/*
 * 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 "look-camera.h"

#include <dali/public-api/events/touch-event.h>
#include <dali/public-api/render-tasks/render-task-list.h>
#include <dali/public-api/render-tasks/render-task.h>

using namespace Dali;

namespace
{
// Input sensitivity, the larger value, the more sensitive input
// Default value has been chosen empirically
const float CAMERA_SENSITIVITY(90.0f);

// Vertical angle limit of the camera
const float CAMERA_VERTICAL_LIMIT(80.0f);

// Position where camera is instantiated by default
const Vector3 CAMERA_DEFAULT_POSITION(0.0f, 0.0f, 3.0f);

// Field-of-View in degrees
const float CAMERA_DEFAULT_FOV(60.0f);

// Near plane
const float CAMERA_DEFAULT_NEAR(0.1f);

// Far plane
const float CAMERA_DEFAULT_FAR(100.0f);

// Default forward vector
const Vector3 CAMERA_FORWARD(0.0f, 0.0f, 1.0f);

// Default up vector
const Vector3 CAMERA_UP(Vector3::YAXIS);
} // namespace

LookCamera::LookCamera()
: mCameraYawPitch(0.0f, 180.0f),
  mFovY(CAMERA_DEFAULT_FOV),
  mNear(CAMERA_DEFAULT_NEAR),
  mFar(CAMERA_DEFAULT_FAR),
  mCameraPosition(CAMERA_DEFAULT_POSITION)
{
}

LookCamera::~LookCamera()
{
  mTimer.Stop();
  mCameraActor.Remove(mInterceptorActor);
}

void LookCamera::Initialise(Window window, const Vector3& position, float fovY, float near, float far)
{
  mWindow = window;

  mFovY = fovY;
  mNear = near;
  mFar  = far;

  // Camera position is shadowed in order to avoid using.GetCurrentProperty< Vector3 >( Actor::Property::POSITION )
  mCameraPosition = position;

  // Initialise default camera
  InitialiseDefaultCamera();

  // Create input interceptor actor
  CreateInterceptorActor();

  // Start timer
  mTimer = Timer::New(16);
  mTimer.TickSignal().Connect(this, &LookCamera::OnTick);
  mTimer.Start();
}

bool LookCamera::OnTick()
{
  Vector2 windowSize = mWindow.GetSize();

  // ---------------------------------------------------------------------
  // update rotation
  Vector2 tmp(mScreenLookDelta);
  mScreenLookDelta = Vector2::ZERO;

  float yaw   = ((tmp.y / windowSize.x) * CAMERA_SENSITIVITY);
  float pitch = ((tmp.x / windowSize.y) * CAMERA_SENSITIVITY);
  mCameraYawPitch.x -= yaw;
  mCameraYawPitch.y -= pitch;
  if(abs(mCameraYawPitch.x) > CAMERA_VERTICAL_LIMIT)
  {
    mCameraYawPitch.x = CAMERA_VERTICAL_LIMIT * ((mCameraYawPitch.x < 0) ? -1.0f : 1.0f);
  }

  Quaternion rotation;
  Quaternion rotX(Degree(mCameraYawPitch.x), Vector3(1.0f, 0.0f, 0.0f));
  Quaternion rotY(Degree(mCameraYawPitch.y), Vector3(0.0f, 1.0f, 0.0f));
  rotation = (rotY * rotX);

  mCameraActor.SetProperty(Actor::Property::ORIENTATION, rotation);

  return true;
}

void LookCamera::InitialiseDefaultCamera()
{
  mCameraActor = mWindow.GetRenderTaskList().GetTask(0).GetCameraActor();
  mCameraActor.SetProperty(Dali::Actor::Property::NAME, "LookCamera");
  mCameraActor.SetProperty(Actor::Property::ANCHOR_POINT, AnchorPoint::CENTER);
  mCameraActor.SetProperty(Actor::Property::PARENT_ORIGIN, ParentOrigin::CENTER);
  mCameraActor.SetFieldOfView(Radian(Degree(mFovY)));

  // should be read from file
  mCameraActor.SetNearClippingPlane(mNear);
  mCameraActor.SetFarClippingPlane(mFar);
  mCameraActor.SetProperty(Actor::Property::POSITION, mCameraPosition);
}

void LookCamera::CreateInterceptorActor()
{
  Vector2 windowSize = mWindow.GetSize();

  mInterceptorActor = Actor::New();
  mInterceptorActor.SetProperty(Dali::Actor::Property::NAME, "InputInterceptor");
  mInterceptorActor.SetProperty(Actor::Property::SIZE, Vector3(windowSize.width, windowSize.height, 1));
  mInterceptorActor.SetProperty(Actor::Property::POSITION, Vector3(0.0, 0.0, 1.0));
  mInterceptorActor.SetProperty(Actor::Property::ANCHOR_POINT, AnchorPoint::CENTER);
  mInterceptorActor.SetProperty(Actor::Property::PARENT_ORIGIN, ParentOrigin::CENTER);
  mCameraActor.Add(mInterceptorActor);

  // Connect TouchedSignal to interceptor actor
  mInterceptorActor.TouchedSignal().Connect(this, &LookCamera::OnTouch);
}

bool LookCamera::OnTouch(Actor actor, const TouchEvent& touch)
{
  for(int i = 0; i < (int)touch.GetPointCount() && i < 3; ++i)
  {
    Vector2 position(touch.GetScreenPosition(i));

    // touch started
    if(touch.GetState(i) == PointState::STARTED)
    {
      mOldTouchLookPosition = position;
    }
    else if(touch.GetState(i) == PointState::FINISHED ||
            touch.GetState(i) == PointState::LEAVE ||
            touch.GetState(i) == PointState::INTERRUPTED)
    {
      mScreenLookDelta      = Vector2::ZERO;
      mOldTouchLookPosition = Vector2::ZERO;
    }
    else // on motion
    {
      mScreenLookDelta.x += (position.x - mOldTouchLookPosition.x);
      mScreenLookDelta.y += (position.y - mOldTouchLookPosition.y);
      mOldTouchLookPosition = position;
    }
  }

  return true;
}