/*=========================================================================
 *
 *  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 itkHuangThresholdCalculator_h
#define itkHuangThresholdCalculator_h

#include "itkHistogramThresholdCalculator.h"

namespace itk
{

/**
 * \class HuangThresholdCalculator
 * \brief Computes the Huang's threshold for an image.
 *
 * This calculator computes the Huang's fuzzy threshold which separates an image
 * into foreground and background components. Uses Shannon's entropy
 * function (one can also use Yager's entropy function)
 * Huang L.-K. and Wang M.-J.J. (1995) "Image Thresholding by Minimizing
 * the Measures of Fuzziness" Pattern Recognition, 28(1): 41-51
 * Reimplemented (to handle 16-bit efficiently) by Johannes Schindelin Jan 31, 2011
 *
 * This class is templated over the input histogram type.
 * \warning This calculator assumes that the input histogram has only one dimension.
 *
 * \author Richard Beare. Department of Medicine, Monash University,
 * Melbourne, Australia.
 * \author Gaetan Lehmann. Biologie du Developpement et de la Reproduction, INRA de Jouy-en-Josas, France.
 *
 * This implementation was taken from the Insight Journal paper:
 * https://www.insight-journal.org/browse/publication/811
 *
 * \ingroup Operators
 * \ingroup ITKThresholding
 */
template <typename THistogram, typename TOutput = double>
class ITK_TEMPLATE_EXPORT HuangThresholdCalculator : public HistogramThresholdCalculator<THistogram, TOutput>
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(HuangThresholdCalculator);

  /** Standard class type aliases. */
  using Self = HuangThresholdCalculator;
  using Superclass = HistogramThresholdCalculator<THistogram, TOutput>;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

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

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

  /** Type definition for the input image. */
  using HistogramType = THistogram;
  using OutputType = TOutput;

protected:
  HuangThresholdCalculator()
  {
    m_FirstBin = 0;
    m_LastBin = 0;
    m_Size = 0;
  }
  ~HuangThresholdCalculator() override = default;
  void
  GenerateData() override;

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

  using TotalAbsoluteFrequencyType = typename HistogramType::TotalAbsoluteFrequencyType;
  using AbsoluteFrequencyType = typename HistogramType::AbsoluteFrequencyType;
  using InstanceIdentifier = typename HistogramType::InstanceIdentifier;
  using SizeValueType = typename HistogramType::SizeValueType;
  using MeasurementType = typename HistogramType::MeasurementType;

private:
  InstanceIdentifier m_FirstBin{};
  InstanceIdentifier m_LastBin{};
  SizeValueType      m_Size{};
};

} // end namespace itk


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

#endif
