/*************************************************************************
 *  Einföld beinagrind fyrir tölvuleiknum Pong.
 *
 *************************************************************************/

import java.awt.event.KeyEvent;

public class Pong {
    public static void main(String[] args) {
        int stig = 0; //stig

        // set the scale of the coordinate system
        StdDraw.setXscale(-1.0, 1.0);
        StdDraw.setYscale(-1.0, 1.0);

        // initial values of ball
        double rx = 0.480, ry = 0.860;     // position
        double vx = 0.015, vy = 0.023;     // velocity
        double radius = 0.05;              // radius

        // initial values of paddle
        double[] px = { -0.2, 0.2, 0.2, -0.2 };
        double[] py = { -0.85, -0.85, -.90, -0.90 };
        double dpx = 0.018;                 // inc. paddle movement

        //initial value of box
        double bx = Math.random(), by = 0.51;
        for (int i = 0; i < 1; i--) {
            by = Math.random();
            if (by > 0.5) {
                break;
            }
        }
        // main animation loop
        while (true) {

            // bounce ball off wall according to law of elastic collision
            if (Math.abs(rx + vx) > 1.0 - radius) vx = -vx;
            if (ry + vy > 1.0 - radius) vy = -vy;


            if (py[0] > ry + vy) {   //Athuga bolta á spaða
                if (px[0] < rx + vx && px[1] > rx + vx) {
                    vy = -vy;
                    stig++;
                }
            }
            if (by + radius > ry + vy && by - radius < ry + vy) { //Athuga bolta á kassa
                if (bx + radius > rx + vx && bx - radius < rx + vx) {
                    bx = Math.random();
                    for (int i = 0; i < 1; i--) {
                        by = Math.random();
                        if (by > 0.5) {
                            break;
                        }
                    }
                    stig += 2;
                }
            }
            StdDraw.text(0.7, 0.9, "Stig: " + stig); //Skrifa stig

            if (ry + vy < -0.9) {  //Athuga bolta á botn gluggans
                break;
            }
            // update ball position
            rx = rx + vx;
            ry = ry + vy;
            // check if paddle moved
            if (StdDraw.isKeyPressed(KeyEvent.VK_LEFT) && px[0] - dpx >= -1.0)
                for (int i = 0; i < 4; i++) px[i] -= dpx;
            if (StdDraw.isKeyPressed(KeyEvent.VK_RIGHT) && px[1] + dpx <= 1.0)
                for (int i = 0; i < 4; i++) px[i] += dpx;

            StdDraw.clear();

            // draw ball on the screen
            StdDraw.setPenColor(StdDraw.RED);
            StdDraw.filledCircle(rx, ry, radius);

            // Teikna kassa
            StdDraw.setPenColor(StdDraw.BOOK_BLUE);
            StdDraw.filledSquare(bx, by, 0.05);

            // draw paddle on the screen
            StdDraw.setPenColor(StdDraw.BLUE);
            StdDraw.filledPolygon(px, py);

            // display and pause for 20 ms
            StdDraw.show();
            StdDraw.pause(20);
        }
        StdDraw.clear();
        StdDraw.text(0.1, 0.1, "Þú tapaðir með " + stig + " stig");
    }
}