/*

  * 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.rdfa.RDFaExtractor;

 import org.apache.any23.vocab.XHTML;

 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 RDFa

  * parser if the document only contains "accidental" RDFa,

  * like stylesheet links and other non-RDFa uses of HTML's

  *

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

  */

 public class IgnoreAccidentalRDFa implements TripleHandler {

     private static final XHTML vXHTML = XHTML.getInstance();

     private final ExtractionContextBlocker blocker;

     private final boolean alwaysSuppressCSSTriples;

     /**

      * Constructor.

      *

      * @param wrapped the decorated triple handler.

      * @param alwaysSuppressCSSTriples if <code>true</code> the <i>CSS</i> triples will be

      *        always suppressed even if the document is not empty.

      *        If <code>false</code> then the <i>CSS</i> triples will be suppressed only if

      *        document is empty.

      */

     public IgnoreAccidentalRDFa(TripleHandler wrapped, boolean alwaysSuppressCSSTriples) {

         this.blocker = new ExtractionContextBlocker(wrapped);

         this.alwaysSuppressCSSTriples = alwaysSuppressCSSTriples;

     }

     public IgnoreAccidentalRDFa(TripleHandler wrapped) {

         this(wrapped, false);

     }

     public void startDocument(URI documentURI) throws TripleHandlerException {

         blocker.startDocument(documentURI);

     }

     public void openContext(ExtractionContext context) throws TripleHandlerException {

         blocker.openContext(context);

         if (isRDFaContext(context)) {

             blocker.blockContext(context);

         }

     }

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

     throws TripleHandlerException {

         // Suppress stylesheet triples.

         if(alwaysSuppressCSSTriples && p.stringValue().equals(vXHTML.stylesheet.stringValue())) {

             return;

         }

         if (isRDFaContext(context)) {

             blocker.unblockContext(context);

         }

         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 isRDFaContext(ExtractionContext context) {

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

     }

     public void endDocument(URI documentURI) throws TripleHandlerException {

         blocker.endDocument(documentURI);

     }

     public void setContentLength(long contentLength) {

         //Ignore.

     }

 }