/*=========================================================================
 *
 *  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 itkRayCastInterpolateImageFunction_h
#define itkRayCastInterpolateImageFunction_h

#include "itkInterpolateImageFunction.h"
#include "itkTransform.h"
#include "itkNumericTraits.h"

namespace itk
{
/** \class RayCastInterpolateImageFunction
 * \brief Projective interpolation of an image at specified positions.
 *
 * RayCastInterpolateImageFunction casts rays through a 3-dimensional
 * image and uses bilinear interpolation to integrate each plane of
 * voxels traversed.
 *
 * \warning This interpolator works for 3-dimensional images only.
 *
 * \ingroup ImageFunctions
 * \ingroup ITKImageFunction
 */
template< typename TInputImage, typename TCoordRep = double >
class ITK_TEMPLATE_EXPORT RayCastInterpolateImageFunction:
  public InterpolateImageFunction< TInputImage, TCoordRep >
{
public:
  ITK_DISALLOW_COPY_AND_ASSIGN(RayCastInterpolateImageFunction);

  /** Standard class type aliases. */
  using Self = RayCastInterpolateImageFunction;
  using Superclass = InterpolateImageFunction< TInputImage, TCoordRep >;
  using Pointer = SmartPointer< Self >;
  using ConstPointer = SmartPointer< const Self >;

  /** Constants for the image dimensions */
  static constexpr unsigned int InputImageDimension = TInputImage::ImageDimension;

  /**
   * Type of the Transform Base class
   * The fixed image should be a 3D image
   */
  using TransformType = Transform< TCoordRep, 3, 3 >;

  using TransformPointer = typename TransformType::Pointer;
  using InputPointType = typename TransformType::InputPointType;
  using OutputPointType = typename TransformType::OutputPointType;
  using TransformParametersType = typename TransformType::ParametersType;
  using TransformJacobianType = typename TransformType::JacobianType;

  using PixelType = typename Superclass::InputPixelType;

  using SizeType = typename TInputImage::SizeType;

  using DirectionType = Vector< TCoordRep, 3 >;

  /**  Type of the Interpolator Base class */
  using InterpolatorType = InterpolateImageFunction< TInputImage, TCoordRep >;

  using InterpolatorPointer = typename InterpolatorType::Pointer;

  /** Run-time type information (and related methods). */
  itkTypeMacro(RayCastInterpolateImageFunction, InterpolateImageFunction);

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

  /** OutputType type alias support */
  using OutputType = typename Superclass::OutputType;

  /** InputImageType type alias support */
  using InputImageType = typename Superclass::InputImageType;

  /** RealType type alias support */
  using RealType = typename Superclass::RealType;

  /** Dimension underlying input image. */
  static constexpr unsigned int ImageDimension = Superclass::ImageDimension;

  /** Point type alias support */
  using PointType = typename Superclass::PointType;

  /** Index type alias support */
  using IndexType = typename Superclass::IndexType;

  /** ContinuousIndex type alias support */
  using ContinuousIndexType = typename Superclass::ContinuousIndexType;

  /** \brief
   * Interpolate the image at a point position.
   *
   * Returns the interpolated image intensity at a
   * specified point position. No bounds checking is done.
   * The point is assume to lie within the image buffer.
   *
   * ImageFunction::IsInsideBuffer() can be used to check bounds before
   * calling the method.
   */
  OutputType Evaluate(const PointType & point) const override;

  /** Interpolate the image at a continuous index position
   *
   * Returns the interpolated image intensity at a
   * specified index position. No bounds checking is done.
   * The point is assume to lie within the image buffer.
   *
   * Subclasses must override this method.
   *
   * ImageFunction::IsInsideBuffer() can be used to check bounds before
   * calling the method.
   */
  OutputType EvaluateAtContinuousIndex(
    const ContinuousIndexType & index) const override;

  /** Connect the Transform.
    * This Transformation is used to calculate the new focal point position.
    * */
  itkSetObjectMacro(Transform, TransformType);
  itkGetModifiableObjectMacro(Transform, TransformType);

  /** Connect the Interpolator. */
  itkSetObjectMacro(Interpolator, InterpolatorType);
  /** Get a pointer to the Interpolator.  */
  itkGetModifiableObjectMacro(Interpolator, InterpolatorType);

  /** The focal point or position of the ray source. */
  itkSetMacro(FocalPoint, InputPointType);
  itkGetConstMacro(FocalPoint, InputPointType);

  /** The threshold above which voxels along the ray path are integrated. */
  itkSetMacro(Threshold, double);
  itkGetConstMacro(Threshold, double);

  /** Check if a point is inside the image buffer.
   * \warning For efficiency, no validity checking of
   * the input image pointer is done. */
  bool IsInsideBuffer(const PointType &) const override
  {
    return true;
  }

  bool IsInsideBuffer(const ContinuousIndexType &) const override
  {
    return true;
  }

  bool IsInsideBuffer(const IndexType &) const override
  {
    return true;
  }

#if !defined(ITKV4_COMPATIBILITY)
  SizeType GetRadius() const override
    {
    const InputImageType* input = this->GetInputImage();
    if ( !input )
      {
      itkExceptionMacro( "Input image required!" );
      }
    return input->GetLargestPossibleRegion().GetSize();
    }
#endif

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

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

  TransformPointer    m_Transform;
  InputPointType      m_FocalPoint;
  double              m_Threshold;
  InterpolatorPointer m_Interpolator;
};
} // namespace itk

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

#endif
