<?php
/**
 * Implementation methode Memoization
 *
 * @package SPIP\memoization\Memo
 **/

// Sécurité
if (!defined('_ECRIRE_INC_VERSION')){
	return;
}

if (!defined('_CACHE_NAMESPACE')){
	define('_CACHE_NAMESPACE', $_SERVER["SERVER_NAME"] . ":" . $_SERVER["SERVER_PORT"] . ":");
}

if (!defined('_CACHE_KEY')){
	define('_CACHE_KEY', '0123456789ABCDEF');
}

class MCacheBackend_apcu implements MCacheBackend {

	private function key_for_lock($str){
		return _CACHE_NAMESPACE . 'lock:' . md5($str . "locked");
	}

	private function _xor($message){
		$key = _CACHE_KEY;
		$keylen = strlen($key);
		if (!$keylen){
			return $message;
		}

		$messagelen = strlen($message);
		for ($i = 0; $i<$messagelen; $i++){
			$message[$i] = ~($message[$i] ^ $key[$i%$keylen]);
		}
		return $message;
	}

	private function store_value($value){
		if (is_object($value)
			or is_array($value)
			or is_bool($value)
			or !$value){
			return array($this->_xor(serialize($value)));
		}
		return $this->_xor($value);
	}

	private function unstore_value($a){
		if (is_null($a)){
			return $a;
		}
		// maybe_unserialize
		if (is_array($a)){
			return @unserialize($this->_xor($a[0]));
		}
		return $this->_xor($a);
	}

	/* Interface */

	public function init($params = null){

	}

	public function get($key){
		$a = apcu_fetch(_CACHE_NAMESPACE . $key);
		return $this->unstore_value($a);
	}

	public function set($key, $value, $ttl = null){
		return is_null($ttl)
			? apcu_store(_CACHE_NAMESPACE . $key, $this->store_value($value))
			: apcu_store(_CACHE_NAMESPACE . $key, $this->store_value($value), $ttl);
	}

	public function exists($key){
		return apcu_exists(_CACHE_NAMESPACE . $key);
	}

	public function del($key){
		return apcu_delete(_CACHE_NAMESPACE . $key);
	}

	public function inc($key, $value = null, $ttl = null){
		while (true){
			if ($this->lock($key)){
				$value = isset($value) ? intval($value) : 1;
				$value += intval($this->get($key));
				$this->set($key, $value, $ttl);
				$this->unlock($key);
				return $value;
			}
		}
	}

	public function dec($key, $value = null, $ttl = null){
		$value = isset($value) ? intval($value) : 1;
		return $this->inc($key, -$value, $ttl);
	}

	public function lock($key, /* private */ $unlock = false){
		return apcu_add($this->key_for_lock($key), true);
	}

	public function unlock($key){
		return apcu_delete($this->key_for_lock($key));
	}

	public function size(){
		if (!class_exists('APCUIterator')){
			return false;
		}
		$a = new APCUIterator('/^' . preg_quote(_CACHE_NAMESPACE) . '/', APC_ITER_ALL, 256*256);
		return $a->getTotalSize();
	}

	public function purge(){
		// le cache en memoire est de toute facon invalide par la globale cache_mark et le ttl est cense nettoyer le reste
		if (!class_exists('APCUIterator')){
			return false;
		}
		$a = new APCUIterator('/^' . preg_quote(_CACHE_NAMESPACE) . '/', APC_ITER_ALL, 256*256);
		apcu_delete($a);
		return true;
	}

}