<?php
/**
 * @package     Joomla.Plugin
 * @subpackage  System.sef
 *
 * @copyright   Copyright (C) 2005 - 2017 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE.txt
 */

defined('_JEXEC') or die;

/**
 * Joomla! SEF Plugin.
 *
 * @since  1.5
 */
class PlgSystemSef extends JPlugin
{
	/**
	 * Application object.
	 *
	 * @var    JApplicationCms
	 * @since  3.5
	 */
	protected $app;

	/**
	 * Add the canonical uri to the head.
	 *
	 * @return  void
	 *
	 * @since   3.5
	 */
	public function onAfterDispatch()
	{
		$doc = $this->app->getDocument();

		if (!$this->app->isClient('site') || $doc->getType() !== 'html')
		{
			return;
		}

		$sefDomain = $this->params->get('domain', '');

		// Don't add a canonical html tag if no alternative domain has added in SEF plugin domain field.
		if (empty($sefDomain))
		{
			return;
		}

		// Check if a canonical html tag already exists (for instance, added by a component).
		$canonical = '';

		foreach ($doc->_links as $linkUrl => $link)
		{
			if (isset($link['relation']) && $link['relation'] === 'canonical')
			{
				$canonical = $linkUrl;
				break;
			}
		}

		// If a canonical html tag already exists get the canonical and change it to use the SEF plugin domain field.
		if (!empty($canonical))
		{
			// Remove current canonical link.
			unset($doc->_links[$canonical]);

			// Set the current canonical link but use the SEF system plugin domain field.
			$canonical = $sefDomain . JUri::getInstance($canonical)->toString(array('path', 'query', 'fragment'));
		}
		// If a canonical html doesn't exists already add a canonical html tag using the SEF plugin domain field.
		else
		{
			$canonical = $sefDomain . JUri::getInstance()->toString(array('path', 'query', 'fragment'));
		}

		// Add the canonical link.
		$doc->addHeadLink(htmlspecialchars($canonical), 'canonical');
	}

	/**
	 * Convert the site URL to fit to the HTTP request.
	 *
	 * @return  void
	 */
	public function onAfterRender()
	{
		if (!$this->app->isClient('site'))
		{
			return;
		}

		// Replace src links.
		$base   = JUri::base(true) . '/';
		$buffer = $this->app->getBody();

		// For feeds we need to search for the URL with domain.
		$prefix = $this->app->getDocument()->getType() === 'feed' ? JUri::root() : '';

		// Replace index.php URI by SEF URI.
		if (strpos($buffer, 'href="' . $prefix . 'index.php?') !== false)
		{
			preg_match_all('#href="' . $prefix . 'index.php\?([^"]+)"#m', $buffer, $matches);

			foreach ($matches[1] as $urlQueryString)
			{
				$buffer = str_replace(
					'href="' . $prefix . 'index.php?' . $urlQueryString . '"',
					'href="' . trim($prefix, '/') . JRoute::_('index.php?' . $urlQueryString) . '"',
					$buffer
				);
			}

			$this->checkBuffer($buffer);
		}

		// Check for all unknown protocals (a protocol must contain at least one alpahnumeric character followed by a ":").
		$protocols  = '[a-zA-Z0-9\-]+:';
		$attributes = array('href=', 'src=', 'poster=');

		foreach ($attributes as $attribute)
		{
			if (strpos($buffer, $attribute) !== false)
			{
				$regex  = '#\s' . $attribute . '"(?!/|' . $protocols . '|\#|\')([^"]*)"#m';
				$buffer = preg_replace($regex, ' ' . $attribute . '"' . $base . '$1"', $buffer);
				$this->checkBuffer($buffer);
			}
		}
		
		if (strpos($buffer, 'srcset=') !== false) 
		{
			$regex = '#\s+srcset="([^"]+)"#m';
			
			$buffer = preg_replace_callback(
				$regex,
				function ($match) use ($base, $protocols)
				{
					$data = array();
					foreach (explode(",", $match[1]) as $url)
					{
						$data[] = preg_replace('#^(?!/|' . $protocols . '|\#|\')(.+)#', $base . '$1', trim($url));
					}
					return ' srcset="' . implode(",", $data) . '"';
				},
				$buffer
			);	

			$this->checkBuffer($buffer);
		}

		// Replace all unknown protocals in javascript window open events.
		if (strpos($buffer, 'window.open(') !== false)
		{
			$regex  = '#onclick="window.open\(\'(?!/|' . $protocols . '|\#)([^/]+[^\']*?\')#m';
			$buffer = preg_replace($regex, 'onclick="window.open(\'' . $base . '$1', $buffer);
			$this->checkBuffer($buffer);
		}

		// Replace all unknown protocols in onmouseover and onmouseout attributes.
		$attributes = array('onmouseover=', 'onmouseout=');

		foreach ($attributes as $attribute)
		{
			if (strpos($buffer, $attribute) !== false)
			{
				$regex  = '#' . $attribute . '"this.src=([\']+)(?!/|' . $protocols . '|\#|\')([^"]+)"#m';
				$buffer = preg_replace($regex, $attribute . '"this.src=$1' . $base . '$2"', $buffer);
				$this->checkBuffer($buffer);
			}
		}

		// Replace all unknown protocols in CSS background image.
		if (strpos($buffer, 'style=') !== false)
		{
			$regex_url  = '\s*url\s*\(([\'\"]|\&\#0?3[49];)?(?!/|\&\#0?3[49];|' . $protocols . '|\#)([^\)\'\"]+)([\'\"]|\&\#0?3[49];)?\)';
			$regex  = '#style=\s*([\'\"])(.*):' . $regex_url . '#m';
			$buffer = preg_replace($regex, 'style=$1$2: url($3' . $base . '$4$5)', $buffer);
			$this->checkBuffer($buffer);
		}

		// Replace all unknown protocols in OBJECT param tag.
		if (strpos($buffer, '<param') !== false)
		{
			// OBJECT <param name="xx", value="yy"> -- fix it only inside the <param> tag.
			$regex  = '#(<param\s+)name\s*=\s*"(movie|src|url)"[^>]\s*value\s*=\s*"(?!/|' . $protocols . '|\#|\')([^"]*)"#m';
			$buffer = preg_replace($regex, '$1name="$2" value="' . $base . '$3"', $buffer);
			$this->checkBuffer($buffer);

			// OBJECT <param value="xx", name="yy"> -- fix it only inside the <param> tag.
			$regex  = '#(<param\s+[^>]*)value\s*=\s*"(?!/|' . $protocols . '|\#|\')([^"]*)"\s*name\s*=\s*"(movie|src|url)"#m';
			$buffer = preg_replace($regex, '<param value="' . $base . '$2" name="$3"', $buffer);
			$this->checkBuffer($buffer);
		}

		// Replace all unknown protocols in OBJECT tag.
		if (strpos($buffer, '<object') !== false)
		{
			$regex  = '#(<object\s+[^>]*)data\s*=\s*"(?!/|' . $protocols . '|\#|\')([^"]*)"#m';
			$buffer = preg_replace($regex, '$1data="' . $base . '$2"', $buffer);
			$this->checkBuffer($buffer);
		}

		// Use the replaced HTML body.
		$this->app->setBody($buffer);
	}

	/**
	 * Check the buffer.
	 *
	 * @param   string  $buffer  Buffer to be checked.
	 *
	 * @return  void
	 */
	private function checkBuffer($buffer)
	{
		if ($buffer === null)
		{
			switch (preg_last_error())
			{
				case PREG_BACKTRACK_LIMIT_ERROR:
					$message = 'PHP regular expression limit reached (pcre.backtrack_limit)';
					break;
				case PREG_RECURSION_LIMIT_ERROR:
					$message = 'PHP regular expression limit reached (pcre.recursion_limit)';
					break;
				case PREG_BAD_UTF8_ERROR:
					$message = 'Bad UTF8 passed to PCRE function';
					break;
				default:
					$message = 'Unknown PCRE error calling PCRE function';
			}

			throw new RuntimeException($message);
		}
	}

	/**
	 * Replace the matched tags.
	 *
	 * @param   array  &$matches  An array of matches (see preg_match_all).
	 *
	 * @return  string
	 *
	 * @deprecated  4.0  No replacement.
	 */
	protected static function route(&$matches)
	{
		JLog::add(__METHOD__ . ' is deprecated, no replacement.', JLog::WARNING, 'deprecated');

		$url   = $matches[1];
		$url   = str_replace('&amp;', '&', $url);
		$route = JRoute::_('index.php?' . $url);

		return 'href="' . $route;
	}
}
