// Copyright (c) 1997  ETH Zurich (Switzerland).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1.1/SearchStructures/include/CGAL/Range_tree_d.h $
// $Id: include/CGAL/Range_tree_d.h 08b27d3db14 $
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s)     : Gabriele Neyer


#ifndef CGAL_RANGE_TREE_D_H
#define CGAL_RANGE_TREE_D_H

#include <CGAL/license/SearchStructures.h>


#include <algorithm>
#include <iterator>
#include <functional>
#include <CGAL/Tree_base.h>
#include <list>
#include <vector>

// A d-dimensional Range Tree or a multilayer tree consisting of Range
// and other trees that are derived public
// Tree_base<C_Data, C_Window, C_Interface>
// can be constructed within this class.
// C_Data: container class which contains the d-dimensional data the tree holds.
// C_Window: Query window -- a d-dimensional interval
// C_Interface: Interface for the class with functions that allow to
// access the data.
// cf. file Tree_interface.h, class point_interface for the requirements.

namespace CGAL {

template <class C_Data, class C_Window, class C_Interface>
class Range_tree_d;

template <class C_Data, class C_Window, class C_Interface>
struct Range_tree_node: public Tree_node_base<Range_tree_node<C_Data, C_Window, C_Interface> >
{
  private:
  typedef  C_Data Data;
  typedef  C_Window Window;
  typedef typename C_Interface::Key Key;
  typedef  C_Interface Interface;
  typedef typename Tree_base< C_Data,  C_Window>::Tree_base_type Tree_base_type;
  //  protected:
  //typedef Range_tree_d< C_Data,  C_Window,  C_Interface> rT_d;
public:
  friend class Range_tree_d< C_Data,  C_Window,  C_Interface>;

  typedef Tree_node_base<Range_tree_node<C_Data, C_Window, C_Interface> >  Base;

  Range_tree_node()
    : sublayer(0)
  {}

  Range_tree_node( Range_tree_node    * p_left,
                   Range_tree_node    * p_right,
                   const  Data & v_obj,
                   const  Key  & v_key )
    : Base(p_left, p_right), object( v_obj ), key( v_key ), sublayer(0)
  {}

  Range_tree_node( Range_tree_node    * p_left,
                   Range_tree_node    * p_right,
                   const  Key  & v_key )
    : Base(p_left, p_right), key( v_key ), sublayer(0)
  {}

  virtual ~Range_tree_node()
  {
    if (sublayer != 0)
      delete sublayer;
  }

  Data object;
  Key key;
  Tree_base_type *sublayer;
};


template <class C_Data, class C_Window, class C_Interface>
class Range_tree_d: public Tree_base< C_Data,  C_Window>
{
 private:
  typedef  C_Data Data;
  typedef  C_Window Window;
  typedef typename C_Interface::Key Key;
  typedef  C_Interface Interface;
  typedef Tree_base< C_Data,  C_Window>  tbt;
protected:
  //  typedef Range_tree_d< C_Data,  C_Window,  C_Interface> rT_d;
  Tree_base<C_Data, C_Window> *sublayer_tree;
  C_Interface m_interface;
  int is_built;


  // A vertex is of this type:
  //  struct Range_tree_node;

  friend struct Range_tree_node<C_Data,C_Window,C_Interface>;

  typedef Range_tree_node<C_Data,C_Window,C_Interface> Range_tree_node2;
  typedef Range_tree_node<C_Data,C_Window,C_Interface> *link_type;

  static link_type& left(link_type x) {
    return x->left_link;
  }
  static link_type& right(link_type x) {
    return x->right_link;
  }

  static link_type& parent(link_type x) {
    return x->parent_link;
  }

  link_type header;
  link_type node;
  link_type rightmost(){return right(header);}
  link_type leftmost(){return left(header);}
  link_type root() const {
    if(header!=0)
      return header->parent_link;
    // return parent(header);
    else
      return 0;
  }

  bool is_less_equal(const Key&  x, const Key&  y) const
  {
    return (!m_interface.comp(y,x));
  }

  // this tree is not a recursion anchor
  bool is_anchor() const {return false;}

  // returns true, if the object lies inside of win
  bool is_inside( C_Window const &win,  C_Data const& object) const
  {
    if(is_less_equal(m_interface.get_left(win), m_interface.get_key(object))
       && m_interface.comp(m_interface.get_key(object),m_interface.get_right(win)))
   //half open
//       && is_less_equal(m_interface.get_key(object),m_interface.get_right(win)))
   //closed interval
    {
      return sublayer_tree->is_inside(win,object);
    }

    return false;
  }


  // merge sort algorithms that takes O(n) time if the sequence to
  // be sorted consists of two sorted subsequences.
  template <class T>
  void dynamic_merge(const T& first, const T& last) // af: was not const
  {
    T prev, current=first;
    T current_first, current_middle, current_last;

    std::list<T> startpoints, tmp_startpoints;
    startpoints.push_back(current);
    prev = current++;

    while(current!=last)
    {
      if (m_interface.comp(m_interface.get_key(*current),m_interface.get_key(*prev)))
        startpoints.push_back(current);
      prev = current++;
    }
    while(startpoints.size()>1)
    {
      while(startpoints.size()>1)
      {
        current_first = startpoints.front();
        startpoints.erase(startpoints.begin());
        current_middle = startpoints.front();
        startpoints.erase(startpoints.begin());
        if(startpoints.size()>0)
          current_last = startpoints.front();
        else
          current_last = last;
        tmp_startpoints.push_back(current_first);
        std::inplace_merge(current_first, current_middle, current_last,
                      m_interface.key_comp);
      }
      if(startpoints.size()>0)
      {
        tmp_startpoints.push_back(startpoints.front());
        startpoints.erase(startpoints.begin());
      }
      startpoints.swap(tmp_startpoints);
    }
  }


  // recursive function
  // (current,last) describe an interval of length n of sorted elements,
  // for this interval a tree is build containing these elements.
  // the most left child is returned in prevchild.

  template <class T>
  void build_range_tree(int n, link_type& leftchild,
                        link_type& rightchild,
                        link_type& prevchild,
                        link_type& leftmostlink,
                        T& current,
                        const T& last,
                        T& sublevel_first,
                        T& sublevel_last)
  {
    // only two elements ==> two leaves and a parent is constructed
    if (n==2)
    {
      sublevel_first = current;

      link_type  vleft = new Range_tree_node2( 0, 0,
                                  (*current), m_interface.get_key(*current) );
      //CGAL_NIL CGAL_NIL first two arguments
      CGAL_assertion( vleft != 0);

      ++current;
      link_type  vright = new Range_tree_node2( 0,0,
                                  (*current), m_interface.get_key(*current) );
      //CGAL_NIL CGAL_NIL first two arguments
      CGAL_assertion( vright != 0);
      current++;
      sublevel_last = current;

      link_type  vparent = new Range_tree_node2( vleft, vright, vleft->key );
      CGAL_assertion( vparent != 0);

      vleft->parent_link = vparent;
      vright->parent_link = vparent;
      leftchild = vleft;
      rightchild = vright;
      prevchild = vparent;
      if ( leftmostlink == 0)
        leftmostlink = leftchild;

      Tree_base<C_Data, C_Window> *g = sublayer_tree->clone();

      T sub_first = sublevel_first;
      T sub_last = sublevel_last;

      g->make_tree(sub_first, sub_last);

      vparent->sublayer= g;
    }
    else
      // only one element ==> one leaf is constructed
      if(n==1)
      {
        sublevel_first = current;
        link_type vright = new Range_tree_node2( 0, 0,
                                   (*current), m_interface.get_key(*current) );
        //CGAL_NIL CGAL_NIL first two arguments
        CGAL_assertion( vright != 0); //CGAL_NIL
        current++;
        sublevel_last = current;
        prevchild = vright;
        rightchild = vright;
      }
      else
      {
        // recursiv call for the construction. the interval is divided.
        T sublevel_left, sublevel_right;
        build_range_tree(n - (int)n/2, leftchild, rightchild,
                         prevchild, leftmostlink, current, last,
                         sublevel_first, sublevel_left);
        link_type vparent = new Range_tree_node2( prevchild, 0,
                                        rightchild->key );
        //CGAL_NIL argument
        CGAL_assertion( vparent != 0);

        prevchild->parent_link = vparent;

        build_range_tree((int)n/2, leftchild, rightchild,
                         prevchild, leftmostlink, current,
                         last, sublevel_right, sublevel_last);
        vparent->right_link = prevchild;
        prevchild->parent_link = vparent;
        prevchild = vparent;
        Tree_base<C_Data, C_Window> *g = sublayer_tree->clone();
        T sub_first = sublevel_first;
        T sub_last = sublevel_last;
        g->make_tree(sub_first, sub_last);
        vparent->sublayer = g;
      }
  }



  void delete_tree(link_type v)
  {
    if (v->left_link != 0)
    {
       delete_tree(left(v));
       delete_tree(right(v));
    }
    delete v;
  }


  // the vertex from that the way from root to the left interval bound
  // and the right interval bound splits.
  link_type findSplitNode(Window const &key)
  {
    link_type v = root();

    while(v->left_link!=0)
    {
//      if(m_interface.comp(m_interface.get_right(key), v->key))
      if(is_less_equal(m_interface.get_right(key), v->key))
        v = left(v);
      else
        if(m_interface.comp(v->key, m_interface.get_left(key)))
          v = right(v);
        else
          break;
    }

    return v;
  }

  template <class T>
  void report_subtree(link_type v,
                      T result)
  {
    if(left(v)!=0)
    {
      report_subtree(left(v), result);
      report_subtree(right(v), result);
    }
    else
      (*result++)=v->object;
  }

  bool is_valid(link_type& v, link_type&  leftmost_child,
                link_type& rightmost_child) const
  {
    link_type leftmost_child_l, rightmost_child_l,  leftmost_child_r,
      rightmost_child_r;
    if (v->sublayer != 0)
    {
      Tree_base<C_Data, C_Window> *T= v->sublayer;
      if(! T->is_valid())
        return false;
    }
    if(left(v)!=0)
    {
      if(!is_valid(left(v), leftmost_child_l, rightmost_child_l))
        return false;
      if(!is_valid(right(v), leftmost_child_r, rightmost_child_r))
        return false;
      if(m_interface.comp(v->key, rightmost_child_l->key) ||
         m_interface.comp(rightmost_child_l->key, v->key))
        return false;
      rightmost_child = rightmost_child_r;
      leftmost_child = leftmost_child_l;
    }
    else
    {
      rightmost_child = v;
      leftmost_child = v;
    }
    return true;
  }




public:

  // construction of a tree
  Range_tree_d(Range_tree_d const &fact, bool):
    sublayer_tree(fact.sublayer_tree->clone()), is_built(false), header(0)
  {}

  // construction of a tree
  Range_tree_d(Tree_base<C_Data, C_Window> const &fact):
    sublayer_tree(fact.clone()), is_built(false), header(0)
  {}

  // destruction
  virtual ~Range_tree_d()
  {
    link_type v=root();

    if (v!=0)
      delete_tree(v);
    if (header!=0)
      delete header;
    if (sublayer_tree!=0)
      delete sublayer_tree;
  }


 // a prototype of the tree is returned
  Tree_base<C_Data, C_Window> *clone() const
  {
    return new Range_tree_d(*this, true);
  }

  bool make_tree(const typename std::list< C_Data>::iterator& beg,
                 const typename std::list< C_Data>::iterator& end,
                 typename tbt::lit * =0){
    return make_tree_impl(beg,end);
  }

#ifdef stlvector
  bool make_tree(const typename std::vector< C_Data>::iterator& beg,
                 const typename std::vector< C_Data>::iterator& end,
                 typename tbt::vbit * =0){
    return make_tree_impl(beg,end);
  }
#endif
#ifdef carray
  bool make_tree(const C_Data *beg,
                 const C_Data *end){
    return make_tree_impl(beg,end);
  }
#endif

  // the tree is build according to the input elements in [first,last)
  template<class T>
  inline
  bool make_tree_impl(T first,
                      T last) // af: was &   todo: can we turn it in const& ??
  {
    link_type leftchild, rightchild, prevchild, leftmostlink;

    if(!is_built)
      is_built = true;
    else
      return false;

    if(first == last) {
      is_built = false;
      return true;
    }

    int n = static_cast<int>(std::distance(first,last));
    dynamic_merge(first, last);

    leftmostlink = 0;
    T sublevel_first, sublevel_last;

    build_range_tree(n, leftchild, rightchild, prevchild,
                     leftmostlink, first, last,
                     sublevel_first, sublevel_last);

    header = new Range_tree_node2();
    header->right_link = rightchild;
    header->parent_link = prevchild;
    header->left_link = leftmostlink;

    return true;
  }


  std::back_insert_iterator< std::list< C_Data> > window_query
          ( C_Window const &win,
            std::back_insert_iterator< std::list< C_Data> > out,
            typename tbt::lbit * =0){
    return window_query_impl(win,out);
  }


  std::back_insert_iterator< std::vector< C_Data> > window_query
          ( C_Window const &win,
            std::back_insert_iterator< std::vector< C_Data> > out,
            typename tbt::vbit * =0){
    return window_query_impl(win,out);
  }


#ifdef carray
  C_Data *window_query( C_Window const &win, C_Data *out){
    return window_query_impl(win,out);
  }
#endif

#ifdef ostreamiterator
  std::ostream_iterator< C_Data>  window_query( C_Window const &win,
                     std::ostream_iterator< C_Data> out,
                     typename tbt::oit *dummy=0){
    return window_query_impl(win,out);
  }
#endif

  // all elements that ly in win are inserted in result
  template <class X>
  inline
  X window_query_impl( C_Window const &win, X result)
  {
    if(is_less_equal(m_interface.get_right(win), m_interface.get_left(win)))
       return result;
    if(root()==0)
      return result;
    link_type split_node = findSplitNode(win);
    if(left(split_node)==0)
    {
      if(is_inside(win,split_node->object))
        (*result++)=split_node->object;
    }
    else
    {
      link_type v = (link_type) split_node->left_link;

      while(left(v)!=0)
      {
        if(is_less_equal(m_interface.get_left(win),v->key))
        {
          link_type w = right(v);
          if(left(w)!=0)
          {
            Tree_base<C_Data, C_Window> *T= (w)->sublayer;
            if(T->is_anchor())
              report_subtree(w,result);
            else
              T->window_query(win, result);
          }
          else
            if(is_inside(win,w->object))
              (*result++)=(w)->object;
          v = left(v);
        }
        else
          v = right(v);
      }                 // end while
      if(is_inside(win,v->object))
        (*result++)=v->object;
      v = right(split_node);
      while(right(v)!=0)
      {
//        if(is_less_equal(v->key, m_interface.get_right(win))) closed interval
        if(m_interface.comp(v->key, m_interface.get_right(win)))
          //half open interval
        {
          if(left(left(v))!=0)
          {
            Tree_base<C_Data, C_Window> *T= (left(v))->sublayer;
            if(T->is_anchor())
              report_subtree(left(v),result);
            else
              T->window_query(win, result);
          }
          else
          {
            if(is_inside(win,left(v)->object))
              (*result++)=left(v)->object;
          }
          v = right(v);
        }
        else
          v = left(v);
      }//end while
      if(is_inside(win,v->object))
      {
        (*result++)=v->object;
      }
    }
    return result;
  }

  std::back_insert_iterator< std::list< C_Data> > enclosing_query( C_Window const &win,
                             std::back_insert_iterator< std::list< C_Data> > out,
                             typename tbt::lbit * =0){
    return enclosing_query_impl(win,out);
  }

  std::back_insert_iterator< std::vector< C_Data> > enclosing_query( C_Window const &win,
                             std::back_insert_iterator< std::vector< C_Data> > out,
                             typename tbt::vbit * =0){
    return enclosing_query_impl(win,out);
  }


#ifdef carray
  C_Data *enclosing_query( C_Window const &win, C_Data *out){
    return enclosing_query_impl(win,out);
  }
#endif

#ifdef ostreamiterator
  std::ostream_iterator< C_Data>  enclosing_query( C_Window const &win,
                             std::ostream_iterator< C_Data> out,
                             typename tbt::oit *dummy=0){
    return enclosing_query_impl(win,out);
  }
#endif

  // a window query is performed
  template <class T>
  inline
  T enclosing_query_impl(C_Window const &win, T result)
  {
    return window_query_impl(win, result);
  }

  bool is_valid() const
  {
    link_type u,v,w;
    u=v=w=root();
    if(v!=0)
      return is_valid(u, v, w);
    return true;
  }
};

} //namespace CGAL
#endif // CGAL_RANGE_TREE_D_H
