<?php
/**
 * @package     Joomla.Platform
 * @subpackage  Cache
 *
 * @copyright   Copyright (C) 2005 - 2011 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE
 */

defined('JPATH_PLATFORM') or die;

/**
 * Joomla! Cache page type object
 *
 * @package     Joomla.Platform
 * @subpackage  Cache
 * @since       11.1
 */
class JCacheControllerPage extends JCacheController
{
    /**
     * ID property for the cache page object.
     *
     * @var     integer
     * @since   11.1
     */
    private $_id;

    /**
     * Cache group
     *
     * @var     string
     * @since   11.1
     */
    private $_group;

    /**
     * Cache lock test
     *
     * @var     object
     * @since   11.1
     */
    private $_locktest = null;

    /**
     * Get the cached page data
     *
     * @param   string  $id     The cache data id
     * @param   string  $group  The cache data group
     * 
     * @return  boolean True if the cache is hit (false else)
     * @since   11.1
     */
    public function get($id=false, $group='page', $wrkarounds=true)
    {
        // Initialise variables.
        $data = false;

        // If an id is not given generate it from the request
        if ($id == false) {
            $id = $this->_makeId();
        }

        // If the etag matches the page id ... set a no change header and exit : utilize browser cache
        if (!headers_sent() && isset($_SERVER['HTTP_IF_NONE_MATCH'])){
            $etag = stripslashes($_SERVER['HTTP_IF_NONE_MATCH']);
            if ($etag == $id) {
                $browserCache = isset($this->options['browsercache']) ? $this->options['browsercache'] : false;
                if ($browserCache) {
                    $this->_noChange();
                }
            }
        }

        // We got a cache hit... set the etag header and echo the page data
        $data = $this->cache->get($id, $group);

        $this->_locktest = new stdClass;
        $this->_locktest->locked = null;
        $this->_locktest->locklooped = null;

        if ($data === false) {
            $this->_locktest = $this->cache->lock($id, $group);
            if ($this->_locktest->locked == true && $this->_locktest->locklooped == true) {
                $data = $this->cache->get($id, $group);
            }
        }

        if ($data !== false) {
            $data = unserialize(trim($data));
            if ($wrkarounds === true) {
                echo JCache::getWorkarounds($data);
            }

            $this->_setEtag($id);
            if ($this->_locktest->locked == true) {
                $this->cache->unlock($id, $group);
            }
            return $data;
        }

        // Set id and group placeholders
        $this->_id      = $id;
        $this->_group   = $group;
        return false;
    }

    /**
     * Stop the cache buffer and store the cached data
     *
     * @return  boolean True if cache stored
     * @since   11.1
     */
    public function store($wrkarounds=true)
    {
        // Get page data from JResponse body
        $data = JResponse::getBody();

        // Get id and group and reset the placeholders
        $id     = $this->_id;
        $group  = $this->_group;
        $this->_id      = null;
        $this->_group   = null;

        // Only attempt to store if page data exists
        if ($data) {
            $data = $wrkarounds==false ? $data : JCache::setWorkarounds($data);

            if ($this->_locktest->locked == false) {
                $this->_locktest = $this->cache->lock($id, $group);
            }

            $sucess = $this->cache->store(serialize($data), $id, $group);

            if ($this->_locktest->locked == true) {
                $this->cache->unlock($id, $group);
            }

            return $sucess;
        }
        return false;
    }

    /**
     * Generate a page cache id
     *
     * @todo    TODO: Discuss whether this should be coupled to a data hash or a request 
     *          hash ... perhaps hashed with a serialized request
     *
     * @return  string  MD5 Hash : page cache id
     * @since   11.1
     */
    private function _makeId()
    {
        //return md5(JRequest::getURI());
        return JCache::makeId();
    }

    /**
     * There is no change in page data so send a not modified header and die gracefully
     *
     * @return  void
     * @since   11.1
     */
    private function _noChange()
    {
        $app = JFactory::getApplication();

        // Send not modified header and exit gracefully
        header('HTTP/1.x 304 Not Modified', true);
        $app->close();
    }

    /**
     * Set the ETag header in the response
     *
     * @return  void
     * @since   11.1
     */
    private function _setEtag($etag)
    {
        JResponse::setHeader('ETag', $etag, true);
    }
}