/*=========================================================================
 *
 *  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 itkBSplineExponentialDiffeomorphicTransform_hxx
#define itkBSplineExponentialDiffeomorphicTransform_hxx


#include "itkAddImageFilter.h"
#include "itkImageDuplicator.h"
#include "itkImportImageFilter.h"
#include "itkMultiplyImageFilter.h"

namespace itk
{

template <typename TParametersValueType, unsigned int VDimension>
BSplineExponentialDiffeomorphicTransform<TParametersValueType, VDimension>::BSplineExponentialDiffeomorphicTransform()

{
  this->m_NumberOfControlPointsForTheConstantVelocityField.Fill(4);
  this->m_NumberOfControlPointsForTheUpdateField.Fill(4);
}

template <typename TParametersValueType, unsigned int VDimension>
void
BSplineExponentialDiffeomorphicTransform<TParametersValueType, VDimension>::SetMeshSizeForTheUpdateField(
  const ArrayType & meshSize)
{
  ArrayType numberOfControlPoints;
  for (unsigned int d = 0; d < Dimension; ++d)
  {
    numberOfControlPoints[d] = meshSize[d] + this->m_SplineOrder;
  }
  this->SetNumberOfControlPointsForTheUpdateField(numberOfControlPoints);
}

template <typename TParametersValueType, unsigned int VDimension>
void
BSplineExponentialDiffeomorphicTransform<TParametersValueType, VDimension>::SetMeshSizeForTheConstantVelocityField(
  const ArrayType & meshSize)
{
  ArrayType numberOfControlPoints;
  for (unsigned int d = 0; d < Dimension; ++d)
  {
    numberOfControlPoints[d] = meshSize[d] + this->m_SplineOrder;
  }
  this->SetNumberOfControlPointsForTheConstantVelocityField(numberOfControlPoints);
}

template <typename TParametersValueType, unsigned int VDimension>
void
BSplineExponentialDiffeomorphicTransform<TParametersValueType, VDimension>::UpdateTransformParameters(
  const DerivativeType & update,
  ScalarType             factor)
{
  //
  // Smooth the update field
  //
  bool smoothUpdateField = true;
  for (unsigned int d = 0; d < Dimension; ++d)
  {
    if (this->GetNumberOfControlPointsForTheUpdateField()[d] <= this->GetSplineOrder())
    {
      itkDebugMacro("Not smooothing the update field.");
      smoothUpdateField = false;
      break;
    }
  }

  const ConstantVelocityFieldPointer velocityField = this->GetModifiableConstantVelocityField();
  if (!velocityField)
  {
    itkExceptionStringMacro("The velocity field has not been set.");
  }

  const typename ConstantVelocityFieldType::RegionType & bufferedRegion = velocityField->GetBufferedRegion();
  const SizeValueType                                    numberOfPixels = bufferedRegion.GetNumberOfPixels();

  auto * updateFieldPointer =
    reinterpret_cast<DisplacementVectorType *>(const_cast<DerivativeType &>(update).data_block());

  using ImporterType = ImportImageFilter<DisplacementVectorType, VDimension>;
  const bool importFilterWillReleaseMemory = false;

  auto importer = ImporterType::New();
  importer->SetImportPointer(updateFieldPointer, numberOfPixels, importFilterWillReleaseMemory);
  importer->SetRegion(velocityField->GetBufferedRegion());
  importer->SetOrigin(velocityField->GetOrigin());
  importer->SetSpacing(velocityField->GetSpacing());
  importer->SetDirection(velocityField->GetDirection());

  ConstantVelocityFieldPointer updateField = importer->GetOutput();
  updateField->Update();
  updateField->DisconnectPipeline();

  if (smoothUpdateField)
  {
    itkDebugMacro("Smoothing the update field.");

    const ConstantVelocityFieldPointer updateSmoothField =
      this->BSplineSmoothConstantVelocityField(updateField, this->GetNumberOfControlPointsForTheUpdateField());

    updateField = updateSmoothField;
  }

  using RealImageType = Image<ScalarType, VDimension>;

  using MultiplierType = MultiplyImageFilter<ConstantVelocityFieldType, RealImageType, ConstantVelocityFieldType>;
  auto multiplier = MultiplierType::New();
  multiplier->SetInput(updateField);
  multiplier->SetConstant(factor);
  multiplier->Update();

  using AdderType = AddImageFilter<ConstantVelocityFieldType, ConstantVelocityFieldType, ConstantVelocityFieldType>;
  auto adder = AdderType::New();
  adder->SetInput1(velocityField);
  adder->SetInput2(multiplier->GetOutput());

  const ConstantVelocityFieldPointer updatedVelocityField = adder->GetOutput();
  updatedVelocityField->Update();
  updatedVelocityField->DisconnectPipeline();

  // Smooth the velocity field
  bool smoothVelocityField = true;
  for (unsigned int d = 0; d < Dimension; ++d)
  {
    if (this->GetNumberOfControlPointsForTheConstantVelocityField()[d] <= this->GetSplineOrder())
    {
      itkDebugMacro("Not smoothing the velocity field.");
      smoothVelocityField = false;
      break;
    }
  }

  if (smoothVelocityField)
  {
    itkDebugMacro("Smoothing the velocity field.");

    const ConstantVelocityFieldPointer velocitySmoothField = this->BSplineSmoothConstantVelocityField(
      updatedVelocityField, this->GetNumberOfControlPointsForTheConstantVelocityField());

    this->SetConstantVelocityField(velocitySmoothField);
  }
  else
  {
    this->SetConstantVelocityField(updatedVelocityField);
  }

  this->IntegrateVelocityField();
}

template <typename TParametersValueType, unsigned int VDimension>
auto
BSplineExponentialDiffeomorphicTransform<TParametersValueType, VDimension>::BSplineSmoothConstantVelocityField(
  const ConstantVelocityFieldType * field,
  const ArrayType &                 numberOfControlPoints) -> ConstantVelocityFieldPointer
{
  auto bspliner = BSplineFilterType::New();
  bspliner->SetUseInputFieldToDefineTheBSplineDomain(true);
  bspliner->SetDisplacementField(field);
  bspliner->SetNumberOfControlPoints(numberOfControlPoints);
  bspliner->SetSplineOrder(this->m_SplineOrder);
  bspliner->SetNumberOfFittingLevels(1);
  bspliner->SetEnforceStationaryBoundary(true);
  bspliner->SetEstimateInverse(false);
  bspliner->Update();

  ConstantVelocityFieldPointer smoothField = bspliner->GetOutput();

  return smoothField;
}

template <typename TParametersValueType, unsigned int VDimension>
void
BSplineExponentialDiffeomorphicTransform<TParametersValueType, VDimension>::PrintSelf(std::ostream & os,
                                                                                      Indent         indent) const
{
  Superclass::PrintSelf(os, indent);

  os << indent
     << "NumberOfControlPointsForTheConstantVelocityField: " << m_NumberOfControlPointsForTheConstantVelocityField
     << std::endl;
  os << indent << "NumberOfControlPointsForTheUpdateField: " << m_NumberOfControlPointsForTheUpdateField << std::endl;
  os << indent << "SplineOrder: " << static_cast<NumericTraits<SplineOrderType>::PrintType>(m_SplineOrder) << std::endl;
}

} // namespace itk

#endif
