/*******************************************************************************
 * <copyright>
 *
 * Copyright (c) 2005, 2011 SAP AG.
 * 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:
 *    SAP AG - initial API, implementation and documentation
 *    mgorning - Bug 355968 - Only ChopboxAnchors should compute the reference point as the center of its GA
 *
 * </copyright>
 *
 *******************************************************************************/
package org.eclipse.graphiti.ui.internal.util.draw2d;

import org.eclipse.draw2d.ChopboxAnchor;
import org.eclipse.draw2d.IFigure;
import org.eclipse.draw2d.geometry.Point;
import org.eclipse.draw2d.geometry.Rectangle;
import org.eclipse.graphiti.mm.pictograms.AdvancedAnchor;
import org.eclipse.graphiti.ui.internal.services.impl.GefService;

/**
 * The purpose of this class is to fix bugs in the {@link ChopboxAnchor} by
 * overwriting the erroneous methods.
 * 
 * @noinstantiate This class is not intended to be instantiated by clients.
 * @noextend This class is not intended to be subclassed by clients.
 */
public class ChopboxAnchorFixed extends ChopboxAnchor {

	private AdvancedAnchor advancedAnchor = null;

	public ChopboxAnchorFixed(IFigure figure, AdvancedAnchor advancedAnchor) {
		super(figure);
		this.advancedAnchor = advancedAnchor;
	}

	/**
	 * CHANGED: if the reference is in the center of the figure, the result was
	 * not correct. This method has to be kept in sync with
	 * {@link GefService#getChopboxLocationOnBox(Point, Rectangle)}.
	 */
	@Override
	public Point getLocation(Point reference) {

		if (getAdvancedAnchor() != null && getAdvancedAnchor().isUseAnchorLocationAsConnectionEndpoint()) {
			Rectangle box = getBox();
			Rectangle r = Rectangle.SINGLETON;
			r.setBounds(box);
			getOwner().translateToAbsolute(r); // consider zoom etc.
			Point point = new Point(r.x(), r.y());
			return point;
		}

		Rectangle r = Rectangle.SINGLETON;
		r.setBounds(getBox());
		r.translate(-1, -1);
		r.resize(1, 1);

		getOwner().translateToAbsolute(r);
		float centerX = r.x + 0.5f * r.width;
		float centerY = r.y + 0.5f * r.height;

		// CHANGED: returning the center in case of a divide-by-zero is not a
		// good result
		// if (r.isEmpty() || (reference.x == (int)centerX && reference.y ==
		// (int)centerY))
		// return new Point((int)centerX, (int)centerY); //This avoids
		// divide-by-zero

		float dx = reference.x - centerX;
		float dy = reference.y - centerY;

		// r.width, r.height, dx, and dy are guaranteed to be non-zero.

		// CHANGED: in case of "nearly zero" (divide-by-zero or
		// rounding-problems) would happen.
		// Instead return a point on the border of the figure.
		// Doesn't matter which one, because it is directly in the center, so
		// take top-middle.
		float max = Math.max(Math.abs(dx) / r.width, Math.abs(dy) / r.height);
		if (max <= 0.001f) {
			return new Point((int) centerX, r.y);
		}

		float scale = 0.5f / max;

		dx *= scale;
		dy *= scale;
		centerX += dx;
		centerY += dy;

		return new Point(Math.round(centerX), Math.round(centerY));
	}

	protected AdvancedAnchor getAdvancedAnchor() {
		return this.advancedAnchor;
	}
}