/*=========================================================================
 *
 *  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 itkShapePriorMAPCostFunctionBase_h
#define itkShapePriorMAPCostFunctionBase_h

#include "itkSingleValuedCostFunction.h"
#include "itkLevelSet.h"
#include "itkShapeSignedDistanceFunction.h"

namespace itk
{
/** \class ShapePriorMAPCostFunctionBase
 * \brief Represents the base class of maximum aprior (MAP) cost function used
 * ShapePriorSegmentationLevelSetImageFilter to estimate the shape parameters.
 *
 * This class follows the shape and pose parameters estimation developed in [1].
 *
 * This class has two template parameters, the feature image type representing the
 * edge potential map and the pixel type used to
 * represent the output level set in the ShapePriorSegmentationLevelSetImageFilter.
 *
 * \sa ShapePriorSegmentationLevelSetImageFilter
 *
 * \par REFERENCES
 * \par
 * [1] Leventon, M.E. et al. "Statistical Shape Influence in Geodesic Active Contours", CVPR 2000.
 *
 *
 * \ingroup Numerics Optimizers
 * \ingroup ITKLevelSets
 */
template <typename TFeatureImage, typename TOutputPixel>
class ITK_TEMPLATE_EXPORT ShapePriorMAPCostFunctionBase : public SingleValuedCostFunction
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(ShapePriorMAPCostFunctionBase);

  /** Standard class type aliases. */
  using Self = ShapePriorMAPCostFunctionBase;
  using Superclass = SingleValuedCostFunction;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  /** \see LightObject::GetNameOfClass() */
  itkOverrideGetNameOfClassMacro(ShapePriorMAPCostFunctionBase);

  /**  MeasureType type alias.
   *  It defines a type used to return the cost function value. */
  using typename Superclass::MeasureType;

  /** DerivativeType type alias.
   *  It defines a type used to return the cost function derivative.  */
  using typename Superclass::DerivativeType;

  /**  ParametersType type alias.
   *  It defines a position in the optimization search space. */
  using typename Superclass::ParametersType;

  /** Type of the feature image representing the edge potential map. */
  using FeatureImageType = TFeatureImage;
  using FeatureImagePointer = typename FeatureImageType::ConstPointer;

  /** Dimension constant. */
  static constexpr unsigned int ImageDimension = TFeatureImage::ImageDimension;

  /** Type of pixel used to represent the level set. */
  using PixelType = TOutputPixel;

  /** Type of node used to represent the active region around the zero set. */
  using NodeType = LevelSetNode<PixelType, Self::ImageDimension>;

  /** Type of container used to store the level set nodes. */
  using NodeContainerType = VectorContainer<unsigned int, NodeType>;
  using NodeContainerPointer = typename NodeContainerType::ConstPointer;

  /** Type of the shape signed distance function. */
  using ShapeFunctionType = ShapeSignedDistanceFunction<double, Self::ImageDimension>;
  using ShapeFunctionPointer = typename ShapeFunctionType::Pointer;

  /** Set/Get the shape distance function. */
  itkSetObjectMacro(ShapeFunction, ShapeFunctionType);
  itkGetModifiableObjectMacro(ShapeFunction, ShapeFunctionType);

  /** Set/Get the active region. */
  itkSetConstObjectMacro(ActiveRegion, NodeContainerType);
  itkGetConstObjectMacro(ActiveRegion, NodeContainerType);

  /** Set/Get the feature image. */
  itkSetConstObjectMacro(FeatureImage, FeatureImageType);
  itkGetConstObjectMacro(FeatureImage, FeatureImageType);

  /** This method returns the value of the cost function corresponding
   * to the specified parameters.    */
  MeasureType
  GetValue(const ParametersType & parameters) const override;

  /** This method returns the derivative of the cost function corresponding
   * to the specified parameters.   */
  void
  GetDerivative(const ParametersType &, DerivativeType &) const override
  {
    itkExceptionMacro("This function is currently not supported.");
  }

  /** Return the number of parameters. */
  unsigned int
  GetNumberOfParameters() const override
  {
    return m_ShapeFunction->GetNumberOfParameters();
  }

  /** Compute the inside term component of the MAP cost function.
   * Subclasses should override this function */
  virtual MeasureType
  ComputeLogInsideTerm(const ParametersType &) const = 0;

  /** Compute the gradient term component of the MAP cost function.
   * Subclasses should override this function */
  virtual MeasureType
  ComputeLogGradientTerm(const ParametersType &) const = 0;

  /** Compute the shape prior component of the MAP cost function.
   * Subclasses should override this function */
  virtual MeasureType
  ComputeLogShapePriorTerm(const ParametersType &) const = 0;

  /** Compute the pose prior component of the MAP cost function.
   * Subclasses should override this function */
  virtual MeasureType
  ComputeLogPosePriorTerm(const ParametersType &) const = 0;

  /** Initialize the cost function by making sure that all the components
   *  are present. */
  virtual void
  Initialize();

protected:
  ShapePriorMAPCostFunctionBase();
  ~ShapePriorMAPCostFunctionBase() override = default;

  void
  PrintSelf(std::ostream & os, Indent indent) const override;

  ShapeFunctionPointer m_ShapeFunction{};
  NodeContainerPointer m_ActiveRegion{};

  FeatureImagePointer m_FeatureImage{};
};
} // end namespace itk

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

#endif