import java.awt.Canvas;
import java.awt.Graphics2D;
import java.awt.Dimension;
import java.awt.BorderLayout;

import java.awt.event.KeyListener;
import java.awt.event.KeyEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseWheelListener;
import java.awt.event.MouseWheelEvent;
import java.awt.image.BufferStrategy;

import javax.swing.JFrame;
import javax.swing.JPanel;

// TODO: implement pause (rendering) function
public abstract class Scene extends JPanel
	implements Runnable, KeyListener, MouseListener,
				MouseMotionListener, MouseWheelListener {
	
	protected final long DESIRED_FPS = 60;
	protected final long DESIRED_DELTA_LOOP = (1000*1000*1000)/DESIRED_FPS;

	protected BufferStrategy buffer;

	protected Dimension canvasSize;
	protected boolean running;
	protected Canvas canvas;

	// TODO: make accessible from user settings
	protected int guiSize = 2;

	protected Scene() {
		this.canvasSize = GameWindow.WINDOW_SIZE;
		this.canvas = new Canvas();	

		this.canvas.setBounds(0, 0, this.canvasSize.width, this.canvasSize.height);
		this.canvas.setIgnoreRepaint(true);

		this.canvas.addKeyListener(this);
		this.canvas.addMouseListener(this);
		this.canvas.addMouseMotionListener(this);
		this.canvas.addMouseWheelListener(this);
	}

	public void initCanvasBuffer() {
		this.canvas.createBufferStrategy(2);
		this.buffer = this.canvas.getBufferStrategy();

		this.canvas.requestFocus();	
	}

	public void run() {
		long beginLoopTime;
		long endLoopTime;
		long currentUpdateTime = System.nanoTime();
		long lastUpdateTime;
		long deltaLoop;

		this.initCanvasBuffer();

		this.running = true;

		while (running) {
			beginLoopTime = System.nanoTime();

			this.render();

			lastUpdateTime = currentUpdateTime;
			currentUpdateTime = System.nanoTime();
			this.update((int) ((currentUpdateTime - lastUpdateTime)/(1000*1000)));

			endLoopTime = System.nanoTime();
			deltaLoop = endLoopTime - beginLoopTime;

			if (deltaLoop > this.DESIRED_DELTA_LOOP) {
				// TODO: late => skip frame
			} else {
				try {
					Thread.sleep((this.DESIRED_DELTA_LOOP - deltaLoop)/(1000*1000));
				} catch (InterruptedException e ) {
					
				}
			}
		}
	}

	// automagically set the canvas size to the parent's size
	public void updateCanvasSize() {
		this.canvasSize = this.getParent().getSize();
	}

	public void setCanvasSize(Dimension newSize) {
		this.canvasSize = newSize;
	}

	protected abstract void render();
	protected abstract void update(int deltaNanoTime);

	@Override
	public void keyTyped(KeyEvent e) {}
	public void keyPressed(KeyEvent e) {}
	public void keyReleased(KeyEvent e) {}
	public void mouseClicked(MouseEvent e) {}
	public void mouseEntered(MouseEvent e) {}
	public void mouseExited(MouseEvent e) {}
	public void mousePressed(MouseEvent e) {}
	public void mouseReleased(MouseEvent e) {}
	public void mouseDragged(MouseEvent e) {}
	public void mouseMoved(MouseEvent e) {}
	public void mouseWheelMoved(MouseWheelEvent e) {}

}