/*******************************************************************************
 * Copyright (c) 2000, 2011 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Patrick Chuong (Texas Instruments) - Improve usability of the breakpoint view (Bug 238956)
 *******************************************************************************/
package org.eclipse.debug.internal.ui.views.breakpoints;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.util.LocalSelectionTransfer;
import org.eclipse.jface.util.TransferDragSourceListener;
import org.eclipse.jface.viewers.AbstractTreeViewer;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.ITreeSelection;
import org.eclipse.jface.viewers.TreePath;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DragSourceAdapter;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.widgets.Item;

/**
 * A drag adapter for the breakpoints viewer
 */
public class BreakpointsDragAdapter extends DragSourceAdapter implements TransferDragSourceListener {

    /**
     * the associated viewer for the adapter
     */
    private AbstractTreeViewer fViewer;
    private Item[] fItems = null;

    private BreakpointsView fView;
    private TreePath[] fTreePaths = null;

    /**
     * Constructor
     * @param viewer the associated viewer, which acts as the selection provider and therefore <b>must</b> implement <code>ISelectionProvider</code>
     */
    public BreakpointsDragAdapter(BreakpointsViewer viewer) {
        Assert.isNotNull(viewer);
        fViewer = viewer;
    }
    public BreakpointsDragAdapter(AbstractTreeViewer viewer, BreakpointsView view) {
        Assert.isNotNull(view);
        fViewer = viewer;
        fView = view;
    }

    /* (non-Javadoc)
     * @see org.eclipse.jface.util.TransferDragSourceListener#getTransfer()
     */
    @Override
	public Transfer getTransfer() {
        return LocalSelectionTransfer.getTransfer();
    }

    /* non Java-doc
     * @see org.eclipse.swt.dnd.DragSourceListener#dragStart
     */
    @Override
	public void dragStart(DragSourceEvent event) {
        ISelection selection = fViewer.getSelection();
        LocalSelectionTransfer.getTransfer().setSelection(selection);
        LocalSelectionTransfer.getTransfer().setSelectionSetTime(event.time & 0xFFFFFFFFL);
        if (fViewer instanceof BreakpointsViewer) {
        	BreakpointsViewer viewer = (BreakpointsViewer)fViewer;
	        fItems = viewer.getSelectedItems();
	        event.doit = viewer.canDrag(fItems);
        } else {
        	if (selection instanceof ITreeSelection) {
            	fTreePaths = ((ITreeSelection) selection).getPaths();
        	} else {
        		fTreePaths = new TreePath[0];
        	}
	        event.doit = fView.canDrag(fTreePaths);
        }
    }

    /* non Java-doc
     * @see org.eclipse.swt.dnd.DragSourceListener#dragSetData
     */
    @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();
    }

    /* non Java-doc
     * @see org.eclipse.swt.dnd.DragSourceListener#dragFinished
     */
    @Override
	public void dragFinished(DragSourceEvent event) {
        if (event.detail == DND.DROP_MOVE) {
            // remove from source on move operation
            if (fViewer instanceof BreakpointsViewer) {
            	BreakpointsViewer viewer = (BreakpointsViewer)fViewer;
            	viewer.performDrag(fItems);
            } else {
            	fView.performDrag(fTreePaths);
            }
        }
        fItems = null;
        LocalSelectionTransfer.getTransfer().setSelection(null);
        LocalSelectionTransfer.getTransfer().setSelectionSetTime(0);
    }
}