/*

  * Licensed to the Apache Software Foundation (ASF) under one or more

  * contributor license agreements.  See the NOTICE file distributed with

  * this work for additional information regarding copyright ownership.

  * The ASF licenses this file to You 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.any23.filter;

 import org.apache.any23.extractor.ExtractionContext;

 import org.apache.any23.extractor.html.TitleExtractor;

 import org.apache.any23.writer.TripleHandler;

 import org.apache.any23.writer.TripleHandlerException;

 import org.openrdf.model.Resource;

 import org.openrdf.model.URI;

 import org.openrdf.model.Value;

 /**

  * A {@link TripleHandler} that suppresses output of the

  * {@link TitleExtractor} unless some other triples could

  * be parsed from the document. This is used when we don't

  * want to have single-triple RDF documents around that

  * contain only the title triple.

  *

  * @author Richard Cyganiak (richard@cyganiak.de)

  */

 public class IgnoreTitlesOfEmptyDocuments implements TripleHandler {

     private final ExtractionContextBlocker blocker;

     public IgnoreTitlesOfEmptyDocuments(TripleHandler wrapped) {

         blocker = new ExtractionContextBlocker(wrapped);

     }

     public void startDocument(URI documentURI) throws TripleHandlerException {

         blocker.startDocument(documentURI);

     }

     public void openContext(ExtractionContext context) throws TripleHandlerException {

         blocker.openContext(context);

         if (isTitleContext(context)) {

             blocker.blockContext(context);

         }

     }

     public void receiveTriple(Resource s, URI p, Value o, URI g, ExtractionContext context)

     throws TripleHandlerException {

         if (!isTitleContext(context)) {

             blocker.unblockDocument();

         }

         blocker.receiveTriple(s, p, o, g, context);

     }

     public void receiveNamespace(String prefix, String uri,

                                  ExtractionContext context) throws TripleHandlerException {

         blocker.receiveNamespace(prefix, uri, context);

     }

     public void closeContext(ExtractionContext context) {

         blocker.closeContext(context);

     }

     public void close() throws TripleHandlerException {

         blocker.close();

     }

     private boolean isTitleContext(ExtractionContext context) {

         return context.getExtractorName().equals(TitleExtractor.NAME);

     }

     public void endDocument(URI documentURI) throws TripleHandlerException {

         blocker.endDocument(documentURI);

     }

     public void setContentLength(long contentLength) {

         //Ignore.

     }

 }