/*=========================================================================
 *
 *  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 itkVnlComplexToComplexFFTImageFilter_hxx
#define itkVnlComplexToComplexFFTImageFilter_hxx

#include "itkProgressReporter.h"
#include "itkVnlFFTCommon.h"
#include "itkImageRegionIteratorWithIndex.h"
#include "itkImageAlgorithm.h"


namespace itk
{

template <typename TInputImage, typename TOutputImage>
VnlComplexToComplexFFTImageFilter<TInputImage, TOutputImage>::VnlComplexToComplexFFTImageFilter()
{
  this->DynamicMultiThreadingOn();
}


template <typename TInputImage, typename TOutputImage>
void
VnlComplexToComplexFFTImageFilter<TInputImage, TOutputImage>::BeforeThreadedGenerateData()
{
  const ImageType * input = this->GetInput();
  ImageType *       output = this->GetOutput();

  const typename ImageType::RegionType bufferedRegion = input->GetBufferedRegion();
  const typename ImageType::SizeType & imageSize = bufferedRegion.GetSize();

  for (unsigned int ii = 0; ii < ImageDimension; ++ii)
  {
    if (!VnlFFTCommon::IsDimensionSizeLegal(imageSize[ii]))
    {
      itkExceptionMacro("Cannot compute FFT of image with size "
                        << imageSize
                        << ". VnlComplexToComplexFFTImageFilter operates only on images whose size in each dimension "
                           "has only a combination of 2,3, and 5 as prime factors.");
    }
  }

  // Copy the input to the output, and we will work in place on the output.
  ImageAlgorithm::Copy<ImageType, ImageType>(input, output, bufferedRegion, bufferedRegion);

  using VclPixelType = std::complex<typename PixelType::value_type>;
  auto * outputBuffer = static_cast<VclPixelType *>(output->GetBufferPointer());

  // call the proper transform, based on compile type template parameter
  VnlFFTCommon::VnlFFTTransform<Image<typename PixelType::value_type, ImageDimension>> vnlfft(imageSize);
  if (this->GetTransformDirection() == Superclass::TransformDirectionEnum::INVERSE)
  {
    vnlfft.transform(outputBuffer, 1);
  }
  else
  {
    vnlfft.transform(outputBuffer, -1);
  }
}


template <typename TInputImage, typename TOutputImage>
void
VnlComplexToComplexFFTImageFilter<TInputImage, TOutputImage>::DynamicThreadedGenerateData(
  const OutputImageRegionType & outputRegionForThread)
{
  // Normalize the output if backward transform
  if (this->GetTransformDirection() == Superclass::TransformDirectionEnum::INVERSE)
  {
    using IteratorType = ImageRegionIterator<OutputImageType>;
    SizeValueType totalOutputSize = this->GetOutput()->GetRequestedRegion().GetNumberOfPixels();
    IteratorType  it(this->GetOutput(), outputRegionForThread);
    while (!it.IsAtEnd())
    {
      PixelType val = it.Value();
      val /= totalOutputSize;
      it.Set(val);
      ++it;
    }
  }
}

} // end namespace itk

#endif // _itkVnlComplexToComplexFFTImageFilter_hxx
