/*=========================================================================
 *
 *  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 itkAttributeKeepNObjectsLabelMapFilter_h
#define itkAttributeKeepNObjectsLabelMapFilter_h

#include "itkInPlaceLabelMapFilter.h"
#include "itkAttributeLabelObject.h"

namespace itk {
/** \class AttributeKeepNObjectsLabelMapFilter
 * \brief keep N objects according to their attribute value
 *
 * AttributeKeepNObjectsLabelMapFilter keeps the N objects in a label collection image
 * with the highest (or lowest) attribute value. The attribute is provided by an
 * attribute accessor given in template parameter.
 *
 * This implementation was taken from the Insight Journal paper:
 * https://hdl.handle.net/1926/584  or
 * http://www.insight-journal.org/browse/publication/176
 *
 * \author Gaetan Lehmann. Biologie du Developpement et de la Reproduction, INRA de Jouy-en-Josas, France.
 *
 * \ingroup ImageEnhancement  MathematicalMorphologyImageFilters
 * \ingroup ITKLabelMap
 */
template<typename TImage, typename TAttributeAccessor=
    typename Functor::AttributeLabelObjectAccessor< typename TImage::LabelObjectType > >
class ITK_TEMPLATE_EXPORT AttributeKeepNObjectsLabelMapFilter :
    public InPlaceLabelMapFilter<TImage>
{
public:
  ITK_DISALLOW_COPY_AND_ASSIGN(AttributeKeepNObjectsLabelMapFilter);

  /** Standard class type aliases. */
  using Self = AttributeKeepNObjectsLabelMapFilter;
  using Superclass = InPlaceLabelMapFilter<TImage>;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  /** Some convenient type alias. */
  using ImageType = TImage;
  using ImagePointer = typename ImageType::Pointer;
  using ImageConstPointer = typename ImageType::ConstPointer;
  using PixelType = typename ImageType::PixelType;
  using IndexType = typename ImageType::IndexType;
  using LabelObjectType = typename ImageType::LabelObjectType;

  using AttributeAccessorType = TAttributeAccessor;
  using AttributeValueType = typename AttributeAccessorType::AttributeValueType;

  /** ImageDimension constants */
  static constexpr unsigned int ImageDimension = TImage::ImageDimension;

  /** Standard New method. */
  itkNewMacro(Self);

  /** Runtime information support. */
  itkTypeMacro(AttributeKeepNObjectsLabelMapFilter,
               InPlaceLabelMapFilter);

#ifdef ITK_USE_CONCEPT_CHECKING
  // Begin concept checking
/*  itkConceptMacro(InputEqualityComparableCheck,
    (Concept::EqualityComparable<InputImagePixelType>));
  itkConceptMacro(IntConvertibleToInputCheck,
    (Concept::Convertible<int, InputImagePixelType>));
  itkConceptMacro(InputOStreamWritableCheck,
    (Concept::OStreamWritable<InputImagePixelType>));*/
  // End concept checking
#endif

  /**
   * Set/Get the ordering of the objects. By default, the ones with the
   * highest value are kept. Turming ReverseOrdering to true make this filter
   * keep the objects with the smallest values
   */
  itkSetMacro( ReverseOrdering, bool );
  itkGetConstReferenceMacro( ReverseOrdering, bool );
  itkBooleanMacro( ReverseOrdering );

  /**
   * Set/Get the number of objects to keep
   */
  itkSetMacro( NumberOfObjects, SizeValueType );
  itkGetConstReferenceMacro( NumberOfObjects, SizeValueType );

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

  void GenerateData() override;

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

  class ReverseComparator
    {
    public:
    bool operator()( const typename LabelObjectType::Pointer & a, const typename LabelObjectType::Pointer & b )
      {
      return m_Accessor( a ) < m_Accessor( b );
      }
    ReverseComparator() : m_Accessor() {}
    private:
     AttributeAccessorType m_Accessor;
    };

  class Comparator
    {
  public:
    bool operator()( const typename LabelObjectType::Pointer & a, const typename LabelObjectType::Pointer & b )
      {
      return m_Accessor( a ) > m_Accessor( b );
      }
    Comparator(): m_Accessor () {}
  private:
    AttributeAccessorType m_Accessor;
    };

private:
  bool           m_ReverseOrdering;
  SizeValueType  m_NumberOfObjects;

}; // end of class

} // end namespace itk

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

#endif
