using System;
using System.Collections.Generic;
using System.Linq;
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.Media;

namespace WindowsGame1
{
    /// <summary>
    /// This is the main type for your game
    /// </summary>
    public class Game1 : Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;
        Rect _rect;

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

        /// <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();

            _rect = new Rect(GraphicsDevice, Vector3.Zero, new[] { Color.Red, Color.Green, Color.Blue, Color.Yellow }, 50f);
        }

        /// <summary>
        /// LoadContent will be called once per game and is the place to load
        /// all of your content.
        /// </summary>
        protected override void LoadContent()
        {
            // 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()
        {
            // 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();

            // TODO: Add your update logic here

            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)
        {
            GraphicsDevice.Clear(Color.CornflowerBlue);

            // TODO: Add your drawing code here
            _rect.Draw();

            base.Draw(gameTime);
        }
    }

    public abstract class Shape
    {
        public Vector3 Center;
        public Color[] Colors;
        public bool SetColorsOnUpdate;

        public virtual Rectangle BoundingBox { get; set; }
        public float Radius { get { return mRadius; } }

        public GraphicsDevice Device { get; private set; }

        protected VertexBuffer mVertexBuf;
        protected IndexBuffer mIndexBuf;
        protected float mRadius;
        protected BasicEffect mShader;

        public Shape(GraphicsDevice device, Vector3 center, Color[] colors, int numVertices, float radius)
        {
            Device = device;
            Colors = colors;
            Center = center;
            mVertexBuf = new VertexBuffer(device, typeof(VertexPositionColor), numVertices, BufferUsage.WriteOnly);
            mIndexBuf = new IndexBuffer(device, IndexElementSize.SixteenBits, 6, BufferUsage.WriteOnly);
            SetColorsOnUpdate = true;
            mShader = new BasicEffect(device);
            mRadius = radius;
        }

        public abstract void Update();
        public abstract void Draw();
    }

    public class Rect : Shape
    {
        public override Rectangle BoundingBox
        {
            get
            {
                int x = (int)Center.X, y = (int)Center.Y;
                int diameter = (int)mRadius * 2;

                return new Rectangle(
                    x, y,
                    x + diameter,
                    y + diameter
                );
            }
        }

        const float TestRectZCoordinate = 0;
        const int NumVertices = 4;

        public Rect(GraphicsDevice device, Vector3 center, Color[] colors, float radius)
            : base(device, center, colors, NumVertices, radius)
        {
            if (colors.Length < NumVertices)
                throw new IndexOutOfRangeException(string.Format("Color array passed to Rect constructor MUST have an element index size of 4. Current length passed is {0}", colors.Length));

            mShader.VertexColorEnabled = true;

            mVertexBuf.SetData<VertexPositionColor>(
                    new VertexPositionColor[]
                {
                    new VertexPositionColor(new Vector3(Center.X - mRadius, Center.Y - mRadius, TestRectZCoordinate), Colors[2]),
                    new VertexPositionColor(new Vector3(Center.X + mRadius, Center.Y - mRadius, TestRectZCoordinate), Colors[1]),
                    new VertexPositionColor(new Vector3(Center.X + mRadius, Center.Y + mRadius, TestRectZCoordinate), Colors[0]),
                    new VertexPositionColor(new Vector3(Center.X - mRadius, Center.Y + mRadius, TestRectZCoordinate), Colors[3])
                });

            mIndexBuf.SetData<short>(new short[] { 0, 1, 2, 0, 2, 3 });
        }

        public override void Update()
        {
            //TODO
        }

        public override void Draw()
        {
            var halfWidth = Device.Viewport.Width / 2f;
            var halfHeight = Device.Viewport.Height / 2f;

            // mShader.World = Matrix.CreateWorld(Center, Vector3.Forward, Vector3.Up);
            mShader.Projection = Matrix.CreateOrthographicOffCenter(-halfWidth, halfWidth, halfHeight, -halfHeight, 0, 1);

            Device.SetVertexBuffer(mVertexBuf);
            Device.Indices = mIndexBuf;
            foreach (var pass in mShader.CurrentTechnique.Passes)
            {
                pass.Apply();

                Device.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, NumVertices, 0, 2);
            }
        }
    }
}