/*=========================================================================
 *
 *  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 itkGPUGradientNDAnisotropicDiffusionFunction_hxx
#define itkGPUGradientNDAnisotropicDiffusionFunction_hxx

#include "itkNumericTraits.h"

#include "itkOpenCLUtil.h"

namespace itk
{
template <typename TImage>
double GPUGradientNDAnisotropicDiffusionFunction<TImage>::m_MIN_NORM = 1.0e-10;

template <typename TImage>
GPUGradientNDAnisotropicDiffusionFunction<TImage>::GPUGradientNDAnisotropicDiffusionFunction()
{
  unsigned int i, j;
  RadiusType   r;

  for (i = 0; i < ImageDimension; ++i)
  {
    r[i] = 1;
  }
  this->SetRadius(r);

  // Dummy neighborhood used to set up the slices.
  Neighborhood<PixelType, ImageDimension> it;
  it.SetRadius(r);

  // Slice the neighborhood
  m_Center = it.Size() / 2;

  for (i = 0; i < ImageDimension; ++i)
  {
    m_Stride[i] = it.GetStride(i);
  }

  for (i = 0; i < ImageDimension; ++i)
  {
    x_slice[i] = std::slice(m_Center - m_Stride[i], 3, m_Stride[i]);
  }

  for (i = 0; i < ImageDimension; ++i)
  {
    for (j = 0; j < ImageDimension; ++j)
    {
      // For taking derivatives in the i direction that are offset one
      // pixel in the j direction.
      xa_slice[i][j] = std::slice((m_Center + m_Stride[j]) - m_Stride[i], 3, m_Stride[i]);
      xd_slice[i][j] = std::slice((m_Center - m_Stride[j]) - m_Stride[i], 3, m_Stride[i]);
    }
  }

  // Allocate the derivative operator.
  m_DerivativeOperator.SetDirection(0); // Not relevant, will be applied in a slice-based
                                        // fashion.
  m_DerivativeOperator.SetOrder(1);
  m_DerivativeOperator.CreateDirectional();

  //
  // Create GPU Kernel
  //
  std::ostringstream defines;

  if (TImage::ImageDimension > 3)
  {
    itkExceptionMacro("GPUGradientNDAnisotropicDiffusionFunction supports 1/2/3D image.");
  }

  defines << "#define DIM_" << TImage::ImageDimension << '\n'
          << "#define BLOCK_SIZE " << OpenCLGetLocalBlockSize(TImage::ImageDimension) << '\n';

  std::string pixeltypename = GetTypename(typeid(typename TImage::PixelType));
  defines << "#define PIXELTYPE " << pixeltypename << '\n';
#ifdef __APPLE__
  // This is to work around a bug in the OpenCL compiler on Mac OS 10.6 and 10.7 with NVidia drivers
  // where the compiler was not handling unsigned char arguments correctly.
  // be sure to define the kernel arguments as ArgType in the kernel source
  // Using unsigned short instead of unsigned char in the kernel definition
  // is a known workaround to this problem.
  if (pixeltypename == "unsigned char")
  {
    defines << "#define ARGTYPE unsigned short\n";
  }
  else
  {
    defines << "#define ARGTYPE " << pixeltypename << '\n';
  }
#else
  defines << "#define ARGTYPE " << pixeltypename << '\n';
#endif

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

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

  // create kernel
  this->m_ComputeUpdateGPUKernelHandle = this->m_GPUKernelManager->CreateKernel("ComputeUpdate");
}

template <typename TImage>
void
GPUGradientNDAnisotropicDiffusionFunction<TImage>::GPUComputeUpdate(const typename TImage::Pointer output,
                                                                    typename TImage::Pointer       buffer,
                                                                    void * itkNotUsed(globalData))
{
  /** Launch GPU kernel to update buffer with output
   * GPU version of ComputeUpdate() - compute entire update buffer */
  using GPUImageType = typename itk::GPUTraits<TImage>::Type;

  typename GPUImageType::Pointer  inPtr = dynamic_cast<GPUImageType *>(output.GetPointer());
  typename GPUImageType::Pointer  bfPtr = dynamic_cast<GPUImageType *>(buffer.GetPointer());
  typename GPUImageType::SizeType outSize = bfPtr->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);

  for (int i = 0; i < ImageDim; ++i)
  {
    imgSize[i] = outSize[i];
    imgScale[i] = this->m_ScaleCoefficients[i];
  }

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

  for (int i = 0; i < ImageDim; ++i)
  {
    // total # of threads
    globalSize[i] =
      localSize[i] * static_cast<unsigned int>(ceil(static_cast<float>(outSize[i]) / static_cast<float>(localSize[i])));
  }

  // arguments set up
  int argidx = 0;
  this->m_GPUKernelManager->SetKernelArgWithImage(
    this->m_ComputeUpdateGPUKernelHandle, argidx++, inPtr->GetGPUDataManager());
  this->m_GPUKernelManager->SetKernelArgWithImage(
    this->m_ComputeUpdateGPUKernelHandle, argidx++, bfPtr->GetGPUDataManager());
  this->m_GPUKernelManager->SetKernelArg(
    this->m_ComputeUpdateGPUKernelHandle, argidx++, sizeof(typename TImage::PixelType), &(m_K));

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

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

  // launch kernel
  this->m_GPUKernelManager->LaunchKernel(this->m_ComputeUpdateGPUKernelHandle, ImageDim, globalSize, localSize);
}

} // end namespace itk

#endif
