/*=========================================================================
 *
 *  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 itkVectorRescaleIntensityImageFilter_h
#define itkVectorRescaleIntensityImageFilter_h

#include "itkMath.h"
#include "itkUnaryFunctorImageFilter.h"

namespace itk
{
// This functor class applies a scaling transformation A.x
// to input values.
namespace Functor
{
template <typename TInput, typename TOutput>
class ITK_TEMPLATE_EXPORT VectorMagnitudeLinearTransform
{
public:
  using RealType = typename NumericTraits<typename TInput::ValueType>::RealType;
  VectorMagnitudeLinearTransform()
    : m_Factor(0.0)
  {}
  ~VectorMagnitudeLinearTransform() = default;
  void
  SetFactor(RealType a)
  {
    m_Factor = a;
  }
  static constexpr unsigned int VectorDimension = TInput::Dimension;

  bool
  operator==(const VectorMagnitudeLinearTransform & other) const
  {
    return Math::ExactlyEquals(m_Factor, other.m_Factor);
  }

  ITK_UNEQUAL_OPERATOR_MEMBER_FUNCTION(VectorMagnitudeLinearTransform);

  inline TOutput
  operator()(const TInput & x) const
  {
    TOutput result;

    for (unsigned int i = 0; i < VectorDimension; ++i)
    {
      const RealType scaledComponent = static_cast<RealType>(x[i]) * m_Factor;
      result[i] = static_cast<typename TOutput::ValueType>(scaledComponent);
    }
    return result;
  }

private:
  RealType m_Factor;
};
} // end namespace Functor

/**
 * \class VectorRescaleIntensityImageFilter
 * \brief Applies a linear transformation to the magnitude of pixel vectors in a
 * vector Image.
 *
 * VectorRescaleIntensityImageFilter applies pixel-wise a linear transformation
 * to the intensity values of input image pixels. The linear transformation is
 * defined by the user in terms of the maximum magnitude value of the vectors
 * in the pixels that the output image should have.
 *
 * All computations are performed in the precision of the input pixel's
 * RealType. Before assigning the computed value to the output pixel.
 *
 * \sa RescaleIntensityImageFilter
 *
 * \ingroup IntensityImageFilters  MultiThreaded
 *
 * \ingroup ITKImageIntensity
 *
 * \sphinx
 * \sphinxexample{Filtering/ImageIntensity/TransformVectorValuedImagePixels,Transform Magnitude Of Vector Valued Image
 * Pixels} \endsphinx
 */
template <typename TInputImage, typename TOutputImage = TInputImage>
class ITK_TEMPLATE_EXPORT VectorRescaleIntensityImageFilter
  : public UnaryFunctorImageFilter<
      TInputImage,
      TOutputImage,
      Functor::VectorMagnitudeLinearTransform<typename TInputImage::PixelType, typename TOutputImage::PixelType>>
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(VectorRescaleIntensityImageFilter);

  /** Standard class type aliases. */
  using Self = VectorRescaleIntensityImageFilter;
  using Superclass = UnaryFunctorImageFilter<
    TInputImage,
    TOutputImage,
    Functor::VectorMagnitudeLinearTransform<typename TInputImage::PixelType, typename TOutputImage::PixelType>>;

  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  using OutputPixelType = typename TOutputImage::PixelType;
  using InputPixelType = typename TInputImage::PixelType;
  using InputValueType = typename InputPixelType::ValueType;
  using OutputValueType = typename OutputPixelType::ValueType;
  using InputRealType = typename NumericTraits<InputValueType>::RealType;
  using OutputRealType = typename NumericTraits<OutputValueType>::RealType;

  using typename Superclass::InputImageType;
  using typename Superclass::InputImagePointer;

  /** \see LightObject::GetNameOfClass() */
  itkOverrideGetNameOfClassMacro(VectorRescaleIntensityImageFilter);

  /** Method for creation through the object factory. */
  itkNewMacro(Self);

  itkSetMacro(OutputMaximumMagnitude, OutputRealType);
  itkGetConstReferenceMacro(OutputMaximumMagnitude, OutputRealType);

  /** Get the Scale and Shift used for the linear transformation
      of magnitude values.
   \warning These values are only valid after the filter has been updated. */
  itkGetConstReferenceMacro(Scale, InputRealType);
  itkGetConstReferenceMacro(Shift, InputRealType);

  /** Get the Maximum value of the input image magnitudes.
   \warning These values are only valid after the filter has been updated. */
  itkGetConstReferenceMacro(InputMaximumMagnitude, InputRealType);

  /** Process to execute before entering the multithreaded section. */
  void
  BeforeThreadedGenerateData() override;

  void
  PrintSelf(std::ostream & os, Indent indent) const override;

#ifdef ITK_USE_CONCEPT_CHECKING
  // Begin concept checking
  itkConceptMacro(InputHasNumericTraitsCheck, (Concept::HasNumericTraits<InputValueType>));
  itkConceptMacro(OutputHasNumericTraitsCheck, (Concept::HasNumericTraits<OutputValueType>));
  // End concept checking
#endif

protected:
  VectorRescaleIntensityImageFilter();
  ~VectorRescaleIntensityImageFilter() override = default;

private:
  InputRealType m_Scale{};
  InputRealType m_Shift{};

  InputRealType  m_InputMaximumMagnitude{};
  OutputRealType m_OutputMaximumMagnitude{};
};
} // end namespace itk

#ifndef ITK_MANUAL_INSTANTIATION
#  include "itkVectorRescaleIntensityImageFilter.hxx"
#endif

#endif
