/*=========================================================================
 *
 *  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 itkMultiResolutionImageRegistrationMethod_h
#define itkMultiResolutionImageRegistrationMethod_h

#include "itkProcessObject.h"
#include "itkImageToImageMetric.h"
#include "itkSingleValuedNonLinearOptimizer.h"
#include "itkMultiResolutionPyramidImageFilter.h"
#include "itkNumericTraits.h"
#include "itkDataObjectDecorator.h"

namespace itk
{
/** \class MultiResolutionImageRegistrationMethod
 * \brief Base class for multi-resolution image registration methods
 *
 * This class provides a generic interface for multi-resolution
 * registration using components of the registration framework.
 * See documentation for ImageRegistrationMethod for a description
 * of the registration framework components.
 *
 * The registration process is initiated by method Update().
 * The user must set the parameters of each component before calling
 * this method.
 *
 * The number of resolution level to process can be set via
 * SetNumberOfLevels(). At each resolution level, the user specified
 * registration components are used to register downsampled version of the
 * images by computing the transform parameters that will map one image onto
 * the other image.
 *
 * A user can specify schedules for the fixed and moving image using
 * SetSchedules() method.  However, SetNumberOfLevels() and SetSchedules()
 * should not be used together. An exception will be thrown if that happens.
 *
 * The downsampled images are provided by user specified
 * MultiResolutionPyramidImageFilters. User must specify the schedule
 * for each pyramid externally prior to calling Update().
 *
 * \warning If there is discrepancy between the number of level requested
 * and a pyramid schedule. The pyramid schedule will be overridden
 * with a default one.
 *
 * Before each resolution level an IterationEvent is invoked providing an
 * opportunity for a user interface to change any of the components,
 * change component parameters, or stop the registration.
 *
 * This class is templated over the fixed image type and the moving image
 * type.
 *
 * \sa ImageRegistrationMethod
 * \ingroup RegistrationFilters
 * \ingroup ITKRegistrationCommon
 */
template <typename TFixedImage, typename TMovingImage>
class ITK_TEMPLATE_EXPORT MultiResolutionImageRegistrationMethod : public ProcessObject
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(MultiResolutionImageRegistrationMethod);

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

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

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

  /**  Type of the Fixed image. */
  using FixedImageType = TFixedImage;
  using FixedImageConstPointer = typename FixedImageType::ConstPointer;
  using FixedImageRegionType = typename FixedImageType::RegionType;

  /**  Type of the Moving image. */
  using MovingImageType = TMovingImage;
  using MovingImageConstPointer = typename MovingImageType::ConstPointer;

  /**  Type of the metric. */
  using MetricType = ImageToImageMetric<FixedImageType, MovingImageType>;
  using MetricPointer = typename MetricType::Pointer;

  /**  Type of the Transform . */
  using TransformType = typename MetricType::TransformType;
  using TransformPointer = typename TransformType::Pointer;

  /** Type for the output: Using Decorator pattern for enabling
   *  the Transform to be passed in the data pipeline */
  using TransformOutputType = DataObjectDecorator<TransformType>;
  using TransformOutputPointer = typename TransformOutputType::Pointer;
  using TransformOutputConstPointer = typename TransformOutputType::ConstPointer;

  /**  Type of the Interpolator. */
  using InterpolatorType = typename MetricType::InterpolatorType;
  using InterpolatorPointer = typename InterpolatorType::Pointer;

  /**  Type of the optimizer. */
  using OptimizerType = SingleValuedNonLinearOptimizer;

  /** Type of the Fixed image multiresolution pyramid. */
  using FixedImagePyramidType = MultiResolutionPyramidImageFilter<FixedImageType, FixedImageType>;
  using FixedImagePyramidPointer = typename FixedImagePyramidType::Pointer;

  /** Type of pyramid schedule type */
  using ScheduleType = typename FixedImagePyramidType::ScheduleType;

  /** Type of the moving image multiresolution pyramid. */
  using MovingImagePyramidType = MultiResolutionPyramidImageFilter<MovingImageType, MovingImageType>;
  using MovingImagePyramidPointer = typename MovingImagePyramidType::Pointer;

  /** Type of the Transformation parameters This is the same type used to
   *  represent the search space of the optimization algorithm */
  using ParametersType = typename MetricType::TransformParametersType;

  /** Smart Pointer type to a DataObject. */
  using DataObjectPointer = typename DataObject::Pointer;

  /** Stop the registration. */
  void
  StopRegistration();

  /** Set/Get the Fixed image. */
  itkSetConstObjectMacro(FixedImage, FixedImageType);
  itkGetConstObjectMacro(FixedImage, FixedImageType);

  /** Set/Get the Moving image. */
  itkSetConstObjectMacro(MovingImage, MovingImageType);
  itkGetConstObjectMacro(MovingImage, MovingImageType);

  /** Set/Get the Optimizer. */
  itkSetObjectMacro(Optimizer, OptimizerType);
  itkGetModifiableObjectMacro(Optimizer, OptimizerType);

  /** Set/Get the Metric. */
  itkSetObjectMacro(Metric, MetricType);
  itkGetModifiableObjectMacro(Metric, MetricType);

  /** Set/Get the Metric. */
  itkSetMacro(FixedImageRegion, FixedImageRegionType);
  itkGetConstReferenceMacro(FixedImageRegion, FixedImageRegionType);

  /** Set/Get the Transform. */
  itkSetObjectMacro(Transform, TransformType);
  itkGetModifiableObjectMacro(Transform, TransformType);

  /** Set/Get the Interpolator. */
  itkSetObjectMacro(Interpolator, InterpolatorType);
  itkGetModifiableObjectMacro(Interpolator, InterpolatorType);

  /** Set/Get the Fixed image pyramid. */
  itkSetObjectMacro(FixedImagePyramid, FixedImagePyramidType);
  itkGetModifiableObjectMacro(FixedImagePyramid, FixedImagePyramidType);

  /** Set/Get the Moving image pyramid. */
  itkSetObjectMacro(MovingImagePyramid, MovingImagePyramidType);
  itkGetModifiableObjectMacro(MovingImagePyramid, MovingImagePyramidType);

  /** Set/Get the schedules for the fixed and moving image pyramid. */
  void
  SetSchedules(const ScheduleType & fixedImagePyramidSchedule, const ScheduleType & movingImagePyramidSchedule);

  itkGetConstMacro(FixedImagePyramidSchedule, ScheduleType);
  itkGetConstMacro(MovingImagePyramidSchedule, ScheduleType);

  /** Set/Get the number of multi-resolution levels. */
  void
  SetNumberOfLevels(SizeValueType numberOfLevels);

  itkGetConstMacro(NumberOfLevels, SizeValueType);

  /** Get the current resolution level being processed. */
  itkGetConstMacro(CurrentLevel, SizeValueType);

  /** Set/Get the initial transformation parameters. */
  itkSetMacro(InitialTransformParameters, ParametersType);
  itkGetConstReferenceMacro(InitialTransformParameters, ParametersType);

  /** Set/Get the initial transformation parameters of the next resolution
   level to be processed. The default is the last set of parameters of
   the last resolution level. */
  itkSetMacro(InitialTransformParametersOfNextLevel, ParametersType);
  itkGetConstReferenceMacro(InitialTransformParametersOfNextLevel, ParametersType);

  /** Get the last transformation parameters visited by
   * the optimizer. */
  itkGetConstReferenceMacro(LastTransformParameters, ParametersType);

  /** Returns the transform resulting from the registration process  */
  const TransformOutputType *
  GetOutput() const;

  /** Make a DataObject of the correct type to be used as the specified
   * output. */
  using DataObjectPointerArraySizeType = ProcessObject::DataObjectPointerArraySizeType;
  using Superclass::MakeOutput;
  DataObjectPointer
  MakeOutput(DataObjectPointerArraySizeType output) override;

  /** Method to return the latest modified time of this object or
   * any of its cached ivars */
  ModifiedTimeType
  GetMTime() const override;

protected:
  MultiResolutionImageRegistrationMethod();
  ~MultiResolutionImageRegistrationMethod() override = default;
  void
  PrintSelf(std::ostream & os, Indent indent) const override;

  /** Method invoked by the pipeline in order to trigger the computation of
   * the registration. */
  void
  GenerateData() override;

  /** Initialize by setting the interconnects between the components.
      This method is executed at every level of the pyramid with the
      values corresponding to this resolution
   */
  void
  Initialize();

  /** Compute the size of the fixed region for each level of the pyramid. */
  void
  PreparePyramids();

  /** Set the current level to be processed */
  itkSetMacro(CurrentLevel, SizeValueType);

private:
  MetricPointer          m_Metric{};
  OptimizerType::Pointer m_Optimizer{};

  MovingImageConstPointer m_MovingImage{};
  FixedImageConstPointer  m_FixedImage{};

  TransformPointer    m_Transform{};
  InterpolatorPointer m_Interpolator{};

  MovingImagePyramidPointer m_MovingImagePyramid{};
  FixedImagePyramidPointer  m_FixedImagePyramid{};

  ParametersType m_InitialTransformParameters{};
  ParametersType m_InitialTransformParametersOfNextLevel{};
  ParametersType m_LastTransformParameters{};

  FixedImageRegionType              m_FixedImageRegion{};
  std::vector<FixedImageRegionType> m_FixedImageRegionPyramid{};

  SizeValueType m_NumberOfLevels{};
  SizeValueType m_CurrentLevel{};

  bool m_Stop{};

  ScheduleType m_FixedImagePyramidSchedule{};
  ScheduleType m_MovingImagePyramidSchedule{};

  bool m_ScheduleSpecified{};
  bool m_NumberOfLevelsSpecified{};
};
} // end namespace itk

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

#endif