<?php

/** This file is part of KCFinder project
  *
  *      @desc HTTP cache helper class
  *   @package KCFinder
  *   @version 2.21
  *    @author Pavel Tzonkov <pavelc@users.sourceforge.net>
  * @copyright 2010 KCFinder Project
  *   @license http://www.opensource.org/licenses/gpl-2.0.php GPLv2
  *   @license http://www.opensource.org/licenses/lgpl-2.1.php LGPLv2
  *      @link http://kcfinder.sunhater.com
  */

class httpCache {
    const DEFAULT_TYPE = "text/html";
    const DEFAULT_EXPIRE = 604800; // in seconds

  /** Cache a file. The $type parameter might define the MIME type of the file
    * or path to magic file to autodetect the MIME type. If you skip $type
    * parameter the method will try with the default magic file. Autodetection
    * of MIME type requires Fileinfo PHP extension used in file::getMimeType()
    * @param string $file
    * @param string $type
    * @param integer $expire
    * @param array $headers */

    static function file($file, $type=null, $expire=null, array $headers=null) {
        $mtime = @filemtime($file);
        if ($mtime !== false) self::checkMTime($mtime);

        if ($type === null) {
            $magic = ((substr($type, 0, 1) == "/") || preg_match('/^[a-z]\:/i', $type))
                ? $type : null;
            $type = file::getMimeType($file, $magic);
            if (!$type) $type = null;
        }

        self::content(@file_get_contents($file), $mtime, $type, $expire, $headers, false);
    }

  /** Cache the given $content with $mtime modification time.
    * @param binary $content
    * @param integer $mtime
    * @param string $type
    * @param integer $expire
    * @param array $headers
    * @param bool $checkMTime */

    static function content($content, $mtime, $type=null, $expire=null, array $headers=null, $checkMTime=true) {
        if ($checkMTime) self::checkMTime($mtime);
        if ($type === null) $type = self::DEFAULT_TYPE;
        if ($expire === null) $expire = self::DEFAULT_EXPIRE;
        $size = strlen($content);
        $expires = gmdate("D, d M Y H:i:s", time() + $expire) . " GMT";
        header("Content-Type: $type");
        header("Expires: $expires");
        header("Cache-Control: max-age=$expire");
        header("Pragma: !invalid");
        header("Content-Length: $size");
        if ($headers !== null) foreach ($headers as $header) header($header);
        echo $content;
    }

  /** Check if given modification time is newer than client-side one. If not,
    * the method will tell the client to get the content from its own cache.
    * Afterwards the script process will be terminated. This feature requires
    * the PHP to be configured as Apache module.
    * @param integer $mtime */

    static function checkMTime($mtime) {
        header("Last-Modified: " . gmdate("D, d M Y H:i:s", $mtime) . " GMT");

        $headers = function_exists("getallheaders")
            ? getallheaders()
            : (function_exists("apache_request_headers")
                ? apache_request_headers()
                : false);

        if (is_array($headers) && isset($headers['If-Modified-Since'])) {
            $client_mtime = explode(';', $headers['If-Modified-Since']);
            $client_mtime = strtotime($client_mtime[0]);
            if ($client_mtime >= $mtime) {
                header('HTTP/1.1 304 Not Modified');
                die;
            }
        }
    }
}

?>