import objectdraw.*;
import java.util.Random;

// a ball in a game of pong
public class PongBall extends ActiveObject {

    // size of the ball
    private static final int BALL_SIZE = 30;
    
    // speed of the ball
    private double yspeed = 0.1, xspeed = 0.1;
    
    // pause time in between movements
    private static final int PAUSE_TIME = 30;

    private FilledOval ball;
    
    private FramedRect court;
    private FilledRect paddle;
    
    private DrawingCanvas canvas;
    
    private Random rand = new Random();

    public PongBall(Location point, FilledRect paddle,
            FramedRect court, DrawingCanvas aCanvas) {
        ball = new FilledOval(point, BALL_SIZE, BALL_SIZE, aCanvas);
        canvas = aCanvas;
        this.court = court;
        this.paddle = paddle;
        yspeed = (rand.nextDouble() - 0.5) / 2;
        xspeed = (rand.nextDouble() - 0.5) / 2;
        start();
    }

    public void run() {
        double lastTime = System.currentTimeMillis();

        // move the ball repeatedly until it falls off screen
        while (ball.getY() < canvas.getHeight()) {

            // determine how much time has passed
            double currentTime = System.currentTimeMillis();
            double elapsedTime = currentTime - lastTime;
            
            // restart timing
            lastTime = currentTime;
            
            // move the ball the appropriate amount given the time passed       
            
            ball.move(xspeed * elapsedTime, yspeed * elapsedTime);

            if (ball.getX() < court.getX()
                    || ball.getX() > court.getX() + court.getWidth() - ball.getWidth()) {
                xspeed = -xspeed;
            }
            
            if (ball.overlaps(paddle) || ball.getY() < court.getY()){
                yspeed = -yspeed;
            }
            
            // pass a bit more time
            pause(PAUSE_TIME);
        }

        ball.removeFromCanvas();
    }

}