/*=========================================================================
 *
 *  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 itkLevelSetDomainMapImageFilter_hxx
#define itkLevelSetDomainMapImageFilter_hxx


namespace itk
{
template <typename TInputImage, typename TOutputImage>
LevelSetDomainMapImageFilter<TInputImage, TOutputImage>::LevelSetDomainMapImageFilter()
  : m_InputImage(nullptr)
  , m_OutputImage(nullptr)
{
  this->Superclass::SetNumberOfRequiredInputs(1);
  this->Superclass::SetNumberOfRequiredOutputs(1);
}

template <typename TInputImage, typename TOutputImage>
auto
LevelSetDomainMapImageFilter<TInputImage, TOutputImage>::GetDomainMap() const -> const DomainMapType &
{
  return this->m_DomainMap;
}

template <typename TInputImage, typename TOutputImage>
auto
LevelSetDomainMapImageFilter<TInputImage, TOutputImage>::ComputeConsistentRegion(
  const InputImageRegionType & inputRegion) const -> InputImageRegionType
{
  bool regionWasModified = false;

  InputImageRegionType subRegion = inputRegion;

  do
  {
    regionWasModified = false;

    InputConstIteratorType  iIt(this->m_InputImage, subRegion);
    OutputConstIteratorType oIt(this->m_OutputImage, subRegion);

    iIt.GoToBegin();
    oIt.GoToBegin();

    const InputImagePixelType   firstCornerPixelValue = iIt.Get();
    const InputImageIndexType & firstCornerIndex = iIt.GetIndex();

    while (!iIt.IsAtEnd())
    {
      const OutputImagePixelType segmentPixel = oIt.Get();
      const InputImagePixelType  nextPixel = iIt.Get();

      if ((nextPixel != firstCornerPixelValue) || (segmentPixel != OutputImagePixelType{}))
      {
        const InputImageIndexType & stopIdx = iIt.GetIndex();
        InputImageSizeType          sizeOfRegion;
        for (unsigned int i = 0; i < ImageDimension; ++i)
        {
          sizeOfRegion[i] = stopIdx[i] - firstCornerIndex[i] + 1;
        }
        subRegion.SetSize(sizeOfRegion);

        regionWasModified = true;
        break;
      }

      ++iIt;
      ++oIt;
    }
  } while (regionWasModified);

  return subRegion;
}


template <typename TInputImage, typename TOutputImage>
void
LevelSetDomainMapImageFilter<TInputImage, TOutputImage>::GenerateData()
{
  // Clear any prior contents.
  this->m_DomainMap.clear();

  this->m_InputImage = this->GetInput();
  const InputImageRegionType & region = this->m_InputImage->GetLargestPossibleRegion();
  const InputImageSizeType     size = region.GetSize();

  this->m_OutputImage = this->GetOutput();
  this->m_OutputImage->SetBufferedRegion(region);
  this->m_OutputImage->AllocateInitialized();

  InputImageIndexType end;

  for (unsigned int i = 0; i < ImageDimension; ++i)
  {
    end[i] = size[i] - 1;
  }

  IdentifierType segmentId = NumericTraits<IdentifierType>::OneValue();

  InputConstIteratorType  iIt(this->m_InputImage, region);
  OutputIndexIteratorType oIt(this->m_OutputImage, region);

  iIt.GoToBegin();
  oIt.GoToBegin();

  while (!iIt.IsAtEnd())
  {
    const InputImageIndexType &  startIdx = iIt.GetIndex();
    InputImageIndexType          stopIdx = startIdx;
    const InputImagePixelType &  inputPixel = iIt.Get();
    const OutputImagePixelType & outputPixel = oIt.Get();

    // outputPixel is null when it has not been processed yet,
    // or there is nothing to be processed
    if ((!inputPixel.empty()) && (outputPixel == OutputImagePixelType{}))
    {

      InputImageSizeType sizeOfRegion;
      for (unsigned int i = 0; i < ImageDimension; ++i)
      {
        bool sameOverlappingLevelSetIds = true;
        stopIdx = startIdx;
        while ((sameOverlappingLevelSetIds) && (stopIdx[i] <= end[i]))
        {
          const InputImagePixelType &  nextPixel = this->m_InputImage->GetPixel(stopIdx);
          const OutputImagePixelType & currentOutputPixel = this->m_OutputImage->GetPixel(stopIdx);

          // Check if the input list pixels are different, or
          // the output image already has been assigned to another region
          if ((nextPixel != inputPixel) || (currentOutputPixel != OutputImagePixelType{}))
          {
            sameOverlappingLevelSetIds = false;
          }
          else
          {
            ++stopIdx[i];
          }
        }
        sizeOfRegion[i] = stopIdx[i] - startIdx[i];
      }

      InputImageRegionType subRegion = { startIdx, sizeOfRegion };

      // Compute the consistent subregion
      subRegion = this->ComputeConsistentRegion(subRegion);

      this->m_DomainMap[segmentId] = LevelSetDomain(subRegion, inputPixel);

      OutputIndexIteratorType ooIt(this->m_OutputImage, subRegion);
      ooIt.GoToBegin();

      while (!ooIt.IsAtEnd())
      {
        ooIt.Set(segmentId);
        ++ooIt;
      }
      ++segmentId;
    }
    ++iIt;
    ++oIt;
  }
}

template <typename TInputImage, typename TOutputImage>
void
LevelSetDomainMapImageFilter<TInputImage, TOutputImage>::PrintSelf(std::ostream & os, Indent indent) const
{
  Superclass::PrintSelf(os, indent);
  os << indent << "DomainMap size: " << this->m_DomainMap.size() << std::endl;
}

} /* end namespace itk */

#endif
