/*
 * Copyright 2017 The Cobalt Authors. All Rights Reserved.
 *
 * 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.
 */

#ifndef COBALT_DOM_CAMERA_3D_H_
#define COBALT_DOM_CAMERA_3D_H_

#include "base/timer.h"
#include "cobalt/dom/event_target.h"
#include "cobalt/input/camera_3d.h"
#include "cobalt/script/wrappable.h"

namespace cobalt {
namespace dom {

// 3D camera is used for setting the key mapping.
class Camera3D : public script::Wrappable {
 public:
  enum CameraAxes {
    // Restricted to [0deg, 360deg]
    kDomCameraRoll = input::Camera3D::kCameraRoll,
    // Restricted to [-90deg, 90deg]
    kDomCameraPitch = input::Camera3D::kCameraPitch,
    // Restricted to [0deg, 360deg]
    kDomCameraYaw = input::Camera3D::kCameraYaw,
  };

  // The frequency at which Camera3D will poll the hardware implementation.
  // Effectively the maximum frequency at which orientation events will be
  // dispatched.
  static constexpr double ORIENTATION_POLL_FREQUENCY_HZ = 30.0;
  // The minimum frequency at which Camera3D will dispatch events. Its inverse
  // is the most that will elapse between dispatching consecutive events (might
  // not be true in practice due to other processing done on the web thread).
  static constexpr double ORIENTATION_EVENT_MIN_FREQUENCY_HZ = 0.5;
  // The minimum change in any of the angles that will trigger an event. The
  // above frequencies still have precedence to decide the timing.
  static constexpr double ORIENTATION_EVENT_DELTA_THRESHOLD_DEGREES = 0.5;

  explicit Camera3D(const scoped_refptr<input::Camera3D>& impl);

  // Creates a mapping between the specified keyCode and the specified camera
  // axis, such that while the key is pressed, the cameraAxis will rotate at a
  // constant rate of degrees_per_second.
  void CreateKeyMapping(int keycode, uint32 camera_axis,
                        float degrees_per_second);
  // Clears any key mapping associated with the specified keyCode, if they
  // exist.
  void ClearKeyMapping(int keycode);
  // Clears all key mappings created by previous calls to |CreateKeyMapping|.
  void ClearAllKeyMappings();

  // Resets the camera's orientation.
  void Reset();

  // Custom, not in any spec.
  scoped_refptr<input::Camera3D> impl() { return impl_; }

  void StartOrientationEvents(const base::WeakPtr<EventTarget>& target);
  void StopOrientationEvents();

  DEFINE_WRAPPABLE_TYPE(Camera3D);

 private:
  void FireOrientationEvent(const base::WeakPtr<EventTarget> target);

  // We delegate all calls to the implementation of Camera3D so that all camera
  // state is stored within an object that is *not* a script::Wrappable. This
  // is important because input::Camera3D will typically be attached to a render
  // tree, and render trees passed to the rasterizer have the potential to
  // outlive the WebModule that created them, and input::Camera3D is designed
  // for just this.
  scoped_refptr<input::Camera3D> impl_;

  // State to control the polling and event firing rate.
  base::RepeatingTimer<Camera3D> orientation_event_timer_;
  base::optional<base::TimeTicks> last_event_time_;
  double last_event_alpha_;
  double last_event_beta_;
  double last_event_gamma_;

  DISALLOW_COPY_AND_ASSIGN(Camera3D);
};

}  // namespace dom
}  // namespace cobalt

#endif  // COBALT_DOM_CAMERA_3D_H_