/*=========================================================================
 *
 *  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 itkImageSliceConstIteratorWithIndex_h
#define itkImageSliceConstIteratorWithIndex_h

#include "itkImageConstIteratorWithIndex.h"

namespace itk
{
/** \class ImageSliceConstIteratorWithIndex
 * \brief Multi-dimensional image iterator which only walks a region.
 *
 * A multi-dimensional image iterator that extends the
 * ImageLinearConstIteratorWithIndex from iteration along lines in an image to
 * iteration along both lines and planes (slices) within an image.  A slice is
 * defined as a 2D plane spanned by two vectors pointing along orthogonal
 * coordinate axes. The slice orientation of the iterator is defined by
 * specifying its two spanning axes using the methods:
   \code
   SetFirstDirection(n)
   SetSecondDirection(n)
   \endcode
 * where n is the number of the axis.
 *
 * Use the following methods to move the iterator between slices:
   \code
   NextSlice()
   PreviousSlice()
   \endcode
 *
 * To test the position of the iterator with respect to the end or beginning of
 * the slice use the following methods:
   \code
   IsAtReverseEndOfSlice()
   IsAtEndOfSlice()
   \endcode
 *
 * The following code, for example, illustrates the typical use of this
 * iterator.  For more information please see the Software Guide.
 *
   \code

   ImageSliceConstIteratorWithIndex<ImageType> it( image, image->GetRequestedRegion() );

   it.SetFirstDirection(2);
   it.SetSecondDirection(0);

   it.GoToBegin();
   while( !it.IsAtEnd() )
   {
     while( !it.IsAtEndOfSlice() )
     {
       while( !it.IsAtEndOfLine() )
       {
          value = it.Get();  // it.Set() doesn't exist in the Const Iterator
          ++it;
       }
       it.NextLine();
     }
     it.NextSlice();
    }

    \endcode
 *
 *
 * \par MORE INFORMATION
 * For a complete description of the ITK Image Iterators and their API, please
 * see the Iterators chapter in the ITK Software Guide.  The ITK Software Guide
 * is available in print and as a free .pdf download from https://www.itk.org.
 *
 * \ingroup ImageIterators
 *
 * \sa ImageConstIterator \sa ConditionalConstIterator
 * \sa ConstNeighborhoodIterator \sa ConstShapedNeighborhoodIterator
 * \sa ConstSliceIterator  \sa CorrespondenceDataStructureIterator
 * \sa FloodFilledFunctionConditionalConstIterator
 * \sa FloodFilledImageFunctionConditionalConstIterator
 * \sa FloodFilledImageFunctionConditionalIterator
 * \sa FloodFilledSpatialFunctionConditionalConstIterator
 * \sa FloodFilledSpatialFunctionConditionalIterator
 * \sa ImageConstIterator \sa ImageConstIteratorWithIndex
 * \sa ImageIterator \sa ImageIteratorWithIndex
 * \sa ImageLinearConstIteratorWithIndex  \sa ImageLinearIteratorWithIndex
 * \sa ImageRandomConstIteratorWithIndex  \sa ImageRandomIteratorWithIndex
 * \sa ImageRegionConstIterator \sa ImageRegionConstIteratorWithIndex
 * \sa ImageRegionExclusionConstIteratorWithIndex
 * \sa ImageRegionExclusionIteratorWithIndex
 * \sa ImageRegionIterator  \sa ImageRegionIteratorWithIndex
 * \sa ImageRegionReverseConstIterator  \sa ImageRegionReverseIterator
 * \sa ImageReverseConstIterator  \sa ImageReverseIterator
 * \sa ImageSliceConstIteratorWithIndex  \sa ImageSliceIteratorWithIndex
 * \sa NeighborhoodIterator \sa PathConstIterator  \sa PathIterator
 * \sa ShapedNeighborhoodIterator  \sa SliceIterator
 * \sa ImageConstIteratorWithIndex
 * \ingroup ITKCommon
 */
template <typename TImage>
class ITK_TEMPLATE_EXPORT ImageSliceConstIteratorWithIndex : public ImageConstIteratorWithIndex<TImage>
{
public:
  /** Standard class type aliases. */
  using Self = ImageSliceConstIteratorWithIndex;
  using Superclass = ImageConstIteratorWithIndex<TImage>;

  /** Inherit types from the superclass */
  using typename Superclass::IndexType;
  using typename Superclass::SizeType;
  using typename Superclass::OffsetType;
  using typename Superclass::RegionType;
  using typename Superclass::ImageType;
  using typename Superclass::PixelContainer;
  using typename Superclass::PixelContainerPointer;
  using typename Superclass::InternalPixelType;
  using typename Superclass::PixelType;
  using typename Superclass::AccessorType;

  /** Default constructor. Needed since we provide a cast constructor. */
  ImageSliceConstIteratorWithIndex()
    : ImageConstIteratorWithIndex<TImage>()
  {}

  /** Constructor establishes an iterator to walk a particular image and a
   * particular region of that image. */
  ImageSliceConstIteratorWithIndex(const ImageType * ptr, const RegionType & region)
    : ImageConstIteratorWithIndex<TImage>(ptr, region)
    , m_PixelJump(0)
    , m_LineJump(0)
    , m_Direction_A(0)
    , m_Direction_B(1)
  {}

  /** Constructor that can be used to cast from an ImageIterator to an
   * ImageSliceConstIteratorWithIndex. Many routines return an ImageIterator, but for a
   * particular task, you may want an ImageSliceConstIteratorWithIndex.  Rather than
   * provide overloaded APIs that return different types of Iterators, itk
   * returns ImageIterators and uses constructors to cast from an
   * ImageIterator to a ImageSliceConstIteratorWithIndex. */
  ImageSliceConstIteratorWithIndex(const ImageConstIteratorWithIndex<TImage> & it)
  {
    this->ImageConstIteratorWithIndex<TImage>::operator=(it);
  }

  /** Go to the next line
   * \sa operator++ \sa EndOfLine \sa End \sa NextSlice */
  void
  NextLine();

  /** Go to the first pixel of the current slice */
  void
  GoToBeginOfSlice();

  /** Go to the next slice
   * \sa operator++ \sa EndOfLine \sa End */
  void
  NextSlice();

  /** Go to the next line
   * \sa operator-- \sa BeginOfLine \sa BeginOfSlice \sa Begin */
  void
  PreviousLine();

  /** Go to the next slice
   * \sa operator-- \sa BeginOfLine \sa BeginOfSlice \sa Begin */
  void
  PreviousSlice();

  /** Test if the index is at the end of line */
  bool
  IsAtEndOfLine() const;

  /** Test if the index is at the end of the slice */
  bool
  IsAtEndOfSlice() const;

  /** Test if the index is at the begin of line */
  bool
  IsAtReverseEndOfLine() const;

  /** Test if the index is at the begin of the slice */
  bool
  IsAtReverseEndOfSlice() const;

  /** Set the fastest direction of movement */
  void
  SetFirstDirection(unsigned int direction);

  /** Set the second fastest direction of movement */
  void
  SetSecondDirection(unsigned int direction);

  /** Increment (prefix) the selected dimension.
   * No bounds checking is performed.
   * \sa operator-- \sa GetIndex */
  inline Self &
  operator++();

  /** Decrement (prefix) the selected dimension.
   * No bounds checking is performed.
   * \sa operator++ \sa GetIndex */
  inline Self &
  operator--();

private:
  SizeValueType m_PixelJump;
  SizeValueType m_LineJump;
  unsigned int  m_Direction_A;
  unsigned int  m_Direction_B;
};
} // end namespace itk

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

#endif