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

namespace SemiColinGames {
  static class Debug {
    struct DebugRect {
      public Rectangle Rect;
      public Color Color;

      public DebugRect(Rectangle rect, Color color) {
        Rect = rect;
        Color = color;
      }
    }

    struct DebugLine {
      public Point Start;
      public Point End;
      public Color Color;

      public DebugLine(Point start, Point end, Color color) {
        Start = start;
        End = end;
        Color = color;
      }
    }

    public static bool Enabled = true;
    // This is a LinkedList instead of a List because SetFpsText() adds to its front.
    static readonly LinkedList<string> toasts = new LinkedList<string>();
    static readonly List<DebugRect> rects = new List<DebugRect>();
    static readonly List<DebugLine> lines = new List<DebugLine>();

    static Texture2D whiteTexture;

    public static void Initialize(GraphicsDevice graphics) {
      whiteTexture = new Texture2D(graphics, 1, 1);
      whiteTexture.SetData(new Color[] { Color.White });
    }

    public static void WriteLine(string s) {
      System.Diagnostics.Debug.WriteLine(s);
    }

    public static void WriteLine(string s, params object[] args) {
      System.Diagnostics.Debug.WriteLine(s, args);
    }

    public static void Clear(bool paused) {
      toasts.Clear();
      if (!paused) {
        rects.Clear();
        lines.Clear();
      }
    }

    public static void AddToast(string s) {
      toasts.AddLast(s);
    }

    // FPS text is always displayed as the first toast (if set).
    public static void SetFpsText(string s) {
      toasts.AddFirst(s);
    }

    public static void AddRect(Rectangle rect, Color color) {
      rects.Add(new DebugRect(rect, color));
    }

    public static void AddRect(AABB box, Color color) {
      Rectangle rect = new Rectangle(
          (int) (box.Position.X - box.HalfSize.X), (int) (box.Position.Y - box.HalfSize.Y),
          (int) (box.HalfSize.X * 2), (int) (box.HalfSize.Y * 2));
      AddRect(rect, color);
    }

    public static void AddLine(Point start, Point end, Color color) {
      lines.Add(new DebugLine(start, end, color));
    }

    public static void AddLine(int p1x, int p1y, int p2x, int p2y, Color color) {
      lines.Add(new DebugLine(new Point(p1x, p1y), new Point(p2x, p2y), color));
    }

    public static void DrawToasts(SpriteBatch spriteBatch, SpriteFont font) {
      if (!Enabled) {
        return;
      }
      int y = 10;
      foreach (var toast in toasts) {
        spriteBatch.DrawString(font, toast, new Vector2(10, y), Color.Teal);
        y += 30;
      }
    }

    public static void Draw(SpriteBatch spriteBatch, Camera camera) {
      if (!Enabled) {
        return;
      }
      foreach (var debugRect in rects) {
        var rect = debugRect.Rect;
        rect.Offset(-camera.Left, 0);
        var color = debugRect.Color;
        // top side
        spriteBatch.Draw(
          whiteTexture, new Rectangle(rect.Left, rect.Top, rect.Width, 1), color);
        // bottom side
        spriteBatch.Draw(
          whiteTexture, new Rectangle(rect.Left, rect.Bottom - 1, rect.Width, 1), color);
        // left side
        spriteBatch.Draw(
          whiteTexture, new Rectangle(rect.Left, rect.Top, 1, rect.Height), color);
        // right side
        spriteBatch.Draw(
          whiteTexture, new Rectangle(rect.Right - 1, rect.Top, 1, rect.Height), color);
      }
      foreach (var line in lines) {
        Point[] points = Line.Rasterize(line.Start, line.End);
        foreach (var point in points) {
          spriteBatch.Draw(
            whiteTexture, new Rectangle(point.X, point.Y, 1, 1), line.Color);
        }
      }
    }
  }
}