<?php
if(!class_exists('XSLTProcessor')) die(__FILE__.': Please enable XSLTProcessor in your php.ini');
/**
 *  Copyright (C) 2010  Kai Dorschner
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @author Kai Dorschner <the-hide@address.com>
 * @copyright Copyright 2010, Kai Dorschner
 * @license http://www.gnu.org/licenses/gpl.html GPLv3
 * @package mocovi
 */

/**
 * Require Singleton.
 */
class_exists('Singleton')		or require $GLOBALS['library'].'autoload/Singleton.php';
class_exists('MvcException')	or require $GLOBALS['library'].'autoload/MvcException.php';

/**
 * View is appropriated for the appearance at the user's browser
 *
 * Last but not least here we have the "third main pillar" of this project,
 * although it's not less valuable than the others.
 * This little mighty class has the ability to offer the user  a broad spectrum
 * from simple templates to complex export interfaces, transcripting or
 * undreamed-of possibilities supported by the new forward-looking
 * XSLT technology.
 *
 * @package mocovi
 */
class View extends Singleton
{
	/**
	 * Contains the path to the XSL file
	 *
	 * @access protected
	 */
	protected $xslpath;

	/**
	 * Contains the XSLTProcessor object
	 *
	 * @access protected
	 */
	protected $xsl;

	protected $defaultRenderer = 'xmlRenderer';

	/**
	 * Tells the class which output format should be mimed.
	 *
	 * Media Mapping only takes place if the URL filename differs from the xslt templates.
	 *
	 * Usage:
	 * 'possible file name in the URL' => 'file name of the xslt-supported media output'
	 *
	 */
	protected static $mediaMapping = array
		( 'xhtml'	=> 'html'
		, 'htm'		=> 'html'
		, 'php'		=> 'html'
		, 'php3'	=> 'html'
		, 'php4'	=> 'html'
		, 'php5'	=> 'html'
		, 'asp'		=> 'html'
		, 'aspx'	=> 'html'
		, 'jsp'		=> 'html'
		, 'text'	=> 'txt'
		, 'plain'	=> 'txt'
		, 'raw'		=> 'xml'
		);


	/**
	 * Constructor sets the path to the XSL file or throws an error on fault. (Singleton!)
	 *
	 * @access public
	 * @param string $xslpath Contains the path to the XSL file
	 * @return void;
	 */
	protected function __construct($xslpath)
	{
		if(!is_file($xslpath))
			throw new MvcException('Path to the xsl file could not be found.'); // better use / create a 404 Exception?
		$this->xslpath = $xslpath;
	}

	public static function mediaMapping(&$key)
	{
		if(array_key_exists($key, self::$mediaMapping))
			$key = self::$mediaMapping[$key];
		return $key;
	}

	/**
	 * Renders the source XML against the XSL file
	 *
	 * This method renders the XSL against the source XML.
	 *
	 * @access public
	 * @param object $xml Contains a reference of the source XML
	 * @return string XML Document
	 * @see $xsl
	 * @todo Caching doesn't work properly
	 */
	public function transform(DomDocument $xml)
	{
		$lastModifiedTime = date("r", strtotime($GLOBALS['filesystem']->getLastModified($GLOBALS['page'])));
		$etag = md5($GLOBALS['page'].$GLOBALS['language'].$GLOBALS['theme']);
		if($this->isCached())
		{
			$GLOBALS['header']->status(304);
			$GLOBALS['header']->sendHeader();
			exit(0); // exit without errors.
		}
		//$GLOBALS['header']->lastModified($lastModifiedTime);
		//$GLOBALS['header']->etag($etag);
		$this->createXSLTProcessor($this->xslpath);
		return $this->render($this->xsl->transformToXML($xml));
	}

	protected function isCached()
	{
		return ($GLOBALS['caching'] && isset($_SERVER['HTTP_IF_MODIFIED_SINCE'], $_SERVER['HTTP_IF_NONE_MATCH']) && trim($_SERVER['HTTP_IF_NONE_MATCH']) == $etag && strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']) == $lastModifiedTime);
	}

	protected function render($string)
	{
		$class = $GLOBALS['media'].'Renderer';
		if(!is_file($GLOBALS['renderers'].$class.'.php'))
			$class = $this->defaultRenderer;
		class_exists($class) or require $GLOBALS['renderers'].$class.'.php';
		$renderer = new $class();
		return $renderer->render($string);
	}

	protected function createXSLTProcessor($xslpath)
	{
		if(!is_object($this->xsl))
		{
			$xsl_dom						= new DOMDocument();
			$xsl_dom->preserveWhiteSpace	= false;
			$xsl_dom->formatOutput			= false;
			$xsl_dom->load($xslpath);
			$this->xsl						= new XSLTProcessor();
			$this->xsl->registerPHPFunctions(); // Allows the XSL to access custom PHP functions.
			$this->xsl->importStyleSheet($xsl_dom);
		}
	}
}