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

namespace Joomla\CMS\Feed;

defined('JPATH_PLATFORM') or die;

use Joomla\CMS\Http\HttpFactory;
use Joomla\Registry\Registry;

/**
 * Feed factory class.
 *
 * @since  12.3
 */
class FeedFactory
{
	/**
	 * @var    array  The list of registered parser classes for feeds.
	 * @since  12.3
	 */
	protected $parsers = array('rss' => 'Joomla\\CMS\\Feed\\Parser\\RssParser', 'feed' => 'Joomla\\CMS\\Feed\\Parser\\AtomParser');

	/**
	 * Method to load a URI into the feed reader for parsing.
	 *
	 * @param   string  $uri  The URI of the feed to load. Idn uris must be passed already converted to punycode.
	 *
	 * @return  Feed
	 *
	 * @since   12.3
	 * @throws  \InvalidArgumentException
	 * @throws  \RuntimeException
	 */
	public function getFeed($uri)
	{
		// Create the XMLReader object.
		$reader = new \XMLReader;

		// Open the URI within the stream reader.
		if (!@$reader->open($uri, null, LIBXML_NOERROR | LIBXML_ERR_NONE | LIBXML_NOWARNING))
		{
			// Retry with JHttpFactory that allow using CURL and Sockets as alternative method when available

			// Adding a valid user agent string, otherwise some feed-servers returning an error
			$options = new Registry;
			$options->set('userAgent', 'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:41.0) Gecko/20100101 Firefox/41.0');

			try
			{
				$response = HttpFactory::getHttp($options)->get($uri);
			}
			catch (RuntimeException $e)
			{
				throw new \RuntimeException('Unable to open the feed.', $e->getCode(), $e);
			}

			if ($response->code != 200)
			{
				throw new \RuntimeException('Unable to open the feed.');
			}

			// Set the value to the XMLReader parser
			if (!$reader->xml($response->body, null, LIBXML_NOERROR | LIBXML_ERR_NONE | LIBXML_NOWARNING))
			{
				throw new \RuntimeException('Unable to parse the feed.');
			}
		}

		try
		{
			// Skip ahead to the root node.
			while ($reader->read())
			{
				if ($reader->nodeType == \XMLReader::ELEMENT)
				{
					break;
				}
			}
		}
		catch (\Exception $e)
		{
			throw new \RuntimeException('Error reading feed.', $e->getCode(), $e);
		}

		// Setup the appropriate feed parser for the feed.
		$parser = $this->_fetchFeedParser($reader->name, $reader);

		return $parser->parse();
	}

	/**
	 * Method to register a FeedParser class for a given root tag name.
	 *
	 * @param   string   $tagName    The root tag name for which to register the parser class.
	 * @param   string   $className  The FeedParser class name to register for a root tag name.
	 * @param   boolean  $overwrite  True to overwrite the parser class if one is already registered.
	 *
	 * @return  FeedFactory
	 *
	 * @since   12.3
	 * @throws  \InvalidArgumentException
	 */
	public function registerParser($tagName, $className, $overwrite = false)
	{
		// Verify that the class exists.
		if (!class_exists($className))
		{
			throw new \InvalidArgumentException('The feed parser class ' . $className . ' does not exist.');
		}

		// Validate that the tag name is valid.
		if (!preg_match('/\A(?!XML)[a-z][\w0-9-]*/i', $tagName))
		{
			throw new \InvalidArgumentException('The tag name ' . $tagName . ' is not valid.');
		}

		// Register the given parser class for the tag name if nothing registered or the overwrite flag set.
		if (empty($this->parsers[$tagName]) || (bool) $overwrite)
		{
			$this->parsers[(string) $tagName] = (string) $className;
		}

		return $this;
	}

	/**
	 * Method to return a new JFeedParser object based on the registered parsers and a given type.
	 *
	 * @param   string      $type    The name of parser to return.
	 * @param   \XMLReader  $reader  The XMLReader instance for the feed.
	 *
	 * @return  FeedParser
	 *
	 * @since   12.3
	 * @throws  \LogicException
	 */
	private function _fetchFeedParser($type, \XMLReader $reader)
	{
		// Look for a registered parser for the feed type.
		if (empty($this->parsers[$type]))
		{
			throw new \LogicException('No registered feed parser for type ' . $type . '.');
		}

		return new $this->parsers[$type]($reader);
	}
}
