/*

  * 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.ErrorReporter;

 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.Extractor;

 import org.apache.any23.extractor.ExtractorDescription;

 import org.apache.any23.extractor.ExtractorFactory;

 import org.apache.any23.extractor.SimpleExtractorFactory;

 import org.apache.any23.extractor.rdf.RDFParserFactory;

 import org.apache.any23.rdf.PopularPrefixes;

 import org.openrdf.model.URI;

 import org.openrdf.rio.RDFParseException;

 import org.openrdf.rio.turtle.TurtleParser;

 import org.w3c.dom.Document;

 import org.w3c.dom.Node;

 import java.io.IOException;

 import java.io.StringReader;

 import java.util.Arrays;

 import java.util.List;

 /**

  * Extractor for <i>Turtle/N3</i> format embedded within <i>HTML</i>

  * <i>script</i> tags.

  *

  * See specification draft <a href="http://esw.w3.org/N3inHTML">here</a>. 

  *

  * @author Michele Mostarda (mostarda@fbk.eu)

  */

 public class TurtleHTMLExtractor implements Extractor.TagSoupDOMExtractor {

     public final static String NAME = "html-script-turtle";

     public final static ExtractorFactory<TurtleHTMLExtractor> factory =

             SimpleExtractorFactory.create(

                     NAME,

                     PopularPrefixes.get(),

                     Arrays.asList("text/html;q=0.02", "application/xhtml+xml;q=0.02"),

                     "example-script-turtle.html",

                     TurtleHTMLExtractor.class

             );

     private TurtleParser turtleParser;

     public void run(

             ExtractionParameters extractionParameters,

             ExtractionContext extractionContext,

             Document in,

             ExtractionResult out

     ) throws IOException, ExtractionException {

         List<Node> scriptNodes;

         HTMLDocument htmlDocument = new HTMLDocument(in);

         final URI documentURI = extractionContext.getDocumentURI();

         scriptNodes = htmlDocument.findAll(".//SCRIPT[contains(@type,'text/turtle')]");

         processScriptNodes(documentURI, extractionContext, out, scriptNodes);

         scriptNodes = htmlDocument.findAll(".//SCRIPT[contains(@type,'text/n3')]");

         processScriptNodes(documentURI, extractionContext, out, scriptNodes);

         scriptNodes = htmlDocument.findAll(".//SCRIPT[contains(@type,'text/plain')]");

         processScriptNodes(documentURI, extractionContext,out, scriptNodes);

     }

     public ExtractorDescription getDescription() {

         return factory;

     }

     /**

      * Processes a list of <i>html script</i> nodes retrieving the N3 / Turtle content.

      *

      * @param documentURI the URI of the original HTML document.

      * @param er the extraction result used to store triples.

      * @param ns the list of script nodes.

      */

     private void processScriptNodes(URI documentURI, ExtractionContext ec, ExtractionResult er, List<Node> ns) {

         if(ns.size() > 0 && turtleParser == null) {

             turtleParser = RDFParserFactory.getInstance().getTurtleParserInstance(true, false, ec, er);

         }

         for(Node n : ns) {

             processScriptNode(turtleParser, documentURI, n, er);

         }

     }

     /**

      * Processes a single <i>html script</i> node.

      *

      * @param turtleParser the parser used to digest node content.

      * @param documentURI the URI of the original HTML document.

      * @param n the script node.

      * @param er the extraction result used to store triples.

      */

     private void processScriptNode(TurtleParser turtleParser, URI documentURI, Node n, ExtractionResult er) {

         final Node idAttribute = n.getAttributes().getNamedItem("id");

         final String graphName =

                 documentURI.stringValue() +

                 ( idAttribute == null ? "" : "#" +   idAttribute.getTextContent() ); 

         try {

             turtleParser.parse( new StringReader(n.getTextContent()), graphName );

         } catch (RDFParseException rdfpe) {

             er.notifyError(

                     ErrorReporter.ErrorLevel.ERROR,

                     String.format(

                             "An error occurred while parsing turtle content within script node: %s",

                             Arrays.toString( DomUtils.getXPathListForNode(n) )

                     ),

                     rdfpe.getLineNumber(), rdfpe.getColumnNumber()

             );

         } catch (Exception e) {

             er.notifyError(ErrorReporter.ErrorLevel.ERROR, "An error occurred while processing RDF data.", -1 , -1);

         }

     }

 }