/*=========================================================================
 *
 *  Copyright UMC Utrecht and contributors
 *
 *  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.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 itkMultiResolutionShrinkPyramidImageFilter_hxx
#define itkMultiResolutionShrinkPyramidImageFilter_hxx

#include "itkMultiResolutionShrinkPyramidImageFilter.h"

#include "itkShrinkImageFilter.h"
#include <vnl/vnl_math.h>

namespace itk
{

/*
 * GenerateData
 */
template <typename TInputImage, typename TOutputImage>
void
MultiResolutionShrinkPyramidImageFilter<TInputImage, TOutputImage>::GenerateData()
{
  /** Create the shrinking filter. */
  using ShrinkerType = ShrinkImageFilter<TInputImage, TOutputImage>;
  auto shrinker = ShrinkerType::New();
  shrinker->SetInput(this->GetInput());

  /** Loop over all resolution levels. */
  unsigned int factors[ImageDimension];
  for (unsigned int ilevel = 0; ilevel < this->m_NumberOfLevels; ++ilevel)
  {
    this->UpdateProgress(static_cast<float>(ilevel) / static_cast<float>(this->m_NumberOfLevels));

    // Allocate memory for each output
    OutputImagePointer outputPtr = this->GetOutput(ilevel);
    outputPtr->SetBufferedRegion(outputPtr->GetRequestedRegion());
    outputPtr->Allocate();

    // compute and set shrink factors
    for (unsigned int idim = 0; idim < ImageDimension; ++idim)
    {
      factors[idim] = this->m_Schedule[ilevel][idim];
    }
    shrinker->SetShrinkFactors(factors);
    shrinker->GraftOutput(outputPtr);

    // force to always update in case shrink factors are the same
    shrinker->Modified();
    shrinker->UpdateLargestPossibleRegion();
    this->GraftNthOutput(ilevel, shrinker->GetOutput());
  }
} // end GenerateData()


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


} // namespace itk

#endif
