import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.swing.JComponent;

/**
 * This class represents a drawing surface that can draw bouncing balls.
 * When an action event is triggered on this canvas, it moves the balls
 * around; if done repeatedly at intervals, this produces animation.
 * @author Marty Stepp
 * @version CSE 331 Spring 2011, 05/18/2011
 */
public class BallCanvas extends JComponent implements ActionListener {
	private static final long serialVersionUID = 1L;
	private static final int BALL_COUNT = 1000;
	
	private List<Ball> balls;   // all bouncing balls to draw
	
	/**
	 * Constructs a new empty canvas with no lines.
	 */
	public BallCanvas() {
		balls = new ArrayList<Ball>();
		
		// produce lots of random bouncing balls
		Random randy = new Random();
		for (int i = 0; i < BALL_COUNT; i++) {
			int red = randy.nextInt(255);
			int green = randy.nextInt(255);
			int blue = randy.nextInt(255);
			Ball ball = new Ball(randy.nextInt(100), randy.nextInt(200),
					randy.nextInt(40) + 10, randy.nextInt(11) - 5,
					randy.nextInt(11) - 5, new Color(red, green, blue));
			balls.add(ball);
		}
	}
	
	/**
	 * Handles action events (timer ticks) on this canvas by updating the position
	 * of every ball on the screen.
	 */
	public void actionPerformed(ActionEvent event) {
		// this will be called every ~20ms
		for (Ball ball : balls) {
			ball.move();
			if (ball.getX() < 0 || ball.getRightX() >= this.getWidth()) {
				ball.bounceLeftRight();
			}
			if (ball.getY() < 0 || ball.getBottomY() >= this.getHeight()) {
				ball.bounceTopBottom();
			}
		}
		
		repaint();
	}
	
	/**
	 * Draws all of the balls on this canvas at their given positions.
	 */
	public void paintComponent(Graphics g) {
		super.paintComponent(g);
		Graphics2D g2 = (Graphics2D) g;
		for (Ball ball : balls) {
			Ellipse2D ballLipse = new Ellipse2D.Double(ball.getX(), ball.getY(),
					ball.getSize(), ball.getSize());
			g2.setPaint(ball.getColor());
			g2.fill(ballLipse);
		}
	}
	
}