/*=========================================================================
 *
 *  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 itkFlipImageFilter_hxx
#define itkFlipImageFilter_hxx

#include "itkImageScanlineIterator.h"
#include "itkTotalProgressReporter.h"

namespace itk
{

template <typename TImage>
FlipImageFilter<TImage>::FlipImageFilter()

{
  m_FlipAxes.Fill(false);
  this->DynamicMultiThreadingOn();
  this->ThreaderUpdateProgressOff();
}

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

  // Get pointers to the input and output
  InputImagePointer  inputPtr = const_cast<TImage *>(this->GetInput());
  OutputImagePointer outputPtr = this->GetOutput();

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

  const typename TImage::DirectionType & inputDirection = inputPtr->GetDirection();
  const typename TImage::SizeType &      inputSize = inputPtr->GetLargestPossibleRegion().GetSize();
  const typename TImage::IndexType &     inputStartIndex = inputPtr->GetLargestPossibleRegion().GetIndex();

  typename TImage::PointType outputOrigin;
  typename TImage::IndexType newIndex = inputStartIndex;

  typename TImage::DirectionType flipMatrix;
  flipMatrix.SetIdentity();

  // Need the coordinate of the pixel that will become the first pixel
  // and need a matrix to model the flip
  for (unsigned int j = 0; j < ImageDimension; ++j)
  {
    if (m_FlipAxes[j])
    {
      // If flipping the axis, then we need to know the last pixel in
      // that dimension
      newIndex[j] += (inputSize[j] - 1);

      // What we really want is the index padded out past this point
      // by the amount the start index is from [0,0,0] (because the
      // output regions have the same index layout as the input
      // regions)
      newIndex[j] += inputStartIndex[j];

      // Only flip the directions if we are NOT flipping about the
      // origin (when flipping about the origin, the pixels are
      // ordered in the same direction as the input directions. when
      // NOT flipping about the origin, the pixels traverse space in
      // the opposite direction. when flipping about the origin,
      // increasing indices traverse space in the same direction as
      // the original data.).
      if (!m_FlipAboutOrigin)
      {
        flipMatrix[j][j] = -1.0;
      }
    }
  }

  inputPtr->TransformIndexToPhysicalPoint(newIndex, outputOrigin);

  // Finally, flip about the origin if needed
  if (m_FlipAboutOrigin)
  {
    for (unsigned int j = 0; j < ImageDimension; ++j)
    {
      if (m_FlipAxes[j])
      {
        outputOrigin[j] *= -1;
      }
    }
  }

  outputPtr->SetDirection(inputDirection * flipMatrix);
  outputPtr->SetOrigin(outputOrigin);
}

template <typename TImage>
void
FlipImageFilter<TImage>::GenerateInputRequestedRegion()
{
  // Call the superclass's implementation of this method
  Superclass::GenerateInputRequestedRegion();

  // Get pointers to the input and output
  InputImagePointer  inputPtr = const_cast<TImage *>(this->GetInput());
  OutputImagePointer outputPtr = this->GetOutput();

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

  const typename TImage::SizeType &  outputRequestedSize = outputPtr->GetRequestedRegion().GetSize();
  const typename TImage::IndexType & outputRequestedIndex = outputPtr->GetRequestedRegion().GetIndex();

  const typename TImage::SizeType &  outputLargestPossibleSize = outputPtr->GetLargestPossibleRegion().GetSize();
  const typename TImage::IndexType & outputLargestPossibleIndex = outputPtr->GetLargestPossibleRegion().GetIndex();

  IndexType inputRequestedIndex(outputRequestedIndex);

  for (unsigned int j = 0; j < ImageDimension; ++j)
  {
    if (m_FlipAxes[j])
    {
      inputRequestedIndex[j] = 2 * outputLargestPossibleIndex[j] +
                               static_cast<IndexValueType>(outputLargestPossibleSize[j]) -
                               static_cast<IndexValueType>(outputRequestedSize[j]) - outputRequestedIndex[j];
    }
  }

  typename TImage::RegionType inputRequestedRegion(inputRequestedIndex, outputRequestedSize);

  inputPtr->SetRequestedRegion(inputRequestedRegion);
}

template <typename TImage>
void
FlipImageFilter<TImage>::DynamicThreadedGenerateData(const OutputImageRegionType & outputRegionForThread)
{
  InputImageConstPointer inputPtr = this->GetInput();
  OutputImagePointer     outputPtr = this->GetOutput();

  const typename TImage::SizeType &  outputLargestPossibleSize = outputPtr->GetLargestPossibleRegion().GetSize();
  const typename TImage::IndexType & outputLargestPossibleIndex = outputPtr->GetLargestPossibleRegion().GetIndex();

  // Compute the input region the output region maps to
  typename TImage::RegionType inputReginForThread(outputRegionForThread);
  for (unsigned int j = 0; j < ImageDimension; ++j)
  {
    if (m_FlipAxes[j])
    {
      const IndexValueType idx =
        2 * outputLargestPossibleIndex[j] + static_cast<IndexValueType>(outputLargestPossibleSize[j]) -
        static_cast<IndexValueType>(outputRegionForThread.GetSize(j)) - outputRegionForThread.GetIndex(j);
      inputReginForThread.SetIndex(j, idx);
    }
  }

  // Setup region iterator
  ImageScanlineConstIterator inputIter(inputPtr, inputReginForThread);

  IndexValueType offset[ImageDimension];
  for (unsigned int j = 0; j < ImageDimension; ++j)
  {
    if (m_FlipAxes[j])
    {
      offset[j] = 2 * outputLargestPossibleIndex[j] + static_cast<IndexValueType>(outputLargestPossibleSize[j]) - 1;
    }
    else
    {
      offset[j] = 0;
    }
  }

  TotalProgressReporter progress(this, outputPtr->GetRequestedRegion().GetNumberOfPixels());

  for (ImageScanlineIterator outputIt(outputPtr, outputRegionForThread); !outputIt.IsAtEnd(); outputIt.NextLine())
  {
    // Determine the index of the output line
    const typename TImage::IndexType outputIndex = outputIt.GetIndex();

    // Determine the input pixel location associated with the start of
    // the line
    typename TImage::IndexType inputIndex(outputIndex);
    for (unsigned int j = 0; j < ImageDimension; ++j)
    {
      if (m_FlipAxes[j])
      {
        inputIndex[j] = -1 * outputIndex[j] + offset[j];
      }
    }
    inputIter.SetIndex(inputIndex);

    if (m_FlipAxes[0])
    {
      // Move the across the output scanline
      while (!outputIt.IsAtEndOfLine())
      {
        // Copy the input pixel to the output
        outputIt.Set(inputIter.Get());

        ++outputIt;
        // Read the input scanline in reverse
        --inputIter;
      }
    }
    else
    {
      // Move the across the output scanline
      while (!outputIt.IsAtEndOfLine())
      {
        // Copy the input pixel to the output
        outputIt.Set(inputIter.Get());

        ++outputIt;
        ++inputIter;
      }
    }

    progress.Completed(outputRegionForThread.GetSize()[0]);
  }
}

template <typename TImage>
void
FlipImageFilter<TImage>::PrintSelf(std::ostream & os, Indent indent) const
{
  Superclass::PrintSelf(os, indent);

  os << indent << "FlipAxes: " << m_FlipAxes << std::endl;
  os << indent << "FlipAboutOrigin: " << m_FlipAboutOrigin << std::endl;
}
} // namespace itk

#endif