/*
 * Copyright (C) 2017 Open Source Robotics Foundation
 *
 * 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.
 *
 */

#if __APPLE__
  #include <OpenGL/gl.h>
  #include <OpenGL/OpenGL.h>
  #include <GLUT/glut.h>
#else
  #include <GL/glew.h>
  #include <GL/gl.h>
  #include <GL/glut.h>
#endif

#if !defined(__APPLE__) && !defined(_WIN32)
  #include <GL/glx.h>
#endif

#include <mutex>

#include <gz/common/Console.hh>
#include <gz/rendering/Camera.hh>
#include <gz/rendering/Image.hh>
#include <gz/rendering/RayQuery.hh>
#include <gz/rendering/Scene.hh>
#include <gz/rendering/OrbitViewController.hh>

#include "GlutWindow.hh"

#define KEY_ESC 27
#define KEY_TAB  9

//////////////////////////////////////////////////
unsigned int imgw = 0;
unsigned int imgh = 0;

std::vector<ir::CameraPtr> g_cameras;
ir::CameraPtr g_camera;
ir::CameraPtr g_currCamera;
unsigned int g_cameraIndex = 0;
ir::ImagePtr g_image;


std::vector<ir::NodePtr> g_nodes;

bool g_initContext = false;

#if __APPLE__
  CGLContextObj g_context;
  CGLContextObj g_glutContext;
#elif _WIN32
#else
  GLXContext g_context;
  Display *g_display;
  GLXDrawable g_drawable;
  GLXContext g_glutContext;
  Display *g_glutDisplay;
  GLXDrawable g_glutDrawable;
#endif

// view control variables
ir::RayQueryPtr g_rayQuery;
ir::OrbitViewController g_viewControl;
ir::RayQueryResult g_target;
struct mouseButton
{
  int button = 0;
  int state = GLUT_UP;
  int x = 0;
  int y = 0;
  int motionX = 0;
  int motionY = 0;
  int dragX = 0;
  int dragY = 0;
  int scroll = 0;
  bool buttonDirty = false;
  bool motionDirty = false;
};
struct mouseButton g_mouse;
std::mutex g_mouseMutex;

gz::math::Vector3d g_trackOffset(1.0, 0, 0);
gz::math::Vector3d g_followOffset(-3, 0, 3);


//////////////////////////////////////////////////
void mouseCB(int _button, int _state, int _x, int _y)
{
  // ignore unknown mouse button numbers
  if (_button >= 5)
    return;

  std::lock_guard<std::mutex> lock(g_mouseMutex);
  g_mouse.button = _button;
  g_mouse.state = _state;
  g_mouse.x = _x;
  g_mouse.y = _y;
  g_mouse.motionX = _x;
  g_mouse.motionY = _y;
  g_mouse.buttonDirty = true;
}

//////////////////////////////////////////////////
void motionCB(int _x, int _y)
{
  std::lock_guard<std::mutex> lock(g_mouseMutex);
  int deltaX = _x - g_mouse.motionX;
  int deltaY = _y - g_mouse.motionY;
  g_mouse.motionX = _x;
  g_mouse.motionY = _y;

  if (g_mouse.motionDirty)
  {
    g_mouse.dragX += deltaX;
    g_mouse.dragY += deltaY;
  }
  else
  {
    g_mouse.dragX = deltaX;
    g_mouse.dragY = deltaY;
  }
  g_mouse.motionDirty = true;
}

//////////////////////////////////////////////////
void handleMouse()
{
  std::lock_guard<std::mutex> lock(g_mouseMutex);
  // only ogre supports ray query for now so use
  // ogre camera located at camera index = 0.
  ir::CameraPtr rayCamera = g_cameras[0];
  if (!g_rayQuery)
  {
    g_rayQuery = rayCamera->Scene()->CreateRayQuery();
    if (!g_rayQuery)
    {
      ignerr << "Failed to create Ray Query" << std::endl;
      return;
    }
  }
  if (g_mouse.buttonDirty)
  {
    g_mouse.buttonDirty = false;
    double nx =
        2.0 * g_mouse.x / static_cast<double>(rayCamera->ImageWidth()) - 1.0;
    double ny = 1.0 -
        2.0 * g_mouse.y / static_cast<double>(rayCamera->ImageHeight());
    g_rayQuery->SetFromCamera(rayCamera, gz::math::Vector2d(nx, ny));
    g_target  = g_rayQuery->ClosestPoint();
    if (!g_target)
    {
      // set point to be 10m away if no intersection found
      g_target.point = g_rayQuery->Origin() + g_rayQuery->Direction() * 10;
      return;
    }

    // mouse wheel scroll zoom
    if ((g_mouse.button == 3 || g_mouse.button == 4) &&
        g_mouse.state == GLUT_UP)
    {
      double scroll = (g_mouse.button == 3) ? -1.0 : 1.0;
      double distance = rayCamera->WorldPosition().Distance(
          g_target.point);
      int factor = 1;
      double amount = -(scroll * factor) * (distance / 5.0);
      for (ir::CameraPtr camera : g_cameras)
      {
        g_viewControl.SetCamera(camera);
        g_viewControl.SetTarget(g_target.point);
        g_viewControl.Zoom(amount);
      }
    }
  }

  if (g_mouse.motionDirty)
  {
    g_mouse.motionDirty = false;
    auto drag = gz::math::Vector2d(g_mouse.dragX, g_mouse.dragY);

    // left mouse button pan
    if (g_mouse.button == GLUT_LEFT_BUTTON && g_mouse.state == GLUT_DOWN)
    {
      for (ir::CameraPtr camera : g_cameras)
      {
        g_viewControl.SetCamera(camera);
        g_viewControl.SetTarget(g_target.point);
        g_viewControl.Pan(drag);
      }
    }
    else if (g_mouse.button == GLUT_MIDDLE_BUTTON && g_mouse.state == GLUT_DOWN)
    {
      for (ir::CameraPtr camera : g_cameras)
      {
        g_viewControl.SetCamera(camera);
        g_viewControl.SetTarget(g_target.point);
        g_viewControl.Orbit(drag);
      }
    }
    // right mouse button zoom
    else if (g_mouse.button == GLUT_RIGHT_BUTTON && g_mouse.state == GLUT_DOWN)
    {
      double hfov = rayCamera->HFOV().Radian();
      double vfov = 2.0f * atan(tan(hfov / 2.0f) /
          rayCamera->AspectRatio());
      double distance = rayCamera->WorldPosition().Distance(
          g_target.point);
      double amount = ((-g_mouse.dragY /
          static_cast<double>(rayCamera->ImageHeight()))
          * distance * tan(vfov/2.0) * 6.0);
      for (ir::CameraPtr camera : g_cameras)
      {
        g_viewControl.SetCamera(camera);
        g_viewControl.SetTarget(g_target.point);
        g_viewControl.Zoom(amount);
      }
    }
  }
}


//////////////////////////////////////////////////
void displayCB()
{
#if __APPLE__
  CGLSetCurrentContext(g_context);
#elif _WIN32
#else
  if (g_display)
  {
    glXMakeCurrent(g_display, g_drawable, g_context);
  }
#endif

  g_cameras[g_cameraIndex]->Capture(*g_image);
  handleMouse();

#if __APPLE__
  CGLSetCurrentContext(g_glutContext);
#elif _WIN32
#else
  glXMakeCurrent(g_glutDisplay, g_glutDrawable, g_glutContext);
#endif

  unsigned char *data = g_image->Data<unsigned char>();

  glClearColor(0.5, 0.5, 0.5, 1);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glPixelZoom(1, -1);
  glRasterPos2f(-1, 1);
  glDrawPixels(imgw, imgh, GL_RGB, GL_UNSIGNED_BYTE, data);

  glutSwapBuffers();
}

//////////////////////////////////////////////////
void idleCB()
{
  glutPostRedisplay();
}

//////////////////////////////////////////////////
void keyboardCB(unsigned char _key, int, int)
{
  if (_key == KEY_ESC || _key == 'q' || _key == 'Q')
  {
    exit(0);
  }
  else if (_key == KEY_TAB)
  {
    g_cameraIndex = (g_cameraIndex + 1) % g_cameras.size();
  }

  // main node movement control
  double posIncr = 0.03;
  double yawIncr = 0.03;
  for (ir::NodePtr node : g_nodes)
  {
    if (!node)
    {
      std::cerr << "Main node not found! " << std::endl;
      return;
    }
    if (_key == 'w' || _key == 'W')
    {
      node->SetWorldPosition(node->WorldPosition() +
          node->WorldRotation() * gz::math::Vector3d(posIncr, 0, 0));
    }
    else if (_key == 's' || _key == 'S')
    {
      node->SetWorldPosition(node->WorldPosition() +
          node->WorldRotation() * gz::math::Vector3d(-posIncr, 0, 0));
    }
    else if (_key == 'a' || _key == 'A')
    {
      node->SetWorldRotation(gz::math::Quaterniond(0, 0,
          node->WorldRotation().Yaw() + yawIncr));
    }
    else if (_key == 'd' || _key == 'D')
    {
      node->SetWorldRotation(gz::math::Quaterniond(0, 0,
          node->WorldRotation().Yaw() - yawIncr));
    }
  }

  if (_key == 'u')
  {
    g_trackOffset.X() += 0.1;
  }
  else if (_key == 'U')
  {
    g_trackOffset.X() -= 0.1;
  }
  else if (_key == 'i')
  {
    g_trackOffset.Y() += 0.1;
  }
  else if (_key == 'I')
  {
    g_trackOffset.Y() -= 0.1;
  }
  else if (_key == 'o')
  {
    g_trackOffset.Z() += 0.1;
  }
  else if (_key == 'O')
  {
    g_trackOffset.Z() -= 0.1;
  }
  else if (_key == 'j')
  {
    g_followOffset.X() += 0.1;
  }
  else if (_key == 'J')
  {
    g_followOffset.X() -= 0.1;
  }
  else if (_key == 'k')
  {
    g_followOffset.Y() += 0.1;
  }
  else if (_key == 'K')
  {
    g_followOffset.Y() -= 0.1;
  }
  else if (_key == 'l')
  {
    g_followOffset.Z() += 0.1;
  }
  else if (_key == 'L')
  {
    g_followOffset.Z() -= 0.1;
  }

  for (unsigned int i = 0; i < g_cameras.size(); ++i)
  {
    auto cam = g_cameras[i];
    auto node = g_nodes[i];
    // fixed camera mode
    if (_key == '1')
    {
      cam->SetTrackTarget(node, g_trackOffset);
      cam->SetWorldPosition(0, 0, 3);
      cam->SetFollowTarget(nullptr);
    }
    else if (_key == '2')
    {
      cam->SetTrackTarget(node, g_trackOffset);
      cam->SetFollowTarget(node, g_followOffset, false);
    }
    else if (_key == '3')
    {
      cam->SetTrackTarget(node, g_trackOffset);
      cam->SetFollowTarget(node, g_followOffset, true);
    }
    else
    {
      cam->SetTrackOffset(g_trackOffset);
      cam->SetFollowOffset(g_followOffset);
    }

    if (_key == 't' || _key == 'T')
    {
      double trackPGain = 0.005;
      double p = gz::math::equal(cam->TrackPGain(), 1.0) ?
          trackPGain : 1.0;
      cam->SetTrackPGain(p);
    }
    else if (_key == 'f' || _key == 'F')
    {
      double followPGain = 0.01;
      double p = gz::math::equal(cam->FollowPGain(), 1.0) ?
          followPGain : 1.0;
      cam->SetFollowPGain(p);
    }
  }
}

//////////////////////////////////////////////////
void initCamera(ir::CameraPtr _camera)
{
  g_camera = _camera;
  imgw = g_camera->ImageWidth();
  imgh = g_camera->ImageHeight();
  ir::Image image = g_camera->CreateImage();
  g_image = std::make_shared<ir::Image>(image);
  g_camera->Capture(*g_image);
}

//////////////////////////////////////////////////
void initContext()
{
  glutInitDisplayMode(GLUT_DOUBLE);
  glutInitWindowPosition(0, 0);
  glutInitWindowSize(imgw, imgh);
  glutCreateWindow("Camera Tracking");
  glutDisplayFunc(displayCB);
  glutIdleFunc(idleCB);
  glutKeyboardFunc(keyboardCB);

  glutMouseFunc(mouseCB);
  glutMotionFunc(motionCB);
}

//////////////////////////////////////////////////
void printUsage()
{
  std::cout << "===============================" << std::endl;
  std::cout << "  TAB - Switch render engines  " << std::endl;
  std::cout << "  ESC - Exit                   " << std::endl;
  std::cout << "                               " << std::endl;
  std::cout << "  W: Move box forward          " << std::endl;
  std::cout << "  S: Move box backward         " << std::endl;
  std::cout << "  A: Rotate box to the left    " << std::endl;
  std::cout << "  D: Rotate box to the right   " << std::endl;
  std::cout << "                               " << std::endl;
  std::cout << "  1: Camera tracking only      " << std::endl;
  std::cout << "  2: Camera tracking and       " << std::endl;
  std::cout << "     following                 " << std::endl;
  std::cout << "  3: Camera tracking and       " << std::endl;
  std::cout << "     following (world frame)   " << std::endl;
  std::cout << "                               " << std::endl;
  std::cout << "  T: Toggle smooth tracking    " << std::endl;
  std::cout << "  F: Toggle smooth following   " << std::endl;
  std::cout << "                               " << std::endl;
  std::cout << "  Track offset                 " << std::endl;
  std::cout << "  u/U: +- 0.1 on X             " << std::endl;
  std::cout << "  i/I: +- 0.1 on Y             " << std::endl;
  std::cout << "  o/O: +- 0.1 on Z             " << std::endl;
  std::cout << "                               " << std::endl;
  std::cout << "  Follow offset                " << std::endl;
  std::cout << "  j/J: +- 0.1 on X             " << std::endl;
  std::cout << "  k/K: +- 0.1 on Y             " << std::endl;
  std::cout << "  l/L: +- 0.1 on Z             " << std::endl;
  std::cout << "===============================" << std::endl;
}

//////////////////////////////////////////////////
void run(std::vector<ir::CameraPtr> _cameras,
         const std::vector<ir::NodePtr> &_nodes)
{
  if (_cameras.empty())
  {
    ignerr << "No cameras found. Scene will not be rendered" << std::endl;
    return;
  }

#if __APPLE__
  g_context = CGLGetCurrentContext();
#elif _WIN32
#else
  g_context = glXGetCurrentContext();
  g_display = glXGetCurrentDisplay();
  g_drawable = glXGetCurrentDrawable();
#endif

  g_cameras = _cameras;
  initCamera(_cameras[0]);

  // main node to track
  g_nodes = _nodes;

  initContext();
  printUsage();

#if __APPLE__
  g_glutContext = CGLGetCurrentContext();
#elif _WIN32
#else
  g_glutDisplay = glXGetCurrentDisplay();
  g_glutDrawable = glXGetCurrentDrawable();
  g_glutContext = glXGetCurrentContext();
#endif

  glutMainLoop();
}
