/*******************************************************************************
 * Copyright (c) 2000, 2017 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:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.dnd;

import org.eclipse.swt.graphics.*;
import org.eclipse.swt.internal.*;
import org.eclipse.swt.internal.gtk.*;
import org.eclipse.swt.widgets.*;

/**
 * This class provides a default drag under effect (eg. select, insert, scroll and expand)
 * when a drag occurs over a <code>Tree</code>.
 *
 * <p>Classes that wish to provide their own drag under effect for a <code>Tree</code>
 * can extend the <code>TreeDropTargetEffect</code> class and override any applicable methods
 * in <code>TreeDropTargetEffect</code> to display their own drag under effect.</p>
 *
 * Subclasses that override any methods of this class must call the corresponding
 * <code>super</code> method to get the default drag under effect implementation.
 *
 * <p>The feedback value is either one of the FEEDBACK constants defined in
 * class <code>DND</code> which is applicable to instances of this class,
 * or it must be built by <em>bitwise OR</em>'ing together
 * (that is, using the <code>int</code> "|" operator) two or more
 * of those <code>DND</code> effect constants.
 * </p>
 * <dl>
 * <dt><b>Feedback:</b></dt>
 * <dd>FEEDBACK_SELECT, FEEDBACK_INSERT_BEFORE, FEEDBACK_INSERT_AFTER, FEEDBACK_EXPAND, FEEDBACK_SCROLL</dd>
 * </dl>
 * <p>
 * Note: Only one of the styles FEEDBACK_SELECT, FEEDBACK_INSERT_BEFORE or
 * FEEDBACK_INSERT_AFTER may be specified.
 * </p>
 *
 * @see DropTargetAdapter
 * @see DropTargetEvent
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 *
 * @since 3.3
 */
public class TreeDropTargetEffect extends DropTargetEffect {
	static final int SCROLL_HYSTERESIS = 150; // milli seconds
	static final int EXPAND_HYSTERESIS = 1000; // milli seconds

	int scrollIndex = -1;
	long scrollBeginTime;

	int expandIndex = -1;
	long expandBeginTime;

	/**
	 * Creates a new <code>TreeDropTargetEffect</code> to handle the drag under effect on the specified
	 * <code>Tree</code>.
	 *
	 * @param tree the <code>Tree</code> over which the user positions the cursor to drop the data
	 */
	public TreeDropTargetEffect(Tree tree) {
		super(tree);
	}

	int checkEffect(int effect) {
		// Some effects are mutually exclusive.  Make sure that only one of the mutually exclusive effects has been specified.
		if ((effect & DND.FEEDBACK_SELECT) != 0) effect = effect & ~DND.FEEDBACK_INSERT_AFTER & ~DND.FEEDBACK_INSERT_BEFORE;
		if ((effect & DND.FEEDBACK_INSERT_BEFORE) != 0) effect = effect & ~DND.FEEDBACK_INSERT_AFTER;
		return effect;
	}

	/**
	 * This implementation of <code>dragEnter</code> provides a default drag under effect
	 * for the feedback specified in <code>event.feedback</code>.
	 *
	 * For additional information see <code>DropTargetAdapter.dragEnter</code>.
	 *
	 * Subclasses that override this method should call <code>super.dragEnter(event)</code>
	 * to get the default drag under effect implementation.
	 *
	 * @param event  the information associated with the drag enter event
	 *
	 * @see DropTargetAdapter
	 * @see DropTargetEvent
	 */
	@Override
	public void dragEnter(DropTargetEvent event) {
		expandBeginTime = 0;
		expandIndex = -1;
		scrollBeginTime = 0;
		scrollIndex = -1;
	}

	/**
	 * This implementation of <code>dragLeave</code> provides a default drag under effect
	 * for the feedback specified in <code>event.feedback</code>.
	 *
	 * For additional information see <code>DropTargetAdapter.dragLeave</code>.
	 *
	 * Subclasses that override this method should call <code>super.dragLeave(event)</code>
	 * to get the default drag under effect implementation.
	 *
	 * @param event  the information associated with the drag leave event
	 *
	 * @see DropTargetAdapter
	 * @see DropTargetEvent
	 */
	@Override
	public void dragLeave(DropTargetEvent event) {
		Tree tree = (Tree) control;
		long handle = tree.handle;
		GTK.gtk_tree_view_set_drag_dest_row(handle, 0, GTK.GTK_TREE_VIEW_DROP_BEFORE);

		scrollBeginTime = 0;
		scrollIndex = -1;
		expandBeginTime = 0;
		expandIndex = -1;
	}

	/**
	 * This implementation of <code>dragOver</code> provides a default drag under effect
	 * for the feedback specified in <code>event.feedback</code>.
	 *
	 * For additional information see <code>DropTargetAdapter.dragOver</code>.
	 *
	 * Subclasses that override this method should call <code>super.dragOver(event)</code>
	 * to get the default drag under effect implementation.
	 *
	 * @param event  the information associated with the drag over event
	 *
	 * @see DropTargetAdapter
	 * @see DropTargetEvent
	 * @see DND#FEEDBACK_SELECT
	 * @see DND#FEEDBACK_INSERT_BEFORE
	 * @see DND#FEEDBACK_INSERT_AFTER
	 * @see DND#FEEDBACK_SCROLL
	 */
	@Override
	public void dragOver(DropTargetEvent event) {
		Tree tree = (Tree) control;
		int effect = checkEffect(event.feedback);

		long handle = tree.handle;
		Point coordinates = new Point(event.x, event.y);
		coordinates = DPIUtil.autoScaleUp(tree.toControl(coordinates));
		long [] path = new long [1];
		GTK.gtk_tree_view_get_path_at_pos (handle, coordinates.x, coordinates.y, path, null, null, null);
		int index = -1;
		if (path[0] != 0) {
			long indices = GTK.gtk_tree_path_get_indices(path[0]);
			if (indices != 0) {
				int depth = GTK.gtk_tree_path_get_depth(path[0]);
				int[] temp = new int[depth];
				C.memmove (temp, indices, temp.length * 4);
				index = temp[temp.length - 1];
			}
		}
		if ((effect & DND.FEEDBACK_SCROLL) == 0) {
			scrollBeginTime = 0;
			scrollIndex = -1;
		} else {
			if (index != -1 && scrollIndex == index && scrollBeginTime != 0) {
				if (System.currentTimeMillis() >= scrollBeginTime) {
					GdkRectangle cellRect = new GdkRectangle ();
					GTK.gtk_tree_view_get_cell_area (handle, path[0], 0, cellRect);
					if (cellRect.y < cellRect.height) {
						int[] tx = new int[1], ty = new int[1];
						GTK.gtk_tree_view_convert_bin_window_to_tree_coords(handle, cellRect.x, cellRect.y - cellRect.height, tx, ty);
						GTK.gtk_tree_view_scroll_to_point (handle, -1, ty[0]);
					} else {
						//scroll down
						GTK.gtk_tree_view_get_path_at_pos (handle, coordinates.x, coordinates.y + cellRect.height, path, null, null, null);
						if (path[0] != 0) {
							GTK.gtk_tree_view_scroll_to_cell(handle, path[0], 0, false, 0, 0);
							GTK.gtk_tree_path_free(path[0]);
							path[0] = 0;
						}
						GTK.gtk_tree_view_get_path_at_pos (handle, coordinates.x, coordinates.y, path, null, null, null);
					}
					scrollBeginTime = 0;
					scrollIndex = -1;
				}
			} else {
				scrollBeginTime = System.currentTimeMillis() + SCROLL_HYSTERESIS;
				scrollIndex = index;
			}
		}
		if ((effect & DND.FEEDBACK_EXPAND) == 0) {
			expandBeginTime = 0;
			expandIndex = -1;
		} else {
			if (index != -1 && expandIndex == index && expandBeginTime != 0) {
				if (System.currentTimeMillis() >= expandBeginTime) {
					GTK.gtk_tree_view_expand_row (handle, path[0], false);
					expandBeginTime = 0;
					expandIndex = -1;
				}
			} else {
				expandBeginTime = System.currentTimeMillis() + EXPAND_HYSTERESIS;
				expandIndex = index;
			}
		}
		if (path[0] != 0) {
			int position = -1;
			if ((effect & DND.FEEDBACK_SELECT) != 0) position = GTK.GTK_TREE_VIEW_DROP_INTO_OR_BEFORE;
			if ((effect & DND.FEEDBACK_INSERT_BEFORE) != 0) position = GTK.GTK_TREE_VIEW_DROP_BEFORE;
			if ((effect & DND.FEEDBACK_INSERT_AFTER) != 0) position = GTK.GTK_TREE_VIEW_DROP_AFTER;
			if (position != -1) {
				GTK.gtk_tree_view_set_drag_dest_row(handle, path[0], position);
			} else {
				GTK.gtk_tree_view_set_drag_dest_row(handle, 0, GTK.GTK_TREE_VIEW_DROP_BEFORE);
			}
		} else {
			GTK.gtk_tree_view_set_drag_dest_row(handle, 0, GTK.GTK_TREE_VIEW_DROP_BEFORE);
		}

		if (path[0] != 0) GTK.gtk_tree_path_free (path [0]);
	}

}