/*

  * 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.extractor.html;

 import org.apache.any23.extractor.ExtractionContext;

 import org.apache.any23.extractor.ExtractionException;

 import org.apache.any23.extractor.ExtractionParameters;

 import org.apache.any23.extractor.ExtractionResult;

 import org.apache.any23.extractor.ExtractorDescription;

 import org.apache.any23.extractor.ExtractorFactory;

 import org.apache.any23.extractor.SimpleExtractorFactory;

 import org.apache.any23.rdf.PopularPrefixes;

 import org.apache.any23.vocab.XHTML;

 import org.apache.any23.extractor.Extractor.TagSoupDOMExtractor;

 import org.openrdf.model.URI;

 import org.openrdf.model.ValueFactory;

 import org.openrdf.model.impl.ValueFactoryImpl;

 import org.w3c.dom.Document;

 import org.w3c.dom.Node;

 import java.io.IOException;

 import java.util.Arrays;

 import java.util.List;

 /**

  * This {@link org.apache.any23.extractor.Extractor.TagSoupDOMExtractor} implementation

  * retrieves the <code>LINK</code>s declared within the <code>HTML/HEAD</code> page header.

  */

 public class HeadLinkExtractor implements TagSoupDOMExtractor {

     public void run(

             ExtractionParameters extractionParameters,

             ExtractionContext extractionContext,

             Document in,

             ExtractionResult out

     ) throws IOException, ExtractionException {

         HTMLDocument html = new HTMLDocument(in);

         ValueFactory vf = ValueFactoryImpl.getInstance();

         final List<Node> headLinkNodes = DomUtils.findAll(

                 in,

                 "/HTML/HEAD/LINK[(" +

                         "@type='application/rdf+xml' or " +

                         "@type='text/rdf' or " +

                         "@type='application/x-turtle' or " +

                         "@type='application/turtle' or " +

                         "@type='text/turtle' or " +

                         "@type='text/rdf+n3'" +

                         ") and @href and @rel]"

         );

         for (Node node : headLinkNodes) {

             final URI href = html.resolveURI(DomUtils.find(node, "@href"));

             final String rel = DomUtils.find(node, "@rel");

             out.writeTriple(

                     extractionContext.getDocumentURI(),

                     vf.createURI(XHTML.NS + rel),

                     href

             );

             final String title = DomUtils.find(node, "@title");

             if (title != null && !"".equals(title)) {

                 out.writeTriple(

                         href,

                         factory.getPrefixes().expand("dcterms:title"),

                         vf.createLiteral(title)

                 );

             }

             final String type = DomUtils.find(node, "@type");

             if (type != null && !"".equals(type)) {

                 out.writeTriple(

                         href,

                         factory.getPrefixes().expand("dcterms:format"),

                         vf.createLiteral(type)

                 );

             }

         }

     }

     public ExtractorDescription getDescription() {

         return factory;

     }

     public final static ExtractorFactory<HeadLinkExtractor> factory =

             SimpleExtractorFactory.create(

                     "html-head-links",

                     PopularPrefixes.createSubset("xhtml", "dcterms"),

                     Arrays.asList("text/html;q=0.05", "application/xhtml+xml;q=0.05"),

                     "example-head-link.html",

                     HeadLinkExtractor.class);

 }