/*=========================================================================
 *
 *  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 itkIntensityWindowingImageFilter_h
#define itkIntensityWindowingImageFilter_h

#include "itkUnaryFunctorImageFilter.h"

namespace itk
{
// This functor class applies a linear transformation A.x + B inside a specified
// range. Values below the range are mapped to a constant. Values over the range
// are mapped to another constant.
namespace Functor
{
template <typename TInput, typename TOutput>
class ITK_TEMPLATE_EXPORT IntensityWindowingTransform
{
public:
  using RealType = typename NumericTraits<TInput>::RealType;
  IntensityWindowingTransform()
    : m_Factor(0.0)
    , m_Offset(0.0)
    , m_OutputMaximum(0)
    , m_OutputMinimum(0)
    , m_WindowMaximum(0)
    , m_WindowMinimum(0)
  {}
  ~IntensityWindowingTransform() = default;

  bool
  operator==(const IntensityWindowingTransform & other) const
  {
    return Math::ExactlyEquals(m_Factor, other.m_Factor) && Math::ExactlyEquals(m_Offset, other.m_Offset) &&
           Math::ExactlyEquals(m_OutputMaximum, other.m_OutputMaximum) &&
           Math::ExactlyEquals(m_OutputMinimum, other.m_OutputMinimum) &&
           Math::ExactlyEquals(m_WindowMaximum, other.m_WindowMaximum) &&
           Math::ExactlyEquals(m_WindowMinimum, other.m_WindowMinimum);
  }

  ITK_UNEQUAL_OPERATOR_MEMBER_FUNCTION(IntensityWindowingTransform);

  void
  SetFactor(RealType a)
  {
    m_Factor = a;
  }
  void
  SetOffset(RealType b)
  {
    m_Offset = b;
  }
  void
  SetOutputMinimum(TOutput min)
  {
    m_OutputMinimum = min;
  }
  void
  SetOutputMaximum(TOutput max)
  {
    m_OutputMaximum = max;
  }
  void
  SetWindowMinimum(TInput min)
  {
    m_WindowMinimum = min;
  }
  void
  SetWindowMaximum(TInput max)
  {
    m_WindowMaximum = max;
  }
  inline TOutput
  operator()(const TInput & x) const
  {
    if (x < m_WindowMinimum)
    {
      return m_OutputMinimum;
    }
    if (x > m_WindowMaximum)
    {
      return m_OutputMaximum;
    }
    const RealType value = static_cast<RealType>(x) * m_Factor + m_Offset;
    const auto     result = static_cast<TOutput>(value);
    return result;
  }

private:
  RealType m_Factor;
  RealType m_Offset;
  TOutput  m_OutputMaximum;
  TOutput  m_OutputMinimum;
  TInput   m_WindowMaximum;
  TInput   m_WindowMinimum;
};
} // end namespace Functor

/**
 * \class IntensityWindowingImageFilter
 * \brief Applies a linear transformation to the intensity levels of the
 * input Image that are inside a user-defined interval. Values below this
 * interval are mapped to a constant. Values over the interval are mapped
 * to another constant.
 *
 * IntensityWindowingImageFilter 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 minimum and maximum values that
 * the output image should have and the lower and upper limits of the intensity
 * window of the input image. This operation is very common in visualization,
 * and can also be applied as a convenient preprocessing operation for image
 * segmentation.
 *
 * All computations are performed in the precision of the input pixel's
 * RealType. Before assigning the computed value to the output pixel.
 *
 * \ingroup IntensityImageFilters  MultiThreaded
 *
 * \ingroup ITKImageIntensity
 *
 * \sphinx
 * \sphinxexample{Filtering/ImageIntensity/IntensityWindowing,Intensity Windowing}
 * \endsphinx
 *
 * \sa RescaleIntensityImageFilter
 */
template <typename TInputImage, typename TOutputImage = TInputImage>
class ITK_TEMPLATE_EXPORT IntensityWindowingImageFilter
  : public UnaryFunctorImageFilter<
      TInputImage,
      TOutputImage,
      Functor::IntensityWindowingTransform<typename TInputImage::PixelType, typename TOutputImage::PixelType>>
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(IntensityWindowingImageFilter);

  /** Standard class type aliases. */
  using Self = IntensityWindowingImageFilter;
  using Superclass = UnaryFunctorImageFilter<
    TInputImage,
    TOutputImage,
    Functor::IntensityWindowingTransform<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 RealType = typename NumericTraits<InputPixelType>::RealType;

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

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

  /** Set/Get the values of the maximum and minimum
   *  intensities of the output image. */
  itkSetMacro(OutputMinimum, OutputPixelType);
  itkSetMacro(OutputMaximum, OutputPixelType);
  itkGetConstReferenceMacro(OutputMinimum, OutputPixelType);
  itkGetConstReferenceMacro(OutputMaximum, OutputPixelType);

  /** Set/Get the values of the maximum and minimum
   *  intensities of the input intensity window. */
  itkSetMacro(WindowMinimum, InputPixelType);
  itkSetMacro(WindowMaximum, InputPixelType);
  itkGetConstReferenceMacro(WindowMinimum, InputPixelType);
  itkGetConstReferenceMacro(WindowMaximum, InputPixelType);

  /** Set/Get the window width and level. This is an alternative API
   * to using the SetWindowMinimum()/SetWindowMaximum(). The window
   * minimum and maximum are set as [level-window/2,
   * level+window/2]. */
  void
  SetWindowLevel(const InputPixelType & window, const InputPixelType & level);

  InputPixelType
  GetWindow() const;

  InputPixelType
  GetLevel() const;

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

  /** 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<InputPixelType>));
  // End concept checking
#endif

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

private:
  RealType m_Scale{};
  RealType m_Shift{};

  InputPixelType m_WindowMinimum{};
  InputPixelType m_WindowMaximum{};

  OutputPixelType m_OutputMinimum{};
  OutputPixelType m_OutputMaximum{};
};
} // end namespace itk

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

#endif
