . '.d' . $timestamp;

  		try {
  			$sizeOfAddedFiles = self::copy_recursive('/files/'.$file_path, $trashPath, $view);
  		} catch (\OCA\Files_Trashbin\Exceptions\CopyRecursiveException $e) {
  			$sizeOfAddedFiles = false;
  			if ($view->file_exists($trashPath)) {
  				$view->deleteAll($trashPath);
  			}
  			\OC_Log::write('files_trashbin', 'Couldn\'t move ' . $file_path . ' to the trash bin', \OC_log::ERROR);
  		}

  		\OC_FileProxy::$enabled = $proxyStatus;

  		if ($sizeOfAddedFiles !== false) {

  			$size = $sizeOfAddedFiles;

  			$query = \OC_DB::prepare("INSERT INTO `*PREFIX*files_trash` (`id`,`timestamp`,`location`,`user`) VALUES (?,?,?,?)");
  			$result = $query->execute(array($filename, $timestamp, $location, $user));
  			if (!$result) {

  				\OC_Log::write('files_trashbin', 'trash bin database couldn\'t be updated', \OC_log::ERROR);

  			}
  			\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)));

  			$size += self::retainVersions($file_path, $filename, $timestamp);
  			$size += self::retainEncryptionKeys($file_path, $filename, $timestamp);
  
  			// if owner !== user we need to also add a copy to the owners trash
  			if ($user !== $owner) {

  				self::copyFilesToOwner($file_path, $owner, $ownerPath, $timestamp);

  			}

  		}

  		$userTrashSize += $size;
  		$userTrashSize -= self::expire($userTrashSize, $user);

  		// if owner !== user we also need to update the owners trash size

  		if ($owner !== $user) {

  			$ownerTrashSize = self::getTrashbinSize($owner);

  			$ownerTrashSize += $size;
  			$ownerTrashSize -= self::expire($ownerTrashSize, $owner);

  		}

  	}
  
  	/**
  	 * Move file versions to trash so that they can be restored later
  	 *

  	 * @param string $file_path path to original file
  	 * @param string $filename of deleted file
  	 * @param integer $timestamp when the file was deleted

  	 *

  	 * @return int size of stored versions

  	 */

  	private static function retainVersions($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));

  				if ($owner !== $user) {

  					self::copy_recursive($owner . '/files_versions/' . $ownerPath, $owner . '/files_trashbin/versions/' . basename($ownerPath) . '.d' . $timestamp, $rootView);

  				}

  				$rootView->rename($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']);

  					if ($owner !== $user) {
  						$rootView->copy($owner . '/files_versions' . $v['path'] . '.v' . $v['version'], $owner . '/files_trashbin/versions/' . $v['name'] . '.v' . $v['version'] . '.d' . $timestamp);
  					}

  					$rootView->rename($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 string $file_path path to original file
  	 * @param string $filename of deleted file
  	 * @param integer $timestamp when the file was deleted

  	 *

  	 * @return int size of encryption keys

  	 */

  	private static function retainEncryptionKeys($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);

  			$util = new \OCA\Encryption\Util(new \OC\Files\View('/'), $user);

  
  			// disable proxy to prevent recursive calls
  			$proxyStatus = \OC_FileProxy::$enabled;
  			\OC_FileProxy::$enabled = false;
  
  			if ($util->isSystemWideMountPoint($ownerPath)) {
  				$baseDir = '/files_encryption/';
  			} else {
  				$baseDir = $owner . '/files_encryption/';
  			}
  
  			$keyfile = \OC\Files\Filesystem::normalizePath($baseDir . '/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));

  					if ($owner !== $user) {

  						self::copy_recursive($keyfile, $owner . '/files_trashbin/keyfiles/' . basename($ownerPath) . '.d' . $timestamp, $rootView);

  					}

  					$rootView->rename($keyfile, $user . '/files_trashbin/keyfiles/' . $filename . '.d' . $timestamp);
  				} else {
  					$size += $rootView->filesize($keyfile . '.key');

  					if ($owner !== $user) {
  						$rootView->copy($keyfile . '.key', $owner . '/files_trashbin/keyfiles/' . basename($ownerPath) . '.key.d' . $timestamp);
  					}

  					$rootView->rename($keyfile . '.key', $user . '/files_trashbin/keyfiles/' . $filename . '.key.d' . $timestamp);
  				}
  			}
  
  			// retain share keys
  			$sharekeys = \OC\Files\Filesystem::normalizePath($baseDir . '/share-keys/' . $ownerPath);
  
  			if ($rootView->is_dir($sharekeys)) {
  				$size += self::calculateSize(new \OC\Files\View($sharekeys));

  				if ($owner !== $user) {

  					self::copy_recursive($sharekeys, $owner . '/files_trashbin/share-keys/' . basename($ownerPath) . '.d' . $timestamp, $rootView);

  				}

  				$rootView->rename($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 users key so we can access the private key
  					$userShareKey = $filename . '.' . $user . '.shareKey';

  
  					// if we found the share-key for the owner, we need to move it to files_trashbin

  					if ($pathinfo['basename'] == $userShareKey) {

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

  						$rootView->rename($sharekeys . '.' . $user . '.shareKey', $user . '/files_trashbin/share-keys/' . $userShareKey . '.d' . $timestamp);
  					} elseif ($owner !== $user) {
  						$ownerShareKey = basename($ownerPath) . '.' . $owner . '.shareKey';
  						if ($pathinfo['basename'] == $ownerShareKey) {
  							$rootView->rename($sharekeys . '.' . $owner . '.shareKey', $owner . '/files_trashbin/share-keys/' . $ownerShareKey . '.d' . $timestamp);
  						}

  					} else {

  						// don't keep other share-keys
  						unlink($src);
  					}
  				}
  			}
  
  			// enable proxy
  			\OC_FileProxy::$enabled = $proxyStatus;
  		}
  		return $size;
  	}
  
  	/**
  	 * restore files from trash bin

  	 *
  	 * @param string $file path to the deleted file
  	 * @param string $filename name of the file
  	 * @param int $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);

  		$location = '';

  		if ($timestamp) {

  			$query = \OC_DB::prepare('SELECT `location` 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);

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

  			}

  		}

  		// we need a  extension in case a file/dir with the same name already exists

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

  		$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);

  
  		// handle the restore result
  		if ($restoreResult) {
  			$fakeRoot = $view->getRoot();
  			$view->chroot('/' . $user . '/files');

  			$view->touch('/' . $location . '/' . $uniqueFilename, $mtime);

  			$view->chroot($fakeRoot);

  			\OCP\Util::emitHook('\OCA\Files_Trashbin\Trashbin', 'post_restore', array('filePath' => \OC\Files\Filesystem::normalizePath('/' . $location . '/' . $uniqueFilename),

  				'trashPath' => \OC\Files\Filesystem::normalizePath($file)));

  			self::restoreVersions($view, $file, $filename, $uniqueFilename, $location, $timestamp);
  			self::restoreEncryptionKeys($view, $file, $filename, $uniqueFilename, $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));
  			}

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

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

  		return false;
  	}
  
  	/**

  	 * restore versions from trash bin

  	 *
  	 * @param \OC\Files\View $view file view

  	 * @param string $file complete path to file
  	 * @param string $filename name of file once it was deleted
  	 * @param string $uniqueFilename new file name to restore the file without overwriting existing files
  	 * @param string $location location if file
  	 * @param int $timestamp deleteion time

  	 *

  	 */

  	private static function restoreVersions($view, $file, $filename, $uniqueFilename, $location, $timestamp) {

  		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 . '/' . $uniqueFilename);

  
  			list($owner, $ownerPath) = self::getUidAndFilename($target);
  
  			if ($timestamp) {
  				$versionedFile = $filename;
  			} else {
  				$versionedFile = $file;
  			}
  
  			if ($view->is_dir('/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) {

  						$rootView->rename($user . '/files_trashbin/versions/' . $versionedFile . '.v' . $v . '.d' . $timestamp, $owner . '/files_versions/' . $ownerPath . '.v' . $v);
  					} else {

  						$rootView->rename($user . '/files_trashbin/versions/' . $versionedFile . '.v' . $v, $owner . '/files_versions/' . $ownerPath . '.v' . $v);
  					}
  				}
  			}
  
  			// enable proxy
  			\OC_FileProxy::$enabled = $proxyStatus;
  		}

  	}
  
  	/**

  	 * restore encryption keys from trash bin

  	 *
  	 * @param \OC\Files\View $view

  	 * @param string $file complete path to file
  	 * @param string $filename name of file
  	 * @param string $uniqueFilename new file name to restore the file without overwriting existing files
  	 * @param string $location location of file
  	 * @param int $timestamp deleteion time

  	 *

  	 */

  	private static function restoreEncryptionKeys($view, $file, $filename, $uniqueFilename, $location, $timestamp) {

  		// Take care of encryption keys TODO! Get '.key' in file between file name and delete date (also for permanent delete!)

  		if (\OCP\App::isEnabled('files_encryption')) {
  			$user = \OCP\User::getUser();
  			$rootView = new \OC\Files\View('/');

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

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

  			$util = new \OCA\Encryption\Util(new \OC\Files\View('/'), $user);

  
  			if ($util->isSystemWideMountPoint($ownerPath)) {
  				$baseDir = '/files_encryption/';
  			} else {
  				$baseDir = $owner . '/files_encryption/';
  			}
  
  			$path_parts = pathinfo($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

  					$rootView->rename($keyfile, $baseDir . '/keyfiles/' . $ownerPath);
  
  					// handle share-keys
  					if ($timestamp) {
  						$sharekey .= '.d' . $timestamp;
  					}

  					$rootView->rename($sharekey, $baseDir . '/share-keys/' . $ownerPath);
  				} else {
  					// handle keyfiles

  					$rootView->rename($keyfile, $baseDir . '/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;
  					}

  					// move only owners key
  					$rootView->rename($ownerShareKey, $baseDir . '/share-keys/' . $ownerPath . '.' . $user . '.shareKey');
  
  					// try to re-share if file is shared

  					$filesystemView = new \OC\Files\View('/');

  					$session = new \OCA\Encryption\Session($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 users sharing this file

  					$usersSharing = $util->getSharingUsersArray($sharingEnabled, $target);

  
  					// Attempt to set shareKey

  					$util->setSharedFileKeyfiles($session, $usersSharing, $target);

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

  	}
  
  	/**

  	 * delete all files from the trash

  	 */
  	public static function deleteAll() {
  		$user = \OCP\User::getUser();
  		$view = new \OC\Files\View('/' . $user);
  		$view->deleteAll('files_trashbin');

  		$query = \OC_DB::prepare('DELETE FROM `*PREFIX*files_trash` WHERE `user`=?');
  		$query->execute(array($user));
  
  		return true;
  	}
  
  
  	/**

  	 * delete file from trash bin permanently

  	 *

  	 * @param string $filename path to the file
  	 * @param string $user
  	 * @param int $timestamp of deletion time

  	 *

  	 * @return int size of deleted files

  	 */

  	public static function delete($filename, $user, $timestamp = null) {

  		$view = new \OC\Files\View('/' . $user);
  		$size = 0;

  		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);
  		}

  		\OC_Hook::emit('\OCP\Trashbin', 'preDelete', array('path' => '/files_trashbin/files/' . $file));

  		$view->unlink('/files_trashbin/files/' . $file);

  		\OC_Hook::emit('\OCP\Trashbin', 'delete', array('path' => '/files_trashbin/files/' . $file));

  
  		return $size;
  	}

  	/**
  	 * @param \OC\Files\View $view
  	 */

  	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;
  	}

  	/**
  	 * @param \OC\Files\View $view
  	 */

  	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 string $filename path to the file
  	 * @param int $timestamp of deletion time
  	 * @return bool 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);
  	}
  
  	/**

  	 * deletes used space for trash bin in db if user was deleted

  	 *

  	 * @param string $uid id of deleted user
  	 * @return bool result of db delete operation

  	 */
  	public static function deleteUser($uid) {
  		$query = \OC_DB::prepare('DELETE FROM `*PREFIX*files_trash` WHERE `user`=?');

  		return $query->execute(array($uid));

  	}
  
  	/**
  	 * calculate remaining free space for trash bin
  	 *

  	 * @param integer $trashbinSize current size of the trash bin
  	 * @param string $user
  	 * @return int available free space for trash bin

  	 */

  	private static function calculateFreeSpace($trashbinSize, $user) {

  		$softQuota = true;

  		$quota = \OC_Preferences::getValue($user, 'files', 'quota');
  		$view = new \OC\Files\View('/' . $user);
  		if ($quota === null || $quota === 'default') {

  			$quota = \OC::$server->getAppConfig()->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/', false);

  			$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;
  	}
  
  	/**

  	 * resize trash bin if necessary after a new file was added to ownCloud

  	 * @param string $user user id
  	 */
  	public static function resizeTrash($user) {
  
  		$size = self::getTrashbinSize($user);

  		$freeSpace = self::calculateFreeSpace($size, $user);

  
  		if ($freeSpace < 0) {

  			self::expire($size, $user);

  		}
  	}
  
  	/**

  	 * clean up the trash bin

  	 *

  	 * @param int $trashbinSize current size of the trash bin
  	 * @param string $user
  	 * @return int size of expired files

  	 */

  	private static function expire($trashbinSize, $user) {
  
  		// let the admin disable auto expire
  		$autoExpire = \OC_Config::getValue('trashbin_auto_expire', true);
  		if ($autoExpire === false) {
  			return 0;
  		}

  		$availableSpace = self::calculateFreeSpace($trashbinSize, $user);

  		$size = 0;

  		$retention_obligation = \OC_Config::getValue('trashbin_retention_obligation', self::DEFAULT_RETENTION_OBLIGATION);
  
  		$limit = time() - ($retention_obligation * 86400);

  		$dirContent = Helper::getTrashFiles('/', $user, 'mtime');
  
  		// delete all files older then $retention_obligation
  		list($delSize, $count) = self::deleteExpiredFiles($dirContent, $user, $limit, $retention_obligation);
  
  		$size += $delSize;

  		$availableSpace += $size;

  
  		// delete files from trash until we meet the trash bin size limit again
  		$size += self::deleteFiles(array_slice($dirContent, $count), $user, $availableSpace);
  
  		return $size;
  	}
  
  	/**
  	 * if the size limit for the trash bin is reached, we delete the oldest
  	 * files in the trash bin until we meet the limit again
  	 * @param array $files
  	 * @param string $user
  	 * @param int $availableSpace available disc space
  	 * @return int size of deleted files
  	 */
  	protected static function deleteFiles($files, $user, $availableSpace) {
  		$size = 0;

  		if ($availableSpace < 0) {

  			foreach ($files as $file) {
  				if ($availableSpace < 0) {
  					$tmp = self::delete($file['name'], $user, $file['mtime']);
  					\OC_Log::write('files_trashbin', 'remove "' . $file['name'] . '" (' . $tmp . 'B) to meet the limit of trash bin size (50% of available quota)', \OC_log::INFO);
  					$availableSpace += $tmp;
  					$size += $tmp;
  				} else {
  					break;
  				}

  			}
  		}

  		return $size;
  	}
  
  	/**

  	 * delete files older then max storage time
  	 *
  	 * @param array $files list of files sorted by mtime
  	 * @param string $user
  	 * @param int $limit files older then limit should be deleted
  	 * @param int $retention_obligation max age of file in days
  	 * @return array size of deleted files and number of deleted files
  	 */
  	protected static function deleteExpiredFiles($files, $user, $limit, $retention_obligation) {
  		$size = 0;
  		$count = 0;
  		foreach ($files as $file) {
  			$timestamp = $file['mtime'];
  			$filename = $file['name'];
  			if ($timestamp < $limit) {
  				$count++;
  				$size += self::delete($filename, $user, $timestamp);
  				\OC_Log::write('files_trashbin', 'remove "' . $filename . '" from trash bin because it is older than ' . $retention_obligation, \OC_log::INFO);
  			} else {
  				break;
  			}
  		}
  
  		return array($size, $count);
  	}
  
  	/**

  	 * recursive copy to copy a whole directory
  	 *

  	 * @param string $source source path, relative to the users files directory
  	 * @param string $destination destination path relative to the users root directoy
  	 * @param \OC\Files\View $view file view for the users root directory

  	 */
  	private static function copy_recursive($source, $destination, $view) {
  		$size = 0;

  		if ($view->is_dir($source)) {

  			$view->mkdir($destination);

  			$view->touch($destination, $view->filemtime($source));
  			foreach ($view->getDirectoryContent($source) as $i) {

  				$pathDir = $source . '/' . $i['name'];

  				if ($view->is_dir($pathDir)) {

  					$size += self::copy_recursive($pathDir, $destination . '/' . $i['name'], $view);
  				} else {

  					$size += $view->filesize($pathDir);

  					$result = $view->copy($pathDir, $destination . '/' . $i['name']);
  					if (!$result) {
  						throw new \OCA\Files_Trashbin\Exceptions\CopyRecursiveException();
  					}

  					$view->touch($destination . '/' . $i['name'], $view->filemtime($pathDir));

  				}
  			}
  		} else {

  			$size += $view->filesize($source);

  			$result = $view->copy($source, $destination);
  			if (!$result) {
  				throw new \OCA\Files_Trashbin\Exceptions\CopyRecursiveException();
  			}

  			$view->touch($destination, $view->filemtime($source));

  		}
  		return $size;
  	}
  
  	/**
  	 * find all versions which belong to the file we want to restore

  	 *
  	 * @param string $filename name of the file which should be restored
  	 * @param int $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 . '*');

  		}

  		if (is_array($matches)) {
  			foreach ($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 string $location where the file should be restored
  	 * @param string $filename name of the file
  	 * @param \OC\Files\View $view filesystem view relative to users root directory

  	 * @return string with unique extension
  	 */

  	private static function getUniqueFilename($location, $filename, $view) {
  		$ext = pathinfo($filename, PATHINFO_EXTENSION);
  		$name = pathinfo($filename, PATHINFO_FILENAME);
  		$l = \OC_L10N::get('files_trashbin');
  
  		// if extension is not empty we set a dot in front of it
  		if ($ext !== '') {
  			$ext = '.' . $ext;
  		}

  		if ($view->file_exists('files' . $location . '/' . $filename)) {

  			$i = 2;

  			$uniqueName = $name . " (" . $l->t("restored") . ")" . $ext;

  			while ($view->file_exists('files' . $location . '/' . $uniqueName)) {

  				$uniqueName = $name . " (" . $l->t("restored") . " " . $i . ")" . $ext;

  				$i++;
  			}

  
  			return $uniqueName;

  		}

  
  		return $filename;

  	}
  
  	/**

  	 * get the size from a given root folder
  	 * @param \OC\Files\View $view file view on the root folder
  	 * @return integer 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;

                  /**
  		 * RecursiveDirectoryIterator on an NFS path isn't iterable with foreach
  		 * This bug is fixed in PHP 5.5.9 or before
  		 * See #8376
  		 */
  		$iterator->rewind();
  		while ($iterator->valid()) {
  			$path = $iterator->current();

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

  			$iterator->next();

  		}
  		return $size;
  	}
  
  	/**
  	 * get current size of trash bin from a given user
  	 *

  	 * @param string $user user who owns the trash bin
  	 * @return integer trash bin size

  	 */
  	private static function getTrashbinSize($user) {

  		$view = new \OC\Files\View('/' . $user);
  		$fileInfo = $view->getFileInfo('/files_trashbin');
  		return isset($fileInfo['size']) ? $fileInfo['size'] : 0;

  	}
  
  	/**
  	 * 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");

  		//Listen to post write hook
  		\OCP\Util::connectHook('OC_Filesystem', 'post_write', "OCA\Files_Trashbin\Hooks", "post_write_hook");

  	}

  	/**

  	 * check if trash bin is empty for a given user

  	 * @param string $user
  	 */
  	public static function isEmpty($user) {
  
  		$view = new \OC\Files\View('/' . $user . '/files_trashbin');

  		if ($view->is_dir('/files') && $dh = $view->opendir('/files')) {
  			while ($file = readdir($dh)) {
  				if ($file !== '.' and $file !== '..') {
  					return false;
  				}
  			}

  		}

  		return true;
  	}
  
  	public static function preview_icon($path) {

  		return \OC_Helper::linkToRoute('core_ajax_trashbin_preview', array('x' => 36, 'y' => 36, 'file' => $path));

  	}

  }