/*
    * Copyright (c) 2008, The JUNG Authors
    *
    * All rights reserved.
    *
    * This software is open-source under the BSD license; see either
    * "license.txt" or
    * https://github.com/jrtom/jung/blob/master/LICENSE for a description.
    */
  
  package edu.uci.ics.jung.io.graphml.parser;
  
  import java.util.Iterator;
  
  import javax.xml.stream.XMLEventReader;
  import javax.xml.stream.events.Attribute;
  import javax.xml.stream.events.Characters;
  import javax.xml.stream.events.EndElement;
  import javax.xml.stream.events.StartElement;
  import javax.xml.stream.events.XMLEvent;
  
  import edu.uci.ics.jung.graph.Hypergraph;
  import edu.uci.ics.jung.io.GraphIOException;
  import edu.uci.ics.jung.io.graphml.DataMetadata;
  import edu.uci.ics.jung.io.graphml.GraphMLConstants;
  import edu.uci.ics.jung.io.graphml.ExceptionConverter;
  
  /**
   * Parses the data element.
   *
   * @author Nathan Mittler - nathan.mittler@gmail.com
   */
  public class DataElementParser<G extends Hypergraph<V,E>,V,E> extends AbstractElementParser<G,V,E> {
  
      public DataElementParser(ParserContext<G,V,E> parserContext) {
          super(parserContext);
      }
      
      public DataMetadata parse(XMLEventReader xmlEventReader, StartElement start)
              throws GraphIOException {
  
          try {
              // Create the new port.
              DataMetadata data = new DataMetadata();
  
              // Parse the attributes.
              @SuppressWarnings("unchecked")
  			Iterator<Attribute> iterator = start.getAttributes();
              while (iterator.hasNext()) {
                  Attribute attribute = (Attribute) iterator.next();
                  String name = attribute.getName().getLocalPart();
                  String value = attribute.getValue();
                  if (data.getKey() == null && GraphMLConstants.KEY_NAME.equals(name)) {
                      data.setKey(value);
                  }
              }
  
              // Make sure the key has been set.
              if (data.getKey() == null) {
                  throw new GraphIOException(
                          "Element 'data' is missing attribute 'key'");
              }
  
              while (xmlEventReader.hasNext()) {
  
                  XMLEvent event = xmlEventReader.nextEvent();
                  if (event.isStartElement()) {
                      StartElement element = (StartElement) event;
                          
                      // Treat any child elements as unknown
                      getUnknownParser().parse(xmlEventReader, element);
                  }
                  if (event.isCharacters()) {
                      Characters characters = (Characters) event;
                      data.setValue(characters.getData());
                  }
                  if (event.isEndElement()) {
                      EndElement end = (EndElement) event;
                      verifyMatch(start, end);
                      break;
                  }
              }
  
              return data;
              
          } catch (Exception e) {
              ExceptionConverter.convert(e);
          }
  
          return null;
      }
  }