/*=========================================================================
 *
 *  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 itkCorrelationImageToImageMetricv4_hxx
#define itkCorrelationImageToImageMetricv4_hxx


namespace itk
{

template <typename TFixedImage,
          typename TMovingImage,
          typename TVirtualImage,
          typename TInternalComputationValueType,
          typename TMetricTraits>
CorrelationImageToImageMetricv4<TFixedImage,
                                TMovingImage,
                                TVirtualImage,
                                TInternalComputationValueType,
                                TMetricTraits>::CorrelationImageToImageMetricv4()
  : m_HelperDenseThreader(CorrelationHelperDenseThreaderType::New())
  , m_HelperSparseThreader(CorrelationHelperSparseThreaderType::New())
  , m_AverageFix(0.0)
  , m_AverageMov(0.0)
{
  this->m_DenseGetValueAndDerivativeThreader = CorrelationDenseGetValueAndDerivativeThreaderType::New();
  this->m_SparseGetValueAndDerivativeThreader = CorrelationSparseGetValueAndDerivativeThreaderType::New();

  if (this->m_MovingTransform->GetTransformCategory() == MovingTransformType::TransformCategoryEnum::DisplacementField)
  {
    itkExceptionStringMacro("does not support displacement field transforms!!");
  }
}

template <typename TFixedImage,
          typename TMovingImage,
          typename TVirtualImage,
          typename TInternalComputationValueType,
          typename TMetricTraits>
void
CorrelationImageToImageMetricv4<TFixedImage,
                                TMovingImage,
                                TVirtualImage,
                                TInternalComputationValueType,
                                TMetricTraits>::PrintSelf(std::ostream & os, Indent indent) const
{
  Superclass::PrintSelf(os, indent);
}


template <typename TFixedImage,
          typename TMovingImage,
          typename TVirtualImage,
          typename TInternalComputationValueType,
          typename TMetricTraits>
void
CorrelationImageToImageMetricv4<TFixedImage,
                                TMovingImage,
                                TVirtualImage,
                                TInternalComputationValueType,
                                TMetricTraits>::InitializeForIteration() const
{

  Superclass::InitializeForIteration();

  this->m_AverageFix = MeasureType{};
  this->m_AverageMov = MeasureType{};

  // compute the average intensity of the sampled pixels
  // Invoke the pipeline in the helper threader
  // refer to DomainThreader::Execute()

  if (this->m_UseSampledPointSet) // sparse sampling
  {
    const SizeValueType numberOfPoints = this->GetNumberOfDomainPoints();
    if (numberOfPoints < 1)
    {
      itkExceptionStringMacro("FixedSampledPointSet must have 1 or more points.");
    }
    typename ImageToImageMetricv4GetValueAndDerivativeThreader<ThreadedIndexedContainerPartitioner, Self>::DomainType
      range;
    range[0] = 0;
    range[1] = numberOfPoints - 1;
    this->m_HelperSparseThreader->Execute(const_cast<Self *>(this), range);
  }
  else // dense sampling
  {
    this->m_HelperDenseThreader->Execute(const_cast<Self *>(this), this->GetVirtualRegion());
  }

  /*
   * the results:
   *  this->m_AverageFix
   *  this->m_AverageMov
   * will be stored during helper::AfterThreadedExecution()
   */
}

} // end namespace itk


#endif
