/*=========================================================================
 *
 *  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 itkHalfToFullHermitianImageFilter_hxx
#define itkHalfToFullHermitianImageFilter_hxx


#include "itkImageAlgorithm.h"
#include "itkImageRegionIteratorWithIndex.h"
#include "itkTotalProgressReporter.h"

namespace itk
{

template <typename TInputImage>
HalfToFullHermitianImageFilter<TInputImage>::HalfToFullHermitianImageFilter()
{
  this->ActualXDimensionIsOddOff();
  this->DynamicMultiThreadingOn();
  this->ThreaderUpdateProgressOff();
}

template <typename TInputImage>
void
HalfToFullHermitianImageFilter<TInputImage>::GenerateOutputInformation()
{
  // Call the superclass' implementation of this method
  Superclass::GenerateOutputInformation();

  // Get pointers to the input and output
  const typename InputImageType::ConstPointer inputPtr = this->GetInput();
  const typename OutputImageType::Pointer     outputPtr = this->GetOutput();

  if (!inputPtr || !outputPtr)
  {
    return;
  }

  const typename InputImageType::SizeType &  inputSize = inputPtr->GetLargestPossibleRegion().GetSize();
  const typename InputImageType::IndexType & inputStartIndex = inputPtr->GetLargestPossibleRegion().GetIndex();

  typename OutputImageType::SizeType  outputSize;
  typename OutputImageType::IndexType outputStartIndex;

  for (unsigned int i = 0; i < OutputImageType::ImageDimension; ++i)
  {
    outputSize[i] = inputSize[i];
    outputStartIndex[i] = inputStartIndex[i];
  }
  outputSize[0] = (inputSize[0] - 1) * 2;
  if (this->GetActualXDimensionIsOdd())
  {
    outputSize[0]++;
  }

  const typename OutputImageType::RegionType outputLargestPossibleRegion(outputStartIndex, outputSize);

  outputPtr->SetLargestPossibleRegion(outputLargestPossibleRegion);
}

template <typename TInputImage>
void
HalfToFullHermitianImageFilter<TInputImage>::GenerateInputRequestedRegion()
{
  Superclass::GenerateInputRequestedRegion();

  // Get pointers to the input and output
  const typename InputImageType::Pointer inputPtr = const_cast<InputImageType *>(this->GetInput());
  if (inputPtr)
  {
    inputPtr->SetRequestedRegionToLargestPossibleRegion();
  }
}

template <typename TInputImage>
void
HalfToFullHermitianImageFilter<TInputImage>::DynamicThreadedGenerateData(
  const OutputImageRegionType & outputRegionForThread)
{
  const typename InputImageType::ConstPointer inputPtr = this->GetInput();
  const typename OutputImageType::Pointer     outputPtr = this->GetOutput();

  if (!inputPtr || !outputPtr)
  {
    return;
  }

  const InputImageRegionType  inputRegion = inputPtr->GetLargestPossibleRegion();
  const InputImageIndexType & inputRegionIndex = inputRegion.GetIndex();
  const InputImageSizeType &  inputRegionSize = inputRegion.GetSize();
  InputImageIndexType         inputRegionMaximumIndex = inputRegionIndex + inputRegionSize;

  // Copy the non-reflected region.
  OutputImageRegionType copyRegion(outputRegionForThread);
  const bool            copy = copyRegion.Crop(inputRegion);

  // Set up the ProgressReporter.
  TotalProgressReporter progress(this, outputPtr->GetRequestedRegion().GetNumberOfPixels());

  if (copy)
  {
    ImageAlgorithm::Copy(inputPtr.GetPointer(), outputPtr.GetPointer(), copyRegion, copyRegion);
    progress.Completed(copyRegion.GetNumberOfPixels());
  }

  // Now copy the redundant complex conjugate region, if there is one
  // in this thread's output region.
  OutputImageIndexType      outputRegionIndex = outputRegionForThread.GetIndex();
  const OutputImageSizeType outputRegionSize = outputRegionForThread.GetSize();
  OutputImageIndexType      outputRegionMaximumIndex = outputRegionIndex + outputRegionSize;

  if (outputRegionMaximumIndex[0] > inputRegionMaximumIndex[0])
  {
    OutputImageIndexType conjugateRegionIndex(outputRegionIndex);
    conjugateRegionIndex[0] = std::max(outputRegionIndex[0], inputRegionMaximumIndex[0]);
    OutputImageSizeType conjugateRegionSize(outputRegionSize);
    conjugateRegionSize[0] = outputRegionMaximumIndex[0] - conjugateRegionIndex[0];
    const OutputImageRegionType conjugateRegion(conjugateRegionIndex, conjugateRegionSize);

    for (ImageRegionIteratorWithIndex<OutputImageType> oIt(outputPtr, conjugateRegion); !oIt.IsAtEnd(); ++oIt)
    {
      OutputImageIndexType conjugateIndex = oIt.GetIndex();

      // Flip the indices in each dimension.
      OutputImageIndexType index(conjugateIndex);
      for (unsigned int i = 0; i < ImageDimension; ++i)
      {
        const OutputImageRegionType outputLargestPossibleRegion = outputPtr->GetLargestPossibleRegion();
        OutputImageIndexType        outputLargestPossibleRegionIndex = outputLargestPossibleRegion.GetIndex();
        OutputImageSizeType         outputLargestPossibleRegionSize = outputLargestPossibleRegion.GetSize();
        if (conjugateIndex[i] != outputLargestPossibleRegionIndex[i])
        {
          index[i] = outputLargestPossibleRegionSize[i] - conjugateIndex[i] + 2 * outputLargestPossibleRegionIndex[i];
        }
      }

      oIt.Set(std::conj(inputPtr->GetPixel(index)));
      progress.CompletedPixel();
    }
  }
}

} // end namespace itk

#endif // itkHalfToFullHermitianImageFilter_hxx
