import java.applet.*;
import java.awt.*;

public class TicTacToe extends Applet
{
	private int[][] moves;
	private int turn;
	private boolean endGame;

	public void init()
	{
		turn = 1;
		moves = new int[3][3];
		endGame = false;
	}

	public void start()
	{
		turn = 1;
		endGame = false;
		for( int i=0; i<3; i++ )
			for( int j=0; j<3; j++ )
				moves[i][j] = 0;
	}

	public void stop() { start(); }

	private int whichTile( int x, int maxX )
	{
		if( x < maxX / 3 )
			return 0;
		else if( x < 2 * maxX / 3 )
			return 1;
		else
			return 2;
	}

	private boolean checkEndGame()
	{

		// if no remaining squares, end of game
		endGame = true;
		for( int i=0; i<3; i++ )
			for( int j=0; j<3; j++ )
				if( moves[i][j] == 0 )
					endGame = false;

		for( int i=0; i<3; i++ ) {
			if( moves[i][0] == moves[i][1]
			 && moves[i][0] == moves[i][2]
			 && moves[i][0] > 0 ) {
				moves[i][0] += 2;
				moves[i][1] += 2;
				moves[i][2] += 2;
				endGame = true;
			}
			if( moves[0][i] == moves[1][i]
			 && moves[0][i] == moves[2][i]
			 && moves[0][i] > 0 ) {
				moves[0][i] += 2;
				moves[1][i] += 2;
				moves[2][i] += 2;
				endGame = true;
			}
		}
		if( moves[0][0] == moves[1][1]
		 && moves[0][0] == moves[2][2]
		 && moves[0][0] > 0 ) {
			moves[0][0] += 2;
			moves[1][1] += 2;
			moves[2][2] += 2;
			endGame = true;
		}
		if( moves[0][2] == moves[1][1]
		 && moves[0][2] == moves[2][0]
		 && moves[0][2] > 0 ) {
			moves[0][2] += 2;
			moves[1][1] += 2;
			moves[2][0] += 2;
			endGame = true;
		}
		return endGame;
	}

	public boolean mouseDown( Event e, int x, int y )
	{
		Dimension d = size();
		if( endGame ) {
			start();
			repaint();
			return true;
		}
		int tileX = whichTile(x,d.width);
		int tileY = whichTile(y,d.height);
		if( moves[tileY][tileX] == 0 ) {
			moves[tileY][tileX] = turn;
			turn = (turn%2)+1;
			drawOneTile( getGraphics(), tileY, tileX );
		} else {
			// error, flash the screen
			repaint();
		}
		// is this the end of the game?
		if( checkEndGame() )
			repaint();
		return true;
	}

	private Color myColor( int turn )
	{
		if( turn == 0 )
			return Color.black;
		else if( turn == 1 || turn == 3 )
			return Color.red;
		else if( turn == 2 || turn == 4 )
			return Color.green;
		else
			return Color.black;
	}

	private void drawOneTile( Graphics g, int i, int j )
	{
		Dimension d = size();

		// draw X or O
		if( moves[i][j] == 1 ) {
			g.setColor( myColor(moves[i][j]) );
			g.drawLine( j*d.width/3, i*d.height/3,
				    (j+1)*d.width/3,   (i+1)*d.height/3 );
			g.drawLine( j*d.width/3, (i+1)*d.height/3,
			            (j+1)*d.width/3, i*d.height/3 );
		} else if( moves[i][j] == 3 ) {
			g.setColor( myColor(moves[i][j]) );
			g.fillRect( j*d.width/3, i*d.height/3,
				    d.width/3,   d.height/3 );
			g.setColor( Color.black );
			g.drawLine( j*d.width/3, i*d.height/3,
				    (j+1)*d.width/3,   (i+1)*d.height/3 );
			g.drawLine( j*d.width/3, (i+1)*d.height/3,
			            (j+1)*d.width/3, i*d.height/3 );
		} else if( moves[i][j] == 2 ) {
			g.setColor( myColor(moves[i][j]) );
			g.drawOval( j*d.width/3, i*d.height/3,
				      d.width/3,   d.height/3 );
		} else if( moves[i][j] == 4 ) {
			g.setColor( myColor(moves[i][j]) );
			g.fillOval( j*d.width/3, i*d.height/3,
				      d.width/3,   d.height/3 );
		}
	}

	public void paint( Graphics g )
	{
		Dimension d = size();

		g.setColor( Color.black );
		g.fillRect( 0, 0, d.width, d.height );

		// draw red/green/black squares of the board
		// black squares are "unused"
		// red is for player "X"
		// green is for player "O"
		for( int i=0; i<3; i++ ) {
			for( int j=0; j<3; j++ ) {
				drawOneTile(g, i, j);
			}
		}

		// draw white separating lines between the tiles
		for( int i=1; i<3; i++ ) {
			g.setColor( Color.white );
			g.drawLine( i*d.width/3, 0,
			            i*d.width/3, d.height );
			g.drawLine( 0,       i*d.height/3,
			            d.width, i*d.height/3 );
		}

	}

}