<?php
  /**
   * Copyright (c) 2012 Bart Visscher <bartv@thisnet.nl>
   * This file is licensed under the Affero General Public License version 3 or
   * later.
   * See the COPYING-README file.
   */
  
  namespace OC\Memcache;
  
  class Memcached extends Cache {
  	/**
  	 * @var \Memcached $cache
  	 */
  	private static $cache = null;
  
  	public function __construct($prefix = '') {
  		parent::__construct($prefix);
  		if (is_null(self::$cache)) {
  			self::$cache = new \Memcached();

  			$servers = \OC_Config::getValue('memcached_servers');
  			if (!$servers) {
  				$server = \OC_Config::getValue('memcached_server');
  				if ($server) {
  					$servers = array($server);
  				} else {
  					$servers = array(array('localhost', 11211));
  				}
  			}
  			self::$cache->addServers($servers);

  		}
  	}
  
  	/**
  	 * entries in XCache gets namespaced to prevent collisions between owncloud instances and users
  	 */
  	protected function getNameSpace() {
  		return $this->prefix;
  	}
  
  	public function get($key) {
  		$result = self::$cache->get($this->getNamespace() . $key);
  		if ($result === false and self::$cache->getResultCode() == \Memcached::RES_NOTFOUND) {
  			return null;
  		} else {
  			return $result;
  		}
  	}
  
  	public function set($key, $value, $ttl = 0) {
  		if ($ttl > 0) {
  			return self::$cache->set($this->getNamespace() . $key, $value, $ttl);
  		} else {
  			return self::$cache->set($this->getNamespace() . $key, $value);
  		}
  	}
  
  	public function hasKey($key) {
  		self::$cache->get($this->getNamespace() . $key);

  		return self::$cache->getResultCode() === \Memcached::RES_SUCCESS;

  	}
  
  	public function remove($key) {
  		return self::$cache->delete($this->getNamespace() . $key);
  	}
  
  	public function clear($prefix = '') {
  		$prefix = $this->getNamespace() . $prefix;
  		$allKeys = self::$cache->getAllKeys();
  		$keys = array();
  		$prefixLength = strlen($prefix);
  		foreach ($allKeys as $key) {
  			if (substr($key, 0, $prefixLength) === $prefix) {
  				$keys[] = $key;
  			}
  		}
  		self::$cache->deleteMulti($keys);
  		return true;
  	}
  
  	static public function isAvailable() {
  		return extension_loaded('memcached');
  	}
  }