/*=========================================================================
 *
 *  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 itkScalarRegionBasedLevelSetFunction_h
#define itkScalarRegionBasedLevelSetFunction_h

#include "itkRegionBasedLevelSetFunction.h"
#include "itkNeighborhoodIterator.h"
#include "itkImageRegionConstIterator.h"
#include "itkImageRegionIteratorWithIndex.h"

namespace itk
{
/** \class ScalarRegionBasedLevelSetFunction
 *
 * \brief LevelSet function that computes a speed image based on regional integrals
 *
 * This class implements a level set function that computes the speed image by
 * integrating values on the image domain. NOTE: The convention followed is
 * inside of the level-set function is negative and outside is positive.
 *
 * Based on the paper:
 *
 *        "An active contour model without edges"
 *         T. Chan and L. Vese.
 *         In Scale-Space Theories in Computer Vision, pages 141-151, 1999.
 *
 * \author Mosaliganti K., Smith B., Gelas A., Gouaillard A., Megason S.
 *
 *  This code was taken from the Insight Journal paper:
 *
 *      "Cell Tracking using Coupled Active Surfaces for Nuclei and Membranes"
 *      https://www.insight-journal.org/browse/publication/642
 *
 *  That is based on the papers:
 *
 *      "Level Set Segmentation: Active Contours without edge"
 *      https://www.insight-journal.org/browse/publication/322
 *
 *      and
 *
 *      "Level set segmentation using coupled active surfaces"
 *      https://www.insight-journal.org/browse/publication/323
 *
 *
 * \ingroup ITKReview
 */
template <typename TInputImage, typename TFeatureImage, typename TSharedData>
class ITK_TEMPLATE_EXPORT ScalarRegionBasedLevelSetFunction
  : public RegionBasedLevelSetFunction<TInputImage, TFeatureImage, TSharedData>
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(ScalarRegionBasedLevelSetFunction);

  using Self = ScalarRegionBasedLevelSetFunction;
  using Superclass = RegionBasedLevelSetFunction<TInputImage, TFeatureImage, TSharedData>;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  // itkNewMacro() is not provided since this is an abstract class.

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

  static constexpr unsigned int ImageDimension = TFeatureImage::ImageDimension;

  using typename Superclass::InputImageType;
  using typename Superclass::InputImageConstPointer;
  using typename Superclass::InputImagePointer;
  using typename Superclass::InputPixelType;
  using typename Superclass::InputIndexType;
  using typename Superclass::InputIndexValueType;
  using typename Superclass::InputSizeType;
  using typename Superclass::InputSizeValueType;
  using typename Superclass::InputRegionType;
  using typename Superclass::InputPointType;

  using typename Superclass::FeatureImageType;
  using FeatureImageConstPointer = typename FeatureImageType::ConstPointer;
  using typename Superclass::FeaturePixelType;
  using typename Superclass::FeatureIndexType;
  using typename Superclass::FeatureOffsetType;

  using typename Superclass::ScalarValueType;
  using typename Superclass::NeighborhoodType;
  using typename Superclass::FloatOffsetType;
  using typename Superclass::RadiusType;
  using typename Superclass::TimeStepType;
  using typename Superclass::GlobalDataStruct;
  using typename Superclass::PixelType;
  using typename Superclass::VectorType;

  using typename Superclass::SharedDataType;
  using typename Superclass::SharedDataPointer;

  using ImageIteratorType = ImageRegionIteratorWithIndex<InputImageType>;
  using ConstImageIteratorType = ImageRegionConstIteratorWithIndex<InputImageType>;
  using FeatureImageIteratorType = ImageRegionIteratorWithIndex<FeatureImageType>;
  using ConstFeatureIteratorType = ImageRegionConstIterator<FeatureImageType>;

  using ListPixelType = std::list<unsigned int>;
  using ListPixelConstIterator = typename ListPixelType::const_iterator;
  using ListPixelIterator = typename ListPixelType::iterator;
  using ListImageType = Image<ListPixelType, Self::ImageDimension>;

  /** Performs the narrow-band update of the Heaviside function for each
   *  voxel. The characteristic function of each region is recomputed (note the
   *  shared data which contains information from the other level sets). Using the
   *  new $H$ values, the previous $c_i$ are updated. */
  void
  UpdatePixel(const unsigned int                  idx,
              NeighborhoodIterator<TInputImage> & iterator,
              InputPixelType &                    newValue,
              bool &                              status);

protected:
  ScalarRegionBasedLevelSetFunction()
    : Superclass()
  {}
  ~ScalarRegionBasedLevelSetFunction() override = default;

  /** Compute the overlap multiplicative factors for the penalty term (sum) and
   *  the background intensity fitting terms in multiphase level-sets. */
  ScalarValueType
  ComputeOverlapParameters(const FeatureIndexType & featIndex, ScalarValueType & product) override;

  /** Update the background and foreground constants for pixel updates.
   *  Called only when sparse filters are used to prevent iteration through the
   *  entire image. */
  virtual void
  UpdateSharedDataInsideParameters(const unsigned int &     iId,
                                   const FeaturePixelType & iVal,
                                   const ScalarValueType &  iChange) = 0;

  virtual void
  UpdateSharedDataOutsideParameters(const unsigned int &     iId,
                                    const FeaturePixelType & iVal,
                                    const ScalarValueType &  iChange) = 0;
};
} // namespace itk

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

#endif