/*
 * $Header: /home/cvs/WEBPUMP2.0/WebPumpIDE_Src/WebPumpIDE/src/com/webpump/ui/gefmodule/util/DataTransfer.java,v 1.1.1.1 2004/07/01 09:07:49 wang_j Exp $
 * $Revision: 1.1.1.1 $
 * $Date: 2004/07/01 09:07:49 $
 *
 * ====================================================================
 *
 * The NanJing HopeRun(IT-FOREST) Software License, Version 2.0.0
 *
 * Copyright 2003-2004 by NanJing HopeRun(IT-FOREST) Information System Co., Ltd, CHINA and
 *                        IT Forest Corporation
 * All rights reserved.
 *
 * This software is the confidential and proprietary information of
 * HopeRun(IT-FOREST) Information System Co., Ltd, CHINA and IT Forest Corporation.
 * You shall not disclose such Confidential Information and shall use it only in
 * accordance with the terms of the license agreement you entered into with
 * HopeRun(IT-FOREST) Information System Co., Ltd, CHINA and IT Forest Corporation.
 */

package com.webpump.ui.gefmodule.util;

import java.io.*;

import org.eclipse.swt.dnd.*;

/**
 * Class for DataTransfer
 * 
 * @author shi_l
 * @version 2.0.0 2004-5-30
 */
public class DataTransfer extends ByteArrayTransfer {
	/**
	 * Singleton instance.
	 */
	private static final DataTransfer instance = new DataTransfer();
	// Create a unique ID to make sure that different Eclipse
	// applications use different "types" of <code>ModelDataTransfer</code>

	public static final String TYPE_PREFIX = "webpump-model-transfer-format";
	private static final String TYPE_NAME =
		TYPE_PREFIX + ":" + System.currentTimeMillis() + ":" + instance.hashCode();

	private static final int TYPEID = registerType(TYPE_NAME);

	public static DataTransfer getInstance() {
		return instance;
	}

	/**
	 * Constructor for ModelDataTransfer.
	 */
	public DataTransfer() {
		super();
	}

	/* (non-Javadoc)
	 * Method declared on Transfer.
	 */
	protected int[] getTypeIds() {
		return new int[] { TYPEID };
	}
	/* (non-Javadoc)
	 * Returns the type names.
	 *
	 * @return the list of type names
	 */
	protected String[] getTypeNames() {
		return new String[] { TYPE_NAME };
	}
	/* (non-Javadoc)
		* Method declared on Transfer.
		*/
	protected void javaToNative(Object data, TransferData transferData) {
		if (!(data instanceof Object[])) {
			return;
		}
		Object[] objects = (Object[]) data;
		int count = objects.length;

		try {
			ByteArrayOutputStream out = new ByteArrayOutputStream();
			ObjectOutputStream objectOut = new ObjectOutputStream(out);

			//write the number of resources
			objectOut.writeInt(count);

			//write each object
			for (int i = 0; i < objects.length; i++) {
				objectOut.writeObject(objects[i]);
			}

			//cleanup
			objectOut.close();
			out.close();
			byte[] bytes = out.toByteArray();
			super.javaToNative(bytes, transferData);
		} catch (IOException e) {
			//it's best to send nothing if there were problems
			System.out.println(e);
		}

	}
	/* (non-Javadoc)
	 * Method declared on Transfer.
	 */
	protected Object nativeToJava(TransferData transferData) {
		byte[] bytes = (byte[]) super.nativeToJava(transferData);
		if (bytes == null)
			return null;
		try {
			ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(bytes));

			int count = in.readInt();
			Object[] objects = new Object[count];
			for (int i = 0; i < count; i++) {
				objects[i] = in.readObject();
			}
			in.close();
			return objects;
		} catch (ClassNotFoundException e) {
			return null;
		} catch (IOException e) {
			return null;
		}
	}
}