/*
 * 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 otbEnvelopeSavitzkyGolayInterpolationFunctor_h
#define otbEnvelopeSavitzkyGolayInterpolationFunctor_h

#include "otbSavitzkyGolayInterpolationFunctor.h"


namespace otb
{
namespace Functor
{
/** \class otbEnvelopeSavitzkyGolayInterpolationFunctor
 *
 *  \brief: This class implements a Savitzky-Golay interpolation
 *  fitting the upper or lower envelope of the series being interpolated.
 *
 * \sa otbSavitzkyGolayInterpolationFunctor
 *
 * \ingroup OTBTimeSeries
 */
template <unsigned int Radius, class TSeries, class TDates, class TWeight = TSeries>
class EnvelopeSavitzkyGolayInterpolationFunctor
{
public:
  typedef typename TSeries::ValueType ValueType;
  typedef typename TDates::ValueType  DateType;
  typedef typename TWeight::ValueType WeightType;
  static const unsigned int           Degree = 2;
  typedef double                      CoefficientPrecisionType;
  typedef otb::PolynomialTimeSeries<Degree, CoefficientPrecisionType> TSFunctionType;
  static const unsigned int nbDates = TSeries::Dimension;

  typedef otb::Functor::SavitzkyGolayInterpolationFunctor<Radius, TSeries, TDates, TWeight> SGFunctorType;

  /// Constructor
  EnvelopeSavitzkyGolayInterpolationFunctor() : m_Iterations(2), m_UpperEnvelope(true), m_DecreaseFactor(0.5)
  {
  }
  /// Destructor
  virtual ~EnvelopeSavitzkyGolayInterpolationFunctor()
  {
  }

  inline void SetWeights(const TWeight weights)
  {
    for (unsigned int i = 0; i < m_WeightSeries.Size(); ++i)
      m_WeightSeries[i] = weights[i];
    m_SGFunctor.SetWeights(weights);
  }

  inline void SetDates(const TDates doy)
  {
    m_SGFunctor.SetDates(doy);
  }

  inline void SetUpperEnvelope()
  {
    m_UpperEnvelope = true;
  }

  inline void SetLowerEnvelope()
  {
    m_UpperEnvelope = false;
  }

  inline void SetDecreaseFactor(double df)
  {
    if (df > 0.0 && df < 1.0)
      m_DecreaseFactor = df;
  }

  inline void SetIterations(unsigned int its)
  {
    m_Iterations = its;
  }

  inline TSeries operator()(const TSeries& series)
  {
    TSeries outSeries = m_SGFunctor(series);

    for (unsigned int i = 0; i < m_Iterations; ++i)
    {
      for (unsigned int j = 0; j < nbDates; ++j)
      {
        if (m_UpperEnvelope && outSeries[j] < series[j])
          m_WeightSeries[j] = m_WeightSeries[j] * m_DecreaseFactor;
        if (!m_UpperEnvelope && outSeries[j] > series[j])
          m_WeightSeries[j] = m_WeightSeries[j] * m_DecreaseFactor;
      }

      m_SGFunctor.SetWeights(m_WeightSeries);
      outSeries = m_SGFunctor(series);
    }

    return outSeries;
  }

private:
  TWeight       m_WeightSeries;
  SGFunctorType m_SGFunctor;
  unsigned int  m_Iterations;
  bool          m_UpperEnvelope;
  double        m_DecreaseFactor;
};
}
} // namespace otb
#endif
