using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Input;

namespace SemiColinGames {
  readonly struct Input {
    public readonly Vector2 Motion;
    public readonly bool Jump;
    public readonly bool Attack;

    public readonly bool Pause;
    public readonly bool Debug;
    public readonly bool Exit;
    public readonly bool Restart;
    public readonly bool FullScreen;

    public Input(GamePadState gamePad, KeyboardState keyboard) {
      Motion = new Vector2();

      // We check for debugging buttons first. If any are pressed, we suppress normal input;
      // other button-presses correspond to special debugging things.
      Exit = keyboard.IsKeyDown(Keys.Escape);
      Restart = keyboard.IsKeyDown(Keys.F5);
      FullScreen = keyboard.IsKeyDown(Keys.F12);
      if (gamePad.IsButtonDown(Buttons.LeftShoulder) &&
          gamePad.IsButtonDown(Buttons.RightShoulder)) {
        Exit |= gamePad.IsButtonDown(Buttons.Start);
        Restart |= gamePad.IsButtonDown(Buttons.Back);
        FullScreen |= gamePad.IsButtonDown(Buttons.Y);
      }
      if (Exit || Restart || FullScreen) {
        Jump = false;
        Attack = false;
        Pause = false;
        Debug = false;
        return;
      }

      // Then we process normal buttons.
      Jump = gamePad.IsButtonDown(Buttons.A) || gamePad.IsButtonDown(Buttons.B) ||
          keyboard.IsKeyDown(Keys.J);
      Attack = gamePad.IsButtonDown(Buttons.X) || gamePad.IsButtonDown(Buttons.Y) ||
          keyboard.IsKeyDown(Keys.K);

      Debug = gamePad.IsButtonDown(Buttons.Back) || keyboard.IsKeyDown(Keys.OemMinus);
      Pause = gamePad.IsButtonDown(Buttons.Start) || keyboard.IsKeyDown(Keys.P);

      // Then potential motion directions. If the player attempts to input opposite directions at
      // once (up & down or left & right), those inputs cancel out, resulting in no motion.
      Vector2 leftStick = gamePad.ThumbSticks.Left;
      bool left = leftStick.X < -0.5 || gamePad.IsButtonDown(Buttons.DPadLeft) ||
          keyboard.IsKeyDown(Keys.A);
      bool right = leftStick.X > 0.5 || gamePad.IsButtonDown(Buttons.DPadRight) ||
          keyboard.IsKeyDown(Keys.D);
      bool up = leftStick.Y > 0.5 || gamePad.IsButtonDown(Buttons.DPadUp) ||
          keyboard.IsKeyDown(Keys.W);
      bool down = leftStick.Y < -0.5 || gamePad.IsButtonDown(Buttons.DPadDown) ||
          keyboard.IsKeyDown(Keys.S);
      if (left && !right) {
        Motion.X = -1;
      }
      if (right && !left) {
        Motion.X = 1;
      }
      if (up && !down) {
        Motion.Y = 1;
      }
      if (down && !up) {
        Motion.Y = -1;
      }
    }
  }
}