/* ========================================================================
 * PlantUML : a free UML diagram generator
 * ========================================================================
 *
 * (C) Copyright 2009-2014, Arnaud Roques
 *
 * Project Info:  http://plantuml.sourceforge.net
 * 
 * This file is part of PlantUML.
 *
 * Licensed under The MIT License (Massachusetts Institute of Technology License)
 * 
 * See http://opensource.org/licenses/MIT
 * 
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
 * IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 * 
 *
 * Original Author:  Arnaud Roques
 */
package net.sourceforge.plantuml.graph2;

import java.awt.geom.Line2D;
import java.awt.geom.Point2D;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.TreeSet;

public class Singularity2 {

	private final TreeSet<Double> angles = new TreeSet<Double>();

	final private Point2D.Double center;

	public Singularity2(Point2D.Double center) {
		this.center = center;
	}

	@Override
	public String toString() {
		final StringBuilder sb = new StringBuilder(center.toString());
		for (Double a : angles) {
			final int degree = (int) (a * 180 / Math.PI);
			sb.append(' ');
			sb.append(degree);
		}
		return sb.toString();
	}

	public void addLineSegment(Line2D.Double seg) {
		if (seg.getP1().equals(center)) {
			angles.add(convertAngle(getAngle(seg)));
		} else if (seg.getP2().equals(center)) {
			angles.add(convertAngle(getOppositeAngle(seg)));
		} else {
			throw new IllegalArgumentException();
		}
		assert betweenZeroAndTwoPi();

	}

	static final double getAngle(Line2D.Double line) {
		if (line.getP1().equals(line.getP2())) {
			throw new IllegalArgumentException();
		}
		return Math.atan2(line.getP2().getY() - line.getP1().getY(), line.getP2().getX() - line.getP1().getX());
	}

	static final double getOppositeAngle(Line2D.Double line) {
		return Math.atan2(line.getP1().getY() - line.getP2().getY(), line.getP1().getX() - line.getP2().getX());
	}

	static double convertAngle(double a) {
		while (a < 0) {
			a += 2 * Math.PI;
		}
		return a;
	}

	private boolean betweenZeroAndTwoPi() {
		for (Double d : angles) {
			assert d >= 0;
			assert d < 2 * Math.PI;
		}
		return true;
	}

	List<Double> getAngles() {
		return new ArrayList<Double>(angles);
	}

	public boolean crossing(Point2D.Double direction1, Point2D.Double direction2) {
		final boolean result = crossingInternal(direction1, direction2);
		assert result == crossingInternal(direction2, direction1);
		return result;
	}

	private boolean crossingInternal(Point2D.Double direction1, Point2D.Double direction2) {
		if (angles.size() < 2) {
			return false;
		}
		final double angle1 = convertAngle(getAngle(new Line2D.Double(center, direction1)));
		final double angle2 = convertAngle(getAngle(new Line2D.Double(center, direction2)));

		Double last = null;
		for (Double current : angles) {
			if (last != null) {
				assert last < current;
				if (isBetween(angle1, last, current) && isBetween(angle2, last, current)) {
					return false;
				}
			}
			last = current;
		}
		final double first = angles.first();
		if ((angle1 <= first || angle1 >= last) && (angle2 <= first || angle2 >= last)) {
			return false;
		}
		return true;
	}

	private boolean isBetween(double test, double v1, double v2) {
		assert v1 < v2;
		return test >= v1 && test <= v2;
	}

	protected final Point2D.Double getCenter() {
		return center;
	}

	public void merge(Singularity2 other) {
		this.angles.addAll(other.angles);
	}

	public List<Neighborhood2> getNeighborhoods() {
		if (angles.size() == 0) {
			return Collections.singletonList(new Neighborhood2(center));
		}
		final List<Neighborhood2> result = new ArrayList<Neighborhood2>();
		double last = angles.last();
		for (Double currentAngle : angles) {
			result.add(new Neighborhood2(center, last, currentAngle));
			last = currentAngle;
		}
		return Collections.unmodifiableList(result);
	}

}