/**
    * Copyright 2008-2010 Digital Enterprise Research Institute (DERI)
    *
    * Licensed 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.deri.any23.extractor.html;
  
  import org.deri.any23.extractor.ErrorReporter;
  import org.deri.any23.extractor.ExtractionContext;
  import org.deri.any23.extractor.ExtractionException;
  import org.deri.any23.extractor.ExtractionParameters;
  import org.deri.any23.extractor.ExtractionResult;
  import org.deri.any23.extractor.Extractor;
  import org.deri.any23.extractor.ExtractorDescription;
  import org.deri.any23.extractor.ExtractorFactory;
  import org.deri.any23.extractor.SimpleExtractorFactory;
  import org.deri.any23.extractor.rdf.RDFParserFactory;
  import org.deri.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"),
                      null,
                      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);
         }
     }
 
 }