ball

import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)

/**
 * The ball of the game. It moves and bounces off the walls and the paddle and increases speed every level.
 * 
 * @author (Nathaniel Hailu)
 * @version June 17 2013
 */

/**
 * Credits:
 */
public class Ball extends Actor
{
    private int xMove;         // x movement speed
    private int yMove;         // y movement speed
    private int count = 2;
    private boolean inPlay = true;
    private boolean stuck = true;   // stuck to paddle
    private Counter counter;

    /**
     * Moves the ball if the ball is not stuck on the paddle
     */
    public void act() 
    {
        if (!stuck) 
        {
            //Moves the ball
            move();
            //Checks if the ball is outside the boundaries of the game (which is how the user loses a life)
            checkOut();
        }
    }

    /**
     * Moves the ball. Then check if the ball has hit the paddle, brick, or the wall
     */
    public void move()
    {
        //Gets the location of the ball
        setLocation (getX() + xMove, getY() + yMove);
        //Checks if the ball has hit the paddle or a brick
        checkPaddleAndBrick();
        //Checks if the ball has hit a wall
        checkWalls();
    }

    /**
     * Checks whether the ball has hit one of the three walls. Reverses direction if necessary.
     */
    private void checkWalls()
    {
        //Reverses the movement of the ball in the horizontal direction
        if (getX() == 0 || getX() == getWorld().getWidth()-1) {
            xMove = -xMove;
        }
        //Reverses the movement of the ball in the vertical direction
        if (getY() == 0) {
            yMove = -yMove;
        }     
    }

    /**
     * Check whether the ball has reached the bottom of the screen.
     */
    public void checkOut()
    {
        if (getY() == getWorld().getHeight()-1)
        {
            ((BrickWorld) getWorld()).ballIsOut();
            getWorld().removeObject(this);
        }
    }

    /**
     * Checks if the ball has hit the paddle or a brick
     * Borrowed code from mit
     */

    private void checkPaddleAndBrick()  //Beginning of borrowed code
    {
        Actor paddle = getOneIntersectingObject(Paddle.class);
        if (paddle != null) {
            yMove = -yMove;
            int offset = getX() - paddle.getX();
            xMove = xMove + (offset/10);
            if (xMove > 7) {
                xMove = 7;
            }
            if (xMove < -7) {
                xMove = -7;
            }
        }
        if(canSee(Brick.class))
        {
            Actor brick = getOneIntersectingObject(Brick.class);
            if (brick != null) {
                yMove = -yMove;
                int offset = getX() - brick.getX();
                xMove = xMove + (offset/10);
                if (xMove > 7) {
                    xMove = 7;
                }
                if (xMove < -7) {
                    xMove = -7;
                }
            }
            BrickWorld myBrickWorld = (BrickWorld) getWorld();
            myBrickWorld.score();
            eat(Brick.class);
        }
    }       //End of borrowed code

    /**
     * Moves the ball a given distance sideways.
     */
    public void move(int dist)
    {
        setLocation (getX() + 45, getY());
    }

    /**
     * Releases the ball from the paddle.
     */
    public void release()
    {
        //Generates a random number to move the ball horizontally when released
        xMove = Greenfoot.getRandomNumber(11) - 5;
        yMove = -5;
        //Ball no longer stuck on paddle
        stuck = false;
    }

    /**
     * Return true if we can see an object of class 'clss' right where we are. 
     * False if there is no such object here.
     * Borrowed code from mit
     */
    public boolean canSee(Class clss)
    {
        Actor actor = getOneObjectAtOffset(0, 0, clss);
        return actor != null;        
    }

    /**
     * Try to eat an object of class 'clss'. This is only successful if there
     * is such an object where we currently are. Otherwise this method does
     * nothing.
     * Borrowed code from mit
     */
    public void eat(Class clss)
    {
        Actor actor = getOneObjectAtOffset(0, 0, clss);
        if(actor != null) {
            getWorld().removeObject(actor);
        }
    }
}