/*
    * 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.IssueReport;
  import org.apache.any23.extractor.TagSoupExtractionResult;
  import org.apache.any23.extractor.html.annotations.Includes;
  import org.apache.any23.rdf.Any23ValueFactoryWrapper;
  import org.apache.any23.extractor.Extractor.TagSoupDOMExtractor;
  import org.openrdf.model.BNode;
  import org.openrdf.model.Literal;
  import org.openrdf.model.Resource;
  import org.openrdf.model.URI;
  import org.openrdf.model.impl.ValueFactoryImpl;
  import org.w3c.dom.Document;
  import org.w3c.dom.Node;
  
  import java.io.IOException;
  
  /**
   * The abstract base class for any
   * <a href="microformats.org/">Microformat specification</a> extractor.
   */
  public abstract class MicroformatExtractor implements TagSoupDOMExtractor {
  
      public static final String BEGIN_SCRIPT = "<script>";
      public static final String END_SCRIPT   = "</script>";
  
      private HTMLDocument htmlDocument;
  
      private ExtractionContext context;
  
      private URI documentURI;
  
      private ExtractionResult out;
  
      protected final Any23ValueFactoryWrapper valueFactory =
              new Any23ValueFactoryWrapper(ValueFactoryImpl.getInstance());
  
      /**
       * Returns the description of this extractor.
       *
       * @return a human readable description.
       */
      public abstract ExtractorDescription getDescription();
  
      /**
       * Performs the extraction of the data and writes them to the model.
       * The nodes generated in the model can have any name or implicit label
       * but if possible they </i>SHOULD</i> have names (either URIs or AnonId) that
       * are uniquely derivable from their position in the DOM tree, so that
       * multiple extractors can merge information.
       */
      protected abstract boolean extract() throws ExtractionException;
  
      public HTMLDocument getHTMLDocument() {
          return htmlDocument;
      }
  
      public ExtractionContext getExtractionContext() {
          return context;
      }
  
      public URI getDocumentURI() {
          return documentURI;
      }
  
      public final void run(
              ExtractionParameters extractionParameters,
              ExtractionContext extractionContext,
              Document in,
              ExtractionResult out
      ) throws IOException, ExtractionException {
          this.htmlDocument = new HTMLDocument(in);
          this.context      = extractionContext;
          this.documentURI  = extractionContext.getDocumentURI();
          this.out          = out;
          valueFactory.setIssueReport(out);
          try {
             extract();
         } finally {
             valueFactory.setIssueReport(null);
         }
     }
 
     /**
      * Returns the {@link org.apache.any23.extractor.ExtractionResult} associated
      * to the extraction session.
      *
      * @return a valid extraction result.
      */
     protected ExtractionResult getCurrentExtractionResult() {
         return out;
     }
 
     protected ExtractionResult openSubResult(ExtractionContext context) {
         return out.openSubResult(context);
     }
 
     /**
      * Helper method that adds a literal property to a subject only if the value of the property
      * is a valid string.
      *
      * @param n the <i>HTML</i> node from which the property value has been extracted.
      * @param subject the property subject.
      * @param p the property URI.
      * @param value the property value.
      * @return returns <code>true</code> if the value has been accepted and added, <code>false</code> otherwise.
      */
     protected boolean conditionallyAddStringProperty(
             Node n,
             Resource subject, URI p, String value
     ) {
         if (value == null) return false;
         value = value.trim();
         return
                 value.length() > 0 
                         &&
                 conditionallyAddLiteralProperty(
                         n,
                         subject, p, valueFactory.createLiteral(value)
                 );
     }
 
     /**
      * Helper method that adds a literal property to a node.
      *
      * @param n the <i>HTML</i> node from which the property value has been extracted.
      * @param subject subject the property subject.
      * @param property the property URI.
      * @param literal value the property value.
      * @return returns <code>true</code> if the literal has been accepted and added, <code>false</code> otherwise.
      */
     protected boolean conditionallyAddLiteralProperty(
             Node n,
             Resource subject,
             URI property,
             Literal literal
     ) {
         final String literalStr = literal.stringValue();
         if( containsScriptBlock(literalStr) ) {
             out.notifyIssue(
                     IssueReport.IssueLevel.Warning,
                     String.format("Detected script in literal: [%s]", literalStr)
                     , -1
                     , -1
             );
             return false;
         }
         out.writeTriple(subject, property, literal);
         TagSoupExtractionResult tser = (TagSoupExtractionResult) out;
         tser.addPropertyPath(this.getClass(), subject, property, null, DomUtils.getXPathListForNode(n) );
         return true;
     }
 
     /**
      * Helper method that adds a URI property to a node.
      * @param subject the property subject.
      * @param property the property URI.
      * @param uri the property object.
      * @return <code>true</code> if the the resource has been added, <code>false</code> otherwise. 
      */
     protected boolean conditionallyAddResourceProperty(Resource subject, URI property, URI uri) {
         if (uri == null) return false;
         out.writeTriple(subject, property, uri);
         return true;
     }
 
     /**
      * Helper method that adds a BNode property to a node.
      *
      * @param n the <i>HTML</i> node used for extracting such property.
      * @param subject the property subject.
      * @param property the property URI.
      * @param bnode the property value.
      */
     protected void addBNodeProperty(Node n, Resource subject, URI property, BNode bnode) {
         out.writeTriple(subject, property, bnode);
         TagSoupExtractionResult tser = (TagSoupExtractionResult) out;
         tser.addPropertyPath(this.getClass(), subject, property, bnode, DomUtils.getXPathListForNode(n) );
     }
 
     /**
      * Helper method that adds a BNode property to a node.
      *
      * @param subject the property subject.
      * @param property the property URI.
      * @param bnode the property value.
      */
     protected void addBNodeProperty( Resource subject, URI property, BNode bnode) {
         out.writeTriple(subject, property, bnode);
     }
 
     /**
      * Helper method that adds a URI property to a node.
      *
      * @param subject
      * @param property
      * @param object
      */
     protected void addURIProperty(Resource subject, URI property, URI object) {
         out.writeTriple(subject, property, object);    
     }
 
     protected URI fixLink(String link) {
         return valueFactory.fixLink(link, null);
     }
 
     protected URI fixLink(String link, String defaultSchema) {
         return valueFactory.fixLink(link, defaultSchema);
     }
 
     private boolean containsScriptBlock(String in) {
         final String inLowerCase = in.toLowerCase();
         final int beginBlock = inLowerCase.indexOf(BEGIN_SCRIPT);
         if(beginBlock == -1) {
             return false;
         }
         return inLowerCase.indexOf(END_SCRIPT, beginBlock + BEGIN_SCRIPT.length()) != -1;
     }
 
         /**
      * This method checks if there is a native nesting relationship between two
      * {@link MicroformatExtractor}.
      *
      * @see org.apache.any23.extractor.html.annotations.Includes
      * @param including the including {@link MicroformatExtractor}
      * @param included the included {@link MicroformatExtractor}
      * @return <code>true</code> if there is a declared nesting relationship
      */
     public static boolean includes(
             Class<? extends MicroformatExtractor>including,
             Class<? extends MicroformatExtractor> included) {
         Includes includes = including.getAnnotation(Includes.class);
         if (includes != null) {
             Class<? extends MicroformatExtractor>[] extractors = includes.extractors();
             if (extractors != null && extractors.length > 0) {
                 for (Class<? extends MicroformatExtractor> extractor : extractors) {
                     if (extractor.equals(included)) {
                         return true;
                     }
                 }
             }
         }
         return false;
     }
 
 }