/*
 * Copyright (C) 2005-2020 Centre National d'Etudes Spatiales (CNES)
 *
 * 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 otbSarBrightnessFunctor_h
#define otbSarBrightnessFunctor_h

#include "otbMath.h"
#include "itkNumericTraits.h"

namespace otb
{

namespace Functor
{
/**
 * \class SarBrightnessFunctor
 * \brief Compute the brightness value.
 *  \f$ \beta^{0} = (scale * DN^{2} + offset) * OldGain / NewGain * RangeSpreadLoss \f$
 *
 *
 * \ingroup OTBSARCalibration
 */
template <class TInput, class TOutput>
class ITK_EXPORT SarBrightnessFunctor
{
public:
  typedef TInput                                          InputType;
  typedef TOutput                                         OutputType;
  typedef typename itk::NumericTraits<InputType>::AbsType RealType;

  SarBrightnessFunctor()
  {
    m_Noise                 = 0.0;
    m_Scale                 = 1.0;
    m_AntennaPatternOldGain = 1.0;
    m_AntennaPatternNewGain = 1.0;
    m_RangeSpreadLoss       = 1.0;
  };

  ~SarBrightnessFunctor(){};

  inline TOutput operator()(const TInput& value) const
  {
    RealType digitalNumber = static_cast<RealType>(std::abs(value));
    RealType beta;

    beta = m_Scale * (digitalNumber * digitalNumber - m_Noise);
    beta *= m_AntennaPatternOldGain;
    beta /= m_AntennaPatternNewGain;
    beta *= m_RangeSpreadLoss;

    if (beta < 0.0)
    {
      beta = 0.0;
    }

    return static_cast<OutputType>(beta);
  }

  /** Set offset method */
  void SetNoise(RealType value)
  {
    m_Noise = value;
  }

  /** Get offset method */
  RealType GetNoise() const
  {
    return m_Noise;
  }

  /** Set scale method */
  void SetScale(RealType value)
  {
    m_Scale = value;
  }

  /** Get scale method */
  RealType GetScale() const
  {
    return m_Scale;
  }

  /** Set antennaPatternNewGain method */
  void SetAntennaPatternNewGain(RealType value)
  {
    m_AntennaPatternNewGain = value;
  }

  /** Get antennaPatternNewGain method */
  RealType GetAntennaPatternNewGain() const
  {
    return m_AntennaPatternNewGain;
  }

  /** Set antennaPatternOldGain method */
  void SetAntennaPatternOldGain(RealType value)
  {
    m_AntennaPatternOldGain = value;
  }

  /** Get antennaPatternOldGain method */
  RealType GetAntennaPatternOldGain() const
  {
    return m_AntennaPatternOldGain;
  }

  /** Set rangeSpreadLoss method */
  void SetRangeSpreadLoss(RealType value)
  {
    m_RangeSpreadLoss = value;
  }

  /** Get scale method */
  RealType GetRangeSpreadLoss() const
  {
    return m_RangeSpreadLoss;
  }

private:
  RealType m_Noise;
  RealType m_Scale;
  RealType m_AntennaPatternNewGain;
  RealType m_AntennaPatternOldGain;
  RealType m_RangeSpreadLoss;
};
}
}

#endif
