// Copyright (c) 2002,2011 Utrecht University (The Netherlands).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
//
// $URL: https://github.com/CGAL/cgal/blob/v6.0.1/Spatial_searching/include/CGAL/Weighted_Minkowski_distance.h $
// $Id: include/CGAL/Weighted_Minkowski_distance.h 50cfbde3b84 $
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s)     : Hans Tangelder (<hanst@cs.uu.nl>)

// Note: Use p=0 to denote the weighted Linf-distance
// For 0<p<1 Lp is not a metric

#ifndef CGAL_WEIGHTED_MINKOWSKI_DISTANCE_H
#define CGAL_WEIGHTED_MINKOWSKI_DISTANCE_H

#include <CGAL/license/Spatial_searching.h>

#include <CGAL/array.h>
#include <CGAL/assertions.h>
#include <CGAL/number_utils.h>
#include <CGAL/double.h>
#include <CGAL/Kd_tree_rectangle.h>
#include <CGAL/Spatial_searching/internal/Get_dimension_tag.h>

#include <cmath>
#include <vector>

namespace CGAL {
  namespace internal {
    template<class T, class Dim>
      struct Array_or_vector_selector {
        typedef std::vector<T> type;
        static void resize(type&v, std::size_t d) { v.resize(d); }
      };
    template<class T, int D>
      struct Array_or_vector_selector<T, Dimension_tag<D> > {
        typedef std::array<T,D> type;
        static void resize(type&, std::size_t CGAL_assertion_code(d)) { CGAL_assertion(d==D); }
      };
  }

  template <class SearchTraits>
  class Weighted_Minkowski_distance {
    SearchTraits traits;
    public:

    typedef typename SearchTraits::Point_d Point_d;
    typedef Point_d                        Query_item;
    typedef typename SearchTraits::FT      FT;
    typedef typename internal::Get_dimension_tag<SearchTraits>::Dimension Dimension;
    typedef internal::Array_or_vector_selector<FT,Dimension> Weight_vector_traits;
    typedef typename Weight_vector_traits::type Weight_vector;

    private:

    typedef typename SearchTraits::Cartesian_const_iterator_d Coord_iterator;
    double power;


    Weight_vector the_weights;


    FT pow(FT ft) const
    {
      return FT(std::pow(to_double(ft), power));
    }

    FT pow(FT ft, FT p) const
    {
      return FT(std::pow(to_double(ft), to_double(p)));
    }

    public:


    // default constructor
    Weighted_Minkowski_distance(const SearchTraits& traits_=SearchTraits())
      : traits(traits_),power(2)
    {}

    Weighted_Minkowski_distance(const int d,const SearchTraits& traits_=SearchTraits())
      : traits(traits_),power(2), the_weights(d)
    {
      for (int i = 0; i < d; ++i) the_weights[i]=FT(1);
    }

    //default copy constructor and destructor


    template <class InputIterator>
    Weighted_Minkowski_distance (FT pow, int dim,
                                 InputIterator begin,
                                 InputIterator CGAL_assertion_code(end),
                                 const SearchTraits& traits_=SearchTraits())
      : traits(traits_),power(to_double(pow))
    {
      CGAL_assertion(is_positive(power));
      Weight_vector_traits::resize(the_weights, dim);
      for (int i = 0; i < dim; ++i){
        the_weights[i] = *begin;
        ++begin;
        CGAL_assertion(the_weights[i]>=FT(0));
      }
      CGAL_assertion(begin == end);
    }


    inline FT transformed_distance(const Query_item& q, const Point_d& p) const {
        return transformed_distance(q,p, Dimension());
    }

    //Dynamic version for runtime dimension
    inline
    FT
    transformed_distance(const Query_item& q, const Point_d& p, Dynamic_dimension_tag) const
    {
      FT distance = FT(0);
      typename SearchTraits::Construct_cartesian_const_iterator_d construct_it=
        traits.construct_cartesian_const_iterator_d_object();
      Coord_iterator qit = construct_it(q),
                     qe = construct_it(q,1),
                     pit = construct_it(p);
      if (is_zero(power)) {
        for (unsigned int i = 0; qit != qe; ++qit, ++i)
          if (the_weights[i] * CGAL::abs((*qit) - (*pit)) > distance)
            distance = the_weights[i] * CGAL::abs((*qit)-(*pit));
      }
      else
        for (unsigned int i = 0; qit != qe; ++qit, ++i)
          distance +=
            the_weights[i] * pow(CGAL::abs((*qit)-(*pit)));
      return distance;
    }

    //Generic version for DIM > 3
    template <int DIM>
    inline FT
    transformed_distance(const Query_item& q, const Point_d& p, Dimension_tag<DIM>) const
    {
      FT distance = FT(0);
      typename SearchTraits::Construct_cartesian_const_iterator_d construct_it=
        traits.construct_cartesian_const_iterator_d_object();
      Coord_iterator qit = construct_it(q),
                     qe = construct_it(q,1),
                     pit = construct_it(p);
      if (is_zero(power)) {
        for (unsigned int i = 0; qit != qe; ++qit, ++i)
          if (the_weights[i] * CGAL::abs((*qit) - (*pit)) > distance)
            distance = the_weights[i] * CGAL::abs((*qit)-(*pit));
      }
      else
        for (unsigned int i = 0; qit != qe; ++qit, ++i)
          distance +=
            the_weights[i] * pow(CGAL::abs((*qit)-(*pit)));
      return distance;
    }

    //DIM = 2 loop unrolled
    inline FT
    transformed_distance(const Query_item& q, const Point_d& p, Dimension_tag<2>) const
    {
      FT distance = FT(0);
      typename SearchTraits::Construct_cartesian_const_iterator_d construct_it=
        traits.construct_cartesian_const_iterator_d_object();
      Coord_iterator qit = construct_it(q),
                     pit = construct_it(p);
      if (is_zero(power)) {
          if (the_weights[0] * CGAL::abs((*qit) - (*pit)) > distance)
            distance = the_weights[0] * CGAL::abs((*qit)-(*pit));
          qit++;pit++;
          if (the_weights[1] * CGAL::abs((*qit) - (*pit)) > distance)
            distance = the_weights[1] * CGAL::abs((*qit)-(*pit));
      }
      else{
          distance +=
            the_weights[0] * pow(CGAL::abs((*qit)-(*pit)));
          qit++;pit++;
          distance +=
            the_weights[1] * pow(CGAL::abs((*qit)-(*pit)));
      }
      return distance;
    }

    //DIM = 3 loop unrolled
    inline FT
    transformed_distance(const Query_item& q, const Point_d& p, Dimension_tag<3>) const
    {
      FT distance = FT(0);
      typename SearchTraits::Construct_cartesian_const_iterator_d construct_it=
        traits.construct_cartesian_const_iterator_d_object();
      Coord_iterator qit = construct_it(q),
                     pit = construct_it(p);
      if (is_zero(power)) {
          if (the_weights[0] * CGAL::abs((*qit) - (*pit)) > distance)
            distance = the_weights[0] * CGAL::abs((*qit)-(*pit));
          qit++;pit++;
          if (the_weights[1] * CGAL::abs((*qit) - (*pit)) > distance)
            distance = the_weights[1] * CGAL::abs((*qit)-(*pit));
          qit++;pit++;
          if (the_weights[2] * CGAL::abs((*qit) - (*pit)) > distance)
            distance = the_weights[2] * CGAL::abs((*qit)-(*pit));
      }
      else{
          distance +=
            the_weights[0] * pow(CGAL::abs((*qit)-(*pit)));
          qit++;pit++;
          distance +=
            the_weights[1] * pow(CGAL::abs((*qit)-(*pit)));
          qit++;pit++;
          distance +=
            the_weights[2] * pow(CGAL::abs((*qit)-(*pit)));
      }
      return distance;
    }

    inline
    FT
    min_distance_to_rectangle(const Query_item& q,
                              const Kd_tree_rectangle<FT,Dimension>& r) const
    {
      FT distance = FT(0);
      typename SearchTraits::Construct_cartesian_const_iterator_d construct_it=
        traits.construct_cartesian_const_iterator_d_object();
      Coord_iterator qit = construct_it(q), qe = construct_it(q,1);
      if (is_zero(power))
        {
          for (unsigned int i = 0; qit != qe; ++qit, ++i) {
            if (the_weights[i]*(r.min_coord(i) -
                                (*qit)) > distance)
              distance = the_weights[i] * (r.min_coord(i)-
                                           (*qit));
            if (the_weights[i] * ((*qit) - r.max_coord(i)) >
                distance)
              distance = the_weights[i] *
                ((*qit)-r.max_coord(i));
          }
        }
      else
        {
          for (unsigned int i = 0; qit != qe; ++qit, ++i) {
            if ((*qit) < r.min_coord(i))
              distance += the_weights[i] *
                pow(r.min_coord(i)-(*qit));
            if ((*qit) > r.max_coord(i))
              distance += the_weights[i] *
                pow((*qit)-r.max_coord(i));
          }
        };
      return distance;
    }

    inline
    FT
    min_distance_to_rectangle(const Query_item& q,
                              const Kd_tree_rectangle<FT,Dimension>& r,std::vector<FT>& dists) const {
      FT distance = FT(0);
      typename SearchTraits::Construct_cartesian_const_iterator_d construct_it=
        traits.construct_cartesian_const_iterator_d_object();
      Coord_iterator qit = construct_it(q), qe = construct_it(q,1);
      if (is_zero(power))
        {
          for (unsigned int i = 0; qit != qe; ++qit, ++i) {
            if (the_weights[i]*(r.min_coord(i) -
                                (*qit)) > distance){
              dists[i] = (r.min_coord(i)-
                (*qit));
              distance = the_weights[i] * dists[i];
            }
            if (the_weights[i] * ((*qit) - r.max_coord(i)) >
                distance){
                  dists[i] =
                ((*qit)-r.max_coord(i));
              distance = the_weights[i] * dists[i];
            }
          }
        }
      else
        {
          for (unsigned int i = 0; qit != qe; ++qit, ++i) {
            if ((*qit) < r.min_coord(i)){
              dists[i] = r.min_coord(i)-(*qit);
              distance += the_weights[i] *
                pow(dists[i]);
            }
            if ((*qit) > r.max_coord(i)){
              dists[i] = (*qit)-r.max_coord(i);
              distance += the_weights[i] *
                pow(dists[i]);
            }
          }
        };
      return distance;
    }

    inline
    FT
    max_distance_to_rectangle(const Query_item& q,
                              const Kd_tree_rectangle<FT,Dimension>& r) const {
      FT distance=FT(0);
      typename SearchTraits::Construct_cartesian_const_iterator_d construct_it=
        traits.construct_cartesian_const_iterator_d_object();
      Coord_iterator qit = construct_it(q), qe = construct_it(q,1);
      if (is_zero(power))
        {
          for (unsigned int i = 0; qit != qe; ++qit, ++i) {
            if ((*qit) >= (r.min_coord(i) +
                         r.max_coord(i))/FT(2.0)) {
              if (the_weights[i] * ((*qit) -
                                    r.min_coord(i)) > distance)
                distance = the_weights[i] *
                  ((*qit)-r.min_coord(i));
              else
                if (the_weights[i] *
                    (r.max_coord(i) - (*qit)) > distance)
                  distance = the_weights[i] *
                    ( r.max_coord(i)-(*qit));
            }
          }
        }
      else
        {
          for (unsigned int i = 0; qit != qe; ++qit, ++i) {
            if ((*qit) <= (r.min_coord(i)+r.max_coord(i))/FT(2.0))
              distance += the_weights[i] * pow(r.max_coord(i)-(*qit));
            else
              distance += the_weights[i] * pow((*qit)-r.min_coord(i));
          }
        };
      return distance;
    }

     inline
    FT
    max_distance_to_rectangle(const Query_item& q,
                              const Kd_tree_rectangle<FT,Dimension>& r,std::vector<FT>& dists) const {
      FT distance=FT(0);
      typename SearchTraits::Construct_cartesian_const_iterator_d construct_it=
        traits.construct_cartesian_const_iterator_d_object();
      Coord_iterator qit = construct_it(q), qe = construct_it(q,1);
      if (is_zero(power))
        {
          for (unsigned int i = 0; qit != qe; ++qit, ++i) {
            if ((*qit) >= (r.min_coord(i) +
                         r.max_coord(i))/FT(2.0)) {
              if (the_weights[i] * ((*qit) -
                                    r.min_coord(i)) > distance){
                dists[i] = (*qit)-r.min_coord(i);
                distance = the_weights[i] *
                  (dists[i]);
              }
              else
                if (the_weights[i] *
                    (r.max_coord(i) - (*qit)) > distance){
                      dists[i] =  r.max_coord(i)-(*qit);
                  distance = the_weights[i] *
                    (dists[i]);
                }
            }
          }
        }
      else
        {
          for (unsigned int i = 0; qit != qe; ++qit, ++i) {
            if ((*qit) <= (r.min_coord(i)+r.max_coord(i))/FT(2.0)){
              dists[i] = r.max_coord(i)-(*qit);
              distance += the_weights[i] * pow(dists[i]);
            }
            else{
              dists[i] = (*qit)-r.min_coord(i);
              distance += the_weights[i] * pow(dists[i]);
            }
          }
        };
      return distance;
    }

    inline
    FT
    new_distance(FT dist, FT old_off, FT new_off,
                 int cutting_dimension)  const
    {
      FT new_dist;
      if (is_zero(power))
        {
          if (the_weights[cutting_dimension]*CGAL::abs(new_off)
              > dist)
            new_dist=
              the_weights[cutting_dimension]*CGAL::abs(new_off);
          else new_dist=dist;
        }
      else
        {
          new_dist = dist + the_weights[cutting_dimension] *
            (pow(CGAL::abs(new_off))-pow(CGAL::abs(old_off)));
        }
      return new_dist;
    }

    inline
    FT
    transformed_distance(FT d) const
    {
      if (! is_positive(power)) return d;
      else return pow(d);

    }

    inline
    FT
    inverse_of_transformed_distance(FT d) const
    {
      if (! is_positive(power)) return d;
      else return pow(d,1/power);

    }

  }; // class Weighted_Minkowski_distance

} // namespace CGAL

#endif // CGAL_WEIGHTED_MINKOWSKI_DISTANCE_H

