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#ifndef PCL_PYRAMID_FEATURE_MATCHING_H_
#define PCL_PYRAMID_FEATURE_MATCHING_H_

#include <pcl/pcl_base.h>
#include <pcl/point_representation.h>

namespace pcl
{
  /**
   * \brief Class that compares two sets of features by using a multiscale representation of the features inside a
   * pyramid. Each level of the pyramid offers information about the similarity of the two feature sets.
   * \note Works with any Point/Feature type which has a PointRepresentation implementation
   * \note The only parameters it needs are the input dimension ranges and the output dimension ranges. The input
   * dimension ranges represent the ranges in which each dimension of the feature vector lies. As described in the
   * paper, a minimum inter-vector distance of sqrt(nr_dims)/2 is needed. As such, the target dimension range parameter
   * is used in order to augment/reduce the range for each dimension in order to obtain the necessary minimal
   * inter-vector distance and to add/subtract weight to/from certain dimensions of the feature vector.
   *
   * Follows the algorithm presented in the publication:
   *    Grauman, K. & Darrell, T.
   *    The Pyramid Match Kernel: Discriminative Classification with Sets of Image Features
   *    Tenth IEEE International Conference on Computer Vision ICCV05 Volume 1
   *    October 2005
   *
   * \author Alexandru-Eugen Ichim
   */
  template <typename PointFeature>
  class PyramidFeatureHistogram : public PCLBase<PointFeature>
  {
    public:
      using PCLBase<PointFeature>::input_;

      typedef boost::shared_ptr<PyramidFeatureHistogram<PointFeature> > Ptr;
      typedef Ptr PyramidFeatureHistogramPtr;
      typedef boost::shared_ptr<const pcl::PointRepresentation<PointFeature> > FeatureRepresentationConstPtr;


      /** \brief Empty constructor that instantiates the feature representation variable */
      PyramidFeatureHistogram ();

      /** \brief Method for setting the input dimension range parameter.
       * \note Please check the PyramidHistogram class description for more details about this parameter.
       */
      inline void
      setInputDimensionRange (std::vector<std::pair<float, float> > &dimension_range_input)
      { dimension_range_input_ = dimension_range_input; }

      /** \brief Method for retrieving the input dimension range vector */
      inline std::vector<std::pair<float, float> >
      getInputDimensionRange () { return dimension_range_input_; }

      /** \brief Method to set the target dimension range parameter.
       * \note Please check the PyramidHistogram class description for more details about this parameter.
       */
      inline void
      setTargetDimensionRange (std::vector<std::pair<float, float> > &dimension_range_target)
      { dimension_range_target_ = dimension_range_target; }

      /** \brief Method for retrieving the target dimension range vector */
      inline std::vector<std::pair<float, float> >
      getTargetDimensionRange () { return dimension_range_target_; }

      /** \brief Provide a pointer to the feature representation to use to convert features to k-D vectors.
       * \param feature_representation the const boost shared pointer to a PointRepresentation
       */
      inline void
      setPointRepresentation (const FeatureRepresentationConstPtr& feature_representation) { feature_representation_ = feature_representation; }

      /** \brief Get a pointer to the feature representation used when converting features into k-D vectors. */
      inline FeatureRepresentationConstPtr const
      getPointRepresentation () { return feature_representation_; }

      /** \brief The central method for inserting the feature set inside the pyramid and obtaining the complete pyramid */
      void
      compute ();

      /** \brief Checks whether the pyramid histogram has been computed */
      inline bool
      isComputed () { return is_computed_; }

      /** \brief Static method for comparing two pyramid histograms that returns a floating point value between 0 and 1,
       * representing the similiarity between the feature sets on which the two pyramid histograms are based.
       * \param pyramid_a Pointer to the first pyramid to be compared (needs to be computed already).
       * \param pyramid_b Pointer to the second pyramid to be compared (needs to be computed already).
       */
      static float
      comparePyramidFeatureHistograms (const PyramidFeatureHistogramPtr &pyramid_a,
                                       const PyramidFeatureHistogramPtr &pyramid_b);


    private:
      size_t nr_dimensions, nr_levels, nr_features;
      std::vector<std::pair<float, float> > dimension_range_input_, dimension_range_target_;
      FeatureRepresentationConstPtr feature_representation_;
      bool is_computed_;

      /** \brief Checks for input inconsistencies and initializes the underlying data structures */
      bool
      initializeHistogram ();

      /** \brief Converts a feature in templated form to an STL vector. This is the point where the conversion from the
       * input dimension range to the target dimension range is done.
       */
      void
      convertFeatureToVector (const PointFeature &feature,
                              std::vector<float> &feature_vector);

      /** \brief Adds a feature vector to its corresponding bin at each level in the pyramid */
      void
      addFeature (std::vector<float> &feature);

      /** \brief Access the pyramid bin given the position of the bin at the given pyramid level
       * and the pyramid level
       * \param access index of the bin at the respective level
       * \param level the level in the pyramid
       */
      inline unsigned int&
      at (std::vector<size_t> &access,
          size_t &level);

      /** \brief Access the pyramid bin given a feature vector and the pyramid level
       * \param feature the feature in vectorized form
       * \param level the level in the pyramid
       */
      inline unsigned int&
      at (std::vector<float> &feature,
          size_t &level);

      /** \brief Structure for representing a single pyramid histogram level */
      struct PyramidFeatureHistogramLevel
      {
        PyramidFeatureHistogramLevel () :
          hist (), 
          bins_per_dimension (),
          bin_step ()
        {
        }

        PyramidFeatureHistogramLevel (std::vector<size_t> &a_bins_per_dimension, std::vector<float> &a_bin_step) : 
          hist (), 
          bins_per_dimension (a_bins_per_dimension),
          bin_step (a_bin_step)
        {
          initializeHistogramLevel ();
        }

        void
        initializeHistogramLevel ();

        std::vector<unsigned int> hist;
        std::vector<size_t> bins_per_dimension;
        std::vector<float> bin_step;
      };
      std::vector<PyramidFeatureHistogramLevel> hist_levels;
  };
}

#ifdef PCL_NO_PRECOMPILE
#include <pcl/registration/impl/pyramid_feature_matching.hpp>
#endif

#endif    // PCL_PYRAMID_FEATURE_MATCHING_H_
