/*=========================================================================
 *
 *  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 itkDemonsImageToImageMetricv4_hxx
#define itkDemonsImageToImageMetricv4_hxx


namespace itk
{

template <typename TFixedImage,
          typename TMovingImage,
          typename TVirtualImage,
          typename TInternalComputationValueType,
          typename TMetricTraits>
DemonsImageToImageMetricv4<TFixedImage, TMovingImage, TVirtualImage, TInternalComputationValueType, TMetricTraits>::
  DemonsImageToImageMetricv4()
{
  // We have our own GetValueAndDerivativeThreader's that we want
  // ImageToImageMetricv4 to use.
  this->m_DenseGetValueAndDerivativeThreader = DemonsDenseGetValueAndDerivativeThreaderType::New();
  this->m_SparseGetValueAndDerivativeThreader = DemonsSparseGetValueAndDerivativeThreaderType::New();

  // Unlike most other metrics, this defaults to using fixed image gradients
  this->SetGradientSource(ObjectToObjectMetricBaseTemplateEnums::GradientSource::GRADIENT_SOURCE_FIXED);

  this->m_Normalizer = NumericTraits<TInternalComputationValueType>::OneValue();
  this->m_DenominatorThreshold = static_cast<TInternalComputationValueType>(1e-9);
  this->m_IntensityDifferenceThreshold = static_cast<TInternalComputationValueType>(0.001);
}

template <typename TFixedImage,
          typename TMovingImage,
          typename TVirtualImage,
          typename TInternalComputationValueType,
          typename TMetricTraits>
void
DemonsImageToImageMetricv4<TFixedImage, TMovingImage, TVirtualImage, TInternalComputationValueType, TMetricTraits>::
  Initialize()
{
  // Make sure user has not set to use both moving and fixed image
  // gradients
  if (this->GetGradientSource() == ObjectToObjectMetricBaseTemplateEnums::GradientSource::GRADIENT_SOURCE_BOTH)
  {
    itkExceptionMacro("GradientSource has been set to GRADIENT_SOURCE_BOTH. "
                      "You must choose either GRADIENT_SOURCE_MOVING or "
                      "GRADIENT_SOURCE_FIXED.");
  }

  // Verify that the transform has local support, and its number of local
  // parameters equals the dimensionality of the image gradient source.
  if (this->m_MovingTransform->GetTransformCategory() != MovingTransformType::TransformCategoryEnum::DisplacementField)
  {
    itkExceptionMacro("The moving transform must be a displacement field transform");
  }

  // compute the normalizer
  ImageDimensionType                dimension;
  typename TFixedImage::SpacingType imageSpacing;
  if (this->GetGradientSource() == ObjectToObjectMetricBaseTemplateEnums::GradientSource::GRADIENT_SOURCE_FIXED)
  {
    imageSpacing = this->m_FixedImage->GetSpacing();
    dimension = FixedImageDimension;
  }
  else
  {
    imageSpacing = this->m_MovingImage->GetSpacing();
    dimension = MovingImageDimension;
  }

  this->m_Normalizer = TInternalComputationValueType{};
  for (ImageDimensionType k = 0; k < dimension; ++k)
  {
    this->m_Normalizer += imageSpacing[k] * imageSpacing[k];
  }
  this->m_Normalizer /= static_cast<TInternalComputationValueType>(dimension);

  Superclass::Initialize();
}

template <typename TFixedImage,
          typename TMovingImage,
          typename TVirtualImage,
          typename TInternalComputationValueType,
          typename TMetricTraits>
void
DemonsImageToImageMetricv4<TFixedImage, TMovingImage, TVirtualImage, TInternalComputationValueType, TMetricTraits>::
  PrintSelf(std::ostream & os, Indent indent) const
{
  Superclass::PrintSelf(os, indent);
  os << indent << "IntensityDifferenceThreshold: " << this->GetIntensityDifferenceThreshold() << std::endl
     << indent << "DenominatorThreshold: " << this->GetDenominatorThreshold() << std::endl
     << indent << "Normalizer: " << this->GetNormalizer() << std::endl;
}

} // end namespace itk


#endif
