/*

  * 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.Any23ValueFactoryWrapper;

 import org.apache.any23.rdf.PopularPrefixes;

 import org.apache.any23.vocab.FOAF;

 import org.apache.any23.vocab.XFN;

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

 import org.openrdf.model.BNode;

 import org.openrdf.model.URI;

 import org.openrdf.model.impl.ValueFactoryImpl;

 import org.openrdf.model.vocabulary.RDF;

 import org.w3c.dom.Document;

 import org.w3c.dom.Node;

 import java.io.IOException;

 import java.util.Arrays;

 /**

  * Extractor for the <a href="http://microformats.org/wiki/xfn">XFN</a>

  * microformat.

  *

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

  */

 public class XFNExtractor implements TagSoupDOMExtractor {

     private static final FOAF vFOAF = FOAF.getInstance();

     private static final XFN vXFN  = XFN.getInstance();

     private final static Any23ValueFactoryWrapper factoryWrapper =

             new Any23ValueFactoryWrapper(ValueFactoryImpl.getInstance());

     private HTMLDocument     document;

     private ExtractionResult out;

     public final static ExtractorFactory<XFNExtractor> factory =

             SimpleExtractorFactory.create(

                 "html-mf-xfn",

                 PopularPrefixes.createSubset("rdf", "foaf", "xfn"),

                 Arrays.asList("text/html;q=0.1", "application/xhtml+xml;q=0.1"),

                 "example-mf-xfn.html",

                 XFNExtractor.class

             );

     public ExtractorDescription getDescription() {

         return factory;

     }

     public void run(

             ExtractionParameters extractionParameters,

             ExtractionContext extractionContext,

             Document in,

             ExtractionResult out

     ) throws IOException, ExtractionException {

         factoryWrapper.setErrorReporter(out);

         try {

             document = new HTMLDocument(in);

             this.out = out;

             BNode subject = factoryWrapper.createBNode();

             boolean foundAnyXFN = false;

             final URI documentURI = extractionContext.getDocumentURI();

             for (Node link : document.findAll("//A[@rel][@href]")) {

                 foundAnyXFN |= extractLink(link, subject, documentURI);

             }

             if (!foundAnyXFN) return;

             out.writeTriple(subject, RDF.TYPE, vFOAF.Person);

             out.writeTriple(subject, vXFN.mePage, documentURI);

         } finally {

             factoryWrapper.setErrorReporter(null);

         }

     }

     private boolean extractLink(Node firstLink, BNode subject, URI documentURI)

     throws ExtractionException {

         String href = firstLink.getAttributes().getNamedItem("href").getNodeValue();

         String rel = firstLink.getAttributes().getNamedItem("rel").getNodeValue();

         String[] rels = rel.split("\\s+");

         URI link = document.resolveURI(href);

         if (containsRelMe(rels)) {

             if (containsXFNRelExceptMe(rels)) {

                 return false;    // "me" cannot be combined with any other XFN values

             }

             out.writeTriple(subject, vXFN.mePage, link);

             out.writeTriple(documentURI, vXFN.getExtendedProperty("me"), link);

         } else {

             BNode person2 = factoryWrapper.createBNode();

             boolean foundAnyXFNRel = false;

             for (String aRel : rels) {

                 foundAnyXFNRel |= extractRel(aRel, subject, documentURI, person2, link);

             }

             if (!foundAnyXFNRel) {

                 return false;

             }

             out.writeTriple(person2, RDF.TYPE, vFOAF.Person);

             out.writeTriple(person2, vXFN.mePage, link);

         }

         return true;

     }

     private boolean containsRelMe(String[] rels) {

         for (String rel : rels) {

             if ("me".equals(rel.toLowerCase())) {

                 return true;

             }

         }

         return false;

     }

     private boolean containsXFNRelExceptMe(String[] rels) {

         for (String rel : rels) {

             if (!"me".equals(rel.toLowerCase()) && vXFN.isXFNLocalName(rel)) {

                 return true;

             }

         }

         return false;

     }

     private boolean extractRel(String rel, BNode person1, URI uri1, BNode person2, URI uri2) {

         URI peopleProp = vXFN.getPropertyByLocalName(rel);

         URI hyperlinkProp = vXFN.getExtendedProperty(rel);

         if (peopleProp == null) {

             return false;

         }

         out.writeTriple(person1, peopleProp, person2);

         out.writeTriple(uri1, hyperlinkProp, uri2);

         return true;

     }

 }