/*=========================================================================
 *
 *  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 itkVectorIndexSelectionCastImageFilter_h
#define itkVectorIndexSelectionCastImageFilter_h

#include "itkUnaryFunctorImageFilter.h"

namespace itk
{
namespace Functor
{
template <typename TInput, typename TOutput>
class VectorIndexSelectionCast
{
public:
  VectorIndexSelectionCast() { m_Index = 0; }
  ~VectorIndexSelectionCast() = default;

  unsigned int
  GetIndex() const
  {
    return m_Index;
  }
  void
  SetIndex(unsigned int i)
  {
    m_Index = i;
  }

  bool
  operator==(const VectorIndexSelectionCast & other) const
  {
    return m_Index == other.m_Index;
  }

  ITK_UNEQUAL_OPERATOR_MEMBER_FUNCTION(VectorIndexSelectionCast);

  inline TOutput
  operator()(const TInput & A) const
  {
    return static_cast<TOutput>(A[m_Index]);
  }

private:
  unsigned int m_Index;
};
} // namespace Functor

/** \class VectorIndexSelectionCastImageFilter
 *
 * \brief Extracts the selected index of the vector that is the input
 * pixel type
 *
 * This filter is templated over the input image type and
 * output image type.
 *
 * The filter expect the input image pixel type to be a vector and
 * the output image pixel type to be a scalar. The only requirement on
 * the type used for representing the vector is that it must provide an
 * operator[].
 *
 * \ingroup IntensityImageFilters  MultiThreaded
 * \ingroup ITKImageIntensity
 *
 * \sa ComposeImageFilter
 *
 * \sphinx
 * \sphinxexample{Filtering/ImageIntensity/ExtractComponentOfVectorImage,Extract Component Of Vector Image}
 * \endsphinx
 */

template <typename TInputImage, typename TOutputImage>
class VectorIndexSelectionCastImageFilter
  : public UnaryFunctorImageFilter<
      TInputImage,
      TOutputImage,
      Functor::VectorIndexSelectionCast<typename TInputImage::PixelType, typename TOutputImage::PixelType>>
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(VectorIndexSelectionCastImageFilter);

  /** Standard class type aliases. */
  using Self = VectorIndexSelectionCastImageFilter;
  using Superclass = UnaryFunctorImageFilter<
    TInputImage,
    TOutputImage,
    Functor::VectorIndexSelectionCast<typename TInputImage::PixelType, typename TOutputImage::PixelType>>;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

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

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

  /** Get/Set methods for the index */
  void
  SetIndex(unsigned int i)
  {
    if (i != this->GetFunctor().GetIndex())
    {
      this->GetFunctor().SetIndex(i);
      this->Modified();
    }
  }

  unsigned int
  GetIndex() const
  {
    return this->GetFunctor().GetIndex();
  }

#ifdef ITK_USE_CONCEPT_CHECKING
  // Begin concept checking
  itkConceptMacro(InputHasNumericTraitsCheck, (Concept::HasNumericTraits<typename TInputImage::PixelType::ValueType>));
  // End concept checking
#endif

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

  void
  BeforeThreadedGenerateData() override
  {
    const unsigned int  index = this->GetIndex();
    const TInputImage * image = this->GetInput();

    const unsigned int numberOfRunTimeComponents = image->GetNumberOfComponentsPerPixel();

    using PixelType = typename TInputImage::PixelType;

    using PixelRealType = typename NumericTraits<PixelType>::RealType;

    using PixelScalarRealType = typename NumericTraits<PixelType>::ScalarRealType;

    const unsigned int numberOfCompileTimeComponents = sizeof(PixelRealType) / sizeof(PixelScalarRealType);

    unsigned int numberOfComponents = numberOfRunTimeComponents;

    if (numberOfCompileTimeComponents > numberOfRunTimeComponents)
    {
      numberOfComponents = numberOfCompileTimeComponents;
    }

    if (index >= numberOfComponents)
    {
      itkExceptionMacro("Selected index = " << index
                                            << " is greater than the number of components = " << numberOfComponents);
    }
  }
};
} // end namespace itk

#endif
