/**
 *
 *  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.tuscany.sdo.helper;

import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.XMLStreamWriter;

import org.apache.tuscany.sdo.util.resource.DataObjectXMLStreamReader;
import org.apache.tuscany.sdo.util.resource.XMLDocumentStreamReader;
import org.apache.tuscany.sdo.util.resource.XMLStreamSerializer;
import org.eclipse.emf.ecore.resource.Resource;

import commonj.sdo.DataObject;
import commonj.sdo.Property;
import commonj.sdo.helper.TypeHelper;
import commonj.sdo.helper.XMLDocument;

/**
 * @version $Rev$ $Date$
 */
public class XMLStreamHelperImpl implements XMLStreamHelper
{
  TypeHelperImpl typeHelper;
  
  public XMLStreamHelperImpl(TypeHelper typeHelper)
  {
    this.typeHelper = (TypeHelperImpl)typeHelper;
  }

  public XMLDocument load(XMLStreamReader reader) throws XMLStreamException, IllegalStateException
  {
    if (reader.getEventType() != XMLStreamConstants.START_DOCUMENT)
      throw new IllegalStateException();
    
    return loadDocument(reader);
  }
  
  public void save(XMLDocument document, XMLStreamWriter writer) throws XMLStreamException
  {
      XMLStreamReader reader = createXMLStreamReader(document);
      new XMLStreamSerializer().serialize(reader, writer);
  }

  public XMLStreamReader createXMLStreamReader(XMLDocument document) throws XMLStreamException
  {
      XMLStreamReader reader =  new DataObjectXMLStreamReader(document.getRootObject(), document.getRootElementURI(), document.getRootElementName(), typeHelper);
      // Wrap the reader so that its position will be START_ELEMENT
      return new XMLDocumentStreamReader(reader);
      
  }

  public DataObject loadObject(XMLStreamReader reader) throws XMLStreamException, IllegalStateException
  {
    if (reader.getEventType() != XMLStreamConstants.START_ELEMENT)
      throw new IllegalStateException();
    
    // StAX2SAXAdapter won't produce START_DOCUMENT if the reader is posisitioned at START_ELEMENT and the EMF loader will fail
    // Wrap the reader so it represents a document
    reader = new XMLDocumentStreamReader(reader);
    
    return loadDocument(reader).getRootObject();
  }

  public void saveObject(DataObject sdo, XMLStreamWriter writer) throws XMLStreamException
  {
      XMLStreamReader reader = createXMLStreamReader(sdo);
      new XMLStreamSerializer().serialize(new XMLDocumentStreamReader(reader), writer);
  }

  public XMLStreamReader createXMLStreamReader(DataObject dataObject)
  {
    String rootElementURI;
    String rootElementName;
    
    Property property = dataObject.getContainmentProperty();
    if (property != null)
    {
      rootElementName = property.getName();
      rootElementURI = property.getType().getURI();
    }
    else
    {
      rootElementName = dataObject.getType().getName();
      rootElementURI = dataObject.getType().getURI();
    }
    
    return new DataObjectXMLStreamReader(dataObject, rootElementURI, rootElementName, typeHelper);
  }
  
  protected XMLDocument loadDocument(XMLStreamReader reader) throws XMLStreamException
  {
    try {
      XMLDocumentImpl document = new XMLDocumentImpl(typeHelper.extendedMetaData, null);
      document.load(reader);
      return document;
    }
    catch (Exception e) {
      if (e instanceof Resource.IOWrappedException)
      {
        Resource.IOWrappedException ioe = (Resource.IOWrappedException)e;
        if (ioe.getWrappedException() instanceof XMLStreamException)
        {
          throw (XMLStreamException)ioe.getWrappedException();
        }
      }
      throw new RuntimeException(e); // ????
    }
  }

}