/*=========================================================================
 *
 *  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 itkStreamingImageFilter_h
#define itkStreamingImageFilter_h

#include "itkImageToImageFilter.h"
#include "itkImageRegionSplitterBase.h"

namespace itk
{
/** \class StreamingImageFilter
 * \brief Pipeline object to control data streaming for large data processing.
 *
 * StreamingImageFilter is a pipeline object that allows the user to control
 * how data is pulled through the pipeline.  To generate its
 * OutputRequestedRegion, this filter will divide the output into several
 * pieces (controlled by SetNumberOfStreamDivisions), and call the upstream
 * pipeline for each piece, tiling the individual outputs into one large
 * output. This reduces the memory footprint for the application since
 * each filter does not have to process the entire dataset at once.
 * This filter will produce the entire output as one image, but the upstream
 * filters will do their processing in pieces.
 *
 * \ingroup ITKSystemObjects
 * \ingroup DataProcessing
 * \ingroup ITKCommon
 */
template <typename TInputImage, typename TOutputImage>
class ITK_TEMPLATE_EXPORT StreamingImageFilter : public ImageToImageFilter<TInputImage, TOutputImage>
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(StreamingImageFilter);

  /** Standard class type aliases. */
  using Self = StreamingImageFilter;
  using Superclass = ImageToImageFilter<TInputImage, TOutputImage>;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

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

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

  /** Some type alias for the input and output. */
  using InputImageType = TInputImage;
  using InputImagePointer = typename InputImageType::Pointer;
  using InputImageRegionType = typename InputImageType::RegionType;
  using InputImagePixelType = typename InputImageType::PixelType;

  using OutputImageType = TOutputImage;
  using OutputImagePointer = typename OutputImageType::Pointer;
  using OutputImageRegionType = typename OutputImageType::RegionType;
  using OutputImagePixelType = typename OutputImageType::PixelType;
  using typename Superclass::DataObjectPointer;

  /** Dimension of input image. */
  static constexpr unsigned int InputImageDimension = InputImageType::ImageDimension;
  static constexpr unsigned int OutputImageDimension = OutputImageType::ImageDimension;

  /** SmartPointer to a region splitting object */
  using SplitterType = ImageRegionSplitterBase;
  using RegionSplitterPointer = SplitterType::Pointer;

  /** Set the number of pieces to divide the input.  The upstream pipeline
   * will be executed this many times. */
  itkSetMacro(NumberOfStreamDivisions, unsigned int);

  /** Get the number of pieces to divide the input. The upstream pipeline
   * will be executed this many times. */
  itkGetConstReferenceMacro(NumberOfStreamDivisions, unsigned int);

  /** Get/Set the helper class for dividing the input into chunks. */
  /** @ITKStartGrouping */
  itkSetObjectMacro(RegionSplitter, SplitterType);
  itkGetModifiableObjectMacro(RegionSplitter, SplitterType);
  /** @ITKEndGrouping */
  /** Override UpdateOutputData() from ProcessObject to divide upstream
   * updates into pieces. This filter does not have a GenerateData()
   * or ThreadedGenerateData() method.  Instead, all the work is done
   * in UpdateOutputData() since it must update a little, execute a little,
   * update some more, execute some more, etc. */
  void
  UpdateOutputData(DataObject * output) override;

  /** Override PropagateRequestedRegion from ProcessObject
   *  Since inside UpdateOutputData we iterate over streaming pieces
   *  we don't need to propagate up the pipeline
   */
  void
  PropagateRequestedRegion(DataObject * output) override;

  itkConceptMacro(SameDimensionCheck, (Concept::SameDimension<InputImageDimension, OutputImageDimension>));
  itkConceptMacro(InputConvertibleToOutputCheck, (Concept::Convertible<InputImagePixelType, OutputImagePixelType>));

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

private:
  unsigned int          m_NumberOfStreamDivisions{};
  RegionSplitterPointer m_RegionSplitter{};
};
} // end namespace itk

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

#endif
