/*=========================================================================
 *
 *  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 itkZeroCrossingImageFilter_hxx
#define itkZeroCrossingImageFilter_hxx

#include "itkConstNeighborhoodIterator.h"
#include "itkImageRegionIterator.h"
#include "itkNeighborhoodAlgorithm.h"
#include "itkFixedArray.h"
#include "itkTotalProgressReporter.h"
#include "itkMath.h"

namespace itk
{

template <typename TInputImage, typename TOutputImage>
ZeroCrossingImageFilter<TInputImage, TOutputImage>::ZeroCrossingImageFilter()
  : m_BackgroundValue(OutputImagePixelType{})
  , m_ForegroundValue(NumericTraits<OutputImagePixelType>::OneValue())
{
  this->DynamicMultiThreadingOn();
  this->ThreaderUpdateProgressOff();
}

template <typename TInputImage, typename TOutputImage>
void
ZeroCrossingImageFilter<TInputImage, TOutputImage>::GenerateInputRequestedRegion()
{
  // call the superclass' implementation of this method
  Superclass::GenerateInputRequestedRegion();

  // get pointers to the input and output
  typename Superclass::InputImagePointer  inputPtr = const_cast<TInputImage *>(this->GetInput());
  typename Superclass::OutputImagePointer outputPtr = this->GetOutput();

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

  // Build an operator so that we can determine the kernel size
  SizeValueType radius{};

  // get a copy of the input requested region (should equal the output
  // requested region)
  typename TInputImage::RegionType inputRequestedRegion;
  inputRequestedRegion = inputPtr->GetRequestedRegion();

  // pad the input requested region by the operator radius
  inputRequestedRegion.PadByRadius(radius);

  // crop the input requested region at the input's largest possible region
  if (inputRequestedRegion.Crop(inputPtr->GetLargestPossibleRegion()))
  {
    inputPtr->SetRequestedRegion(inputRequestedRegion);
    return;
  }
  else
  {
    // Couldn't crop the region (requested region is outside the largest
    // possible region).  Throw an exception.

    // store what we tried to request (prior to trying to crop)
    inputPtr->SetRequestedRegion(inputRequestedRegion);

    // build an exception
    InvalidRequestedRegionError e(__FILE__, __LINE__);
    e.SetLocation(ITK_LOCATION);
    e.SetDescription("Requested region is (at least partially) outside the largest possible region.");
    e.SetDataObject(inputPtr);
    throw e;
  }
}

template <typename TInputImage, typename TOutputImage>
void
ZeroCrossingImageFilter<TInputImage, TOutputImage>::DynamicThreadedGenerateData(
  const OutputImageRegionType & outputRegionForThread)
{
  unsigned int i;

  ZeroFluxNeumannBoundaryCondition<TInputImage> nbc;

  ConstNeighborhoodIterator<TInputImage> bit;
  ImageRegionIterator<TOutputImage>      it;

  typename OutputImageType::Pointer     output = this->GetOutput();
  typename InputImageType::ConstPointer input = this->GetInput();

  // Calculate iterator radius
  static constexpr auto radius = Size<ImageDimension>::Filled(1);

  // Find the data-set boundary "faces"
  NeighborhoodAlgorithm::ImageBoundaryFacesCalculator<TInputImage>                        bC;
  typename NeighborhoodAlgorithm::ImageBoundaryFacesCalculator<TInputImage>::FaceListType faceList =
    bC(input, outputRegionForThread, radius);

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

  InputImagePixelType this_one, that, abs_this_one, abs_that;
  InputImagePixelType zero{};

  FixedArray<OffsetValueType, 2 * ImageDimension> offset;

  bit = ConstNeighborhoodIterator<InputImageType>(radius, input, faceList.front());
  // Set the offset of the neighbors to the center pixel.
  for (i = 0; i < ImageDimension; ++i)
  {
    offset[i] = -1 * static_cast<OffsetValueType>(bit.GetStride(i));
    offset[i + ImageDimension] = bit.GetStride(i);
  }

  // Process each of the boundary faces.  These are N-d regions which border
  // the edge of the buffer.
  for (const auto & face : faceList)
  {
    bit = ConstNeighborhoodIterator<InputImageType>(radius, input, face);
    it = ImageRegionIterator<OutputImageType>(output, face);
    bit.OverrideBoundaryCondition(&nbc);
    bit.GoToBegin();

    static constexpr SizeValueType neighborhoodSize = Math::UnsignedPower(3, ImageDimension);
    static constexpr SizeValueType center = neighborhoodSize / 2;

    while (!bit.IsAtEnd())
    {
      this_one = bit.GetPixel(center);
      it.Set(m_BackgroundValue);
      for (i = 0; i < ImageDimension * 2; ++i)
      {
        that = bit.GetPixel(center + offset[i]);
        if (((this_one < zero) && (that > zero)) || ((this_one > zero) && (that < zero)) ||
            ((Math::ExactlyEquals(this_one, zero)) && (Math::NotExactlyEquals(that, zero))) ||
            ((Math::NotExactlyEquals(this_one, zero)) && (Math::ExactlyEquals(that, zero))))
        {
          abs_this_one = itk::Math::abs(this_one);
          abs_that = itk::Math::abs(that);
          if (abs_this_one < abs_that)
          {
            it.Set(m_ForegroundValue);
            break;
          }
          else if (Math::ExactlyEquals(abs_this_one, abs_that) && i >= ImageDimension)
          {
            it.Set(m_ForegroundValue);
            break;
          }
        }
      }
      ++bit;
      ++it;
      progress.CompletedPixel();
    }
  }
}

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

  os << indent
     << "ForegroundValue: " << static_cast<typename NumericTraits<OutputImagePixelType>::PrintType>(m_ForegroundValue)
     << std::endl;
  os << indent
     << "BackgroundValue: " << static_cast<typename NumericTraits<OutputImagePixelType>::PrintType>(m_BackgroundValue)
     << std::endl;
}
} // namespace itk

#endif
