/*

  * 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.Locale;

 import org.apache.commons.feedparser.tools.RFC3066LocaleParser;

 import org.jaxen.jdom.JDOMXPath;

 import org.jdom.Attribute;

 import org.jdom.Element;

 /**

  * Basic parser support common between RSS, Atom, and FOAF feed impls.

  * 

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

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

  */

 public class BaseParser {

     protected static void doLocale( FeedParserState state,

                                     FeedParserListener listener,

                                     Element element ) throws Exception {

         if ( element == null )

             return;

         if ( state.metaFeedParserlistener == null )

             return;

         String l = getLocaleString( element );

         if ( l != null ) {

             Locale locale = RFC3066LocaleParser.parse( l );

             if ( locale != null )

                 state.metaFeedParserlistener.onLocale( state, locale );

         }

     }

     protected static void doLocaleEnd( FeedParserState state,

                                        FeedParserListener listener,

                                        Element element )

         throws Exception {

         if ( element == null )

             return;

         if ( state.metaFeedParserlistener == null )

             return;

         String l = getLocaleString( element );

         if ( l != null ) 

             state.metaFeedParserlistener.onLocaleEnd();

     }

     protected static String getLocaleString( Element element ) {

         //hm.. crap. how do we get the 'xml' namespace here?

         Attribute attr = element.getAttribute( "lang" );

         if ( attr != null )

             return attr.getValue();

         //when stil null see that we have dc:language

         Element lang = element.getChild( "language", NS.DC );

         if ( lang != null )

             return lang.getText();

         //fall over to just using "language" and if it isn't a local string we

         //won't parse it.  This is for RSS 0.91 and RSS 2.0 content.

         lang = element.getChild( "language" );

         if ( lang != null )

             return lang.getText();

         return null;

     }

     // **** shared code for all parsers *****************************************

     //FIXME: unify this with RSSFeedParser.getChildElementTextByName

     protected static String selectText( String query, Element element ) throws Exception {

         JDOMXPath xpath = new JDOMXPath( query );

         xpath.setNamespaceContext( NS.context );

         //perform onChannel method...  (title, link, description)

         Element e = (Element)xpath.selectSingleNode( element );

         if ( e == null )

             return null;

         String result = e.getText();

         //The normalize method of XML SHOULD take care of this but for some

         //reason it doesnt.

         if ( result != null )

             result = result.trim();

         return result;

     }

     /**

      * Regardless of namespace, get the child node text by name or null if it is not found.

      *

      * 

      */

     protected static String getChildElementTextByName( FeedParserState state,

                                                     String name ) throws Exception {

         //FIXME: this can be rewritten to use getChild()

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

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

         String resultText = null;

         if ( resultNode != null )

             resultText = ((Element)resultNode).getText();

         //The normalize method of XML SHOULD take care of this but for some

         //reason it doesnt.

         if ( resultText != null )

             resultText = resultText.trim();

         return resultText;

     }

 }