/*******************************************************************************
 * Copyright (c) 2007 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 * 	   Wind River - Pawel Piech - Initial Implementation - Drag/Drop to Expressions View (Bug 184057)
 *     IBM Corporation - further implementation and documentation
 *******************************************************************************/
package org.eclipse.debug.internal.ui.views.variables;

import org.eclipse.core.runtime.Assert;
import org.eclipse.debug.internal.ui.viewers.model.provisional.TreeModelViewer;
import org.eclipse.jface.util.LocalSelectionTransfer;
import org.eclipse.jface.util.TransferDragSourceListener;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.swt.dnd.DragSourceAdapter;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.Transfer;

/**
 * Drag adapter for the variables view and expressions view.  Allows selected variables and
 * expressions to be dragged.
 *
 * @see org.eclipse.debug.internal.ui.views.expression.ExpressionDropAdapter
 * @since 3.4
 */
public class SelectionDragAdapter extends DragSourceAdapter implements TransferDragSourceListener {

	/**
	 * The associated viewer for the adapter
	 */
	private final TreeModelViewer fViewer;

	/**
	 * Constructor, takes the viewer that contains the selection provider
	 *
	 * @param viewer the associated viewer
	 */
	public SelectionDragAdapter(TreeModelViewer viewer) {
		Assert.isNotNull(viewer);
		fViewer = viewer;
	}

	@Override
	public Transfer getTransfer() {
		return LocalSelectionTransfer.getTransfer();
	}

	@Override
	public void dragStart(DragSourceEvent event) {
		ISelection selection = fViewer.getSelection();
		LocalSelectionTransfer.getTransfer().setSelection(selection);
		LocalSelectionTransfer.getTransfer().setSelectionSetTime(event.time & 0xFFFFFFFFL);
		event.doit = !selection.isEmpty();
	}

	@Override
	public void dragSetData(DragSourceEvent event) {
		// For consistency set the data to the selection even though
		// the selection is provided by the LocalSelectionTransfer
		// to the drop target adapter.
		event.data = LocalSelectionTransfer.getTransfer().getSelection();
	}

	@Override
	public void dragFinished(DragSourceEvent event) {
		LocalSelectionTransfer.getTransfer().setSelection(null);
		LocalSelectionTransfer.getTransfer().setSelectionSetTime(0);
	}
}
