Stuff

using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Storage;

namespace SnakeGame
{
    /// <summary>
    /// This is the main type for your game
    /// </summary>
    public class SnakeGame : Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;
        ContentManager content;


        public SnakeGame()
        {
            graphics = new GraphicsDeviceManager(this);
            content = new ContentManager(Services);
        }


        /// <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

            base.Initialize();
        }

        Texture2D snakeHeadTexture;
        Rectangle snakeHeadRect;
        Texture2D foodTexture;
        Rectangle foodRect;
        SpriteBatch spriteBatch;
        int snakeHeadSize = 40;
        int playerLives = 3;
        int playerScore = 0;

        /// <summary>
        /// Load your graphics content.  If loadAllContent is true, you should
        /// load content from both ResourceManagementMode pools.  Otherwise, just
        /// load ResourceManagementMode.Manual content.
        /// </summary>
        /// <param name="loadAllContent">Which type of content to load.</param>
        protected override void LoadGraphicsContent(bool loadAllContent)
        {
            if (loadAllContent)
            {
                snakeHeadTexture = content.Load<Texture2D>(@"content\images\SnakeHead");
                foodTexture = content.Load<Texture2D>(@"content\images\Apple");
                spriteBatch = new SpriteBatch(graphics.GraphicsDevice);
                snakeHeadRect = new Rectangle(
                    0, 0,
                    snakeHeadSize, snakeHeadSize);
                foodRect = new Rectangle(
                    50, 50,
                    snakeHeadSize, snakeHeadSize);
            }

            // TODO: Load any ResourceManagementMode.Manual content
        }

        //private bool intersectsWith(Rectangle r1, Rectangle r2)
        //{
        //    return !(r2.Left > r1.Right
        //            || r2.Right < r1.Left
        //            || r2.Top > r1.Bottom
        //            || r2.Bottom < r1.Top
        //            );
        //}

        // r2 has a 5px perimeter for collision detection
        private bool intersectsWith(Rectangle r1, Rectangle r2)
        {
            return (r1.X > r2.X - 5
                && r1.X + r1.Width < r2.X + r2.Width + 5
                && r1.Y > r2.Y - 5
                && r1.Y + r1.Height < r2.Y + r2.Height + 5
            );
        }

        static Rectangle makeFood(Rectangle r1, int X, int Y)
        {
            Random rand = new Random();
            r1.X = rand.Next(X - r1.Width);
            r1.Y = rand.Next(Y - r1.Height);
            return r1;
        }

        /// <summary>
        /// Unload your graphics content.  If unloadAllContent is true, you should
        /// unload content from both ResourceManagementMode pools.  Otherwise, just
        /// unload ResourceManagementMode.Manual content.  Manual content will get
        /// Disposed by the GraphicsDevice during a Reset.
        /// </summary>
        /// <param name="unloadAllContent">Which type of content to unload.</param>
        protected override void UnloadGraphicsContent(bool unloadAllContent)
        {
            if (unloadAllContent == true)
            {
                content.Unload();
            }
        }


        /// <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 default game to exit on Xbox 360 and Windows
            if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
                this.Exit();
            Console.WriteLine(this.TargetElapsedTime.ToString());

            if(snakeHeadRect.Y < 0
            || snakeHeadRect.X < 0
            || snakeHeadRect.X + snakeHeadSize > Window.ClientBounds.Width
            || snakeHeadRect.Y + snakeHeadSize > Window.ClientBounds.Height
            )
            {
                playerLives -= 1;
                snakeHeadRect.X = 0;
                snakeHeadRect.Y = 0;
            }

            if (intersectsWith(snakeHeadRect, foodRect))
            {
                foodRect = makeFood(foodRect, Window.ClientBounds.Width, Window.ClientBounds.Height);
                playerScore += 1;
            }

            KeyboardState keystate = Keyboard.GetState();

            if (keystate.IsKeyDown(Keys.Escape))
            {
                this.Exit();
            }

            if (keystate.IsKeyDown(Keys.Up))
            {
                snakeHeadRect.Y--;
            }

            if (keystate.IsKeyDown(Keys.Down))
            {
                snakeHeadRect.Y++;
            }

            if (keystate.IsKeyDown(Keys.Left))
            {
                snakeHeadRect.X--;
            }

            if (keystate.IsKeyDown(Keys.Right))
            {
                snakeHeadRect.X++;
            }

            //if (keystate.IsKeyDown(Keys.Up))
            //{
            //    snakeHeadRect.Y -= snakeHeadSize;
            //}

            //if (keystate.IsKeyDown(Keys.Down))
            //{
            //    snakeHeadRect.Y += snakeHeadSize;
            //}

            //if (keystate.IsKeyDown(Keys.Left))
            //{
            //    snakeHeadRect.X -= snakeHeadSize;
            //}

            //if (keystate.IsKeyDown(Keys.Right))
            //{
            //    snakeHeadRect.X += snakeHeadSize;
            //}

            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.Black);

            spriteBatch.Begin(SpriteBlendMode.AlphaBlend);

            spriteBatch.Draw(foodTexture, foodRect, Color.White);

            switch (playerLives)
            {
                case 3:
                    spriteBatch.Draw(snakeHeadTexture,snakeHeadRect, Color.White);
                    break;
                case 2:
                    spriteBatch.Draw(snakeHeadTexture, snakeHeadRect, Color.Orange);
                    break;
                case 1:
                    spriteBatch.Draw(snakeHeadTexture, snakeHeadRect, Color.Red);
                    break;
                case 0:
                    this.Exit();
                    break;
            }

            spriteBatch.End();

            base.Draw(gameTime);
        }
    }
}