<?php
/**
 * class.memcached.php
 * @package workflow.engine.ProcessMaker
 *
 * ProcessMaker Open Source Edition
 * Copyright (C) 2004 - 2011 Colosa Inc.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program 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 program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * For more information, contact Colosa Inc, 2566 Le Jeune Rd.,
 * Coral Gables, FL, 33134, USA, or email info@colosa.com.
 *
 */

class FileCache {
  
  function __construct($dir) {
    $this->dir = $dir;
  }
  
  private function _name($key) {
    return sprintf ( "%s/%s", $this->dir, sha1 ( $key ) );
  }
  
  public function get($key, $expiration = 3600) {
    
    if (! is_dir ( $this->dir ) or ! is_writable ( $this->dir )) {
      return FALSE;
    }
    
    $cache_path = $this->_name ( $key );
    
    if (! @file_exists ( $cache_path )) {
      return FALSE;
    }
    
    if (filemtime ( $cache_path ) < (time () - $expiration)) {
      // $this->clear($key);
      // different users can have different timeout requests
      return FALSE;
    }
    
    if (! $fp = @fopen ( $cache_path, 'rb' )) {
      return FALSE;
    }
    
    flock ( $fp, LOCK_SH );
    
    $cache = '';
    
    if (filesize ( $cache_path ) > 0) {
      $cache = unserialize ( fread ( $fp, filesize ( $cache_path ) ) );
    }
    else {
      $cache = NULL;
    }
    
    flock ( $fp, LOCK_UN );
    fclose ( $fp );
    
    return $cache;
  }
  
  public function set($key, $data) {
    
    if (! is_dir ( $this->dir ) or ! is_writable ( $this->dir )) {
      return FALSE;
    }
    
    $cache_path = $this->_name ( $key );
    
    if (! $fp = fopen ( $cache_path, 'wb' )) {
      return FALSE;
    }
    
    if (flock ( $fp, LOCK_EX )) {
      fwrite ( $fp, serialize ( $data ) );
      flock ( $fp, LOCK_UN );
    }
    else {
      return FALSE;
    }
    fclose ( $fp );
    @chmod ( $cache_path, 0777 );
    return TRUE;
  }
  
  public function clear($key) {
    $cache_path = $this->_name ( $key );
    
    if (file_exists ( $cache_path )) {
      unlink ( $cache_path );
      return TRUE;
    }
    
    return FALSE;
  }
}