// Exercise 2.5.25 (Solution published at http://algs4.cs.princeton.edu/)
package algs12;
import stdlib.*;
//import java.util.Arrays;
import java.util.Comparator;
/* ***********************************************************************
 *  Compilation:  javac Point2D.java
 *
 *  Immutable point data type for points in the plane.
 *
 *************************************************************************/

public class Point2D implements Comparable<Point2D> {
	public static final Comparator<Point2D> X_ORDER = new XOrder();
	public static final Comparator<Point2D> Y_ORDER = new YOrder();
	public static final Comparator<Point2D> R_ORDER = new ROrder();

	public final Comparator<Point2D> POLAR_ORDER = new PolarOrder();
	public final Comparator<Point2D> ATAN2_ORDER = new Atan2Order();
	public final Comparator<Point2D> DISTANCE_TO_ORDER = new DistanceToOrder();

	private final double x;    // x coordinate
	private final double y;    // y coordinate

	// create a new point (x, y)
	public Point2D(double x, double y) {
		this.x = x;
		this.y = y;
	}

	// return the x-coorindate of this point
	public double x() { return x; }

	// return the y-coorindate of this point
	public double y() { return y; }

	// return the radius of this point in polar coordinates
	public double r() { return Math.sqrt(x*x + y*y); }

	// return the angle of this point in polar coordinates
	// (between -pi/2 and pi/2)
	public double theta() { return Math.atan2(y, x); }

	// return the polar angle between this point and that point (between -pi and pi);
	// (0 if two points are equal)
	private double angleTo(Point2D that) {
		double dx = that.x - this.x;
		double dy = that.y - this.y;
		return Math.atan2(dy, dx);
	}

	// is a->b->c a counter-clockwise turn?
	// -1 if clockwise, +1 if counter-clockwise, 0 if collinear
	public static int ccw(Point2D a, Point2D b, Point2D c) {
		double area2 = (b.x-a.x)*(c.y-a.y) - (b.y-a.y)*(c.x-a.x);
		if      (area2 < 0) return -1;
		else if (area2 > 0) return +1;
		else                return  0;
	}

	// twice signed area of a-b-c
	public static double area2(Point2D a, Point2D b, Point2D c) {
		return (b.x-a.x)*(c.y-a.y) - (b.y-a.y)*(c.x-a.x);
	}

	// return Euclidean distance between this point and that point
	public double distanceTo(Point2D that) {
		double dx = this.x - that.x;
		double dy = this.y - that.y;
		return Math.sqrt(dx*dx + dy*dy);
	}

	// return square of Euclidean distance between this point and that point
	public double distanceSquaredTo(Point2D that) {
		double dx = this.x - that.x;
		double dy = this.y - that.y;
		return dx*dx + dy*dy;
	}

	// compare by y-coordinate, breaking ties by x-coordinate
	public int compareTo(Point2D that) {
		if (this.y < that.y) return -1;
		if (this.y > that.y) return +1;
		if (this.x < that.x) return -1;
		if (this.x > that.x) return +1;
		return 0;
	}

	// compare points according to their x-coordinate
	private static class XOrder implements Comparator<Point2D> {
		public int compare(Point2D p, Point2D q) {
			if (p.x < q.x) return -1;
			if (p.x > q.x) return +1;
			return 0;
		}
	}

	// compare points according to their y-coordinate
	private static class YOrder implements Comparator<Point2D> {
		public int compare(Point2D p, Point2D q) {
			if (p.y < q.y) return -1;
			if (p.y > q.y) return +1;
			return 0;
		}
	}

	// compare points according to their polar radius
	private static class ROrder implements Comparator<Point2D> {
		public int compare(Point2D p, Point2D q) {
			double delta = (p.x*p.x + p.y*p.y) - (q.x*q.x + q.y*q.y);
			if (delta < 0) return -1;
			if (delta > 0) return +1;
			return 0;
		}
	}

	// compare other points relative to atan2 angle (bewteen -pi/2 and pi/2) they make with this Point
	private class Atan2Order implements Comparator<Point2D> {
		public int compare(Point2D q1, Point2D q2) {
			double angle1 = angleTo(q1);
			double angle2 = angleTo(q2);
			if      (angle1 < angle2) return -1;
			else if (angle1 > angle2) return +1;
			else                      return  0;
		}
	}

	// compare other points relative to polar angle (between 0 and 2pi) they make with this Point
	private class PolarOrder implements Comparator<Point2D> {
		public int compare(Point2D q1, Point2D q2) {
			Trace.draw ();
			double dx1 = q1.x - x;
			double dy1 = q1.y - y;
			double dx2 = q2.x - x;
			double dy2 = q2.y - y;

			if      (dy1 >= 0 && dy2 < 0) return -1;    // q1 above; q2 below
			else if (dy2 >= 0 && dy1 < 0) return +1;    // q1 below; q2 above
			else if (dy1 == 0 && dy2 == 0) {            // 3-collinear and horizontal
				if      (dx1 >= 0 && dx2 < 0) return -1;
				else if (dx2 >= 0 && dx1 < 0) return +1;
				else                          return  0;
			}
			else return -ccw(Point2D.this, q1, q2);     // both above or below

			// Note: ccw() recomputes dx1, dy1, dx2, and dy2
		}
	}

	// compare points according to their distance to this point
	private class DistanceToOrder implements Comparator<Point2D> {
		public int compare(Point2D p, Point2D q) {
			double dist1 = distanceSquaredTo(p);
			double dist2 = distanceSquaredTo(q);
			if      (dist1 < dist2) return -1;
			else if (dist1 > dist2) return +1;
			else                    return  0;
		}
	}


	// does this point equal y?
	public boolean equals(Object other) {
		if (other == this) return true;
		if (other == null) return false;
		if (other.getClass() != this.getClass()) return false;
		Point2D that = (Point2D) other;
		// Don't use == here if x or y could be NaN or -0
		if (Double.compare(this.x,that.x) != 0) return false;
		if (Double.compare(this.y,that.y) != 0) return false;
		return true;
	}

	// must override hashcode if you override equals
	// See Item 9 of Effective Java (2e) by Joshua Block
	private volatile int hashCode;
	public int hashCode() {
		int result = hashCode;
		if (result == 0) {
			result = 17;
			result = 31*result + Double.hashCode(x);
			result = 31*result + Double.hashCode(y);
			hashCode = result;
		}
		return result;
	}

	// convert to string
	public String toString() {
		return "(" + x + "," + y + ")";
	}

	// plot using StdDraw
	public void draw() {
		StdDraw.point(x, y);
	}

	// draw line from this point p to q using StdDraw
	public void drawTo(Point2D that) {
		StdDraw.line(this.x, this.y, that.x, that.y);
	}


	public static void main(String[] args) {
		Trace.run ();
		Point2D origin = new Point2D (0, 0);
		Point2D a = new Point2D (1, -1);
		Point2D b = new Point2D (-1, 1);
		
		StdOut.println (origin.POLAR_ORDER.compare (a, b));
		
		
//		args = new String[] { "20", "20", "100" };
//		
//		int x0 = Integer.parseInt(args[0]);
//		int y0 = Integer.parseInt(args[1]);
//		int N = Integer.parseInt(args[2]);
//
//		StdDraw.setCanvasSize(800, 800);
//		StdDraw.setXscale(0, 100);
//		StdDraw.setYscale(0, 100);
//		StdDraw.setPenRadius(.005);
//		Point2D[] points = new Point2D[N];
//		for (int i = 0; i < N; i++) {
//			int x = StdRandom.uniform(100);
//			int y = StdRandom.uniform(100);
//			points[i] = new Point2D(x, y);
//			points[i].draw();
//		}
//
//		// draw p = (x0, x1) in red
//		Point2D p = new Point2D(x0, y0);
//		StdDraw.setPenColor(StdDraw.RED);
//		StdDraw.setPenRadius(.02);
//		p.draw();
//
//
//		// draw line segments from p to each point, one at a time, in polar order
//		StdDraw.setPenRadius();
//		StdDraw.setPenColor(StdDraw.BLUE);
//		Arrays.sort(points, p.POLAR_ORDER);
//		for (int i = 0; i < N; i++) {
//			p.drawTo(points[i]);
//			StdDraw.show(100);
//		}
	}
}