/*=========================================================================

Program:   Visualization Toolkit

Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
/**
 * @class   vtkOpenVRRenderWindow
 * @brief   OpenVR rendering window
 *
 *
 * vtkOpenVRRenderWindow is a concrete implementation of the abstract
 * class vtkRenderWindow. vtkOpenVRRenderer interfaces to the
 * OpenVR graphics library
 *
 * This class and its similar classes are designed to be drop in
 * replacements for VTK. If you link to this module and turn on
 * the CMake option VTK_OPENVR_OBJECT_FACTORY, the object
 * factory mechanism should replace the core rendering classes such as
 * RenderWindow with OpenVR specialized versions. The goal is for VTK
 * programs to be able to use the OpenVR library with little to no
 * changes.
 *
 * This class handles the bulk of interfacing to OpenVR. It supports one
 * renderer currently. The renderer is assumed to cover the entire window
 * which is what makes sense to VR. Overlay renderers can probably be
 * made to work with this but consider how overlays will appear in a
 * HMD if they do not track the viewpoint etc. This class is based on
 * sample code from the OpenVR project.
 *
 * OpenVR provides HMD and controller positions in "Physical" coordinate
 * system.
 * Origin: user's eye position at the time of calibration.
 * Axis directions: x = user's right; y = user's up; z = user's back.
 * Unit: meter.
 *
 * Renderer shows actors in World coordinate system. Transformation between
 * Physical and World coordinate systems is defined by PhysicalToWorldMatrix.
 * This matrix determines the user's position and orientation in the rendered
 * scene and scaling (magnification) of rendered actors.
 *
 */

#ifndef vtkOpenVRRenderWindow_h
#define vtkOpenVRRenderWindow_h

#include "vtkOpenGLRenderWindow.h"
#include "vtkRenderingOpenVRModule.h" // For export macro

#include "vtkEventData.h"    // for enums
#include "vtkOpenGLHelper.h" // used for ivars
#include "vtk_glew.h"        // used for methods
#include <openvr.h>          // for ivars
#include <vector>            // ivars

class vtkCamera;
class vtkMatrix4x4;
class vtkOpenVRModel;
class vtkOpenVROverlay;
class vtkOpenGLVertexBufferObject;
class vtkTransform;

class VTKRENDERINGOPENVR_EXPORT vtkOpenVRRenderWindow : public vtkOpenGLRenderWindow
{
public:
  enum
  {
    PhysicalToWorldMatrixModified = vtkCommand::UserEvent + 200
  };

  static vtkOpenVRRenderWindow* New();
  vtkTypeMacro(vtkOpenVRRenderWindow, vtkOpenGLRenderWindow);
  void PrintSelf(ostream& os, vtkIndent indent);

  /**
   * Get the system pointer
   */
  vr::IVRSystem* GetHMD() { return this->HMD; }

  /**
   * Create an interactor to control renderers in this window.
   * Creates one specific to OpenVR
   */
  vtkRenderWindowInteractor* MakeRenderWindowInteractor() override;

  /**
   * Draw the overlay
   */
  void RenderOverlay();

  //@{
  /**
   * Set/Get the overlay to use on the VR dashboard
   */
  vtkGetObjectMacro(DashboardOverlay, vtkOpenVROverlay);
  void SetDashboardOverlay(vtkOpenVROverlay*);
  //@}

  /**
   * Update the HMD pose based on hardware pose and physical to world transform.
   * VR camera properties are directly modified based on physical to world to
   * simulate \sa PhysicalTranslation, \sa PhysicalScale, etc.
   */
  void UpdateHMDMatrixPose();

  //@{
  /**
   * Get the frame buffers used for rendering
   */
  GLuint GetLeftResolveBufferId() { return this->LeftEyeDesc.m_nResolveFramebufferId; }
  GLuint GetRightResolveBufferId() { return this->RightEyeDesc.m_nResolveFramebufferId; }
  void GetRenderBufferSize(int& width, int& height)
  {
    width = this->Size[0];
    height = this->Size[1];
  }
  //@}

  /**
   * Get the VRModel corresponding to the tracked device
   */
  vtkOpenVRModel* GetTrackedDeviceModel(vtkEventDataDevice idx)
  {
    return this->GetTrackedDeviceModel(idx, 0);
  }
  vtkOpenVRModel* GetTrackedDeviceModel(vr::TrackedDeviceIndex_t idx)
  {
    return this->TrackedDeviceToRenderModel[idx];
  }
  vtkOpenVRModel* GetTrackedDeviceModel(vtkEventDataDevice idx, uint32_t index);

  /**
   * Get the openVR Render Models
   */
  vr::IVRRenderModels* GetOpenVRRenderModels() { return this->OpenVRRenderModels; }

  /**
   * Get the index corresponding to the tracked device
   */
  vr::TrackedDeviceIndex_t GetTrackedDeviceIndexForDevice(vtkEventDataDevice dev)
  {
    return this->GetTrackedDeviceIndexForDevice(dev, 0);
  }
  vr::TrackedDeviceIndex_t GetTrackedDeviceIndexForDevice(vtkEventDataDevice dev, uint32_t index);
  uint32_t GetNumberOfTrackedDevicesForDevice(vtkEventDataDevice dev);

  /**
   * Get the most recent pose corresponding to the tracked device
   */
  void GetTrackedDevicePose(vtkEventDataDevice idx, vr::TrackedDevicePose_t** pose)
  {
    return this->GetTrackedDevicePose(idx, 0, pose);
  }
  void GetTrackedDevicePose(vtkEventDataDevice idx, uint32_t index, vr::TrackedDevicePose_t** pose);
  vr::TrackedDevicePose_t& GetTrackedDevicePose(vr::TrackedDeviceIndex_t idx)
  {
    return this->TrackedDevicePose[idx];
  }

  /**
   * Initialize the HMD to World setting and camera settings so
   * that the VR world view most closely matched the view from
   * the provided camera. This method is useful for initialing
   * a VR world from an existing on screen window and camera.
   * The Renderer and its camera must already be created and
   * set when this is called.
   */
  void InitializeViewFromCamera(vtkCamera* cam);

  //@{
  /**
   * Set/get physical coordinate system in world coordinate system.
   *
   * View direction is the -Z axis of the physical coordinate system
   * in world coordinate system.
   * \sa SetPhysicalViewUp, \sa SetPhysicalTranslation,
   * \sa SetPhysicalScale, \sa SetPhysicalToWorldMatrix
   */
  virtual void SetPhysicalViewDirection(double, double, double);
  virtual void SetPhysicalViewDirection(double[3]);
  vtkGetVector3Macro(PhysicalViewDirection, double);
  //@}

  //@{
  /**
   * Set/get physical coordinate system in world coordinate system.
   *
   * View up is the +Y axis of the physical coordinate system
   * in world coordinate system.
   * \sa SetPhysicalViewDirection, \sa SetPhysicalTranslation,
   * \sa SetPhysicalScale, \sa SetPhysicalToWorldMatrix
   */
  virtual void SetPhysicalViewUp(double, double, double);
  virtual void SetPhysicalViewUp(double[3]);
  vtkGetVector3Macro(PhysicalViewUp, double);
  //@}

  //@{
  /**
   * Set/get physical coordinate system in world coordinate system.
   *
   * Position of the physical coordinate system origin
   * in world coordinates.
   * \sa SetPhysicalViewDirection, \sa SetPhysicalViewUp,
   * \sa SetPhysicalScale, \sa SetPhysicalToWorldMatrix
   */
  virtual void SetPhysicalTranslation(double, double, double);
  virtual void SetPhysicalTranslation(double[3]);
  vtkGetVector3Macro(PhysicalTranslation, double);
  //@}

  //@{
  /**
   * Set/get physical coordinate system in world coordinate system.
   *
   * Ratio of distance in world coordinate and physical and system
   * (PhysicalScale = distance_World / distance_Physical).
   * Example: if world coordinate system is in mm then
   * PhysicalScale = 1000.0 makes objects appear in real size.
   * PhysicalScale = 100.0 makes objects appear 10x larger than real size.
   */
  virtual void SetPhysicalScale(double);
  vtkGetMacro(PhysicalScale, double);
  //@}

  /**
   * Set physical to world transform matrix. Members calculated and set from the matrix:
   * \sa PhysicalViewDirection, \sa PhysicalViewUp, \sa PhysicalTranslation, \sa PhysicalScale
   * The x axis scale is used for \sa PhysicalScale
   */
  void SetPhysicalToWorldMatrix(vtkMatrix4x4* matrix);
  /**
   * Get physical to world transform matrix. Members used to calculate the matrix:
   * \sa PhysicalViewDirection, \sa PhysicalViewUp, \sa PhysicalTranslation, \sa PhysicalScale
   */
  void GetPhysicalToWorldMatrix(vtkMatrix4x4* matrix);

  //@{
  /**
   * When on the camera will track the HMD position.
   * On is the default.
   */
  vtkSetMacro(TrackHMD, bool);
  vtkGetMacro(TrackHMD, bool);
  //@}

  /**
   * Add a renderer to the list of renderers.
   */
  virtual void AddRenderer(vtkRenderer*) override;

  /**
   * Begin the rendering process.
   */
  virtual void Start(void);

  /**
   * Update the system, if needed, due to stereo rendering. For some stereo
   * methods, subclasses might need to switch some hardware settings here.
   */
  virtual void StereoUpdate();

  /**
   * Intermediate method performs operations required between the rendering
   * of the left and right eye.
   */
  virtual void StereoMidpoint();

  /**
   * Handles work required once both views have been rendered when using
   * stereo rendering.
   */
  virtual void StereoRenderComplete();

  /**
   * Initialize the rendering window.  This will setup all system-specific
   * resources.  This method and Finalize() must be symmetric and it
   * should be possible to call them multiple times, even changing WindowId
   * in-between.  This is what WindowRemap does.
   */
  virtual void Initialize(void);

  /**
   * Finalize the rendering window.  This will shutdown all system-specific
   * resources.  After having called this, it should be possible to destroy
   * a window that was used for a SetWindowId() call without any ill effects.
   */
  virtual void Finalize(void);

  /**
   * Make this windows OpenGL context the current context.
   */
  void MakeCurrent();

  /**
   * Tells if this window is the current OpenGL context for the calling thread.
   */
  virtual bool IsCurrent();

  /**
   * Get report of capabilities for the render window
   */
  const char* ReportCapabilities() { return "OpenVR System"; }

  /**
   * Is this render window using hardware acceleration? 0-false, 1-true
   */
  vtkTypeBool IsDirect() { return 1; }

  /**
   * Check to see if a mouse button has been pressed or mouse wheel activated.
   * All other events are ignored by this method.
   * Maybe should return 1 always?
   */
  virtual vtkTypeBool GetEventPending() { return 0; }

  /**
   * Get the current size of the screen in pixels.
   */
  virtual int* GetScreenSize();

  //@{
  /**
   * Set the size of the window in screen coordinates in pixels.
   * This resizes the operating system's window and redraws it.
   *
   * If the size has changed, this method will fire
   * vtkCommand::WindowResizeEvent.
   */
  void SetSize(int width, int height) override;
  void SetSize(int a[2]) override { this->SetSize(a[0], a[1]); }
  //@}

  //@{
  /**
   * Set the position (x and y) of the rendering window in
   * screen coordinates (in pixels). This resizes the operating
   * system's view/window and redraws it.
   */
  void SetPosition(int x, int y) override;
  void SetPosition(int a[2]) override { this->SetPosition(a[0], a[1]); }
  //@}

  // implement required virtual functions
  void SetWindowInfo(const char*) {}
  void SetNextWindowInfo(const char*) {}
  void SetParentInfo(const char*) {}
  virtual void* GetGenericDisplayId() { return (void*)this->HelperWindow->GetGenericDisplayId(); }
  virtual void* GetGenericWindowId() { return (void*)this->HelperWindow->GetGenericWindowId(); }
  virtual void* GetGenericParentId() { return (void*)nullptr; }
  virtual void* GetGenericContext() { return (void*)this->HelperWindow->GetGenericContext(); }
  virtual void* GetGenericDrawable() { return (void*)this->HelperWindow->GetGenericDrawable(); }
  virtual void SetDisplayId(void*) {}
  void SetWindowId(void*) {}
  void SetParentId(void*) {}
  void HideCursor() {}
  void ShowCursor() {}
  virtual void SetFullScreen(vtkTypeBool) {}
  virtual void WindowRemap(void) {}
  virtual void SetNextWindowId(void*) {}

  /**
   * Does this render window support OpenGL? 0-false, 1-true
   */
  virtual int SupportsOpenGL() { return 1; }

  /**
   * Overridden to not release resources that would interfere with an external
   * application's rendering. Avoiding round trip.
   */
  void Render();

  /**
   * Set/Get the window to use for the openGL context
   */
  vtkGetObjectMacro(HelperWindow, vtkOpenGLRenderWindow);
  void SetHelperWindow(vtkOpenGLRenderWindow* val);

  // Get the state object used to keep track of
  // OpenGL state
  vtkOpenGLState* GetState() override;

  /**
   * Free up any graphics resources associated with this window
   * a value of nullptr means the context may already be destroyed
   */
  void ReleaseGraphicsResources(vtkWindow*) override;

protected:
  vtkOpenVRRenderWindow();
  ~vtkOpenVRRenderWindow() override;

  virtual void CreateAWindow() {}
  virtual void DestroyWindow() {}

  std::string m_strDriver;
  std::string m_strDisplay;
  vr::IVRSystem* HMD;
  vr::IVRRenderModels* OpenVRRenderModels;

  struct FramebufferDesc
  {
    GLuint m_nResolveTextureId;
    GLuint m_nResolveFramebufferId;
  };
  FramebufferDesc LeftEyeDesc;
  FramebufferDesc RightEyeDesc;
  bool CreateFrameBuffer(int nWidth, int nHeight, FramebufferDesc& framebufferDesc);

  // convert a device index to a human string
  std::string GetTrackedDeviceString(vr::IVRSystem* pHmd, vr::TrackedDeviceIndex_t unDevice,
    vr::TrackedDeviceProperty prop, vr::TrackedPropertyError* peError = nullptr);

  // devices may have polygonal models
  // load them
  vtkOpenVRModel* FindOrLoadRenderModel(const char* modelName);
  void RenderModels();
  std::vector<vtkOpenVRModel*> VTKRenderModels;
  vtkOpenVRModel* TrackedDeviceToRenderModel[vr::k_unMaxTrackedDeviceCount];
  vr::TrackedDevicePose_t TrackedDevicePose[vr::k_unMaxTrackedDeviceCount];

  // used in computing the pose
  vtkTransform* HMDTransform;
  /// -Z axis of the Physical to World matrix
  double PhysicalViewDirection[3];
  /// Y axis of the Physical to World matrix
  double PhysicalViewUp[3];
  /// Inverse of the translation component of the Physical to World matrix, in mm
  double PhysicalTranslation[3];
  /// Scale of the Physical to World matrix
  double PhysicalScale;

  // for the overlay
  vtkOpenVROverlay* DashboardOverlay;

  bool TrackHMD;

  vtkOpenGLRenderWindow* HelperWindow;

private:
  vtkOpenVRRenderWindow(const vtkOpenVRRenderWindow&) = delete;
  void operator=(const vtkOpenVRRenderWindow&) = delete;
};

#endif
