/*=========================================================================
 *
 *  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 itkOtsuThresholdCalculator_h
#define itkOtsuThresholdCalculator_h

#include "itkHistogramThresholdCalculator.h"
#include "itkOtsuMultipleThresholdsCalculator.h"

namespace itk
{

/**
 * \class OtsuThresholdCalculator
 * \brief Computes the Otsu's threshold for an image.
 *
 * This calculator computes the Otsu's threshold which separates an image
 * into foreground and background components. The method relies on a
 * histogram of image intensities. The basic idea is to maximize the
 * between-class variance.
 *
 * This class is templated over the input histogram type.
 *
 * \warning This calculator assumes that the input histogram has only one dimension.
 *
 * \ingroup Operators
 * \ingroup ITKThresholding
 */
template <typename THistogram, typename TOutput = double>
class ITK_TEMPLATE_EXPORT OtsuThresholdCalculator : public HistogramThresholdCalculator<THistogram, TOutput>
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(OtsuThresholdCalculator);

  /** Standard class type aliases. */
  using Self = OtsuThresholdCalculator;
  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(OtsuThresholdCalculator);

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

  /** Should the threshold value be mid-point of the bin or the maximum?
   * Default is to return bin maximum. */
  /** @ITKStartGrouping */
  itkSetMacro(ReturnBinMidpoint, bool);
  itkGetConstReferenceMacro(ReturnBinMidpoint, bool);
  itkBooleanMacro(ReturnBinMidpoint);
  /** @ITKEndGrouping */
  /** for backward compatibility. Update() should be preferred. */
  void
  Compute()
  {
    this->Update();
  }

protected:
  OtsuThresholdCalculator()
    : m_OtsuMultipleThresholdsCalculator(OtsuMultipleThresholdsCalculator<THistogram>::New())
  {}
  ~OtsuThresholdCalculator() override = default;
  void
  PrintSelf(std::ostream & os, Indent indent) const override;
  void
  GenerateData() override;

private:
  typename OtsuMultipleThresholdsCalculator<THistogram>::Pointer m_OtsuMultipleThresholdsCalculator{};
  bool                                                           m_ReturnBinMidpoint{ false };
};

} // end namespace itk


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

#endif
