using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using System;
using System.Collections.Generic;

namespace Jumpy {
  enum Terrain {
    Empty,
    Grass,
    Rock
  }

  class Tile {
    Texture2D texture;
    Terrain terrain;
    Rectangle position;

    public Tile(Texture2D texture, Terrain terrain, Rectangle position) {
      this.texture = texture;
      this.terrain = terrain;
      this.position = position;
    }

    public Rectangle Position { get { return position; } }
    public Terrain Terrain { get { return terrain; } }

    public void Draw(SpriteBatch spriteBatch) {
      int size = World.TileSize;
      switch (terrain) {
        case Terrain.Grass: {
          // TODO: hold these rectangles statically instead of making them anew constantly.
          Rectangle source = new Rectangle(3 * size, 0 * size, size, size);
          spriteBatch.Draw(texture, position, source, Color.White);
          break;
        }
        case Terrain.Rock: {
          Rectangle source = new Rectangle(3 * size, 1 * size, size, size);
          spriteBatch.Draw(texture, position, source, Color.White);
          break;
        }
        case Terrain.Empty:
        default:
          break;
      }
    }
  }

  class World {

    public const int TileSize = 16;
    int width;
    int height;
    Tile[,] tiles;

    public int Width { get; }
    public int Height { get; }

    public World(Texture2D texture) {
      width = Camera.Width / TileSize;
      height = Camera.Height / TileSize + 1;
      tiles = new Tile[width, height];
      for (int j = 0; j < height; j++) {
        for (int i = 0; i < width; i++) {
          Terrain terrain;
          if (j < height - 2) {
            terrain = Terrain.Empty;
          } else if (j == height - 2) {
            terrain = Terrain.Grass;
          } else {
            terrain = Terrain.Rock;
          }
          if (j == 6 && 11 < i && i < 16) {
            terrain = Terrain.Grass;
          }
          if (j == 3 && 15 < i && i < 19) {
            terrain = Terrain.Grass;
          }
          if (j == 7 && i == 5) {
            terrain = Terrain.Grass;
          }
          if (7 <= j && j <= 10 && i == 12) {
            terrain = Terrain.Rock;
          }
          var position = new Rectangle(i * TileSize, j * TileSize, TileSize, TileSize);
          tiles[i, j] = new Tile(texture, terrain, position);
        }
      }
    }

    public void Draw(SpriteBatch spriteBatch) {
      for (int j = 0; j < height; j++) {
        for (int i = 0; i < width; i++) {
          tiles[i, j].Draw(spriteBatch);
        }
      }
    }

    public List<Rectangle> CollisionTargets() {
      var result = new List<Rectangle>();
      for (int j = 0; j < height; j++) {
        for (int i = 0; i < width; i++) {
          var t = tiles[i, j];
          if (t.Terrain != Terrain.Empty) {
            result.Add(t.Position);
          }
        }
      }
      return result;
    }
  }
}