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

public class Ball extends Actor
{   
    int scoreLeft = 0;
    int scoreRight = 0;
    /**
     * 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() 
    {
        move(4);
        scorePoint();
        endGame();
    }    
    
    /**
     * Tests if the ball hits the left edge of the world.
     */
    public boolean isAtLeftEdge()
    {
        if (getX() <= 0)
            return true;
        else 
            return false;
    }
    
    /**
     * Tests if the ball hits the right edge of the world.
     */
    public boolean isAtRightEdge()
    {
        if (getX() >= getWorld().getWidth()-1)
            return true;
        else
            return false;
    }
    
    /**
     * If the ball hits either the right or left edge of the world
     * a point is scored for the player of the opposite side.
     * A new Ball is then added to the game while the old one is being removed. 
     */
    public void scorePoint()
    {
        if (isAtLeftEdge() || isAtRightEdge())
        {   
            if (isAtLeftEdge())
            {
                scoreRight++;
            }
            if (isAtRightEdge())
            {
                scoreLeft++;
            }
            getWorld().addObject(new Ball(), 350, 200);
            getWorld().removeObject(this);
        }
    }
    
    /**
     * As one player reaches a score of 5 the game ends.
     */
    public void endGame()
    {
        if (scoreRight == 5)
        {
            Greenfoot.stop();
        }
        if (scoreLeft == 5)
        {
            Greenfoot.stop();
        }
    }
}