<?php

class RSSData {
	public $error;
	public $items;

	/**
	 * Constructor, takes a DOMDocument and returns an array of parsed items.
	 * @param $xml DOMDocument: the pre-parsed XML Document
	 * @return Object RSSData object with a member items that is an array of parsed items,
	 */
	function __construct( $xml ) {
		if ( !( $xml instanceof DOMDocument ) ) {
			$this->error = "Not passed DOMDocument object.";
			return;
		}
		$xpath = new DOMXPath( $xml );
	
		// register namespace as below, and apply a regex to the expression
		// http://de3.php.net/manual/en/domxpath.query.php#103461
		$namespaceURI = $xml->lookupnamespaceURI( NULL );

		if ( ( null !== $namespaceURI ) ) {
			$defaultNS = "defaultNS";
			$xpath->registerNamespace( $defaultNS, $namespaceURI );
			$defaultNS = "defaultNS:";
		} else {
			$defaultNS = "";
		}

		// is it an RSS feed ?
		$items = $xpath->query( $this->namespacePrefixedQuery( "/rss/channel/item", $defaultNS ) ); 

		if ( $items->length === 0 ) {
			 // or is it an ATOM feed ?
			$items = $xpath->query( $this->namespacePrefixedQuery( "/feed/entry", $defaultNS ) );
		}

		if( $items->length !== 0 ) {
			foreach ( $items as $item ) {
				$bit = array();
				foreach ( $item->childNodes as $n ) {
					$name = $this->rssTokenToName( $n->nodeName );
					if ( $name != null ) {
						/**
						 * Because for DOMElements the nodeValue is just
						 * the text of the containing element, without any
						 * tags, it makes this a safe, if unattractive,
						 * value to use. If you want to allow people to
						 * mark up their RSS, some more precautions are
						 * needed.
						 */
						$bit[$name] = $n->nodeValue;
					}
				}
				$this->items[] = $bit;
			}
		} else {
			$this->error = 'No RSS//ATOM items found.';
			return;
		}
	}

	protected function namespacePrefixedQuery( $query, $namespace = "" ) {
		if ( $namespace !== "" ) {
			$ret = preg_replace( '#(::|/\s*|\A)(?![/@].+?|[a-z\-]+::)#', '$1' . $namespace . '$2', $query );
		} else {
			$ret = $query;
		}
		return $ret;
	}
	/**
	 * Return a string that will be used to map RSS elements that
	 * contain similar data (e.g. dc:date, date, and pubDate) to the
	 * same array key.  This works on WordPress feeds as-is, but it
	 * probably needs a way to concert dc:date format dates to be the
	 * same as pubDate.
	 *
	 * @param $n String: name of the element we have
	 * @return String Name to map it to
	 */
	protected function rssTokenToName( $name ) {
		switch( $name ) {
			case 'dc:date':
			case 'pubDate':
			case 'updated':
				return 'date';
			case 'dc:creator':
				return 'author';
			case 'summary':
				return 'description';
			case 'content:encoded':
				return 'encodedContent';

			case 'slash:comments':
			case 'slash:department':
			case 'slash:section':
			case 'slash:hit_parade':
			case 'feedburner:origLink':
			case 'wfw:commentRss':
			case 'comments':
			case 'category':
				return null;
			default:
				return $name;
		}
	}
}