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

  Program:   Visualization Toolkit
  Module:    vtkSobelGradientMagnitudePass.cxx

  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.

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

#include "vtkSobelGradientMagnitudePass.h"
#include "vtkObjectFactory.h"
#include <cassert>

#include "vtkOpenGLError.h"
#include "vtkOpenGLFramebufferObject.h"
#include "vtkOpenGLRenderWindow.h"
#include "vtkOpenGLShaderCache.h"
#include "vtkOpenGLState.h"
#include "vtkOpenGLVertexArrayObject.h"
#include "vtkRenderState.h"
#include "vtkRenderer.h"
#include "vtkShaderProgram.h"
#include "vtkTextureObject.h"

#include "vtkOpenGLHelper.h"

// to be able to dump intermediate passes into png files for debugging.
// only for vtkSobelGradientMagnitudePass developers.
//#define VTK_SOBEL_PASS_DEBUG

#ifdef VTK_SOBEL_BLUR_PASS_DEBUG
#include "vtkImageExtractComponents.h"
#include "vtkImageImport.h"
#include "vtkPNGWriter.h"
#include "vtkPixelBufferObject.h"
#endif

#include "vtkSobelGradientMagnitudePass1FS.h"
#include "vtkSobelGradientMagnitudePass2FS.h"
#include "vtkTextureObjectVS.h" // a pass through shader

vtkStandardNewMacro(vtkSobelGradientMagnitudePass);

// ----------------------------------------------------------------------------
vtkSobelGradientMagnitudePass::vtkSobelGradientMagnitudePass()
{
  this->FrameBufferObject = nullptr;
  this->Pass1 = nullptr;
  this->Gx1 = nullptr;
  this->Gy1 = nullptr;
  this->Program1 = nullptr;
  this->Program2 = nullptr;
}

// ----------------------------------------------------------------------------
vtkSobelGradientMagnitudePass::~vtkSobelGradientMagnitudePass()
{
  if (this->FrameBufferObject != nullptr)
  {
    vtkErrorMacro(<< "FrameBufferObject should have been deleted in ReleaseGraphicsResources().");
  }
  if (this->Pass1 != nullptr)
  {
    vtkErrorMacro(<< "Pass1 should have been deleted in ReleaseGraphicsResources().");
  }
  if (this->Gx1 != nullptr)
  {
    vtkErrorMacro(<< "Gx1 should have been deleted in ReleaseGraphicsResources().");
  }
  if (this->Gy1 != nullptr)
  {
    vtkErrorMacro(<< "Gx1 should have been deleted in ReleaseGraphicsResources().");
  }
}

// ----------------------------------------------------------------------------
void vtkSobelGradientMagnitudePass::PrintSelf(ostream& os, vtkIndent indent)
{
  this->Superclass::PrintSelf(os, indent);
}

// ----------------------------------------------------------------------------
// Description:
// Perform rendering according to a render state \p s.
// \pre s_exists: s!=0
void vtkSobelGradientMagnitudePass::Render(const vtkRenderState* s)
{
  assert("pre: s_exists" && s != nullptr);

  this->NumberOfRenderedProps = 0;

  if (this->DelegatePass == nullptr)
  {
    vtkWarningMacro(<< " no delegate.");
    return;
  }

  vtkRenderer* renderer = s->GetRenderer();

  vtkOpenGLRenderWindow* context = vtkOpenGLRenderWindow::SafeDownCast(renderer->GetRenderWindow());
  vtkOpenGLState* ostate = context->GetState();

  // Test for Hardware support. If not supported, just render the delegate.
  bool fbo_support = vtkOpenGLFramebufferObject::IsSupported(context) != 0;
  bool texture_support = vtkTextureObject::IsSupported(context) != 0;

  bool supported = fbo_support && texture_support;

  if (!supported)
  {
    vtkErrorMacro(<< "The required extensions are not supported."
                  << " fbo_support=" << fbo_support << " texture_support=" << texture_support);

    this->DelegatePass->Render(s);
    this->NumberOfRenderedProps += this->DelegatePass->GetNumberOfRenderedProps();

    return;
  }

  vtkOpenGLClearErrorMacro();

  // 1. Create a new render state with an FBO.
  int width = 0;
  int height = 0;
  int size[2];
  s->GetWindowSize(size);
  width = size[0];
  height = size[1];

  const int extraPixels = 1; // one on each side

  int w = width + 2 * extraPixels;
  int h = height + 2 * extraPixels;

  if (this->Pass1 == nullptr)
  {
    this->Pass1 = vtkTextureObject::New();
    this->Pass1->SetContext(context);
  }

  if (this->FrameBufferObject == nullptr)
  {
    this->FrameBufferObject = vtkOpenGLFramebufferObject::New();
    this->FrameBufferObject->SetContext(context);
  }

  ostate->PushFramebufferBindings();
  this->RenderDelegate(s, width, height, w, h, this->FrameBufferObject, this->Pass1);

#ifdef VTK_SOBEL_PASS_DEBUG
  // Save first pass in file for debugging.
  vtkPixelBufferObject* pbo = this->Pass1->Download();

  unsigned char* openglRawData = new unsigned char[4 * w * h];
  unsigned int dims[2];
  dims[0] = w;
  dims[1] = h;
  vtkIdType incs[2];
  incs[0] = 0;
  incs[1] = 0;
  bool status = pbo->Download2D(VTK_UNSIGNED_CHAR, openglRawData, dims, 4, incs);
  assert("check" && status);
  pbo->Delete();

  // no pbo
  this->Pass1->Bind();
  glGetTexImage(GL_TEXTURE_2D, 0, GL_RGBA, GL_UNSIGNED_BYTE, openglRawData);
  this->Pass1->UnBind();

  vtkImageImport* importer = vtkImageImport::New();
  importer->CopyImportVoidPointer(openglRawData, 4 * w * h * sizeof(unsigned char));
  importer->SetDataScalarTypeToUnsignedChar();
  importer->SetNumberOfScalarComponents(4);
  importer->SetWholeExtent(0, w - 1, 0, h - 1, 0, 0);
  importer->SetDataExtentToWholeExtent();
  delete[] openglRawData;

  vtkImageExtractComponents* rgbaToRgb = vtkImageExtractComponents::New();
  rgbaToRgb->SetInputConnection(importer->GetOutputPort());
  rgbaToRgb->SetComponents(0, 1, 2);

  vtkPNGWriter* writer = vtkPNGWriter::New();
  writer->SetFileName("SobelPass1.png");
  writer->SetInputConnection(rgbaToRgb->GetOutputPort());
  importer->Delete();
  rgbaToRgb->Delete();
  writer->Write();
  writer->Delete();
#endif

  // 3. Same FBO, but two color attachments (new TOs gx1 and gy1).

  if (this->Gx1 == nullptr)
  {
    this->Gx1 = vtkTextureObject::New();
    this->Gx1->SetContext(this->FrameBufferObject->GetContext());
  }

  if (this->Gx1->GetWidth() != static_cast<unsigned int>(w) ||
    this->Gx1->GetHeight() != static_cast<unsigned int>(h))
  {
    this->Gx1->Create2D(w, h, 4, VTK_UNSIGNED_CHAR, false);
  }

  if (this->Gy1 == nullptr)
  {
    this->Gy1 = vtkTextureObject::New();
    this->Gy1->SetContext(this->FrameBufferObject->GetContext());
  }

  if (this->Gy1->GetWidth() != static_cast<unsigned int>(w) ||
    this->Gy1->GetHeight() != static_cast<unsigned int>(h))
  {
    this->Gy1->Create2D(w, h, 4, VTK_UNSIGNED_CHAR, false);
  }
#ifdef VTK_SOBEL_PASS_DEBUG
  cout << "gx1 TOid=" << this->Gx1->GetHandle() << endl;
  cout << "gy1 TOid=" << this->Gy1->GetHandle() << endl;
#endif
  this->FrameBufferObject->AddColorAttachment(0, this->Gx1);
  this->FrameBufferObject->AddColorAttachment(1, this->Gy1);
  unsigned int indices[2] = { 0, 1 };
  this->FrameBufferObject->ActivateDrawBuffers(indices, 2);

  this->FrameBufferObject->Start(w, h);

#ifdef VTK_SOBEL_PASS_DEBUG
  cout << "sobel finish2" << endl;
  glFinish();
#endif

  // Use the horizontal shader to compute the first pass of Gx and Gy.
  // this->Pass1 is the source
  // (this->Gx1 and this->Gy1 are fbo render targets)

  // has something changed that would require us to recreate the shaders?
  if (!this->Program1)
  {
    this->Program1 = new vtkOpenGLHelper;

    // build the shader source code
    std::string VSSource = vtkTextureObjectVS;
    std::string FSSource = vtkSobelGradientMagnitudePass1FS;
    std::string GSSource;

    // compile and bind it if needed
    vtkShaderProgram* newShader = context->GetShaderCache()->ReadyShaderProgram(
      VSSource.c_str(), FSSource.c_str(), GSSource.c_str());

    // if the shader changed reinitialize the VAO
    if (newShader != this->Program1->Program)
    {
      this->Program1->Program = newShader;
      this->Program1->VAO->ShaderProgramChanged(); // reset the VAO as the shader has changed
    }

    this->Program1->ShaderSourceTime.Modified();
  }
  else
  {
    context->GetShaderCache()->ReadyShaderProgram(this->Program1->Program);
  }

#ifdef VTK_SOBEL_PASS_DEBUG
  cout << "sobel finish build 1" << endl;
  glFinish();
#endif

  if (!this->Program1->Program || this->Program1->Program->GetCompiled() != true)
  {
    vtkErrorMacro("Couldn't build the shader program. At this point , it can be an error in a "
                  "shader or a driver bug.");

    // restore some state.
    ostate->PopFramebufferBindings();
    return;
  }

  this->Pass1->Activate();
  int sourceId = this->Pass1->GetTextureUnit();
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  this->Program1->Program->SetUniformi("source", sourceId);

  float fvalue = static_cast<float>(1.0 / w);
  this->Program1->Program->SetUniformf("stepSize", fvalue);

#ifdef VTK_SOBEL_PASS_DEBUG
  cout << "sobel finish3-" << endl;
  glFinish();
#endif

  this->FrameBufferObject->RenderQuad(
    0, w - 1, 0, h - 1, this->Program1->Program, this->Program1->VAO);

#ifdef VTK_SOBEL_PASS_DEBUG
  cout << "sobel finish3" << endl;
  glFinish();
#endif

  this->Pass1->Deactivate();

#ifdef VTK_SOBEL_PASS_DEBUG

  // Save second pass in file for debugging.
  pbo = this->Gx1->Download();
  openglRawData = new unsigned char[4 * w * h];
  status = pbo->Download2D(VTK_UNSIGNED_CHAR, openglRawData, dims, 4, incs);
  assert("check2" && status);
  pbo->Delete();

  importer = vtkImageImport::New();
  importer->CopyImportVoidPointer(openglRawData, 4 * w * h * sizeof(unsigned char));
  importer->SetDataScalarTypeToUnsignedChar();
  importer->SetNumberOfScalarComponents(4);
  importer->SetWholeExtent(0, w - 1, 0, h - 1, 0, 0);
  importer->SetDataExtentToWholeExtent();
  delete[] openglRawData;

  rgbaToRgb = vtkImageExtractComponents::New();
  rgbaToRgb->SetInputConnection(importer->GetOutputPort());
  rgbaToRgb->SetComponents(0, 1, 2);

  writer = vtkPNGWriter::New();
  writer->SetFileName("SobelPass2Gx1.png");
  writer->SetInputConnection(rgbaToRgb->GetOutputPort());
  importer->Delete();
  rgbaToRgb->Delete();
  writer->Write();
  writer->Delete();

  pbo = this->Gy1->Download();
  openglRawData = new unsigned char[4 * w * h];
  status = pbo->Download2D(VTK_UNSIGNED_CHAR, openglRawData, dims, 4, incs);
  assert("check3" && status);
  pbo->Delete();

  importer = vtkImageImport::New();
  importer->CopyImportVoidPointer(openglRawData, 4 * w * h * sizeof(unsigned char));
  importer->SetDataScalarTypeToUnsignedChar();
  importer->SetNumberOfScalarComponents(4);
  importer->SetWholeExtent(0, w - 1, 0, h - 1, 0, 0);
  importer->SetDataExtentToWholeExtent();
  delete[] openglRawData;

  rgbaToRgb = vtkImageExtractComponents::New();
  rgbaToRgb->SetInputConnection(importer->GetOutputPort());
  rgbaToRgb->SetComponents(0, 1, 2);

  writer = vtkPNGWriter::New();
  writer->SetFileName("SobelPass2Gy1.png");
  writer->SetInputConnection(rgbaToRgb->GetOutputPort());
  importer->Delete();
  rgbaToRgb->Delete();
  writer->Write();
  writer->Delete();

#endif

  // 4. Render in original FB (from renderstate in arg)

  ostate->PopFramebufferBindings();

  // has something changed that would require us to recreate the shaders?
  if (!this->Program2)
  {
    this->Program2 = new vtkOpenGLHelper;

    // build the shader source code
    std::string VSSource = vtkTextureObjectVS;
    std::string FSSource = vtkSobelGradientMagnitudePass2FS;
    std::string GSSource;

    // compile and bind it if needed
    vtkShaderProgram* newShader = context->GetShaderCache()->ReadyShaderProgram(
      VSSource.c_str(), FSSource.c_str(), GSSource.c_str());

    // if the shader changed reinitialize the VAO
    if (newShader != this->Program2->Program)
    {
      this->Program2->Program = newShader;
      this->Program2->VAO->ShaderProgramChanged(); // reset the VAO as the shader has changed
    }

    this->Program2->ShaderSourceTime.Modified();
  }
  else
  {
    context->GetShaderCache()->ReadyShaderProgram(this->Program2->Program);
  }

#ifdef VTK_SOBEL_PASS_DEBUG
  cout << "sobel finish build 2" << endl;
  glFinish();
#endif

  if (!this->Program2->Program || this->Program2->Program->GetCompiled() != true)
  {
    vtkErrorMacro("Couldn't build the shader program. At this point , it can be an error in a "
                  "shader or a driver bug.");
    return;
  }

#ifdef VTK_SOBEL_PASS_DEBUG
  cout << "sobel finish build 2" << endl;
  glFinish();
#endif

  // this->Gx1 and this->Gy1 are the sources
  this->Gx1->Activate();
  int id0 = this->Gx1->GetTextureUnit();
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

  this->Gy1->Activate();
  int id1 = this->Gy1->GetTextureUnit();
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

  this->Program2->Program->SetUniformi("gx1", id0);
  this->Program2->Program->SetUniformi("gy1", id1);

  fvalue = static_cast<float>(1.0 / h);
  this->Program2->Program->SetUniformf("stepSize", fvalue);

#ifdef VTK_SOBEL_PASS_DEBUG
  cout << "sobel finish use 2" << endl;
  glFinish();
#endif

#ifdef VTK_SOBEL_PASS_DEBUG
  cout << "sobel finish 4-" << endl;
  glFinish();
#endif

  // Prepare blitting
  ostate->vtkglDisable(GL_BLEND);
  ostate->vtkglDisable(GL_DEPTH_TEST);
  ostate->vtkglDisable(GL_SCISSOR_TEST);

  // Trigger a draw on Gy1 (could be called on Gx1).
  this->Gy1->CopyToFrameBuffer(extraPixels, extraPixels, w - 1 - extraPixels, h - 1 - extraPixels,
    0, 0, width, height, this->Program2->Program, this->Program2->VAO);

  this->Gy1->Deactivate();
  this->Gx1->Deactivate();

#ifdef VTK_SOBEL_PASS_DEBUG
  cout << "sobel finish4" << endl;
  glFinish();
#endif

  vtkOpenGLCheckErrorMacro("failed after Render");
}

// ----------------------------------------------------------------------------
// Description:
// Release graphics resources and ask components to release their own
// resources.
// \pre w_exists: w!=0
void vtkSobelGradientMagnitudePass::ReleaseGraphicsResources(vtkWindow* w)
{
  assert("pre: w_exists" && w != nullptr);

  this->Superclass::ReleaseGraphicsResources(w);

  if (this->Program1 != nullptr)
  {
    this->Program1->ReleaseGraphicsResources(w);
    delete this->Program1;
    this->Program1 = nullptr;
  }
  if (this->Program2 != nullptr)
  {
    this->Program2->ReleaseGraphicsResources(w);
    delete this->Program2;
    this->Program2 = nullptr;
  }

  if (this->FrameBufferObject != nullptr)
  {
    this->FrameBufferObject->Delete();
    this->FrameBufferObject = nullptr;
  }

  if (this->Pass1 != nullptr)
  {
    this->Pass1->Delete();
    this->Pass1 = nullptr;
  }

  if (this->Gx1 != nullptr)
  {
    this->Gx1->Delete();
    this->Gx1 = nullptr;
  }

  if (this->Gy1 != nullptr)
  {
    this->Gy1->Delete();
    this->Gy1 = nullptr;
  }
}
