#ifndef GAME_CAMERA_H
#define GAME_CAMERA_H

/*
 * Copyright (c) 2020 Samsung Electronics Co., Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

#include <dali/public-api/actors/camera-actor.h>
#include <dali/public-api/adaptor-framework/timer.h>
#include <dali/public-api/math/vector2.h>

/**
 * @brief The GameCamera class
 * First-person camera implementation with handling user input
 *
 * GameCamera uses the DALi camera for displaying 3D game view.
 * Additionally it handles simple user input by attaching fullscreen
 * sized 'interceptor' Actor to the front of the CameraActor ( to be always
 * parallel to the view ). It is necessary, as with changing camera orientation
 * the the window cannot be used as a touch signal receiver ( it will simply
 * go offscreen with camera rotation ).
 *
 * DALi camera uses left-handed coordinate system.
 *
 * The control scheme assumes that left half of the screen is responsible for
 * movement, the right half of screen is a rotation.
 */
class GameCamera : public Dali::ConnectionTracker
{
public:
  /**
   * Creates an instance of GameCamera
   */
  GameCamera();

  /**
   * Destroys an instance of GameCamera
   */
  ~GameCamera();

  /**
   * Initialise with given fovY, near, far
   * @param[in] defaultCamera The default camera used by the scene
   * @param[in] fovY Field of view in degrees
   * @param[in] near Near plane
   * @param[in] far Far Plane
   * @param[in] sceneSize The size of the scene this is looking at
   */
  void Initialise(Dali::CameraActor defaultCamera, float fov, float near, float far, const Dali::Vector2& sceneSize);

private:
  /**
   * Sets up a perspective camera using Dali default camera
   */
  void InitialiseDefaultCamera();

  /**
   * Creates 'interceptor' actor. Interceptor actor is always parallel
   * to the camera and positioned little bit in front of it in order to
   * intercept user input.
   */
  void CreateInterceptorActor();

  /**
   * Handles onTouch signal on the 'interceptor' actor
   * @param[in] actor Actor receiving signal
   * @param[in] touch Touch data
   */
  bool OnTouch(Dali::Actor actor, const Dali::TouchEvent& touch);

  /**
   * Handles camera tick() update
   * @return true if continue running timer, false otherwise
   */
  bool OnTick();

private:
  Dali::CameraActor mCameraActor;      /// Camera actor
  Dali::Actor       mInterceptorActor; /// Actor intercepting user input

  Dali::Timer mTimer; /// Per-frame timer

  Dali::Vector2 mScreenLookDelta;      /// Look delta vector in screen space
  Dali::Vector2 mScreenWalkDelta;      /// Walk delta vector in screen space
  Dali::Vector2 mOldTouchLookPosition; /// Previous look vector in screen space
  Dali::Vector2 mOldTouchWalkPosition; /// Previuus walk vector in screen space

  Dali::Vector2 mCameraYawPitch; /// Camera yaw-pitch angles

  float mFovY; /// Camera field-of-view
  float mNear; /// Near plane
  float mFar;  /// Far plane

  int mWalkingTouchId; /// Touch device id bound to the walking action
  int mLookingTouchId; /// Touch device id bound to the looking action

  Dali::Vector3 mCameraPosition; /// Current camera position ( shadowing the actor position )
  Dali::Vector2 mSceneSize;      /// The size of the scene we are looking at

  bool mPortraitMode; /// flag if window is in portrait mode ( physically window width < height )
};

#endif