/*=========================================================================
 *
 *  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 __itkDirectedHausdorffDistanceImageFilter_h
#define __itkDirectedHausdorffDistanceImageFilter_h

#include "itkImageToImageFilter.h"
#include "itkNumericTraits.h"
#include "itkArray.h"
#include "itkCompensatedSummation.h"

namespace itk
{
/** \class DirectedHausdorffDistanceImageFilter
 * \brief Computes the directed Hausdorff distance between the set of
 * non-zero pixels of two images.
 *
 * DirectedHausdorffDistanceImageFilter computes the distance between the set
 * non-zero pixels of two images using the following formula:
 * \f[ h(A,B) = \max_{a \in A} \min_{b \in B} \| a - b\| \f]
 * where \f$A\f$ and \f$B\f$ are respectively the set of non-zero pixels
 * in the first and second input images. It identifies the point \f$ a \in A \f$
 * that is farthest from any point of \f$B\f$ and measures the distance from \f$a\f$
 * to the nearest neighbor in \f$B\f$. Note that this function is not
 * symmetric and hence is not a true distance.
 *
 * In particular, this filter uses the SignedMaurerDistanceMapImageFilter inside to
 * compute distance map from all non-zero pixels in the second image. It then
 * finds the largest distance (in pixels) within the set of all non-zero pixels in the first
 * image.  The largest distance is returned by the method GetDirectedHausdorffDistance().
 *
 * In addition, this filter computes the average Hausdorff distance.
 * This average is defined as the average of all minimum distances with any negative
 * distances set to 0 since they indicate overlapping regions.
 * By definition, the distance map computes the minimum distances.
 * However, since this filter is computed using a signed distance transform, the negative
 * distance values are first set to 0 before calculating the average.
 * The average distance is returned by the method GetAverageHausdorffDistance().
 *
 * Use HausdorffDistanceImageFilter to compute the full Hausdorff distance.
 *
 * This filter requires the largest possible region of the first image
 * and the same corresponding region in the second image.
 * It behaves as filter with
 * two input and one output. Thus it can be inserted in a pipeline with
 * other filters. The filter passes the first input through unmodified.
 *
 * This filter is templated over the two input image type. It assume
 * both image have the same number of dimensions.
 *
 * \sa MaurerDistanceMapImageFilter
 * \sa HausdorffDistanceImageFilter
 *
 * \ingroup MultiThreaded
 * \ingroup ITKDistanceMap
 */
template< typename TInputImage1, typename TInputImage2 >
class DirectedHausdorffDistanceImageFilter:
  public ImageToImageFilter< TInputImage1, TInputImage1 >
{
public:
  /** Standard Self typedef */
  typedef DirectedHausdorffDistanceImageFilter             Self;
  typedef ImageToImageFilter< TInputImage1, TInputImage1 > Superclass;
  typedef SmartPointer< Self >                             Pointer;
  typedef SmartPointer< const Self >                       ConstPointer;

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

  /** Runtime information support. */
  itkTypeMacro(DirectedHausdorffDistanceImageFilter, ImageToImageFilter);

  /** Image related typedefs. */
  typedef TInputImage1                        InputImage1Type;
  typedef TInputImage2                        InputImage2Type;
  typedef typename TInputImage1::Pointer      InputImage1Pointer;
  typedef typename TInputImage2::Pointer      InputImage2Pointer;
  typedef typename TInputImage1::ConstPointer InputImage1ConstPointer;
  typedef typename TInputImage2::ConstPointer InputImage2ConstPointer;

  typedef typename TInputImage1::RegionType RegionType;
  typedef typename TInputImage1::SizeType   SizeType;
  typedef typename TInputImage1::IndexType  IndexType;

  typedef typename TInputImage1::PixelType InputImage1PixelType;
  typedef typename TInputImage2::PixelType InputImage2PixelType;

  /** Image related typedefs. */
  itkStaticConstMacro(ImageDimension, unsigned int,
                      TInputImage1::ImageDimension);

  /** Type to use form computations. */
  typedef typename NumericTraits< InputImage1PixelType >::RealType RealType;

  /** Set the first input. */
  void SetInput1(const InputImage1Type *image);

  /** Set the second input. */
  void SetInput2(const InputImage2Type *image);

  /** Get the first input. */
  const InputImage1Type * GetInput1(void);

  /** Get the second input. */
  const InputImage2Type * GetInput2(void);

  /** Set if image spacing should be used in computing distances. */
  itkSetMacro(UseImageSpacing, bool);
  itkGetConstMacro( UseImageSpacing, bool );

  /** Return the computed directed Hausdorff distance. */
  itkGetConstMacro(DirectedHausdorffDistance, RealType);
  itkGetConstMacro(AverageHausdorffDistance, RealType);

#ifdef ITK_USE_CONCEPT_CHECKING
  // Begin concept checking
  itkConceptMacro( InputHasNumericTraitsCheck,
                   ( Concept::HasNumericTraits< InputImage1PixelType > ) );
  // End concept checking
#endif

protected:
  DirectedHausdorffDistanceImageFilter();
  ~DirectedHausdorffDistanceImageFilter(){}
  void PrintSelf(std::ostream & os, Indent indent) const;

  /** Pass the input through unmodified. Do this by Grafting in the
   * AllocateOutputs method. */
  void AllocateOutputs();

  /** Initialize some accumulators before the threads run. */
  void BeforeThreadedGenerateData();

  /** Do final mean and variance computation from data accumulated in threads.
    */
  void AfterThreadedGenerateData();

  /** Multi-thread version GenerateData. */
  void  ThreadedGenerateData(const RegionType &
                             outputRegionForThread,
                             ThreadIdType threadId);

  // Override since the filter needs all the data for the algorithm
  void GenerateInputRequestedRegion();

  // Override since the filter produces all of its output
  void EnlargeOutputRequestedRegion(DataObject *data);

private:
  DirectedHausdorffDistanceImageFilter(const Self &); //purposely not implemented
  void operator=(const Self &);                       //purposely not implemented

  typedef Image< RealType, itkGetStaticConstMacro(ImageDimension) > DistanceMapType;
  typedef typename DistanceMapType::Pointer                         DistanceMapPointer;


  DistanceMapPointer      m_DistanceMap;

  Array< RealType >       m_MaxDistance;
  Array< IdentifierType > m_PixelCount;

  typedef itk::CompensatedSummation< RealType > CompensatedSummationType;
  std::vector< CompensatedSummationType >       m_Sum;

  RealType                m_DirectedHausdorffDistance;
  RealType                m_AverageHausdorffDistance;
  bool                    m_UseImageSpacing;
}; // end of class
} // end namespace itk

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

#endif
