using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Tutorial020.Managers;
using Tutorial020.Models;

namespace Tutorial020.Sprites
{
  public class Sprite : Component, ICloneable
  {
    protected Dictionary<string, Animation> _animations;

    protected AnimationManager _animationManager;

    protected float _layer { get; set; }

    protected Vector2 _origin { get; set; }

    protected Vector2 _position { get; set; }

    protected float _rotation { get; set; }

    protected float _scale { get; set; }

    protected Texture2D _texture;

    public List<Sprite> Children { get; set; }

    public Color Colour { get; set; }

    public bool IsRemoved { get; set; }

    public float Layer
    {
      get { return _layer; }
      set
      {
        _layer = value;

        if (_animationManager != null)
          _animationManager.Layer = _layer;
      }
    }

    public Vector2 Origin
    {
      get { return _origin; }
      set
      {
        _origin = value;

        if (_animationManager != null)
          _animationManager.Origin = _origin;
      }
    }

    public Vector2 Position
    {
      get
      {
        return _position;
      }
      set
      {
        _position = value;

        if (_animationManager != null)
          _animationManager.Position = _position;
      }
    }

    public Rectangle Rectangle
    {
      get
      {
        if (_texture != null)
        {
          return new Rectangle((int)Position.X - (int)Origin.X, (int)Position.Y - (int)Origin.Y, _texture.Width, _texture.Height);
        }

        if (_animationManager != null)
        {
          var animation = _animations.FirstOrDefault().Value;

          return new Rectangle((int)Position.X - (int)Origin.X, (int)Position.Y - (int)Origin.Y, animation.FrameWidth, animation.FrameHeight);
        }

        throw new Exception("Unknown sprite");
      }
    }

    public float Rotation
    {
      get { return _rotation; }
      set
      {
        _rotation = value;

        if (_animationManager != null)
          _animationManager.Rotation = value;
      }
    }

    public readonly Color[] TextureData;

    public Matrix Transform
    {
      get
      {
        return Matrix.CreateTranslation(new Vector3(-Origin, 0)) *
          Matrix.CreateRotationZ(_rotation) *
          Matrix.CreateTranslation(new Vector3(Position, 0));
      }
    }

    public Sprite Parent;

    /// <summary>
    /// The area of the sprite that could "potentially" be collided with
    /// </summary>
    public Rectangle CollisionArea
    {
      get
      {
        return new Rectangle(Rectangle.X, Rectangle.Y, MathHelper.Max(Rectangle.Width, Rectangle.Height), MathHelper.Max(Rectangle.Width, Rectangle.Height));
      }
    }

    public Sprite(Texture2D texture)
    {
      _texture = texture;

      Children = new List<Sprite>();

      Origin = new Vector2(_texture.Width / 2, _texture.Height / 2);

      Colour = Color.White;

      TextureData = new Color[_texture.Width * _texture.Height];
      _texture.GetData(TextureData);
    }

    public Sprite(Dictionary<string, Animation> animations)
    {
      _texture = null;

      Children = new List<Sprite>();

      Colour = Color.White;

      TextureData = null;

      _animations = animations;

      var animation = _animations.FirstOrDefault().Value;

      _animationManager = new AnimationManager(animation);

      Origin = new Vector2(animation.FrameWidth / 2, animation.FrameHeight / 2);
    }

    public override void Update(GameTime gameTime)
    {

    }

    public override void Draw(GameTime gameTime, SpriteBatch spriteBatch)
    {
      if (_texture != null)
        spriteBatch.Draw(_texture, Position, null, Colour, _rotation, Origin, 1f, SpriteEffects.None, Layer);
      else if (_animationManager != null)
        _animationManager.Draw(spriteBatch);
    }

    public bool Intersects(Sprite sprite)
    {
      if (this.TextureData == null)
        return false;

      if (sprite.TextureData == null)
        return false;

      // Calculate a matrix which transforms from A's local space into
      // world space and then into B's local space
      var transformAToB = this.Transform * Matrix.Invert(sprite.Transform);

      // When a point moves in A's local space, it moves in B's local space with a
      // fixed direction and distance proportional to the movement in A.
      // This algorithm steps through A one pixel at a time along A's X and Y axes
      // Calculate the analogous steps in B:
      var stepX = Vector2.TransformNormal(Vector2.UnitX, transformAToB);
      var stepY = Vector2.TransformNormal(Vector2.UnitY, transformAToB);

      // Calculate the top left corner of A in B's local space
      // This variable will be reused to keep track of the start of each row
      var yPosInB = Vector2.Transform(Vector2.Zero, transformAToB);

      for (int yA = 0; yA < this.Rectangle.Height; yA++)
      {
        // Start at the beginning of the row
        var posInB = yPosInB;

        for (int xA = 0; xA < this.Rectangle.Width; xA++)
        {
          // Round to the nearest pixel
          var xB = (int)Math.Round(posInB.X);
          var yB = (int)Math.Round(posInB.Y);

          if (0 <= xB && xB < sprite.Rectangle.Width &&
              0 <= yB && yB < sprite.Rectangle.Height)
          {
            // Get the colors of the overlapping pixels
            var colourA = this.TextureData[xA + yA * this.Rectangle.Width];
            var colourB = sprite.TextureData[xB + yB * sprite.Rectangle.Width];

            // If both pixel are not completely transparent
            if (colourA.A != 0 && colourB.A != 0)
            {
              return true;
            }
          }

          // Move to the next pixel in the row
          posInB += stepX;
        }

        // Move to the next row
        yPosInB += stepY;
      }

      // No intersection found
      return false;
    }

    //public virtual void OnCollide(Sprite sprite)
    //{

    //}

    public object Clone()
    {
      var sprite = this.MemberwiseClone() as Sprite;

      if (_animations != null)
      {
        sprite._animations = this._animations.ToDictionary(c => c.Key, v => v.Value.Clone() as Animation);
        sprite._animationManager = sprite._animationManager.Clone() as AnimationManager;
      }

      return sprite;
    }
  }
}