/*

  * Copyright 1999,2004 The Apache Software Foundation.

  * 

  * Licensed under the Apache License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  * 

  *      http://www.apache.org/licenses/LICENSE-2.0

  * 

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 package org.apache.commons.feedparser;

 import java.util.Iterator;

 import java.util.List;

 import org.jaxen.jdom.JDOMXPath;

 import org.jdom.Attribute;

 import org.jdom.Element;

 /**

  * Handles parsing RSS .

  *

  * @author <a href="mailto:burton@apache.org">Kevin A. Burton (burtonator)</a>

  * @version $Id: RSSFeedParser.java 373614 2006-01-30 22:31:21Z mvdb $

  */

 public class RSSFeedParser extends BaseParser {

     /**

      * Parse the given document as an OPML document.

      *

      * 

      */

     public static void parse( FeedParserListener listener,

                               org.jdom.Document doc ) throws Exception {

         FeedParserState state = new FeedParserState( listener );

         FeedVersion v = new FeedVersion();

         v.isRSS = true;

         v.version = doc.getRootElement().getAttributeValue( "version" );

         listener.onFeedVersion( v );

         listener.init();

         //*** now process the channel. ***

         JDOMXPath xpath = new JDOMXPath( "/descendant::*[local-name() = 'channel']" );

         Element channel = (Element)xpath.selectSingleNode( doc );

         state.current = channel;

         doLocale( state, listener, channel );

         doChannel( listener, state );

         doLocaleEnd( state, listener, channel );

         //*** now process the image. ***

         xpath = new JDOMXPath( "/descendant::*[local-name() = 'image']" );

         List images = xpath.selectNodes( doc );

         Iterator i = images.iterator();

         //update items.

         while ( i.hasNext() ) {

             Element child = (Element)i.next();

             state.current = child;

             doParseImage( listener, state );

         }

         //*** now process all items. ***

         xpath = new JDOMXPath( "/descendant::*[local-name() = 'item']" );

         List items = xpath.selectNodes( doc );

         i = items.iterator();

         //update items.

         while ( i.hasNext() ) {

             Element item = (Element)i.next();

             state.current = item;

             doLocale( state, listener, item );

             doItem( listener, state );

             doLocaleEnd( state, listener, item );

         }

         listener.finished();

     }

     /**

      * Parse the given channel 

      *

      * 

      */

     private static void doChannel( FeedParserListener listener,

                                    FeedParserState state ) throws Exception {

         String link = getChildElementTextByName( state, "link" );

         if ( link != null )

             link = link.trim();

         listener.onChannel( state, 

                             getChildElementTextByName( state, "title" ),

                             link,

                             getChildElementTextByName( state, "description" ) );

         listener.onChannelEnd();

     }

     /**

      * Parse the given channel 

      *

      * 

      */

     private static void doParseImage( FeedParserListener listener,

                                       FeedParserState state ) throws Exception {

         String title = getChildElementTextByName( state, "title" );

         String link = getChildElementTextByName( state, "link" );

         String url = getChildElementTextByName( state, "url" );

         if ( url != null ) {

             listener.onImage( state, title, link, url );

             listener.onImageEnd();

         } 

     }

     /**

      * 

      *

      * 

      */

     private static void doItem( FeedParserListener listener,

                                 FeedParserState state ) throws Exception {

         String resource = null;

         //FIXME: migrate this to XPath

         JDOMXPath xpath = new JDOMXPath( "@rdf:resource|guid|descendant::*[local-name() = 'link']" );

         xpath.addNamespace( NS.RDF.getPrefix(), NS.RDF.getURI() );

         Object node = xpath.selectSingleNode( state.current );

         //FIXME: if this is a GUID and isPermalink=false don't use it as the

         //permalink.

         if ( node instanceof Element ) {

             Element element = (Element)node;

             resource = element.getText();

             if ( "guid".equals( element.getName() ) ) {

                 boolean isPermaLink =

                     "true".equals( element.getAttributeValue( "isPermaLink" ) );

                 if ( isPermaLink == false ) {

                     //resort to the 'link'

                     Element link = state.current.getChild( "link" );

                     if ( link != null ) {

                         resource = link.getText();

                     }

                 }

             }

         } else if ( node instanceof Attribute ) {

             resource = ((Attribute)node).getValue();

         }

         if ( resource == null )

             return;

         //title, link, description

         listener.onItem( state,

                          getChildElementTextByName( state, "title" ),

                          getChildElementTextByName( state, "link" ),

                          getChildElementTextByName( state, "description" ),

                          resource );

         //see if we have content encoded and if we need to report these events.

         if ( listener instanceof ModContentFeedParserListener ) {

             ModContentFeedParserListener mcpl = (ModContentFeedParserListener)listener;

             Element encoded = state.current.getChild( "encoded", NS.CONTENT );

             if ( encoded != null ) {

                 //FIXME: move to the onContent API defined within the

                 //AtomFeedParser and deprecated this body handling.

                 mcpl.onContentEncoded( new FeedParserState( encoded ),

                                        encoded.getText() );

                 mcpl.onContentEncodedEnd();

             } else {

                 Element items = state.current.getChild( "items", NS.CONTENT );

                 if ( items != null ) {

                     //FIXME: with malformed XML this could throw an NPE. Luckly

                     //this format is rare now.

                     Element value =

                         items.getChild( "Bag", NS.RDF )

                             .getChild( "li", NS.RDF )

                                 .getChild( "item", NS.CONTENT )

                                     .getChild( "value", NS.RDF );

                     //FIXME: move to the onContent API defined within the

                     //AtomFeedParser and deprecated this body handling.

                     mcpl.onContentItem( new FeedParserState( value ),

                                         null,

                                         null,

                                         value );

                     mcpl.onContentItemEnd();

                 }

             }

         } 

         //process xhtml:body

         if ( listener instanceof XHTMLFeedParserListener ) {

             XHTMLFeedParserListener xfp = (XHTMLFeedParserListener)listener;

             Element body = state.current.getChild( "body", NS.XHTML );

             //FIXME: move to the onContent API defined within the AtomFeedParser

             //and deprecated this body handling.

             if ( body != null ) {

                 xfp.onXHTMLBody( new FeedParserState( body ),

                                  body );

                 xfp.onXHTMLBodyEnd();

             } 

         }

         MetaFeedParser.parse( listener, state );

         TagFeedParser.parse( listener, state );

         doEnclosures( listener, state );

         listener.onItemEnd();

     }

     private static void doEnclosures( FeedParserListener listener,

                                       FeedParserState state ) throws Exception {

         if ( listener instanceof LinkFeedParserListener == false )

             return;

         Element element = state.current.getChild( "enclosure" );

         if ( element == null )

             return;

         LinkFeedParserListener linkFeedParserListener = (LinkFeedParserListener)listener;

         String rel = null;

         String type = element.getAttributeValue( "type" );

         String href = element.getAttributeValue( "url" );

         String title = null;

         long length = 0;

         if (element.getAttributeValue("length") != null)

                 length = Integer.parseInt( element.getAttributeValue( "length" ) );

         linkFeedParserListener.onLink( state,

                                        rel,

                                        type,

                                        href,

                                        title,

                                        length );

     }

 }