/*=========================================================================
 *
 *  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 itkLabelVotingImageFilter_hxx
#define itkLabelVotingImageFilter_hxx


#include "itkImageRegionIterator.h"
#include "itkTotalProgressReporter.h"

#include "itkMath.h"

namespace itk
{
template <typename TInputImage, typename TOutputImage>
LabelVotingImageFilter<TInputImage, TOutputImage>::LabelVotingImageFilter()
  : m_LabelForUndecidedPixels(0)

{
  this->ThreaderUpdateProgressOff();
}

template <typename TInputImage, typename TOutputImage>
auto
LabelVotingImageFilter<TInputImage, TOutputImage>::ComputeMaximumInputValue() -> InputPixelType
{
  InputPixelType maxLabel = 0;

  using IteratorType = ImageRegionConstIterator<TInputImage>;

  // Record the number of indexed inputs
  const size_t numberOfInputIndexes = this->GetNumberOfIndexedInputs();

  for (size_t i = 0; i < numberOfInputIndexes; ++i)
  {
    const InputImageType * inputImage = this->GetInput(i);
    IteratorType           it(inputImage, inputImage->GetBufferedRegion());
    for (it.GoToBegin(); !it.IsAtEnd(); ++it)
    {
      maxLabel = std::max(maxLabel, it.Get());
    }
  }

  return maxLabel;
}

template <typename TInputImage, typename TOutputImage>
void
LabelVotingImageFilter<TInputImage, TOutputImage>::BeforeThreadedGenerateData()
{
  Superclass::BeforeThreadedGenerateData();

  // Determine the maximum label in all input images
  this->m_TotalLabelCount = static_cast<size_t>(this->ComputeMaximumInputValue()) + 1;

  if (!this->m_HasLabelForUndecidedPixels)
  {
    if (this->m_TotalLabelCount > itk::NumericTraits<OutputPixelType>::max())
    {
      itkWarningMacro("No new label for undecided pixels, using zero.");
    }
    this->m_LabelForUndecidedPixels = static_cast<OutputPixelType>(this->m_TotalLabelCount);
  }

  // Allocate the output image
  typename TOutputImage::Pointer output = this->GetOutput();
  output->SetBufferedRegion(output->GetRequestedRegion());
  output->Allocate();
}

template <typename TInputImage, typename TOutputImage>
void
LabelVotingImageFilter<TInputImage, TOutputImage>::DynamicThreadedGenerateData(
  const OutputImageRegionType & outputRegionForThread)
{
  using IteratorType = ImageRegionConstIterator<TInputImage>;
  using OutIteratorType = ImageRegionIterator<TOutputImage>;

  typename TOutputImage::Pointer output = this->GetOutput();

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

  // Record the number of indexed inputs
  const size_t numberOfInputIndexes = this->GetNumberOfIndexedInputs();

  // Create and initialize all input image iterators
  std::vector<IteratorType> it(numberOfInputIndexes);
  for (size_t i = 0; i < numberOfInputIndexes; ++i)
  {
    it[i] = IteratorType(this->GetInput(i), outputRegionForThread);
  }

  std::vector<unsigned int> votesByLabel(this->m_TotalLabelCount);

  for (OutIteratorType out(output, outputRegionForThread); !out.IsAtEnd(); ++out)
  {
    // Reset number of votes per label for all labels
    std::fill_n(votesByLabel.begin(), this->m_TotalLabelCount, 0);

    // count number of votes for the labels
    for (unsigned int i = 0; i < numberOfInputIndexes; ++i)
    {
      const InputPixelType label = it[i].Get();
      if (NumericTraits<InputPixelType>::IsNonnegative(label))
      {
        ++votesByLabel[label];
      }
      ++(it[i]);
    }

    // Determine the label with the most votes for this pixel
    out.Set(0);
    unsigned int maxVotes = votesByLabel[0];
    for (size_t l = 1; l < this->m_TotalLabelCount; ++l)
    {
      if (votesByLabel[l] > maxVotes)
      {
        maxVotes = votesByLabel[l];
        out.Set(static_cast<OutputPixelType>(l));
      }
      else
      {
        if (votesByLabel[l] == maxVotes)
        {
          out.Set(this->m_LabelForUndecidedPixels);
        }
      }
    }
    progress.CompletedPixel();
  }
}

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

  os << indent << "LabelForUndecidedPixels: "
     << static_cast<typename NumericTraits<OutputPixelType>::PrintType>(m_HasLabelForUndecidedPixels) << std::endl;
  os << indent << "HasLabelForUndecidedPixels: " << (m_HasLabelForUndecidedPixels ? "On" : "Off") << std::endl;
  os << indent << "TotalLabelCount: " << m_TotalLabelCount << std::endl;
}
} // end namespace itk

#endif
