#region Using Statements
using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Net;
using Microsoft.Xna.Framework.Storage;
#endregion

namespace CellAuto
{
    /// <summary>
    /// This is the main type for your game
    /// </summary>
    public class Game1 : Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;
        SpriteBatch spriteBatch;

        int screenWidth = 800;
        int screenHeight = 600;
        int screenSize = 800 * 600;

        Texture2D CA;
        Color[] caTexture;
        Color[] caBuffer;

        public Game1()
        {
            graphics = new GraphicsDeviceManager(this);
            Content.RootDirectory = "Content";

            caTexture = new Color[screenSize];
            caBuffer = new Color[screenSize];
        }

        public void InitializeCA()
        {
            Random random = new Random();
            Color black = Color.Black;
            Color white = Color.White;

            // Seed the CA with random values
            for (int i = 0; i < screenSize; i++)
            {
                int RandomBinary = random.Next(2); // generate a random number between 0 and 1
                if( 0 == RandomBinary ) // if 0, then add black
                {
                    caTexture = black;
                }
                else // if 1, then add white
                {
                    caTexture = white;
                }
            }
            // Create the texture
            CA = new Texture2D(graphics.GraphicsDevice, screenWidth, screenHeight, 1, TextureUsage.None, SurfaceFormat.Color);
            // Set the new data to the texture
            CA.SetData<Color>(caTexture);
        }

        public void GameOfLife()
        {
            // Update buffer using ruleset
            for (int y = 0; y < screenHeight; y++)
            {
                for (int x = 0; x < screenWidth; x++)
                {
                    caBuffer[y * screenWidth + x] = GameOfLifeRules(x, y);
                }
            }
            // replace original with buffer
            for (int i = 0; i < screenSize; i++)
            {
                caTexture = caBuffer;
            }
        }

        private Color GameOfLifeRules(int X, int Y)
        {
            // Original game of life rules made image converge too quickly, so this is used.
            int temp = LiveNeighborCount(X, Y);
            if (0 <= temp && temp <= 2)
            {
                return Color.Black;
            }
            if (3 == temp)
            {
                return Color.White;
            }
            if (5 == temp)
            {
                return Color.Black;
            }
            if (6 <= temp)
            {
                return Color.White;
            }
            return caTexture[Y*screenWidth+X];
        }

        private int LiveNeighborCount(int X, int Y)
        {
            int retVal = 0;
            // Test for bounds
            int left = 0,
                leftAbove = 0,
                above = 0,
                rightAbove = 0,
                right = 0,
                rightBelow = 0,
                below = 0,
                leftBelow = 0;

            // Left
            if (X > 0)
            {
                if (Color.White == caTexture[Y * screenWidth + X - 1])
                {
                    left = 1;
                }
            }
            // Left Above
            if (X > 0 && Y > 0)
            {
                if (Color.White == caTexture[(Y - 1) * screenWidth + X - 1])
                {
                    leftAbove = 1;
                }
            }
            // Above
            if (Y > 0)
            {
                if (Color.White == caTexture[(Y - 1) * screenWidth + X])
                {
                    above = 1;
                }
            }
            // Right Above
            if (X+1 < screenWidth && Y > 0)
            {
                if (Color.White == caTexture[(Y - 1) * screenWidth + X + 1])
                {
                    rightAbove = 1;
                }
            }
            // Right
            if (X+1 < screenWidth)
            {
                if (Color.White == caTexture[Y * screenWidth + X + 1])
                {
                    right = 1;
                }
            }
            // Right Below
            if (X+1 < screenWidth && Y+1 < screenHeight)
            {
                if (Color.White == caTexture[(Y + 1) * screenWidth + X + 1])
                {
                    rightBelow = 1;
                }
            }
            // Below
            if (Y + 1 < screenHeight)
            {
                if (Color.White == caTexture[(Y + 1) * screenWidth + X])
                {
                    below = 1;
                }
            }
            // Left Below
            if (X > 0 && Y + 1 < screenHeight)
            {
                if (Color.White == caTexture[(Y + 1) * screenWidth + X - 1])
                {
                    leftBelow = 1;
                }
            }

            retVal = left + leftAbove + above + rightAbove + right + rightBelow + below + leftBelow;
            return retVal;
        }

        /// <summary>
        /// Allows the game to perform any initialization it needs to before starting to run.
        /// This is where it can query for any required services and load any non-graphic
        /// related content.  Calling base.Initialize will enumerate through any components
        /// and initialize them as well.
        /// </summary>
        protected override void Initialize()
        {
            // TODO: Add your initialization logic here
            InitializeCA();

            base.Initialize();
        }

        /// <summary>
        /// LoadContent will be called once per game and is the place to load
        /// all of your content.
        /// </summary>
        protected override void LoadContent()
        {
            // Create a new SpriteBatch, which can be used to draw textures.
            spriteBatch = new SpriteBatch(GraphicsDevice);

            // TODO: use this.Content to load your game content here
        }

        /// <summary>
        /// UnloadContent will be called once per game and is the place to unload
        /// all content.
        /// </summary>
        protected override void UnloadContent()
        {
            CA.Dispose();
            // TODO: Unload any non ContentManager content here
        }

        /// <summary>
        /// Allows the game to run logic such as updating the world,
        /// checking for collisions, gathering input, and playing audio.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Update(GameTime gameTime)
        {
            // Allows the game to exit
            if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
                this.Exit();

            base.Update(gameTime);
        }

        /// <summary>
        /// This is called when the game should draw itself.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Draw(GameTime gameTime)
        {
            graphics.GraphicsDevice.Clear(Color.CornflowerBlue);

            // This updates the data in the CA so it actually evolves
            // Uses the game of life rule
            GameOfLife();

            // Hack to refresh the texture, discard the previous one and create a new texture with the
            //  updated buffer
            CA.Dispose();
            CA = new Texture2D(graphics.GraphicsDevice, screenWidth, screenHeight, 1, TextureUsage.None, SurfaceFormat.Color);
            CA.SetData<Color>(caTexture);

            // Draw the sprites to screen
            spriteBatch.Begin();
            spriteBatch.Draw(CA, Vector2.Zero, Color.White);
            spriteBatch.End();

            base.Draw(gameTime);
        }
    }
}