/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  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
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  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 itkGPUScalarAnisotropicDiffusionFunction_hxx
#define itkGPUScalarAnisotropicDiffusionFunction_hxx

#include "itkConstNeighborhoodIterator.h"
#include "itkNeighborhoodInnerProduct.h"
#include "itkNeighborhoodAlgorithm.h"
#include "itkDerivativeOperator.h"
#include "itkMakeUniqueForOverwrite.h"

namespace itk
{

template <typename TImage>
GPUScalarAnisotropicDiffusionFunction<TImage>::GPUScalarAnisotropicDiffusionFunction()
{
  this->m_AnisotropicDiffusionFunctionGPUBuffer = GPUDataManager::New();
  this->m_AnisotropicDiffusionFunctionGPUKernelManager = GPUKernelManager::New();

  // load GPU kernel
  std::ostringstream defines;

  if (ImageDimension > 3 || ImageDimension < 1)
  {
    itkExceptionMacro("GPUScalarAnisotropicDiffusionFunction supports 1/2/3D image.");
  }

  defines << "#define DIM_" << ImageDimension << '\n';

  defines << "#define PIXELTYPE ";

  GetTypenameInString(typeid(typename TImage::PixelType), defines);

  const char * GPUSource = GPUScalarAnisotropicDiffusionFunction::GetOpenCLSource();

  // load and build program
  this->m_AnisotropicDiffusionFunctionGPUKernelManager->LoadProgramFromString(GPUSource, defines.str().c_str());

  // create kernel
  this->m_AverageGradientMagnitudeSquaredGPUKernelHandle =
    this->m_AnisotropicDiffusionFunctionGPUKernelManager->CreateKernel("AverageGradientMagnitudeSquared");
}

template <typename TImage>
void
GPUScalarAnisotropicDiffusionFunction<TImage>::GPUCalculateAverageGradientMagnitudeSquared(TImage * ip)
{
  // GPU kernel to compute Average Squared Gradient Magnitude
  using GPUImageType = typename itk::GPUTraits<TImage>::Type;
  typename GPUImageType::Pointer  inPtr = dynamic_cast<GPUImageType *>(ip);
  typename GPUImageType::SizeType outSize = inPtr->GetLargestPossibleRegion().GetSize();

  int imgSize[3];
  imgSize[0] = imgSize[1] = imgSize[2] = 1;
  float imgScale[3];
  imgScale[0] = imgScale[1] = imgScale[2] = 1.0f;
  int ImageDim = static_cast<int>(TImage::ImageDimension);

  size_t localSize[3], globalSize[3];
  localSize[0] = localSize[1] = localSize[2] = 1;
  globalSize[0] = globalSize[1] = globalSize[2] = 1;
  unsigned int blockSize = OpenCLGetLocalBlockSize(ImageDim);

  unsigned int numPixel = 1;
  unsigned int bufferSize = 1;
  for (int i = 0; i < ImageDim; ++i)
  {
    imgSize[i] = outSize[i];
    imgScale[i] = this->m_ScaleCoefficients[i];
    localSize[i] = (blockSize <= outSize[i]) ? blockSize : 1;
    // total # of threads
    globalSize[i] =
      localSize[i] * static_cast<unsigned int>(ceil(static_cast<float>(outSize[i]) / static_cast<float>(localSize[i])));
    bufferSize *= globalSize[i] / localSize[i];
    numPixel *= imgSize[i];
  }

  // Initialize & Allocate GPU Buffer
  if (bufferSize != this->m_AnisotropicDiffusionFunctionGPUBuffer->GetBufferSize())
  {
    this->m_AnisotropicDiffusionFunctionGPUBuffer->Initialize();
    this->m_AnisotropicDiffusionFunctionGPUBuffer->SetBufferSize(sizeof(float) * bufferSize);
    this->m_AnisotropicDiffusionFunctionGPUBuffer->Allocate();
  }

  typename GPUKernelManager::Pointer kernelManager = this->m_AnisotropicDiffusionFunctionGPUKernelManager;
  int                                kernelHandle = this->m_AverageGradientMagnitudeSquaredGPUKernelHandle;

  // Set arguments
  int argidx = 0;
  kernelManager->SetKernelArgWithImage(kernelHandle, argidx++, inPtr->GetGPUDataManager());
  kernelManager->SetKernelArgWithImage(kernelHandle, argidx++, this->m_AnisotropicDiffusionFunctionGPUBuffer);

  // Set shared memory args
  if (ImageDim == 2)
  {
    kernelManager->SetKernelArg(kernelHandle, argidx++, sizeof(float) * localSize[0] * localSize[1], nullptr);
    kernelManager->SetKernelArg(kernelHandle, argidx++, sizeof(float) * localSize[0], nullptr);
    kernelManager->SetKernelArg(kernelHandle, argidx++, sizeof(float) * localSize[0], nullptr);
    kernelManager->SetKernelArg(kernelHandle, argidx++, sizeof(float) * localSize[1], nullptr);
    kernelManager->SetKernelArg(kernelHandle, argidx++, sizeof(float) * localSize[1], nullptr);
  }
  else if (ImageDim == 3)
  {
    kernelManager->SetKernelArg(
      kernelHandle, argidx++, sizeof(float) * localSize[0] * localSize[1] * localSize[2], nullptr);
    kernelManager->SetKernelArg(kernelHandle, argidx++, sizeof(float) * localSize[0] * localSize[1], nullptr);
    kernelManager->SetKernelArg(kernelHandle, argidx++, sizeof(float) * localSize[0] * localSize[1], nullptr);
    kernelManager->SetKernelArg(kernelHandle, argidx++, sizeof(float) * localSize[0] * localSize[2], nullptr);
    kernelManager->SetKernelArg(kernelHandle, argidx++, sizeof(float) * localSize[0] * localSize[2], nullptr);
    kernelManager->SetKernelArg(kernelHandle, argidx++, sizeof(float) * localSize[1] * localSize[2], nullptr);
    kernelManager->SetKernelArg(kernelHandle, argidx++, sizeof(float) * localSize[1] * localSize[2], nullptr);
  }
  else
  {
    // no need to set shared memory args when dimension is not 2 or 3
  }

  // Set filter scale parameter
  for (int i = 0; i < ImageDim; ++i)
  {
    kernelManager->SetKernelArg(kernelHandle, argidx++, sizeof(float), &(imgScale[i]));
  }

  // Set image size
  for (int i = 0; i < ImageDim; ++i)
  {
    kernelManager->SetKernelArg(kernelHandle, argidx++, sizeof(int), &(imgSize[i]));
  }

  // launch kernel
  kernelManager->LaunchKernel(kernelHandle, ImageDim, globalSize, localSize);

  // Read back intermediate sums from GPU and compute final value
  double     sum = 0;
  const auto intermSum = make_unique_for_overwrite<float[]>(bufferSize);

  this->m_AnisotropicDiffusionFunctionGPUBuffer->SetCPUBufferPointer(intermSum.get());
  this->m_AnisotropicDiffusionFunctionGPUBuffer->SetCPUDirtyFlag(true); //
                                                                        // CPU
                                                                        // is
                                                                        // dirty
  this->m_AnisotropicDiffusionFunctionGPUBuffer->SetGPUDirtyFlag(false);
  this->m_AnisotropicDiffusionFunctionGPUBuffer->UpdateCPUBuffer(); //
                                                                    // Copy
                                                                    // GPU->CPU

  for (int i = 0; i < static_cast<int>(bufferSize); ++i)
  {
    sum += static_cast<double>(intermSum[i]);
  }

  this->SetAverageGradientMagnitudeSquared(static_cast<double>(sum / static_cast<double>(numPixel)));
}

} // end namespace itk

#endif
