import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

/**
 * World.java
 *
 * A class demonstrating Swing 2D graphics using a bouncing
 * ball.  See Ball.java.
 * 
 * @author Jeff Ondich
 *
 * @version 1.0.0
 * date:    02.09.2010
 */

public class World extends JFrame
{
    private JPanel panel;
    private Ball ball;

    /**
     * A bouncing ball demonstration.
     */
    public static void main(String[] args)
    {
        // Initialize the frame window and the bouncing ball object.
        Color backgroundColor = Color.black;
        int worldWidth = 600;
        int worldHeight = 400;

        World world = new World(worldWidth, worldHeight, backgroundColor);
        world.setBall(new Ball(worldWidth / 2, worldHeight / 2, 40));
        world.getBall().setColor(Color.red);
        world.getBall().setVelocity(10, 10);

        world.setVisible(true);
        world.repaint();

        // Run the animation.
        Graphics g = world.getPanel().getGraphics();
        Ball ball = world.getBall();
        while( true )
        {
            try
            {
                Thread.sleep(100);
            }
            catch (Exception e)
            {
            }

            // Erase, bounce if necessary, step, and redraw.
            ball.erase(g, backgroundColor);

            int vx = ball.getVelocityX();
            int vy = ball.getVelocityY();
            int x = ball.getX();
            int y = ball.getY();
            int r = ball.getRadius();
            if( x + r > worldWidth || x - r < 0 )
            {
                ball.setVelocity(-vx, vy);
            }

            if( y + r > worldHeight || y - r < 0 )
            {
                ball.setVelocity(vx, -vy);
            }

            ball.step();

            world.getBall().draw(g);
        }
    }

    /**
     * Default constructor.
     */
    public World()
    {
        this(500, 300, Color.green);
    }

    /**
     * Initialize a World object with the specified width, height
     * and color.  Create a drawing pane to fill the World, and
     * set a listener to shut down the program when the close-box
     * is clicked.
     *
     * @param width The width in pixels of the desired frame window.
     * @param height The height in pixels of the desired frame window.
     * @param backroundColor The color of the frame window's background.
     */
    public World(int width, int height, Color backgroundColor)
    {
        this.setTitle("The World");

        // Fill this frame window with the pane in which drawing will take place.
        panel = new JPanel();
        panel.setBackground(backgroundColor);
        panel.setPreferredSize(new Dimension(width, height));
        panel.setVisible(true);
        this.setContentPane(panel);
        this.pack();

        // This will make the close-box on the frame window shut down the program.
        this.addWindowListener(new WindowAdapter() {
                                public void windowClosing(WindowEvent e) {
                                    setVisible(false);
                                    System.exit(0);
                                }
                            });
    }

    /* ========== World accessors ============ */

    public void setBall(Ball b)
    {
        ball = b;
    }

    public Ball getBall()
    {
        return ball;
    }

    public JPanel getPanel()
    {
        return panel;
    }
}