/*=========================================================================
 *
 *  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 itkCurvatureAnisotropicDiffusionImageFilter_h
#define itkCurvatureAnisotropicDiffusionImageFilter_h

#include "itkAnisotropicDiffusionImageFilter.h"
#include "itkCurvatureNDAnisotropicDiffusionFunction.h"
#include "itkMacro.h"
namespace itk
{
/**
 * \class CurvatureAnisotropicDiffusionImageFilter
 * \brief This filter performs anisotropic diffusion on a scalar
 * itk::Image using the modified curvature diffusion equation (MCDE).
 *
 * For detailed information on anisotropic diffusion and the MCDE see
 * itkAnisotropicDiffusionFunction and
 * itkCurvatureNDAnisotropicDiffusionFunction.
 *
 * \par Inputs and Outputs
 * The input and output to this filter must be a scalar itk::Image with
 * numerical pixel types (float or double).  A user defined type which
 * correctly defines arithmetic operations with floating point accuracy should
 * also give correct results.
 *
 * \par Parameters
 * Please first read all the documentation found in
 * AnisotropicDiffusionImageFilter and AnisotropicDiffusionFunction.  Also see
 * CurvatureNDAnisotropicDiffusionFunction.
 *
 * The default time step for this filter is set to the maximum theoretically
 * stable value: 0.5 / 2^N, where N is the dimensionality of the image.  For a
 * 2D image, this means valid time steps are below 0.1250.  For a 3D image,
 * valid time steps are below 0.0625.
 *
 * \sa AnisotropicDiffusionImageFilter
 * \sa AnisotropicDiffusionFunction
 * \sa CurvatureNDAnisotropicDiffusionFunction
 * \ingroup ImageEnhancement
 * \ingroup ITKAnisotropicSmoothing
 */
template <typename TInputImage, typename TOutputImage>
class ITK_TEMPLATE_EXPORT CurvatureAnisotropicDiffusionImageFilter
  : public AnisotropicDiffusionImageFilter<TInputImage, TOutputImage>
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(CurvatureAnisotropicDiffusionImageFilter);

  /** Standard class type aliases. */
  using Self = CurvatureAnisotropicDiffusionImageFilter;
  using Superclass = AnisotropicDiffusionImageFilter<TInputImage, TOutputImage>;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  /** Standard method for creation through object factory. */
  itkNewMacro(Self);

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

  /** Extract superclass information. */
  using typename Superclass::UpdateBufferType;

  /** Extract superclass image dimension. */
  static constexpr unsigned int ImageDimension = Superclass::ImageDimension;

  itkConceptMacro(OutputHasNumericTraitsCheck, (Concept::HasNumericTraits<typename TOutputImage::PixelType>));

protected:
  CurvatureAnisotropicDiffusionImageFilter()
  {
    auto q = CurvatureNDAnisotropicDiffusionFunction<UpdateBufferType>::New();
    this->SetDifferenceFunction(q);
  }

  ~CurvatureAnisotropicDiffusionImageFilter() override = default;

  void
  InitializeIteration() override
  {
    Superclass::InitializeIteration();
    if (this->GetTimeStep() > 0.5 / double{ 1ULL << ImageDimension })
    {
      itkWarningMacro(
        << "Anisotropic diffusion is using a time step which may introduce instability into the solution.");
    }
  }
};
} // namespace itk

#endif
