/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  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.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 itkDisplacementFieldToBSplineImageFilter_h
#define itkDisplacementFieldToBSplineImageFilter_h

#include "itkImageToImageFilter.h"

#include "itkBSplineScatteredDataPointSetToImageFilter.h"
#include "itkPointSet.h"
#include "itkVector.h"

namespace itk
{

/**
 * \class DisplacementFieldToBSplineImageFilter
 * \brief Class which takes a dense displacement field image and/or a set of points
 * with associated displacements and smooths them using B-splines.  The inverse
 * can also be estimated.
 *
 * \author Nick Tustison
 *
 * \ingroup ITKDisplacementField
 */

template <typename TInputImage,
  typename TInputPointSet = PointSet<typename TInputImage::PixelType, TInputImage::ImageDimension>,
  typename TOutputImage = TInputImage>
class ITK_TEMPLATE_EXPORT DisplacementFieldToBSplineImageFilter
  : public ImageToImageFilter<TInputImage, TOutputImage>
{
public:
  ITK_DISALLOW_COPY_AND_ASSIGN(DisplacementFieldToBSplineImageFilter);

  using Self = DisplacementFieldToBSplineImageFilter;
  using Superclass = ImageToImageFilter<TInputImage, TOutputImage>;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

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

  /** Extract dimension from input image. */
  static constexpr unsigned int ImageDimension = TInputImage::ImageDimension;

  using InputFieldType = TInputImage;
  using InputPointSetType = TInputPointSet;
  using OutputFieldType = TOutputImage;

  using DisplacementFieldType = InputFieldType;
  using InverseDisplacementFieldType = OutputFieldType;
  using InputFieldPointType = typename InputFieldType::PointType;

  /** Image type alias support */
  using PixelType = typename OutputFieldType::PixelType;
  using VectorType = typename OutputFieldType::PixelType;
  using RegionType = typename OutputFieldType::RegionType;
  using IndexType = typename OutputFieldType::IndexType;

  using SpacingType = typename OutputFieldType::SpacingType;
  using OriginType = typename OutputFieldType::PointType;
  using SizeType = typename OutputFieldType::SizeType;
  using DirectionType = typename OutputFieldType::DirectionType;

  using RealType = typename VectorType::RealValueType;
  using RealImageType = Image<RealType, ImageDimension>;

  /** Point set type alias support */
  using PointType = typename InputPointSetType::PointType;
  using PointDataType = typename InputPointSetType::PixelType;
  using PointsContainerType = typename InputPointSetType::PointsContainer;
  using PointDataContainerType = typename InputPointSetType::PointDataContainer;

  /** B-sline filter type alias */
  using BSplineFilterType = BSplineScatteredDataPointSetToImageFilter<
    InputPointSetType, OutputFieldType>;
  using WeightsContainerType = typename BSplineFilterType::WeightsContainerType;
  using DisplacementFieldControlPointLatticeType = typename BSplineFilterType::PointDataImageType;
  using ArrayType = typename BSplineFilterType::ArrayType;

  /** Set the displacement field */
  void SetDisplacementField( const InputFieldType * field )
    {
    this->SetInput( 0, field );
    }

  /** Get the input displacement field. */
  const InputFieldType* GetDisplacementField() const
    {
    return this->GetInput( 0 );
    }

  /**
   * Set confidence image function.  If a confidence image is specified,
   * estimation of the displacement field weights the contribution of each voxel
   * according the value of the corresponding voxel in the confidence image.
   */
  void SetConfidenceImage( const RealImageType *image )
    {
    this->SetNthInput( 1, const_cast<RealImageType *>( image ) );
    }
  void SetInput1( const RealImageType *image ) { this->SetConfidenceImage( image ); }

  /** Get confidence image function. */
  const RealImageType* GetConfidenceImage() const
    {
    return static_cast<const RealImageType*>( this->ProcessObject::GetInput( 1 ) );
    }

  /** Set the input point set */
  void SetPointSet( const InputPointSetType * points )
    {
    this->SetNthInput( 2, const_cast<InputPointSetType *>( points ) );
    }
  void SetInput2( const InputPointSetType * points ) { this->SetPointSet( points ); }

  /** Get the input point set. */
  const InputPointSetType* GetPointSet() const
    {
    return static_cast<const InputPointSetType *>( this->ProcessObject::GetInput( 2 ) );
    }

  /** Set the confidence weights associated with the input point set*/
  void SetPointSetConfidenceWeights( WeightsContainerType *weights );

  /** Get the displacement field control point lattice. */
  const DisplacementFieldControlPointLatticeType * GetDisplacementFieldControlPointLattice() const
    {
    return static_cast<const DisplacementFieldControlPointLatticeType*>( this->GetOutput( 1 ) );
    }

  /** Define the b-spline domain from an image */
  void SetBSplineDomainFromImage( RealImageType * );

  /** Define the b-spline domain from an image */
  void SetBSplineDomainFromImage( const RealImageType *image )
    { this->SetBSplineDomainFromImage( const_cast<RealImageType *>( image ) ); }

  /** Define the b-spline domain from a displacement field */
  void SetBSplineDomainFromImage( InputFieldType * );

  /** Define the b-spline domain from a displacement field */
  void SetBSplineDomainFromImage( const InputFieldType *field )
    { this->SetBSplineDomainFromImage( const_cast<InputFieldType *>( field ) ); }

  /** Define the b-spline domain explicitly. */
  void SetBSplineDomain( OriginType, SpacingType, SizeType, DirectionType );

  /* Set/Get b-spline domain origin. */
  itkGetConstMacro( BSplineDomainOrigin, OriginType );

  /* Set/Get b-spline domain spacing. */
  itkGetConstMacro( BSplineDomainSpacing, SpacingType );

  /* Set/Get b-spline domain size. */
  itkGetConstMacro( BSplineDomainSize, SizeType );

  /* Set/Get b-spline domain direction. */
  itkGetConstMacro( BSplineDomainDirection, DirectionType );

  /* Use input field to define the B-spline doain. */
  itkSetMacro( UseInputFieldToDefineTheBSplineDomain, bool );
  itkGetConstMacro( UseInputFieldToDefineTheBSplineDomain, bool )
  itkBooleanMacro( UseInputFieldToDefineTheBSplineDomain );

  /**
   * Set the spline order defining the bias field estimate.  Default = 3.
   */
  itkSetMacro( SplineOrder, unsigned int );

  /**
   * Get the spline order defining the bias field estimate.  Default = 3.
   */
  itkGetConstMacro( SplineOrder, unsigned int );

  /**
   * Set the control point grid size definining the B-spline estimate of the
   * scalar bias field.  In each dimension, the B-spline mesh size is equal
   * to the number of control points in that dimension minus the spline order.
   * Default = 4 control points in each dimension for a mesh size of 1 in each
   * dimension.
   */
  itkSetMacro( NumberOfControlPoints, ArrayType );

  /**
   * Get the control point grid size definining the B-spline estimate of the
   * scalar bias field.  In each dimension, the B-spline mesh size is equal
   * to the number of control points in that dimension minus the spline order.
   * Default = 4 control points in each dimension for a mesh size of 1 in each
   * dimension.
   */
  itkGetConstMacro( NumberOfControlPoints, ArrayType );

  /**
   * Set the number of fitting levels.  One of the contributions of N4 is the
   * introduction of a multi-scale approach to fitting. This allows one to
   * specify a B-spline mesh size for initial fitting followed by a doubling of
   * the mesh resolution for each subsequent fitting level.  Default = 1 level.
   */
  itkSetMacro( NumberOfFittingLevels, ArrayType );

  /**
   * Set the number of fitting levels.  One of the contributions of N4 is the
   * introduction of a multi-scale approach to fitting. This allows one to
   * specify a B-spline mesh size for initial fitting followed by a doubling of
   * the mesh resolution for each subsequent fitting level.  Default = 1 level.
   */
  void SetNumberOfFittingLevels( unsigned int n )
    {
    ArrayType nlevels;

    nlevels.Fill( n );
    this->SetNumberOfFittingLevels( nlevels );
    }

  /**
   * Get the number of fitting levels.  One of the contributions of N4 is the
   * introduction of a multi-scale approach to fitting. This allows one to
   * specify a B-spline mesh size for initial fitting followed by a doubling of
   * the mesh resolution for each subsequent fitting level.  Default = 1 level.
   */
  itkGetConstMacro( NumberOfFittingLevels, ArrayType );

  /**
   * Estimate the inverse field instead of the forward field.  Default = false.
   */
  itkBooleanMacro( EstimateInverse );
  itkSetMacro( EstimateInverse, bool );
  itkGetConstMacro( EstimateInverse, bool );

  /**
   * Enforce stationary boundary conditions.  Default = false.
   */
  itkBooleanMacro( EnforceStationaryBoundary );
  itkSetMacro( EnforceStationaryBoundary, bool );
  itkGetConstMacro( EnforceStationaryBoundary, bool );

protected:

  /** Constructor */
  DisplacementFieldToBSplineImageFilter();

  /** Deconstructor */
  ~DisplacementFieldToBSplineImageFilter() override = default;

  /** Standard print self function **/
  void PrintSelf( std::ostream& os, Indent indent ) const override;

  /** preprocessing function */
  void GenerateData() override;

private:
  bool                                         m_EstimateInverse{ false };
  bool                                         m_EnforceStationaryBoundary{ true };
  unsigned int                                 m_SplineOrder{ 3 };
  ArrayType                                    m_NumberOfControlPoints;
  ArrayType                                    m_NumberOfFittingLevels;

  typename WeightsContainerType::Pointer       m_PointWeights;
  bool                                         m_UsePointWeights{ false };

  OriginType                                   m_BSplineDomainOrigin;
  SpacingType                                  m_BSplineDomainSpacing;
  SizeType                                     m_BSplineDomainSize;
  DirectionType                                m_BSplineDomainDirection;

  bool                                         m_BSplineDomainIsDefined{ true };
  bool                                         m_UseInputFieldToDefineTheBSplineDomain{ false };
};

} // end namespace itk

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

#endif
