import java.util.Random;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import java.awt.Color;
import java.awt.Dimension;

public class LifeGame
{
	private static Random rand = new Random();	
	
	private final int DEAD = 0;
	private final int GREEN = 1;
	private final int BLUE = 2;
	private final Color GREEN_COLOR = Color.green;
	private final Color BLUE_COLOR = Color.blue;
	private final Color DEAD_COLOR = Color.white;
	
	private final int CELL_SIZE = 10;
	private int gridHeight;
	private int gridWidth;
	private int[][] grid;
	
	private int[] colorCounter = new int[2];
	private int GREEN_INDEX = 0;
	private int BLUE_INDEX = 1;
	
	public LifeGame(int pixelHeight, int pixelWidth)
	{
		gridHeight = pixelHeight / CELL_SIZE;
		gridWidth = pixelWidth / CELL_SIZE;
		grid = new int[gridHeight][gridWidth];
		
		//initialize a random grid
		for(int i = 0; i < gridHeight; i++)
		{
			for(int j = 0; j < gridWidth; j++)
			{
				grid[i][j] = rand.nextInt(3);
			}
		}
	}
	
	public void nextGen()
	{
		int[][] temp = new int[gridHeight][gridWidth];
		
		for(int i = 0; i < gridHeight; i++)
		{
			for(int j = 0; j < gridWidth; j++)
			{
				if(i == 0 || j ==0 || i == gridHeight - 1 || j == gridWidth - 1)
				{
					temp[i][j] = 0;
				}
				else
				{
					calculateNeighbors(i, j);
					
					if((colorCounter[GREEN_INDEX] == 3 || colorCounter[GREEN_INDEX] == 4) || (colorCounter[GREEN_INDEX] == 2 && grid[i][j] == GREEN))
					 temp[i][j] = GREEN;
					
					if(colorCounter[BLUE_INDEX] == 3 || (colorCounter[BLUE_INDEX] == 2 && grid[i][j] == BLUE))
					 temp[i][j] = BLUE;
				}
			}
		}
		
		grid = temp;
	}
	
	
	public void calculateNeighbors(int row, int column)
	{
		colorCounter[0] = 0;
		colorCounter[1] = 0;
		
		if(grid[row][column] == GREEN)
		 colorCounter[GREEN_INDEX] = -1;
		
		if(grid[row][column] == BLUE)
		 colorCounter[BLUE_INDEX] = -1;
		
		for(int i = row - 1; i<= row + 1; i++)
		{
			for(int j = column - 1; j <= column + 1; j++)
			{
				if(grid[i][j] == GREEN)
				 colorCounter[GREEN_INDEX] += 1;
				
				if(grid[i][j] == BLUE)
				 colorCounter[BLUE_INDEX] += 1; 
			}
		}
	}
	
	public void draw(Graphics2D g2)
	{
		for(int i = 0; i < gridHeight; i++)
		{
			for(int j = 0; j < gridWidth; j++)
			{
				if(grid[i][j] != DEAD)
				{
					if(grid[i][j] == GREEN)
				 	 g2.setColor(GREEN_COLOR);
				 
					if(grid[i][j] == BLUE)
				 	 g2.setColor(BLUE_COLOR);
				 
					g2.fill(new Ellipse2D.Double(j * CELL_SIZE, (i + 1) * CELL_SIZE, CELL_SIZE, CELL_SIZE));
				}	
			}
		}
	}
	}