import vtkActor, { IActorInitialValues } from './Actor';
import vtkCamera from './Camera';

/**
 *
 */
export interface IFollowerInitialValues extends IActorInitialValues {
  viewUp?: number[];
  useViewUp?: boolean;
  camera?: vtkCamera;
}

/**
 *
 */
export interface vtkFollower extends vtkActor {
  /**
   * Generate the matrix based on ivars.
   */
  computeMatrix(): void;

  /**
   * Get the camera to follow.
   */
  getCamera(): vtkCamera;

  /**
   * Check whether the view up vector is used.
   */
  getUseViewUp(): boolean;

  /**
   * Get the view up vector.
   */
  getViewUp(): number[];

  /**
   * Get a reference to the view up vector.
   */
  getViewUpByReference(): number[];

  /**
   * Set the camera to follow.
   * If this is not set, then the follower won't know what to follow.
   * @param {vtkCamera} camera
   */
  setCamera(camera: vtkCamera): boolean;

  /**
   * Set whether to use the view up vector.
   * @param {Boolean} useViewUp
   */
  setUseViewUp(useViewUp: boolean): boolean;

  /**
   * Set the viewUp vector.
   * @param {Number[]} viewUp The view up vector.
   */
  setViewUp(viewUp: number[]): boolean;
}

/**
 * Method use to decorate a given object (publicAPI+model) with vtkFollower characteristics.
 *
 * @param publicAPI object on which methods will be bounds (public)
 * @param model object on which data structure will be bounds (protected)
 * @param {IFollowerInitialValues} [initialValues] (default: {})
 */
export function extend(
  publicAPI: object,
  model: object,
  initialValues?: IFollowerInitialValues
): void;

/**
 * Method use to create a new instance of vtkFollower
 * @param {IFollowerInitialValues} [initialValues] for pre-setting some of its content
 */
export function newInstance(
  initialValues?: IFollowerInitialValues
): vtkFollower;

/**
 * vtkFollower is a subclass of Actor that always faces the camera.
 *
 * You must set the camera before use. This class will update the matrix such
 * that the follower always faces the camera. Sepcifically the y axis will up
 * up, the Z axes will point to the camera and the x axis will point to the
 * right. You may need to rotate, scale, position the follower to get your data
 * oriented propoerly for this convention.
 *
 * If useViewUp is set then instea dof using the camera's view up the follow's
 * viewUp will be used. This is usefull in cases where you want up to be locked
 * independent of the camera. This is typically the case for VR or AR
 * annotations where the headset may tilt but text should continue to be
 * relative to a constant view up vector.
 */
export declare const vtkFollower: {
  newInstance: typeof newInstance;
  extend: typeof extend;
};
export default vtkFollower;