package Lect41Applets;

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

// This custom widget uses a timer to move the red square
// many times per second, bouncing it off the widget edges
public class AnimatedRedSquareWidget extends JComponent {
	private static final int STEPS_PER_SECOND = 40;
	private static final int SQUARE_WIDTH = 50;
	private static final int SQUARE_HEIGHT = 50;

	private int dx = 5;
	private int dy = 2;
	private Rectangle2D.Double rect;
	
	public AnimatedRedSquareWidget() {
		setBackground(Color.WHITE);

		rect = new Rectangle2D.Double(50, 50, SQUARE_WIDTH, SQUARE_HEIGHT);
		
		// Make the step method get called regularly through a timer callback
		TimerListener timerListener = new TimerListener(this);
		Timer timer = new Timer(1000 / STEPS_PER_SECOND, timerListener);
		timer.start();
	}
	
	public void setSquareX(int x) {
		rect.setRect(x, rect.getY(), rect.getWidth(), rect.getHeight());
		repaint();  // After model changes, force a repaint so view reflects updated model
	}
	
	public int getSquareX() {
		return (int)rect.getX();
	}
	
	public void setSquareY(int y) {
		rect.setRect(rect.getX(), y, rect.getWidth(), rect.getHeight());
		repaint();  // After model changes, force a repaint so view reflects updated model
	}
	
	public int getSquareY() {
		return (int)rect.getY();
	}
	
	public void paintComponent(Graphics g) {
		Graphics2D g2 = (Graphics2D)g;

		// First fill in background
        g2.setColor(getBackground());
        g2.fill(new Rectangle2D.Double(0, 0, getWidth(), getHeight()));
		
        // Then draw foreground (red square)
		g2.setColor(Color.RED);
		g2.fill(rect);
	}
	
	public void step() {
		// First update square position
		int x = getSquareX();
		int y = getSquareY();
		
		x += dx;
		y += dy;
		
		setSquareX(x);
		setSquareY(y);

		// Then, make sure it stays within the widget borders
		bounceWithinFrame();
	}
	
	public void bounceWithinFrame() {
		int x = getSquareX();
		int y = getSquareY();
		
		if ((x < 0) || ((x + SQUARE_WIDTH) > getWidth())) {
			dx *= -1;
			x += dx;
		}
		
		if ((y < 0) || ((y + SQUARE_HEIGHT) > getHeight())) {
			dy *= -1;
			y += dy;
		}

		setSquareX(x);
		setSquareY(y);
	}
}

class TimerListener implements ActionListener {
	AnimatedRedSquareWidget widget;
	
	public TimerListener(AnimatedRedSquareWidget widget) {
		this.widget = widget;
	}
	
	public void actionPerformed(ActionEvent evt) {
		widget.step();
	}
};