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package org.drools.benchmark.waltz;
/*
 * Copyright 2005 JBoss Inc
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */






/**
 * @author Alexander Bagerman
 * 
 */
public class WaltzUtil {
	private static double PI = 3.1415927;

	private static int MOD_NUM = 100;

	private static int get_y(int val) {
		return val % MOD_NUM;
	}

	private static int get_x(int val) {
		return (int) (val / MOD_NUM);
	}

	/***************************************************************************
	 * This function is passed two points and calculates the angle between the
	 * line defined by these points and the x-axis.
	 **************************************************************************/
	private static double get_angle(int p1, int p2) {
		int delta_x, delta_y;
		double ret = 0.0;
		/*
		 * Calculate (x2 - x1) and (y2 - y1). The points are passed in the form
		 * x1y1 and x2y2. get_x() and get_y() are passed these points and return
		 * the x and y values respectively. For example, get_x(1020) returns 10.
		 */
		delta_x = get_x(p2) - get_x(p1);
		delta_y = get_y(p2) - get_y(p1);

		if (delta_x == 0) {
			if (delta_y > 0) {
				ret = PI / 2;
			} else if (delta_y < 0) {
				ret = -PI / 2;
			}
		} else if (delta_y == 0) {
			if (delta_x > 0) {
				ret = 0.0;
			} else if (delta_x < 0) {
				ret = PI;
			}
		} else {
			ret = Math.atan2(delta_y, delta_x);
		}
		return ret;
	}

	/***************************************************************************
	 * This procedure is passed the basepoint of the intersection of two lines
	 * as well as the other two endpoints of the lines and calculates the angle
	 * inscribed by these three points.
	 **************************************************************************/
	private static double inscribed_angle(int basepoint, int p1, int p2) {
		double angle1, angle2, temp;

		/*
		 * Get the angle between line #1 and the origin and the angle between
		 * line #2 and the origin, and then subtract these values.
		 */
		angle1 = get_angle(basepoint, p1);
		angle2 = get_angle(basepoint, p2);
		temp = angle1 - angle2;
		if (temp < 0.0)
			temp = -temp;

		/*
		 * We always want the smaller of the two angles inscribed, so if the
		 * answer is greater than 180 degrees, calculate the smaller angle and
		 * return it.
		 */
		if (temp > PI)
			temp = 2 * PI - temp;
		if (temp < 0.0)
			return (-temp);
		return (temp);
	}

	public static Junction make_3_junction(int basepoint, int p1, int p2, int p3) {
		int shaft, barb1, barb2;
		double angle12, angle13, angle23;
		double sum, sum1213, sum1223, sum1323;
		double delta;
		String j_type;

		angle12 = inscribed_angle(basepoint, p1, p2);
		angle13 = inscribed_angle(basepoint, p1, p3);
		angle23 = inscribed_angle(basepoint, p2, p3);

		sum1213 = angle12 + angle13;
		sum1223 = angle12 + angle23;
		sum1323 = angle13 + angle23;

		if (sum1213 < sum1223) {
			if (sum1213 < sum1323) {
				sum = sum1213;
				shaft = p1;
				barb1 = p2;
				barb2 = p3;
			} else {
				sum = sum1323;
				shaft = p3;
				barb1 = p1;
				barb2 = p2;
			}
		} else {
			if (sum1223 < sum1323) {
				sum = sum1223;
				shaft = p2;
				barb1 = p1;
				barb2 = p3;
			} else {
				sum = sum1323;
				shaft = p3;
				barb1 = p1;
				barb2 = p2;
			}
		}

		delta = sum - PI;
		if (delta < 0.0)
			delta = -delta;

		if (delta < 0.001) {
			j_type = Junction.TEE;
		} else if (sum > PI) {
			j_type = Junction.FORK;
		} else {
			j_type = Junction.ARROW;
		}

		return new Junction(barb1, shaft, barb2, basepoint, j_type);

	}
}