/*
 * @(#)ShortestDistanceConnector.java
 *
 * Project:		JHotdraw - a GUI framework for technical drawings
 *				http://www.jhotdraw.org
 *				http://jhotdraw.sourceforge.net
 * Copyright:	© by the original author(s) and all contributors
 * License:		Lesser GNU Public License (LGPL)
 *				http://www.opensource.org/licenses/lgpl-license.html
 */

package org.jhotdraw.figures;

import org.jhotdraw.framework.*;
import org.jhotdraw.standard.*;
import org.jhotdraw.util.Geom;
import java.awt.*;

/**
 * A ShortestDistance locates connection points by
 * finding the shortest distance between the start and
 * end of the connection.
 * It doesn't connect to the areas defined by Figure.connectionInsets()
 *
 * @see Figure#connectionInsets
 * @see Connector
 *
 * @version <$CURRENT_VERSION$>
 */
public class ShortestDistanceConnector extends AbstractConnector {

	/*
	 * Serialization support.
	 */
	private static final long serialVersionUID = -2273446020593433887L;

	public ShortestDistanceConnector() { // only used for Storable implementation
		super();
	}

	public ShortestDistanceConnector(Figure owner) {
		super(owner);
	}

	public Point findStart(ConnectionFigure connection) {
		return findPoint(connection, true);
	}

	public Point findEnd(ConnectionFigure connection) {
		return findPoint(connection, false);
	}

	protected Point findPoint(ConnectionFigure connection, boolean getStart) {
		Figure startFigure = connection.getStartConnector().owner();
		Figure endFigure = connection.getEndConnector().owner();

		Rectangle r1 = startFigure.displayBox();
		Rectangle r2 = endFigure.displayBox();

		Insets i1 = startFigure.connectionInsets();
		Insets i2 = endFigure.connectionInsets();

		Point p1, p2;
		Point start = null, end = null, s = null, e = null;
		long len2 = Long.MAX_VALUE, l2;
		int x1, x2, y1, y2; // connection points
		int xmin, xmax, ymin, ymax;

		// X-dimension
		// constrain width connection insets
		int r1x, r1width, r2x, r2width, r1y, r1height, r2y, r2height;
		r1x = r1.x + i1.left;
		r1width = r1.width - i1.left - i1.right-1;
		r2x = r2.x + i2.left;
		r2width = r2.width - i2.left - i2.right-1;

		// find x connection point
		if (r1x + r1width < r2x) {
			x1 = r1x + r1width;
			x2 = r2x;
		}
		else if (r1x > r2x + r2width) {
			x1 = r1x;
			x2 = r2x + r2width;
		}
		else {
			xmax = Math.max(r1x, r2x);
			xmin = Math.min(r1x+r1width, r2x+r2width);
			x1 = x2 = (xmax + xmin) /2;
		}

		// Y-Dimension
		// constrain with connection insets
		r1y = r1.y + i1.top;
		r1height = r1.height - i1.top - i1.bottom-1;
		r2y = r2.y + i2.top;
		r2height = r2.height - i2.top - i2.bottom-1;

		// y connection point
		if (r1y + r1height < r2y) {
			y1 = r1y + r1height;
			y2 = r2y;
		}
		else if (r1y > r2y + r2height) {
			y1 = r1y;
			y2 = r2y + r2height;
		}
		else {
			ymax = Math.max(r1y, r2y);
			ymin = Math.min(r1y+r1height, r2y+r2height);
			y1 = y2 = (ymax + ymin) /2;
		}
		// find shortest connection
		for (int i = 0; i < 4; i++) {
			switch(i) {
			case 0:
				// EAST-WEST
				p1 = Geom.east(r1);
				p2 = Geom.west(r2);
				s = new Point(p1.x, y1);
				e = new Point(p2.x, y2);
				break;
			case 1:
				// WEST-EAST
				p1 = Geom.west(r1);
				p2 = Geom.east(r2);
				s = new Point(p1.x, y1);
				e = new Point(p2.x, y2);
				break;
			case 2:
				// NORTH-SOUTH
				p1 = Geom.north(r1);
				p2 = Geom.south(r2);
				s = new Point(x1, p1.y);
				e = new Point(x2, p2.y);
				break;
			case 3:
				// SOUTH-NORTH
				p1 = Geom.south(r1);
				p2 = Geom.north(r2);
				s = new Point(x1, p1.y);
				e = new Point(x2, p2.y);
				break;
			}
			l2 = Geom.length2(s.x, s.y, e.x, e.y);
			if (l2 < len2) {
				start = s;
				end = e;
				len2 = l2;
			}
		}
		if (getStart) {
			return start;
		}
		return end;
	}
}

