<?php
  
  /**
   * ownCloud – LDAP Backend Proxy
   *
   * @author Arthur Schiwon
   * @copyright 2013 Arthur Schiwon blizzz@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\user_ldap\lib;

  use OCA\user_ldap\lib\Access;

  abstract class Proxy {

  	static private $accesses = array();
  	private $ldap = null;

  	public function __construct(ILDAPWrapper $ldap) {
  		$this->ldap = $ldap;

  		$this->cache = \OC_Cache::getGlobalCache();
  	}

  	private function addAccess($configPrefix) {
  		$connector = new Connection($this->ldap, $configPrefix);
  		self::$accesses[$configPrefix] = new Access($connector, $this->ldap);

  	}

  	protected function getAccess($configPrefix) {
  		if(!isset(self::$accesses[$configPrefix])) {
  			$this->addAccess($configPrefix);

  		}

  		return self::$accesses[$configPrefix];

  	}
  
  	protected function getUserCacheKey($uid) {
  		return 'user-'.$uid.'-lastSeenOn';
  	}
  
  	protected function getGroupCacheKey($gid) {
  		return 'group-'.$gid.'-lastSeenOn';
  	}

  	abstract protected function callOnLastSeenOn($id, $method, $parameters, $passOnWhen);

  	abstract protected function walkBackends($id, $method, $parameters);
  
  	/**
  	 * @brief Takes care of the request to the User backend
  	 * @param $uid string, the uid connected to the request
  	 * @param $method string, the method of the user backend that shall be called
  	 * @param $parameters an array of parameters to be passed
  	 * @return mixed, the result of the specified method
  	 */

  	protected function handleRequest($id, $method, $parameters, $passOnWhen = false) {
  		$result = $this->callOnLastSeenOn($id,  $method, $parameters, $passOnWhen);
  		if($result === $passOnWhen) {

  			$result = $this->walkBackends($id, $method, $parameters);
  		}
  		return $result;
  	}
  
  	private function getCacheKey($key) {
  		$prefix = 'LDAP-Proxy-';
  		if(is_null($key)) {
  			return $prefix;
  		}
  		return $prefix.md5($key);
  	}
  
  	public function getFromCache($key) {
  		if(!$this->isCached($key)) {
  			return null;
  		}
  		$key = $this->getCacheKey($key);
  
  		return unserialize(base64_decode($this->cache->get($key)));
  	}
  
  	public function isCached($key) {
  		$key = $this->getCacheKey($key);
  		return $this->cache->hasKey($key);
  	}
  
  	public function writeToCache($key, $value) {
  		$key   = $this->getCacheKey($key);
  		$value = base64_encode(serialize($value));
  		$this->cache->set($key, $value, '2592000');
  	}
  
  	public function clearCache() {
  		$this->cache->clear($this->getCacheKey(null));
  	}

  }