/*=========================================================================
 *
 *  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 __itkHistogramToRunLengthFeaturesFilter_h
#define __itkHistogramToRunLengthFeaturesFilter_h

#include "itkHistogram.h"
#include "itkMacro.h"
#include "itkProcessObject.h"
#include "itkSimpleDataObjectDecorator.h"

namespace itk {
namespace Statistics {
/** \class HistogramToRunLengthFeaturesFilter
 *  \brief This class computes texture feature coefficients from a grey level
 * run-length matrix.
 *
 * By default, run length features are computed for each spatial
 * direction and then averaged afterward, so it is possible to access the
 * standard deviations of the texture features. These values give a clue as
 * to texture anisotropy. However, doing this is much more work, because it
 * involved computing one for each offset given. To compute a single matrix
 * using the first offset, call FastCalculationsOn(). If this is called,
 * then the texture standard deviations will not be computed (and will be set
 * to zero), but texture computation will be much faster.
 *
 * This class is templated over the input histogram type.
 *
 * Print references:
 * M. M. Galloway. Texture analysis using gray level run lengths. Computer
 * Graphics and Image Processing, 4:172-179, 1975.
 *
 * A. Chu, C. M. Sehgal, and J. F. Greenleaf. Use of gray value distribution of
 * run lengths for texture analysis.  Pattern Recognition Letters, 11:415-420,
 * 1990.
 *
 * B. R. Dasarathy and E. B. Holder. Image characterizations based on joint
 * gray-level run-length distributions. Pattern Recognition Letters, 12:490-502,
 * 1991.
 *
 * IJ article: http://hdl.handle.net/1926/1374
 *
 * \sa ScalarImageToRunLengthFeaturesFilter
 * \sa ScalarImageToRunLengthMatrixFilter
 * \sa HistogramToRunLengthFeaturesFilter
 *
 * \author: Nick Tustison
 * \ingroup ITKStatistics
 */

template< typename THistogram >
class HistogramToRunLengthFeaturesFilter : public ProcessObject
{
public:
  /** Standard typedefs */
  typedef HistogramToRunLengthFeaturesFilter     Self;
  typedef ProcessObject                          Superclass;
  typedef SmartPointer<Self>                     Pointer;
  typedef SmartPointer<const Self>               ConstPointer;

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

  /** standard New() method support */
  itkNewMacro( Self );

  typedef THistogram                                      HistogramType;
  typedef typename HistogramType::Pointer                 HistogramPointer;
  typedef typename HistogramType::ConstPointer            HistogramConstPointer;
  typedef typename HistogramType::MeasurementType         MeasurementType;
  typedef typename HistogramType::MeasurementVectorType   MeasurementVectorType;
  typedef typename HistogramType::IndexType               IndexType;
  typedef typename HistogramType::
    TotalAbsoluteFrequencyType                            FrequencyType;

  /** Method to Set/Get the input Histogram */
  using Superclass::SetInput;
  void SetInput ( const HistogramType * histogram );
  const HistogramType * GetInput() const;

  /** Smart Pointer type to a DataObject. */
  typedef DataObject::Pointer                   DataObjectPointer;

  /** Type of DataObjects used for scalar outputs */
  typedef SimpleDataObjectDecorator<MeasurementType>     MeasurementObjectType;

  /** Methods to return the short run emphasis. */
  MeasurementType GetShortRunEmphasis() const;
  const MeasurementObjectType* GetShortRunEmphasisOutput() const;

  /** Methods to return the long run emphasis. */
  MeasurementType GetLongRunEmphasis() const;
  const MeasurementObjectType* GetLongRunEmphasisOutput() const;

  /** Methods to return the grey level nonuniformity. */
  MeasurementType GetGreyLevelNonuniformity() const;
  const MeasurementObjectType* GetGreyLevelNonuniformityOutput() const;

  /** Methods to return the run length nonuniformity. */
  MeasurementType GetRunLengthNonuniformity() const;
  const MeasurementObjectType* GetRunLengthNonuniformityOutput() const;

  /** Methods to return the low grey level run emphasis. */
  MeasurementType GetLowGreyLevelRunEmphasis() const;
  const MeasurementObjectType* GetLowGreyLevelRunEmphasisOutput() const;

  /** Methods to return the high grey level run emphasis. */
  MeasurementType GetHighGreyLevelRunEmphasis() const;
  const MeasurementObjectType* GetHighGreyLevelRunEmphasisOutput() const;

  /** Methods to return the short run low grey level run emphasis. */
  MeasurementType GetShortRunLowGreyLevelEmphasis() const;
  const MeasurementObjectType* GetShortRunLowGreyLevelEmphasisOutput() const;

  /** Methods to return the short run high grey level run emphasis. */
  MeasurementType GetShortRunHighGreyLevelEmphasis() const;
  const MeasurementObjectType* GetShortRunHighGreyLevelEmphasisOutput() const;

  /** Methods to return the long run low grey level run emphasis. */
  MeasurementType GetLongRunLowGreyLevelEmphasis() const;
  const MeasurementObjectType* GetLongRunLowGreyLevelEmphasisOutput() const;

  /** Methods to return the long run high grey level run emphasis. */
  MeasurementType GetLongRunHighGreyLevelEmphasis() const;
  const MeasurementObjectType* GetLongRunHighGreyLevelEmphasisOutput() const;

  itkGetMacro( TotalNumberOfRuns, unsigned long );

  /** Run-length feature types */
  typedef enum
    {
    ShortRunEmphasis,
    LongRunEmphasis,
    GreyLevelNonuniformity,
    RunLengthNonuniformity,
    LowGreyLevelRunEmphasis,
    HighGreyLevelRunEmphasis,
    ShortRunLowGreyLevelEmphasis,
    ShortRunHighGreyLevelEmphasis,
    LongRunLowGreyLevelEmphasis,
    LongRunHighGreyLevelEmphasis
    }  RunLengthFeatureName;

  /** convenience method to access the run length values */
  MeasurementType GetFeature( RunLengthFeatureName name );

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

  /** Make a DataObject to be used for output output. */
  typedef ProcessObject::DataObjectPointerArraySizeType DataObjectPointerArraySizeType;
  using Superclass::MakeOutput;
  virtual DataObjectPointer MakeOutput( DataObjectPointerArraySizeType ) ITK_OVERRIDE;

  virtual void GenerateData() ITK_OVERRIDE;

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

  unsigned long                           m_TotalNumberOfRuns;

};

} // end of namespace Statistics
} // end of namespace itk

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

#endif
