<?php

/**

* @version		$Id: callback.php 10707 2008-08-21 09:52:47Z eddieajau $

* @package		Joomla.Framework

* @subpackage	Cache

* @copyright	Copyright (C) 2005 - 2008 Open Source Matters. All rights reserved.

* @license		GNU/GPL, see LICENSE.php

* Joomla! is free software. This version may have been modified pursuant

* to the GNU General Public License, and as distributed it includes or

* is derivative of works licensed under the GNU General Public License or

* other free or open source software licenses.

* See COPYRIGHT.php for copyright notices and details.

*/



// Check to ensure this file is within the rest of the framework

defined('JPATH_BASE') or die();



/**

 * Joomla! Cache callback type object

 *

 * @package		Joomla.Framework

 * @subpackage	Cache

 * @since		1.5

 */

class JCacheCallback extends JCache

{

	/**

	 * Executes a cacheable callback if not found in cache else returns cached output and result

	 *

	 * Since arguments to this function are read with func_get_args you can pass any number of arguments to this method

	 * as long as the first argument passed is the callback definition.

	 *

	 * The callback definition can be in several forms:

	 * 	- Standard PHP Callback array <http://php.net/callback> [recommended]

	 * 	- Function name as a string eg. 'foo' for function foo()

	 * 	- Static method name as a string eg. 'MyClass::myMethod' for method myMethod() of class MyClass

	 *

	 * @access	public

	 * @return	mixed	Result of the callback

	 * @since	1.5

	 */

	function call()

	{

		// Get callback and arguments

		$args		= func_get_args();

		$callback	= array_shift($args);



		return $this->get( $callback, $args );

	}



	/**

	 * Executes a cacheable callback if not found in cache else returns cached output and result

	 *

	 * @access	public

	 * @param	mixed	Callback or string shorthand for a callback

	 * @param	array	Callback arguments

	 * @return	mixed	Result of the callback

	 * @since	1.5

	 */

	function get( $callback, $args, $id=false )

	{

		// Normalize callback

		if (is_array( $callback )) {

			// We have a standard php callback array -- do nothing

		} elseif (strstr( $callback, '::' )) {

			// This is shorthand for a static method callback classname::methodname

			list( $class, $method ) = explode( '::', $callback );

			$callback = array( trim($class), trim($method) );

		} elseif (strstr( $callback, '->' )) {

			/*

			 * This is a really not so smart way of doing this... we provide this for backward compatability but this

			 * WILL!!! disappear in a future version.  If you are using this syntax change your code to use the standard

			 * PHP callback array syntax: <http://php.net/callback>

			 *

			 * We have to use some silly global notation to pull it off and this is very unreliable

			 */

			list( $object_123456789, $method ) = explode('->', $callback);

			global $$object_123456789;

			$callback = array( $$object_123456789, $method );

		} else {

			// We have just a standard function -- do nothing

		}



		if (!$id) {

			// Generate an ID

			$id = $this->_makeId($callback, $args);

		}



		// Get the storage handler and get callback cache data by id and group

		$data = parent::get($id);

		if ($data !== false) {

			$cached = unserialize( $data );

			$output = $cached['output'];

			$result = $cached['result'];

		} else {

			ob_start();

			ob_implicit_flush( false );



			$result = call_user_func_array($callback, $args);

			$output = ob_get_contents();



			ob_end_clean();



			$cached = array();

			$cached['output'] = $output;

			$cached['result'] = $result;

			// Store the cache data

			$this->store(serialize($cached), $id);

		}



		echo $output;

		return $result;

	}



	/**

	 * Generate a callback cache id

	 *

	 * @access	private

	 * @param	callback	$callback	Callback to cache

	 * @param	array		$args	Arguments to the callback method to cache

	 * @return	string	MD5 Hash : function cache id

	 * @since	1.5

	 */

	function _makeId($callback, $args)

	{

		if(is_array($callback) && is_object($callback[0])) {

			$vars = get_object_vars($callback[0]);

			$vars[] = strtolower(get_class($callback[0]));

			$callback[0] = $vars;

		}

		return md5(serialize(array($callback, $args)));

	}

}