import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseMotionListener;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.Graphics;
import java.applet.Applet;
import java.awt.Rectangle;
import java.util.ArrayList;
import java.lang.Math;
import java.util.Random;
import java.awt.Color;

public class ShooterApplet extends Applet
{
    private final int FIELD_HEIGHT = 500;
    private final int FIELD_WIDTH = 500;
    private final static Random rand = new Random();
    
    private ArrayList lasers = new ArrayList();
    private ArrayList allShooters = new ArrayList();
    private Shooter ship;
    private int enemiesKilled = 0;
    private int shotsTaken = 0;
    
    private final int WAIT = (int)Math.pow(2.0, 22.0);
    
    public ShooterApplet()
    {       
        spawnNewEnemy();
        allShooters.add(new Shooter(FIELD_WIDTH / 2, FIELD_HEIGHT / 2));
        ((Shooter)allShooters.get(0)).setPlayerShip();
        ship = (Shooter)allShooters.get(0);
        allShooters.add(new Shooter(FIELD_WIDTH / 2, FIELD_HEIGHT / 2));
        
        class ShipListener extends MouseAdapter implements MouseMotionListener
        {            
            public void mouseMoved(MouseEvent event)
            {
                setPlayerShipTurretAngles((double)event.getX(), (double)event.getY());
                repaint();
            }
            
            public void mouseDragged(MouseEvent event) {}
                        
            public void mousePressed(MouseEvent event)
            {
                firePlayerShips();
                shotsTaken++;
            }
        }
        
        MouseMotionListener listener = new ShipListener();
        addMouseMotionListener(listener);
        addMouseListener((MouseListener)listener);
    }
    
    private void setPlayerShipTurretAngles(double angleX, double angleY)
    {
        Shooter s;
        
        for(int i = 0; i < allShooters.size(); i++)
        {
            s = (Shooter)allShooters.get(i);
            if(s.isPlayerShip())
             s.setTurretAngle(angleX, angleY);
        }
    }
    
    private void firePlayerShips()
    {
        Shooter s;
        
        for(int i = 0; i < allShooters.size(); i++)
        {
            s = (Shooter)allShooters.get(i);
            
            if(s.isPlayerShip())
             lasers.add(s.fire());
        }
    }
    
    public void paint(Graphics g) 
    {
         
        Graphics2D g2 = (Graphics2D)g;
        drawBorder(g2);
        printStats(g2);
        renderShips(g2);
        doLasers(g2);
        buffer();
        repaint();
    }
    
    private void printStats(Graphics2D g2)
    {
        g2.setColor(Color.black);
        g2.drawString("Enemies Killed: " + enemiesKilled, 0, FIELD_HEIGHT + 12);
        g2.drawString("Shots Taken: " + shotsTaken, 0, FIELD_HEIGHT + 24);
        if(enemiesKilled > 0)
        {
            g2.drawString("Average Shots Per Enemy: " + (int)((double)shotsTaken / (double)enemiesKilled), 0, FIELD_HEIGHT + 36);
        }
    }
    
    private void buffer()
    {
        int j;
        
        for(int i = WAIT; i >= 0; i--)
        {
            j = i;
        }
    }
    
    private boolean isOffScreen(Laser las)
    {
        return las.getX() < 0 || las.getX() > FIELD_WIDTH || las.getY() < 0 || las.getY() > FIELD_HEIGHT;
    }
    
    private void destroyLaser(int laserIndex)
    {
        lasers.remove(laserIndex);
    }
    
    private void doLasers(Graphics2D g2)
    {
        for(int i = 0; i < lasers.size(); i++)
        {
            Laser las = (Laser)lasers.get(i);
            
            if(isOffScreen(las))
            {
                destroyLaser(i);
            }
            else
            {
                if(!checkEnemyCollisions(las))
                {
                    las.draw(g2);                 
                    las.move();
                }
            }
        }
    }
    
    private boolean checkEnemyCollisions(Laser las)
    {      
        Shooter s;
        
        for(int i =  0; i < allShooters.size(); i++)
        {
            s = (Shooter)allShooters.get(i);
            if(las.isHitting(s))
            {
                s.takeHit();
                destroyLaser(i);
                return true;
            }
         }
         
         return false;
     }
    
    private void drawBorder(Graphics2D g2)
    {
        g2.draw(new Rectangle(0, 0, FIELD_WIDTH, FIELD_HEIGHT));
    }
    
    private void renderShips(Graphics2D g2)
    {       
        for(int i = 0; i < allShooters.size() - 1; i++)
        {
            Shooter s = (Shooter)allShooters.get(i);
            
            if(s.isDead())
            {   
                if(s == ship)
                {
                    ship = findNextPlayerShip(0);
                    if(ship == (Shooter)allShooters.get(i))
                     spawnNewPlayerShip();
                 }
                destroyShooter(i);
                enemiesKilled++;
                if(enemiesKilled % 3 == 0)
                 spawnNewPlayerShip();
                spawnNewEnemy();
            }
            else
            {          
                if(isOffScreen(s))
                {
                    destroyShooter(i);
                    spawnNewEnemy();
                }
                if(!s.isPlayerShip())
                {
                    enemyAI(s);
                }
                s.draw(g2);
            }
        }
    }
    
    private void enemyAI(Shooter s)
    {
        s.move();
        
        if(rand.nextInt(10) == 0)
        {
            s.setTurretAngle(s.getTurretAngle() + .03);
        }
        
        if(rand.nextInt(10) == 0)
        {
            s.setTurretAngle(s.getTurretAngle() - .03);
        }
                    
        if(rand.nextInt(10) == 0)
         lasers.add(s.fire());
    }
    
    private boolean isOffScreen(Shooter s)
    {
        return s.getX() < 0 || s.getX() > FIELD_WIDTH || s.getY() < 0 || s.getY() > FIELD_HEIGHT;
    }
    
    private void destroyShooter(int enemyIndex)
    {    
        allShooters.remove(enemyIndex);
    }
    
    private void spawnNewEnemy()
    {
        Shooter s = new Shooter(rand.nextInt(FIELD_WIDTH), rand.nextInt(FIELD_HEIGHT));
        s.setTurretAngle(2 * Math.PI * rand.nextDouble());
        s.setShipDirection(2 * Math.PI * rand.nextDouble());
        allShooters.add(s);     
    }
    
    private void spawnNewPlayerShip()
    {
        Shooter s = new Shooter(rand.nextInt(FIELD_WIDTH), rand.nextInt(FIELD_HEIGHT));
        s.setTurretAngle(2 * Math.PI * rand.nextDouble());
        s.setPlayerShip();
        allShooters.add(s);
    }
        
    
    public void init() 
    {
        repaint();
    }
    
    private Shooter findNextPlayerShip(int minIndex)
    {
        for(int i = minIndex; i < allShooters.size(); i++)
        {
            if(((Shooter)allShooters.get(i)).isPlayerShip())
             return (Shooter)allShooters.get(i);
        }
         
        return (Shooter)allShooters.get(minIndex);
    }
}