/*
 * Copyright (C) 2005-2020 Centre National d'Etudes Spatiales (CNES)
 * Copyright (C) 2007-2012 Institut Mines Telecom / Telecom Bretagne
 *
 * This file is part of Orfeo Toolbox
 *
 *     https://www.orfeo-toolbox.org/
 *
 * 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
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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 otbKullbackLeiblerSupervizedDistanceImageFilter_h
#define otbKullbackLeiblerSupervizedDistanceImageFilter_h

#include "otbKullbackLeiblerDistanceImageFilter.h"

#include "otbROIdataConversion.h"

namespace otb
{

/** \class KullbackLeiblerSupervizedDistanceImageFilter
 * \brief Implements KullbackLeibler distance over Edgeworth approximation,
 * between a Neighborhood and a predefined Region of Interest.
 *
 * This filter is parametrized over the types of the two
 * input images and the type of the output image.
 *
 * Numeric conversions (castings) are done by the C++ defaults.
 *
 * The filter will walk over all the pixels in the two input
 * images, and for each one of them it will do the following:
 *
 * - cast the input 1 pixel value to \c double
 * - compute the first four cumulants of the ROI
 * - cast the input 2 pixel value to \c double
 * - compute the first four cumulants of the pixel values
 * - compute the value of the Edgeorth approximation of the KL distance
 * - cast the \c double value resulting to the pixel type of the output image
 * - store the casted value into the output image.
 *
 * The filter expect all images to have the same dimension
 * (e.g. all 2D, or all 3D, or all ND)
 *
 * See article of  Lin Saito et Levine
 * "Edgeworth Approximation of the Kullback-Leibler Distance Towards Problems in Image Analysis"
 * and
 * "Edgeworth Expansions of the Kullback-Leibler Information" (submitted to JASA, nov 25, 1999)
 * http://www.math.ucdavis.edu/~saito/publications
 *
 * \sa CumulantsForEdgeworth
 *
 * \ingroup OTBChangeDetection
 */
namespace Functor
{
/** \class KullbackLeiblerSupervizedDistance
 * \brief Functor for KullbackLeiblerSupervizedDistanceImageFilter. Please refer to KullbackLeiblerSupervizedDistanceImageFilter.
 *
 *
 * \ingroup OTBChangeDetection
 */
template <class TInput1, class TInput2, class TInputROIImage, class TOutput>
class KullbackLeiblerSupervizedDistance
{
public:
  KullbackLeiblerSupervizedDistance();
  virtual ~KullbackLeiblerSupervizedDistance();

  /** performs the preprocess calculation on the training area */
  void Evaluate(const typename TInput1::ImageType* img1, const typename TInput2::ImageType* img2, const TInputROIImage* imgROI);

  /** The functor by itself */
  TOutput operator()(const TInput1& it1, const TInput2& it2);

protected:
  typedef ROIdataConversion<typename TInput1::ImageType, TInputROIImage> ROIConversionType1;

  typedef itk::ConstNeighborhoodIterator<typename ROIConversionType1::OutputImageType> ROIInputType1;

  typedef ROIdataConversion<typename TInput2::ImageType, TInputROIImage> ROIConversionType2;

  typedef itk::ConstNeighborhoodIterator<typename ROIConversionType2::OutputImageType> ROIInputType2;

  CumulantsForEdgeworth<ROIInputType1>* m_CumROI1;
  CumulantsForEdgeworth<ROIInputType2>* m_CumROI2;

private:
  KullbackLeiblerSupervizedDistance(const KullbackLeiblerSupervizedDistance&);
};

} // Functor

template <class TInputImage1, class TInputImage2, class TInputROIImage, class TOutputImage>
class ITK_EXPORT KullbackLeiblerSupervizedDistanceImageFilter
    : public otb::BinaryFunctorNeighborhoodImageFilter<
          TInputImage1, TInputImage2, TOutputImage,
          Functor::KullbackLeiblerSupervizedDistance<typename itk::ConstNeighborhoodIterator<TInputImage1>,
                                                     typename itk::ConstNeighborhoodIterator<TInputImage2>, TInputROIImage, typename TOutputImage::PixelType>>
{
public:
  /** Standard class typedefs. */
  typedef KullbackLeiblerSupervizedDistanceImageFilter Self;
  typedef typename otb::BinaryFunctorNeighborhoodImageFilter<
      TInputImage1, TInputImage2, TOutputImage,
      Functor::KullbackLeiblerSupervizedDistance<typename itk::ConstNeighborhoodIterator<TInputImage1>, typename itk::ConstNeighborhoodIterator<TInputImage2>,
                                                 TInputROIImage, typename TOutputImage::PixelType>>
                                        Superclass;
  typedef itk::SmartPointer<Self>       Pointer;
  typedef itk::SmartPointer<const Self> ConstPointer;

  /** Vectors that hold the training area */
  typedef typename TInputImage1::PixelType MeasurementType1;
  typedef typename TInputImage2::PixelType MeasurementType2;

  typedef std::vector<MeasurementType1> TrainingMeasureType1;
  typedef std::vector<MeasurementType2> TrainingMeasureType2;

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

  /** Method for creation of the training area and the computation
   * of some reference cumulants */
  void SetTrainingArea(const TInputROIImage* trainingImage);

protected:
  void BeforeThreadedGenerateData(void) override;

  KullbackLeiblerSupervizedDistanceImageFilter()
  {
    this->SetNumberOfRequiredInputs(3);
  }
  ~KullbackLeiblerSupervizedDistanceImageFilter() override
  {
  }

private:
  KullbackLeiblerSupervizedDistanceImageFilter(const Self&) = delete;
  void operator=(const Self&) = delete;
};

} // namespace otb

#ifndef OTB_MANUAL_INSTANTIATION
#include "otbKullbackLeiblerSupervizedDistanceImageFilter.hxx"
#endif

#endif
