/*=========================================================================
 *
 *  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 itkNeighborhoodOperator_hxx
#define itkNeighborhoodOperator_hxx

#include "itkIntTypes.h"

namespace itk
{
template <typename TPixel, unsigned int VDimension, typename TAllocator>
void
NeighborhoodOperator<TPixel, VDimension, TAllocator>::ScaleCoefficients(PixelRealType s)
{
  for (unsigned int i = 0; i < this->Size(); ++i)
  {
    this->operator[](i) = static_cast<TPixel>(this->operator[](i) * s);
  }
}

template <typename TPixel, unsigned int VDimension, typename TAllocator>
void
NeighborhoodOperator<TPixel, VDimension, TAllocator>::FlipAxes()
{
  // To flip the operator across all of its axes, all we have to do is reverse
  // the order of all coefficients.
  const unsigned int size = this->Size();

  for (unsigned int i = 0; i < size / 2; ++i)
  {
    const unsigned int swap_with = size - 1 - i;
    const PixelType    temp{ this->operator[](i) };

    this->operator[](i) = this->operator[](swap_with);

    this->operator[](swap_with) = temp;
  }
}

template <typename TPixel, unsigned int VDimension, typename TAllocator>
void
NeighborhoodOperator<TPixel, VDimension, TAllocator>::CreateDirectional()
{
  SizeValueType           k[VDimension];
  const CoefficientVector coefficients{ this->GenerateCoefficients() };
  for (unsigned int i = 0; i < VDimension; ++i)
  {
    if (i == this->GetDirection())
    {
      k[i] = static_cast<SizeValueType>(coefficients.size()) >> 1;
    }
    else
    {
      k[i] = 0;
    }
  }
  this->SetRadius(k);
  this->Fill(coefficients);
}

template <typename TPixel, unsigned int VDimension, typename TAllocator>
void
NeighborhoodOperator<TPixel, VDimension, TAllocator>::CreateToRadius(const SizeType & sz)
{
  const CoefficientVector coefficients{ this->GenerateCoefficients() };
  this->SetRadius(sz);
  this->Fill(coefficients);
}

template <typename TPixel, unsigned int VDimension, typename TAllocator>
void
NeighborhoodOperator<TPixel, VDimension, TAllocator>::CreateToRadius(const SizeValueType sz)
{
  SizeType k;

  for (unsigned int i = 0; i < VDimension; ++i)
  {
    k[i] = sz;
  }
  this->CreateToRadius(k);
}

template <typename TPixel, unsigned int VDimension, typename TAllocator>
void
NeighborhoodOperator<TPixel, VDimension, TAllocator>::FillCenteredDirectional(const CoefficientVector & coeff)
{
  // Initialize all coefficients to zero
  this->InitializeToZero();

  // Collect slice information
  unsigned long       start = 0;
  const unsigned long stride = this->GetStride(m_Direction);
  const unsigned long size = this->GetSize(m_Direction);
  for (unsigned int i = 0; i < VDimension; ++i)
  {
    if (i != m_Direction)
    {
      start += this->GetStride(i) * (this->GetSize(i) >> 1);
    }
  }

  // Compare the neighborhood size with the coefficient array size..
  const int sizediff = (static_cast<int>(size) - static_cast<int>(coeff.size())) >> 1;

  // Create a slice iterator centered in the neighborhood.
  std::slice                                 temp_slice;
  typename CoefficientVector::const_iterator it;
  if (sizediff >= 0)
  {
    temp_slice = std::slice(start + sizediff * stride, coeff.size(), stride);
    it = coeff.begin();
  }
  else
  {
    temp_slice = std::slice(start, size, stride);
    it = coeff.begin() - sizediff;
  }


  SliceIteratorType data(this, temp_slice);

  // Copy the coefficients into the neighborhood, truncating them if there
  // are too many.
  for (data = data.Begin(); data < data.End(); ++data, ++it)
  {
    *data = static_cast<TPixel>(*it);
  }
}
} // namespace itk

#endif