/*
 * 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 otbImageRegionTileMapSplitter_hxx
#define otbImageRegionTileMapSplitter_hxx

#include "otbImageRegionTileMapSplitter.h"
#include "otbMath.h"
#include "otbMacro.h"

namespace otb
{

/**
   *
 */
template <unsigned int VImageDimension>
unsigned int ImageRegionTileMapSplitter<VImageDimension>::GetNumberOfSplits(const RegionType& region, unsigned int requestedNumber)
{
  const SizeType&  regionSize  = region.GetSize();
  const IndexType& regionIndex = region.GetIndex();

  // requested number of splits per dimension
  unsigned int numPieces = 1;

  // determine the actual number of pieces that will be generated
  for (unsigned int j = VImageDimension; j > 0; --j)
  {
    //    otbMsgDevMacro(<< "*** Dimension: " << j-1);
    unsigned long int remainingToDo = static_cast<unsigned long int>(std::ceil(static_cast<double>(requestedNumber) / numPieces));
    unsigned int      maxPieces     = (regionIndex[j - 1] + regionSize[j - 1] - 1) / m_AlignStep - regionIndex[j - 1] / m_AlignStep + 1;
    unsigned int      stepPerPiece  = 1;
    if (remainingToDo < maxPieces)
    {
      stepPerPiece = static_cast<unsigned int>(std::floor(static_cast<double>(maxPieces) / remainingToDo));
      if ((remainingToDo - 1) * (stepPerPiece + 1) < maxPieces)
      {
        stepPerPiece += 1;
      }
    }
    unsigned int maxPieceUsed   = static_cast<unsigned int>(std::ceil(static_cast<double>(maxPieces) / stepPerPiece));
    m_SplitsPerDimension[j - 1] = maxPieceUsed;
    //    otbMsgDevMacro("*** maxPieces stepPerPiece maxPieceUsed " << maxPieces
    //                      << " " << stepPerPiece << " " << maxPieceUsed);
    numPieces *= maxPieceUsed;
  }
  //  otbMsgDevMacro("*** numPieces " << numPieces);
  return numPieces;
}

/**
   *
 */
template <unsigned int            VImageDimension>
itk::ImageRegion<VImageDimension> ImageRegionTileMapSplitter<VImageDimension>::GetSplit(unsigned int i, unsigned int numberOfPieces, const RegionType& region)
{
  RegionType splitRegion;
  IndexType  splitIndex, regionIndex;
  SizeType   splitSize, regionSize;

  // Initialize the splitRegion to the requested region
  splitRegion = region;
  splitIndex  = splitRegion.GetIndex();
  splitSize   = splitRegion.GetSize();

  regionSize  = region.GetSize();
  regionIndex = region.GetIndex();

  unsigned int numPieces = GetNumberOfSplits(region, numberOfPieces);
  if (i > numPieces)
  {
    itkDebugMacro("  Cannot Split");
    return splitRegion;
  }

  unsigned int stackSize = 1;
  for (unsigned int j = 0; j < VImageDimension; ++j)
  {
    unsigned int slicePos = (i % (stackSize * m_SplitsPerDimension[j])) / stackSize;
    stackSize *= m_SplitsPerDimension[j];

    unsigned int generalSplitSize =
        static_cast<unsigned int>(std::ceil(static_cast<double>(regionSize[j]) / (m_SplitsPerDimension[j] * m_AlignStep))) * m_AlignStep;
    if (slicePos == 0)
    {
      splitIndex[j] = regionIndex[j];
    }
    else
    {
      splitIndex[j] = (regionIndex[j] / generalSplitSize + slicePos) * generalSplitSize;
    }
    if (slicePos == 0)
    {
      splitSize[j] = generalSplitSize - (regionIndex[j] % generalSplitSize);
    }
    else if (slicePos == m_SplitsPerDimension[j] - 1)
    {
      splitSize[j] = regionSize[j] - (generalSplitSize - (regionIndex[j] % generalSplitSize)) - (m_SplitsPerDimension[j] - 2) * generalSplitSize;
    }
    else
    {
      splitSize[j] = generalSplitSize;
    }
  }

  // set the split region ivars
  splitRegion.SetIndex(splitIndex);
  splitRegion.SetSize(splitSize);

  return splitRegion;
}

/**
       *
 */
template <unsigned int VImageDimension>
void ImageRegionTileMapSplitter<VImageDimension>::PrintSelf(std::ostream& os, itk::Indent indent) const
{
  Superclass::PrintSelf(os, indent);
}

} // end namespace itk

#endif
