/*
 * 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 otbExhaustiveExponentialOptimizer_h
#define otbExhaustiveExponentialOptimizer_h

#include "itkSingleValuedNonLinearOptimizer.h"

namespace otb
{

/** \class ExhaustiveExponentialOptimizer
 * \brief This optimizer performs an exhaustive search on an exponential scale.
 *
 * This optimizer is equivalent to an exhaustive search in a discrete grid
 * defined over the parametric space. The grid is centered on the initial
 * position. The subdivisions of the grid along each one of the dimensions
 * of the parametric space is defined by a exponential progression with
 * scale factor m_ScaleFactor, with the exponant following an
 * arithmetic progression from 0 to m_NumberOfSteps * m_StepLength in
 * both positive and negative direction.
 *
 * This optimizer can be use to perform a preliminary coarse search on
 * the search space.
 *
 * \ingroup Numerics Optimizers
 *
 * \ingroup OTBSupervised
 */
class ITK_ABI_EXPORT ExhaustiveExponentialOptimizer : public itk::SingleValuedNonLinearOptimizer
{
public:
  /** Standard "Self" typedef. */
  typedef ExhaustiveExponentialOptimizer      Self;
  typedef itk::SingleValuedNonLinearOptimizer Superclass;
  typedef itk::SmartPointer<Self>             Pointer;
  typedef itk::SmartPointer<const Self>       ConstPointer;

  typedef itk::Array<unsigned long> StepsType;
  /** Method for creation through the object factory. */
  itkNewMacro(Self);

  /** Run-time type information (and related methods). */
  itkTypeMacro(ExhaustiveExponentialOptimizer, itk::SingleValuedNonLinearOptimizer);

  void StartOptimization(void) override;

  void StartWalking(void);
  void ResumeWalking(void);
  void StopWalking(void);

  itkSetMacro(GeometricProgression, double);
  itkSetMacro(NumberOfSteps, StepsType);
  itkSetMacro(StepLength, double);
  itkGetConstReferenceMacro(GeometricProgression, double);
  itkGetConstReferenceMacro(NumberOfSteps, StepsType);
  itkGetConstReferenceMacro(StepLength, double);
  itkGetConstReferenceMacro(CurrentValue, MeasureType);
  itkGetConstReferenceMacro(MaximumMetricValue, MeasureType);
  itkGetConstReferenceMacro(MinimumMetricValue, MeasureType);
  itkGetConstReferenceMacro(MinimumMetricValuePosition, ParametersType);
  itkGetConstReferenceMacro(MaximumMetricValuePosition, ParametersType);
  itkGetConstReferenceMacro(CurrentIndex, ParametersType);
  itkGetConstReferenceMacro(MaximumNumberOfIterations, unsigned long);

protected:
  ExhaustiveExponentialOptimizer();
  ~ExhaustiveExponentialOptimizer() override
  {
  }
  void PrintSelf(std::ostream& os, itk::Indent indent) const override;

  /** Advance to the next grid position. */
  void AdvanceOneStep(void);
  void IncrementIndex(ParametersType& param);

protected:
  MeasureType    m_CurrentValue;
  StepsType      m_NumberOfSteps;
  double         m_StepLength;
  unsigned long  m_CurrentIteration;
  bool           m_Stop;
  unsigned int   m_CurrentParameter;
  double         m_GeometricProgression;
  ParametersType m_CurrentIndex;
  unsigned long  m_MaximumNumberOfIterations;
  MeasureType    m_MaximumMetricValue;
  MeasureType    m_MinimumMetricValue;
  ParametersType m_MinimumMetricValuePosition;
  ParametersType m_MaximumMetricValuePosition;

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

} // end namespace otb

#endif
