/*

  * 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.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.setErrorReporter(out);

         try {

             extract();

         } finally {

             valueFactory.setErrorReporter(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.notifyError(

                     ExtractionResult.ErrorLevel.WARN,

                     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 {@link 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;

     }

 }