/*

  * 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.ExtractionException;

 import org.apache.any23.extractor.ExtractionResult;

 import org.apache.any23.rdf.RDFUtils;

 import org.openrdf.model.BNode;

 import org.w3c.dom.Node;

 import java.util.List;

 /**

  * Base class for microformat extractors based on entities.

  *

  * @author Gabriele Renzi

  */

 public abstract class EntityBasedMicroformatExtractor extends MicroformatExtractor {

     /**

      * Returns the base class name for the extractor.

      *

      * @return a string containing the base of the extractor.

      */

     protected abstract String getBaseClassName();

     /**

      * Resets the internal status of the extractor to prepare it to a new extraction section.

      */

     protected abstract void resetExtractor();

     /**

      * Extracts an entity from a <i>DOM</i> node.

      *

      * @param node the DOM node.

      * @param out the extraction result collector.

      * @return <code>true</code> if the extraction has produces something, <code>false</code> otherwise.

      * @throws ExtractionException

      */

     protected abstract boolean extractEntity(Node node, ExtractionResult out) throws ExtractionException;

     @Override

     public boolean extract() throws ExtractionException {

         List<Node> nodes = DomUtils.findAllByClassName( getHTMLDocument().getDocument(), getBaseClassName());

         boolean foundAny = false;

         int count = 1;

         for (Node node : nodes) {

             resetExtractor();

             String contextID = Integer.toString(count);

             ExtractionResult subResult = openSubResult( getExtractionContext().copy(contextID) );

             foundAny |= extractEntity(node, subResult);

             subResult.close();

             count++;

         }

         return foundAny;

     }

     /**

      * @param node a DOM node representing a blank node

      * @return an RDF blank node corresponding to that DOM node, by using a

      *         blank node ID like "MD5 of http://doc-uri/#xpath/to/node"

      */

     protected BNode getBlankNodeFor(Node node) {

         return RDFUtils.getBNode(getDocumentURI() + "#" + DomUtils.getXPathForNode(node));

     }

 }