/*
 * Copyright (C) 2005-2020 Centre National d'Etudes Spatiales (CNES)
 *
 * This file is part of Orfeo Toolbox
 *
 *     https://www.orfeo-toolbox.org/
 *
 * 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
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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 otbRealMomentsImageFunction_hxx
#define otbRealMomentsImageFunction_hxx

#include "otbRealMomentsImageFunction.h"
#include "itkConstNeighborhoodIterator.h"
#include "itkNumericTraits.h"

namespace otb
{

/**
   * Constructor
   */
template <class TInputImage, class TCoordRep>
RealMomentsImageFunction<TInputImage, TCoordRep>::RealMomentsImageFunction()
{
  m_NeighborhoodRadius = 1;
  m_Pmax               = 4;
  m_Qmax               = 4;
}

template <class TInputImage, class TCoordRep>
void RealMomentsImageFunction<TInputImage, TCoordRep>::PrintSelf(std::ostream& os, itk::Indent indent) const
{
  this->Superclass::PrintSelf(os, indent);
  os << indent << " p indice maximum value      : " << m_Pmax << std::endl;
  os << indent << " q indice maximum value      : " << m_Qmax << std::endl;
  os << indent << " Neighborhood radius value   : " << m_NeighborhoodRadius << std::endl;
}

template <class TInputImage, class TCoordRep>
typename RealMomentsImageFunction<TInputImage, TCoordRep>::OutputType
RealMomentsImageFunction<TInputImage, TCoordRep>::EvaluateAtIndex(const IndexType& index) const
{
  // Build moments vector
  OutputType moments;
  moments.resize(m_Pmax + 1);

  std::vector<ScalarRealType> valXpY, valXqY;
  valXpY.resize(m_Pmax + 1);
  valXqY.resize(m_Qmax + 1);

  // Initialize moments
  for (unsigned int p = 0; p <= m_Pmax; p++)
  {
    moments.at(p).resize(m_Qmax + 1);
    valXpY.at(p) = 1.0;
    for (unsigned int q = 0; q <= m_Qmax; q++)
    {
      moments.at(p).at(q) = 0.0;
      valXqY.at(q)        = 1.0;
    }
  }

  // Check for input image
  if (!this->GetInputImage())
  {
    return moments;
  }

  // Check for out of buffer
  if (!this->IsInsideBuffer(index))
  {
    return moments;
  }

  // Create an N-d neighborhood kernel, using a zeroflux boundary condition
  typename InputImageType::SizeType kernelSize;
  kernelSize.Fill(m_NeighborhoodRadius);

  itk::ConstNeighborhoodIterator<InputImageType> it(kernelSize, this->GetInputImage(), this->GetInputImage()->GetBufferedRegion());

  // Set the iterator at the desired location
  it.SetLocation(index);

  // Walk the neighborhood
  const unsigned int size = it.Size();
  for (unsigned int i = 0; i < size; ++i)
  {
    // Retrieve value, and centered-reduced position
    ScalarRealType value = static_cast<ScalarRealType>(it.GetPixel(i));
    ScalarRealType x     = static_cast<ScalarRealType>(it.GetOffset(i)[0]) / (2 * m_NeighborhoodRadius + 1);
    ScalarRealType y     = static_cast<ScalarRealType>(it.GetOffset(i)[1]) / (2 * m_NeighborhoodRadius + 1);

    unsigned int pTmp = 1;
    unsigned int qTmp = 1;

    while (pTmp <= m_Pmax)
    {
      valXpY.at(pTmp) = valXpY.at(pTmp - 1) * x;
      pTmp++;
    }
    while (qTmp <= m_Qmax)
    {
      valXqY.at(qTmp) = valXqY.at(qTmp - 1) * y;
      qTmp++;
    }


    // Update cumulants
    for (unsigned int p = 0; p <= m_Pmax; p++)
    {
      for (unsigned int q = 0; q <= m_Qmax; q++)
      {
        moments.at(p).at(q) += valXpY.at(p) * valXqY.at(q) * value;
      }
    }
  }

  // Normalisation
  for (int p = m_Pmax; p >= 0; p--)
  {
    for (int q = m_Qmax; q >= 0; q--)
    {
      moments.at(p).at(q) /= moments.at(0).at(0);
    }
  }

  // Return result
  return moments;
}

} // namespace otb

#endif
