mixin RayCastToMouse on Forge2DGame implements RayCast, MouseMovementDetector {
  late Vector2 _direction = Vector2(1, 0);

  @override
  void onMouseMove(PointerHoverInfo info) {
    final vector = info.eventPosition.game;
    final tempDirection = Vector2(
      vector.x - rayStartPosition.x,
      vector.y - rayStartPosition.y,
    );
    _direction = Vector2(
      tempDirection.x / tempDirection.length.abs(),
      tempDirection.y / tempDirection.length.abs(),
    );
  }

  @override
  Vector2 get rayDirection => _direction;
}

mixin RayCast on Forge2DGame implements HasCollisionDetection {
  final _points = <Vector2>[];

  @override
  void update(double dt) {
    super.update(dt);
    final ray = Ray2(
      origin: Vector2(rayStartPosition.x, rayStartPosition.y),
      direction: rayDirection,
    );
    final result = collisionDetection.raycast(ray);
    if ((result != null) && (result.intersectionPoint != null)) {
      _fireRay(ray.origin, result.intersectionPoint!);
    }
  }

  @override
  void render(Canvas canvas) {
    super.render(canvas);
    for (int i = 0; i < _points.length - 1; i++) {
      canvas.drawLine(
        _points[i].toOffset(),
        _points[i + 1].toOffset(),
        Paint()
          ..color = Colors.red
          ..strokeWidth = 4,
      );
    }
  }

  void _fireRay(
    Vector2 rayStart,
    Vector2 rayTarget,
  ) {
    _points.clear();
    _points.add(worldToScreen(rayStart));

    final nearestCallback = _NearestBoxRayCastCallback();
    world.raycast(nearestCallback, rayStart, rayTarget);

    if (nearestCallback.nearestPoint != null) {
      _points.add(worldToScreen(nearestCallback.nearestPoint!));
    } else {
      _points.add(worldToScreen(rayTarget));
    }
  }

  Vector2 get rayDirection => Vector2(1, 0);

  Vector2 get rayStartPosition;
}

class _NearestBoxRayCastCallback extends RayCastCallback {
  Vector2? nearestPoint;
  double nearestFraction = 0;

  @override
  double reportFixture(
    Fixture fixture,
    Vector2 point,
    Vector2 normal,
    double fraction,
  ) {
    if ((nearestPoint == null) || (fraction < nearestFraction)) {
      nearestPoint = point;
      nearestFraction = fraction;
    }
    return 1;
  }
}