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

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

if (!defined('_DIR_TMP')){
	define('_DIR_TMP', 'tmp/');
}
if (!defined('_DIR_CACHE_FILECACHE')){
	if (defined('_DIR_FILECACHE')){
		define('_DIR_CACHE_FILECACHE', _DIR_TMP . _DIR_FILECACHE);
	} // compat
	elseif (defined('_DIR_CACHE')) {
		define('_DIR_CACHE_FILECACHE', _DIR_CACHE);
	} else {
		define('_DIR_CACHE_FILECACHE', _DIR_TMP . 'cache/');
	}
}

class MCacheBackend_filecache implements MCacheBackend {

	// file named tmp/cache/ab/cd
	// that's a maximum of 16^4 files in 256 directories
	private function filename($u){
		$u = md5($u);
		$d = substr($u, 0, 2);
		$u = substr($u, 2, 2);

		# SPIP
		if (function_exists('sous_repertoire')){
			$rep = _DIR_CACHE_FILECACHE;
			if (!@file_exists(_DIR_CACHE_FILECACHE)){
				$rep = sous_repertoire(_DIR_CACHE_FILECACHE, '');
			}
			return sous_repertoire($rep, $d) . $u;
		}

		# Normal PHP
		if (!is_dir(_DIR_CACHE_FILECACHE)){
			@mkdir(_DIR_CACHE_FILECACHE);
		}
		if (!is_dir($sub = _DIR_CACHE_FILECACHE . $d)){
			@mkdir($sub);
		}
		return $sub . '/' . $u;
	}

	/* Interface */

	public function init($params = null){

	}

	public function get($key){
		if ($c = @file_get_contents($this->filename($key))
			and $r = unserialize($c)
			and $r[1]===$key
			and $r[2]>=time()){
			return $r[0];
		}
	}

	public function set($key, $value, $ttl = null){
		$r = array($value);
		$r[1] = $key;
		$r[2] = isset($ttl)
			? time()+intval($ttl)
			: time()+365*24*3600;

		return (
			$f = $this->filename($key)
			and $n = @tempnam(dirname($f), 'xc')
			and $h = @fopen($n, 'w')
			and @fwrite($h, serialize($r))
			and @fclose($h)
			and @rename($n, $f)
		);
	}

	public function exists($key){
		if ($c = @file_get_contents($this->filename($key))
			and $r = @unserialize($c)
			and $r[1]==$key
			and $r[2]>=time()){
			return true;
		} else {
			return false;
		}
	}

	public function del($key){
		return (
			$c = @file_get_contents($f = $this->filename($key))
			and $s = supprimer_fichier($f)
			and $r = @unserialize($c)
			and $r[1]==$key
			and $r[2]>=time()
		);
	}

	public function inc($key, $value = null, $ttl = null){
		$this->lock($key);
		$value = (isset($value) ? intval($value) : 1)+intval($this->get($key));
		$this->set($key, $value);
		$this->unlock($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){
		static $locks = array();
		$f = $this->filename($key);

		/* unlock */
		if ($unlock){
			if (isset($locks[$f])
				and is_resource($locks[$f])){
				@flock($locks[$f], LOCK_UN);
				@fclose($locks[$f]);
				unset($locks[$f]);
			}
		} /* lock */
		else {
			if (!isset($locks[$f])){
				$locks[$f] = @fopen($f, 'a');
				@flock($locks[$f], LOCK_EX);
				return true;
			}
		}
	}

	public function unlock($key){
		$this->lock($key, true);
	}

	public function size(){
		# check dirs until we reach > 500 files
		$t = 0;
		$n = 0;
		$time = (isset($GLOBALS['meta']['cache_mark']) ? $GLOBALS['meta']['cache_mark'] : 0);
		for ($i = 0; $i<256; $i++){
			$dir = _DIR_CACHE . sprintf('%02s', dechex($i));
			if (@is_dir($dir) and is_readable($dir) and $d = @opendir($dir)){
				while (($f = readdir($d))!==false){
					if (preg_match(',^[0-9a-f][0-9a-f]$,S', $f)
						and $a = stat("$dir/$f")){
						$n++;
						if ($a['mtime']>=$time){
							if ($a['blocks']>0){
								$t += 512*$a['blocks'];
							} else {
								$t += $a['size'];
							}
						}
					}
				}
			}
			if ($n>500){
				return intval(256*$t/(1+$i));
			}
		}
		return $t;
	}

	public function purge(){
		return false;
	}
}