/* 
 * Copyright (c) 2008 Stiftung Deutsches Elektronen-Synchrotron, 
 * Member of the Helmholtz Association, (DESY), HAMBURG, GERMANY.
 *
 * THIS SOFTWARE IS PROVIDED UNDER THIS LICENSE ON AN "../AS IS" BASIS. 
 * WITHOUT WARRANTY OF ANY KIND, EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED 
 * TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR PARTICULAR PURPOSE AND 
 * NON-INFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE 
 * FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR 
 * THE USE OR OTHER DEALINGS IN THE SOFTWARE. SHOULD THE SOFTWARE PROVE DEFECTIVE 
 * IN ANY RESPECT, THE USER ASSUMES THE COST OF ANY NECESSARY SERVICING, REPAIR OR 
 * CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL PART OF THIS LICENSE. 
 * NO USE OF ANY SOFTWARE IS AUTHORIZED HEREUNDER EXCEPT UNDER THIS DISCLAIMER.
 * DESY HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, 
 * OR MODIFICATIONS.
 * THE FULL LICENSE SPECIFYING FOR THE SOFTWARE THE REDISTRIBUTION, MODIFICATION, 
 * USAGE AND OTHER RIGHTS AND OBLIGATIONS IS INCLUDED WITH THE DISTRIBUTION OF THIS 
 * PROJECT IN THE FILE LICENSE.HTML. IF THE LICENSE IS NOT INCLUDED YOU MAY FIND A COPY 
 * AT HTTP://WWW.DESY.DE/LEGAL/LICENSE.HTM
 */
 package org.csstudio.sds.util;

import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DragSourceAdapter;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.dnd.DropTargetAdapter;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.TextTransfer;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.dnd.TransferData;
import org.eclipse.swt.widgets.Text;

/**
 * A util class for adding Drag & Drop support to a {@link Text}.
 * @author Kai Meyer
 *
 */
public final class TextDnDUtil {
	
	/**
	 * Private Constructor.
	 */
	private TextDnDUtil() {
		//do nothing
	}
	
	/**
	 * Adds Drop & Drop support for the given {@link Text}.
	 * @param textWidget The {@link Text} widget
	 */
	public static void addDnDSupport(final Text textWidget) {
		addDropSupport(textWidget);
		addDragSupport(textWidget);
	}
	
	/**
	 * Adds Drop support for the given {@link Text}.
	 * @param textWidget The {@link Text} widget
	 */
	public static void addDropSupport(final Text textWidget) {
        DropTarget dropTarget = new DropTarget(textWidget, DND.DROP_COPY | DND.DROP_MOVE);
		Transfer[] transferTypes = new Transfer[] { TextTransfer.getInstance() };
		dropTarget.setTransfer(transferTypes);
		dropTarget.addDropListener(new DropTargetAdapter() {
			@Override
			public void dragEnter(final DropTargetEvent event) {
				for (TransferData transfer : event.dataTypes) {
					if (TextTransfer.getInstance().isSupportedType(
							transfer)) {
						event.detail = DND.DROP_COPY;
						break;
					}
				}
				super.dragEnter(event);
			}

			@Override
			public void drop(final DropTargetEvent event) {
				if (event.data instanceof String) {
					textWidget.setText((String) event.data);
				}
			}
		});
	}
	
	/**
	 * Adds Drag support for the given {@link Text}.
	 * @param textWidget The {@link Text} widget
	 */
	public static void addDragSupport(final Text textWidget) {	
		DragSource dragSource = new DragSource(textWidget, DND.DROP_COPY);
		Transfer[] transferTypes = new Transfer[] { TextTransfer.getInstance() };
		dragSource.setTransfer(transferTypes);
		dragSource.addDragListener(new DragSourceAdapter() {
			@Override
			public void dragStart(final DragSourceEvent event) {
				if (textWidget.getText().trim().length()==0) {
					event.doit = false;
				}
			}

			@Override
			public void dragSetData(final DragSourceEvent event) {
				if (TextTransfer.getInstance().isSupportedType(event.dataType)) {
					String text = textWidget.getText();
					if (text != null && text.trim().length()>0) {
						event.data = text;
					}
				}
			}
		});
	}

}