import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.Dimension;
import java.awt.Color;
import java.awt.image.BufferedImage;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.AlphaComposite;

public class SpaceWars extends JFrame
{
	static String windowTitle = "SpaceWars";

	public SpaceWars(String name){
		setTitle(name);
		setDefaultCloseOperation(EXIT_ON_CLOSE); //フレームを終了
	}

	public static void main(String args[]){
		SpaceWars obj = new SpaceWars(windowTitle);
		SpaceWarsPanel panel = new SpaceWarsPanel();
		obj.getContentPane().add(panel);
		obj.pack();
		Thread t = new Thread(panel);
		t.start();
		obj.setVisible(true);
	}
}

class SpaceWarsPanel extends JPanel implements Runnable
{
	public int count = 0;
	Thread thread = null;
	Star[] stars = new Star[300];
	ShootingStar shootstars[] = new ShootingStar[10];
	Explosion explosions[] = new Explosion[7];

	static int screenW = 640;
	static int screenH = 480;

	BufferedImage offImage = new BufferedImage(screenW, screenH, BufferedImage.TYPE_INT_BGR);

	public SpaceWarsPanel() {
		Graphics2D g = offImage.createGraphics();
		g.setRenderingHint(
			RenderingHints.KEY_ANTIALIASING,
			RenderingHints.VALUE_ANTIALIAS_ON);
		count = 0;
		for(int i=0 ; i<stars.length ; i++) {
			stars[i] = new Star();
			stars[i].speed = (int)(Math.random() * 20);
			stars[i].x = (int)(Math.random() * screenW);
			stars[i].y = (int)(Math.random() * screenH);
		}

		for(int i=0 ; i<shootstars.length ; i++) {
			shootstars[i] = new ShootingStar();
		}

		for(int i=0 ; i<explosions.length ; i++) {
			explosions[i] = new Explosion();
		}
}

	public void run() {
		while(true) {
			repaint();
			count++;
			for(int i=0 ; i<stars.length ; i++) {
				stars[i].proc();
			}
			for(int i=0 ; i<shootstars.length ; i++) {
				shootstars[i].proc();
			}
			for(int i=0 ; i<explosions.length ; i++) {
				explosions[i].proc();
			}
			try{
				Thread.sleep(30);
			} catch(InterruptedException e) {}
		}
	}

	public void paint(Graphics g) {
		Graphics goff = offImage.getGraphics();
		draw(goff);
		g.drawImage(offImage, 0, 0, 
			screenW, screenH, null);
	}

	public void draw(Graphics g) {
		((Graphics2D)g).setRenderingHint(
			RenderingHints.KEY_ANTIALIASING,
			RenderingHints.VALUE_ANTIALIAS_ON);
		g.setColor(Color.black);
		g.fillRect(0, 0, screenW, screenH);
		for(int i=0 ; i<stars.length ; i++) {
			stars[i].draw(g);
		}
		for(int i=0 ; i<shootstars.length ; i++) {
			shootstars[i].draw(g);
		}
		for(int i=0 ; i<explosions.length ; i++) {
			explosions[i].draw(g);
		}
	}

	Dimension prefSize = null;
	public Dimension getPreferredSize() {
		if(prefSize==null) {
			prefSize = new Dimension(screenW, screenH);
		}
		return prefSize;
	}
}

class Star
{
	public int x = 0;
	public int y = 0;
	public int speed = 10;
	public int brightness = 255;
	public Color color = new Color(255,255,255);
	public void draw(Graphics g) {
		g.setColor(color);
		g.fillOval(x, y, 2, 2);
	}
	public void proc() {
		brightness += speed;
		if(brightness > 255) {
			brightness = 255;
			speed = -speed;
		}
		if(brightness < 0) {
			brightness = 0;
			speed = -speed;
		}
		color = new Color(brightness, brightness, brightness);
	}
}

class ShootingStar
{
	public static final int PHASE0 = 0;
	public static final int PHASE1 = 1;
	public static final int PHASE2 = 2;
	public int phase = PHASE0;

	public double iniX = 10;
	public double iniY = 10;
	public double endX = 100;
	public double endY = 100;

	public double waitcount=0;
	public double waitlimit=100;
	public double t = 0;

	ShootingStar() {
		init();
		phase = PHASE2;
	}
	
	public void init() {
		iniX = Math.random() * SpaceWarsPanel.screenW;
		iniY = Math.random() * SpaceWarsPanel.screenH;
		endX = Math.random() * SpaceWarsPanel.screenW;
		endY = Math.random() * SpaceWarsPanel.screenH;
		waitlimit = Math.random() * 15 + 5;
		phase = PHASE0;
	}
	public void draw(Graphics g) {
		g.setColor(Color.white);
		switch(phase) {
		case PHASE0: phase0(g); break;
		case PHASE1: phase1(g); break;
		}
	}
	public void proc() {
		switch(phase) {
		case PHASE0: 
			t += 0.1;
			if(t>1) {
				t=0;
				phase = PHASE1;
			}
			break;
		case PHASE1:
			t += 0.1;
			if(t>1) {
				t=0;
				phase = PHASE2;
				waitcount = 0;
			}
			break;
		case PHASE2:
			waitcount++;
			if(waitcount>waitlimit) {
				init();
			}
			break;
		}
	}
	public void phase0(Graphics g)
	{
		double px, py;
		px = t*(endX - iniX);
		py = t*(endY - iniY);
		g.drawLine((int)iniX, (int)iniY, (int)(iniX + px), (int)(iniY + py));
	}
	public void phase1(Graphics g)
	{
		double px, py;
		px = t*(endX - iniX);
		py = t*(endY - iniY);
		g.drawLine((int)(iniX + px), (int)(iniY + py), (int)endX, (int)endY);
	}
}

class Explosion
{
	double x;
	double y;
	double r;
	double maxR;
	Color color = null;
	int phase;
	static final int PHASE0 = 0;
	static final int PHASE1 = 1;
	static final int PHASE2 = 2;

	public double waitcount=0;
	public double waitlimit=10;
	public double t = 0;

	public Explosion() {
		init();
		phase = PHASE2;
	}
	
	public void init() {
		x = Math.random() * SpaceWarsPanel.screenW;
		y = Math.random() * SpaceWarsPanel.screenH;
		maxR = Math.random() * 20 + 10;
		waitlimit = Math.random() * 20 + 5;
		color = new Color(255, 255, 255, 255);
		phase = PHASE0;
	}

	public void draw(Graphics g) {
		g.setColor(Color.white);
		switch(phase) {
		case PHASE0: phase0(g); break;
		case PHASE1: phase1(g); break;
		}
	}

	public void proc() {
		switch(phase) {
		case PHASE0: 
			t += 0.05;
			if(t>1) {
				t=1;
				phase = PHASE1;
			}
			color = new Color(1.f, 1.f, (float)(1.5-t>1.0 ? 1.0 : 1.5-t));
			break;
		case PHASE1:
			t -= 0.01;
			color = new Color(1.f, 1.f, (float)(1.5-t>1.0 ? 1.0 : 1.5-t));
			if(t<0.5) {
				t=0;
				phase = PHASE2;
				waitcount = 0;
			}
			break;
		case PHASE2:
			waitcount++;
			if(waitcount>waitlimit) {
				init();
			}
			break;
		}
	}

	public void phase0(Graphics g)
	{
		r = t*maxR;
		Graphics2D g2 = (Graphics2D)g;
		g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 1));
		g.setColor(color);
		g.fillOval((int)(x-r), (int)(y-r), (int)(2*r), (int)(2*r));
	}
	public void phase1(Graphics g)
	{
		r = t*maxR;
		Graphics2D g2 = (Graphics2D)g;
		g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, (float)t));
		g.setColor(color);
		g.fillOval((int)(x-r), (int)(y-r), (int)(2*r), (int)(2*r));

	}
}