Ball.java

import greenfoot.*;


/**
 * A Ball is a thing that bounces of walls and paddles (or at least i should).
 * 
 * @author The teachers 
 * @version 1
 */
public class Ball extends Actor
{
    private static final int BALL_SIZE = 25;
    private static final int BOUNCE_DEVIANCE_MAX = 25;
    private static final int STARTING_ANGLE_WIDTH = 90;
    private static final int DELAY_TIME = 100;

    private Actor lastTouch = this;
    private int speed;
    private boolean hasBouncedHorizontally;
    private boolean hasBouncedVertically;
    private int delay;
    private Color color = Color.BLACK;

    /**
     * Contructs the ball and sets it in motion!
     */
    public Ball()
    {
        createImage();
        init();
    }

    /**
     * Creates and sets an image of a black ball to this actor.
     */
    private void createImage()
    {
        GreenfootImage ballImage = new GreenfootImage(BALL_SIZE,BALL_SIZE);
        ballImage.setColor(color);
        ballImage.fillOval(0, 0, BALL_SIZE, BALL_SIZE);
        setImage(ballImage);
    }

    /**
     * Act - do whatever the Ball wants to do. This method is called whenever
     * the 'Act' or 'Run' button gets pressed in the environment.
     */
    public void act() 
    {
        if (delay > 0)
        {
            delay--;
        }
        else
        {
            move(speed);
            checkBounceOffWalls();
            checkBounceOffPaddle();
            checkRestart();
        }
    }    

    /**
     * Returns true if the ball is touching one of the side walls.
     */
    private boolean isTouchingSides()
    {
        return (getX() <= BALL_SIZE/2 || getX() >= getWorld().getWidth() - BALL_SIZE/2);
    }

    /**
     * Returns true if the ball is touching the ceiling.
     */
    private boolean isTouchingCeiling()
    {
        return (getY() <= BALL_SIZE/2);
    }
    
    private boolean isTouchingPaddle()
    {
        Paddle paddle = (Paddle)getOneIntersectingObject(Paddle.class);
        if(paddle != null)
        {
            switchColor(paddle);
            if(getLastTouch().equals(paddle))
            {
                return false;
            }
            paddle.hitByBall();
            setLastTouch(paddle);
            return true;
        }
        return false;
    }

    /**
     * Returns true if the ball is touching the floor.
     */
    private boolean isTouchingFloor()
    { 
        return (getY() >= getWorld().getHeight() - BALL_SIZE/2);
    }

    /**
     * Check to see if the ball should bounce off one of the walls.
     * If touching one of the walls, the ball is bouncing off.
     */
    private void checkBounceOffWalls()
    {
        if (isTouchingSides())
        {
            if (! hasBouncedHorizontally)
            {
                revertHorizontally();
            }
        }
        else
        {
            hasBouncedHorizontally = false;
        }
    }
    
    private void checkBounceOffPaddle()
    {
        if(isTouchingPaddle())
        {
            revertVertically();
        }
    }

    /**
     * Check to see if the ball should be restarted.
     * If touching the floor the ball is restarted in initial position and speed.
     */
    private void checkRestart()
    {
        if (isTouchingFloor() || isTouchingCeiling())
        {
            init();
            setLocation(getWorld().getWidth() / 2, getWorld().getHeight() / 2);
        }
    }

    /**
     * Bounces the ball back from a vertical surface.
     */
    private void revertHorizontally()
    {
        int randomness = Greenfoot.getRandomNumber(BOUNCE_DEVIANCE_MAX)- BOUNCE_DEVIANCE_MAX / 2;
        setRotation((180 - getRotation()+ randomness + 360) % 360);
        hasBouncedHorizontally = true;
    }

    /**
     * Bounces the ball back from a horizontal surface.
     */
    private void revertVertically()
    {
        int randomness = Greenfoot.getRandomNumber(BOUNCE_DEVIANCE_MAX)- BOUNCE_DEVIANCE_MAX / 2;
        setRotation((360 - getRotation()+ randomness + 360) % 360);
        hasBouncedVertically = true;
    }

    /**
     * Initialize the ball settings.
     */
    private void init()
    {
        speed = 1;
        delay = DELAY_TIME;
        hasBouncedHorizontally = false;
        hasBouncedVertically = false;
        setLastTouch(this);
        setRotation(Greenfoot.getRandomNumber(STARTING_ANGLE_WIDTH)+STARTING_ANGLE_WIDTH/2);
    }

    public void switchColor(Paddle paddle)
    {
        // Implement this method so that the color of the ball changes to match
        // the color of given paddle.
    }
    
    private Actor getLastTouch()
    {
        return lastTouch;
    }
    
    private void setLastTouch(Actor actor)
    {
        lastTouch = actor;
    }
}