// Copyright (c) 2003-2006  INRIA Sophia-Antipolis (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you may redistribute it under
// the terms of the Q Public License version 1.0.
// See the file LICENSE.QPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL$
// $Id$
//
//
// Author(s)     : Steve Oudot, David Rey, Mariette Yvinec, Laurent Rineau, Andreas Fabri

#ifndef CGAL_COMPLEX_2_IN_TRIANGULATION_3_H
#define CGAL_COMPLEX_2_IN_TRIANGULATION_3_H

// TODO: add the iterators
// TODO: document the output/input function of C2T3?

#include <CGAL/circulator.h>
#include <CGAL/iterator.h>
#include <CGAL/Union_find.h>
#include <set>
#include <map>
#include <list>
#include <vector>

namespace CGAL {

template < class Tr >
class Complex_2_in_triangulation_3 {

 public:

  typedef Complex_2_in_triangulation_3 < Tr > Self;

  typedef Tr Triangulation;

  typedef typename Triangulation::Vertex_handle Vertex_handle;
  typedef typename Triangulation::Cell_handle Cell_handle;
  typedef typename Triangulation::Facet Facet;
  typedef typename Triangulation::Edge Edge;

  typedef std::list<Facet> Facets;
  typedef std::list<Cell_handle> Cells;
  typedef typename Facets::iterator Facet_list_iterator;

  typedef std::size_t size_type;

  typedef Const_circulator_from_container<Facets> Facet_circulator;

  typedef std::map <std::pair <Vertex_handle, Vertex_handle>,
		    std::pair<int, std::list<Facet> > >
                                                  Edge_facet_counter;

  enum Face_status{ NOT_IN_COMPLEX, ISOLATED, BOUNDARY, REGULAR, SINGULAR};


  class Iterator_not_in_complex {
    Self* self;
  public:
    Iterator_not_in_complex(Self* self) : self(self) 
    {
    }
    
    template <typename Iterator> // Facet or Edges iterators
    bool operator()(Iterator it) const {
      return ! self->is_in_complex(*it);
    }
  }; // end struct Iterator_not_in_complex

  class Vertex_not_in_complex {
    Self* self;
  public:
    Vertex_not_in_complex(Self* self) : self(self) 
    {
    }
    
    bool operator()(Vertex_handle v) const { // Takes as argument an iterator to a
                                             // Vertex, convertible to Vertex_handle.
      return ! self->is_in_complex(v);
    }
  }; // end struct Vertex_not_in_complex

  class Facet_not_in_complex {
    Self* self;
  public:
    Facet_not_in_complex(Self* self) : self(self) 
    {
    }
    
    bool operator()(Facet f) const {
      return ! self->is_in_complex(f);
    }
  }; // end struct Facet_not_in_complex

  class Iterator_not_on_boundary {
    Self* self;
  public:
    Iterator_not_on_boundary(Self* self) : self(self) 
    {
    }

    template <class Edge_iterator>
    bool operator()(Edge_iterator eit) const {
      return self->face_status(*eit)!= BOUNDARY;
    }

  };

  typedef Filter_iterator<typename Triangulation::Finite_facets_iterator,
                          Iterator_not_in_complex> Facet_iterator;
  typedef Filter_iterator<typename Triangulation::Finite_edges_iterator,
                          Iterator_not_in_complex> Edge_iterator;

  // class to ensure that Vertex_iterator is convertible to Vertex_handle
  class Vertex_iterator : 
    public Filter_iterator<typename Triangulation::Finite_vertices_iterator,
                           Vertex_not_in_complex>
  {
    typedef typename Triangulation::Finite_vertices_iterator Tr_iterator;
    typedef Filter_iterator<typename Triangulation::Finite_vertices_iterator,
                            Vertex_not_in_complex> Base;
    typedef typename Base::Predicate Predicate;
    typedef Vertex_iterator Self;
  public:
    Vertex_iterator(Base i) : Base(i)
    {
    }

    Self & operator++() { Base::operator++(); return *this; }
    Self & operator--() { Base::operator--(); return *this; }
    Self operator++(int) { Self tmp(*this); ++(*this); return tmp; }
    Self operator--(int) { Self tmp(*this); --(*this); return tmp; }
  
    operator Vertex_handle() 
    {
      return Vertex_handle(this->base());
    }
  };

  typedef Filter_iterator<typename Triangulation::Finite_edges_iterator,
                          Iterator_not_on_boundary> Boundary_edges_iterator;

protected:
  Triangulation& tr;
  Edge_facet_counter  edge_facet_counter;
  size_type m_number_of_facets;

 private:
  // computes and return an ordered pair of Vertex
  std::pair<Vertex_handle, Vertex_handle>
  make_ordered_pair(const Vertex_handle vh1, const Vertex_handle vh2) const {
    if (vh1 < vh2) {
      return std::make_pair(vh1, vh2);
    }
    else {
      return std::make_pair(vh2, vh1);
    }
  }

  Facet canonical_facet(Cell_handle c, int i) const {
    Cell_handle c2 = c->neighbor(i);
    return (c2 < c) ? std::make_pair(c2,c2->index(c)) : std::make_pair(c,i);
  }
 public:

  // Constructors

  Complex_2_in_triangulation_3 (Triangulation& t) 
    : tr(t), m_number_of_facets(0)
  {
  }

  void clear()
  {
    m_number_of_facets = 0;
    edge_facet_counter.clear();
  }

  // Access functions

  Triangulation& triangulation()
  {
    return tr;
  }

  const Triangulation& triangulation() const
  {
    return tr;
  }

  Face_status face_status (const Facet& f) const {
    return face_status (f.first, f.second);
  }

  Face_status face_status (const Cell_handle c, const int i) const {
    return (c->is_facet_on_surface(i)) ? REGULAR : NOT_IN_COMPLEX;
  }

  Face_status face_status (const Edge& e) const {
    return face_status(e.first->vertex(e.second), e.first->vertex(e.third));
  }

  Face_status face_status (const Vertex_handle& va,
                           const Vertex_handle& vb) const
  {
    typename Edge_facet_counter::const_iterator it =
      edge_facet_counter.find(make_ordered_pair(va, vb));

    if (it == edge_facet_counter.end())
      return NOT_IN_COMPLEX;

    switch (it->second.first)
    {
    case 0 : return ISOLATED;
    case 1 : return BOUNDARY;
    case 2 : return REGULAR;
    default : return SINGULAR;
    }
  } // end face_status(const Vertex_handle&, const Vertex_handle&)

  Face_status face_status (Vertex_handle v)
  {
    if(v->is_c2t3_cache_valid() && v->cached_number_of_incident_facets() == 0)
      return NOT_IN_COMPLEX;

    //test incident edges for REUGALIRITY and count BOUNDARY edges
    typename std::vector<Vertex_handle> vertices;
    vertices.reserve(64);
    tr.incident_vertices(v, std::back_inserter(vertices));
    int number_of_boundary_incident_edges = 0; //COULD BE a Bool
    for (typename std::vector<Vertex_handle>::iterator vit=vertices.begin();
	 vit != vertices.end();
	 vit++ ) 
    {
      switch( face_status(v, *vit) )
      {
      case NOT_IN_COMPLEX: case REGULAR: break;
      case BOUNDARY: ++number_of_boundary_incident_edges; break;
      default : return SINGULAR;
      }
    }

    // from now on incident edges (in complex) are REGULAR or BOUNDARY

    int i,j;
    union_find_of_incident_facets(v,i,j);

    if ( i == 0 ) 
      return NOT_IN_COMPLEX;
    else if ( j > 1 ) 
      return SINGULAR;
    else // REGULAR OR BOUNDARY
    {
      if (number_of_boundary_incident_edges != 0)
        return BOUNDARY;
      else
        return REGULAR;
    }
  } //end of face_status(Vertex_handle)


  // This function should be called only when incident edges
  // are known to be REGULAR OR BOUNDARY
  bool is_regular_or_boundary_for_vertices(Vertex_handle v)  {
    int i,j;
    union_find_of_incident_facets(v,i,j);
    return (j == 1);
  }

   bool is_in_complex (Vertex_handle v) {
    int i,j;
    union_find_of_incident_facets(v,i,j);
    return ( i != 0);
  }

  // extract the subset F of facets of the complex incident to v
  // set i to the number of facets in F
  // set j to the number of connected component of the adjacency graph
  //     of F
  void union_find_of_incident_facets(const Vertex_handle v, int& i, int& j) {
    if( v->is_c2t3_cache_valid() )
    {
      i = v->cached_number_of_incident_facets();
      j = v->cached_number_of_components();
      return;
    }

    Union_find<Facet> facets;
    incident_facets(v, std::back_inserter(facets));

    typedef std::map<Vertex_handle, 
      typename Union_find<Facet>::handle>  Vertex_Set_map;
    typedef typename Vertex_Set_map::iterator Vertex_Set_map_iterator;

    Vertex_Set_map vsmap;

    for(typename Union_find<Facet>::iterator it = facets.begin();
	it != facets.end();
	++it){
      const Cell_handle& ch = (*it).first;
      const int& i = (*it).second;
      for(int j=0; j < 3; ++j){
	const Vertex_handle w = ch->vertex(tr.vertex_triple_index(i,j));
	if(w != v){
	  Vertex_Set_map_iterator vsm_it = vsmap.find(w);
	  if(vsm_it != vsmap.end()){
	    facets.unify_sets(vsm_it->second, it);
	  } else {
	    vsmap.insert(std::make_pair(w, it));
	  }
	}
      }
    }
    
    i = facets.size(); 
    j = facets.number_of_sets();
    v->set_c2t3_cache(i, j);
    return;
  }
  
  bool is_in_complex (const Facet& f) const {
    return is_in_complex (f.first, f.second);
  } 

  bool is_in_complex (const Cell_handle c, const int i) const {
    return  face_status(c,i) != NOT_IN_COMPLEX;
  }

  bool is_in_complex (const Edge& e) const {
    return  face_status(e) != NOT_IN_COMPLEX;
  }

  size_type number_of_facets() const
  {
    return m_number_of_facets;
  }

  Facet_circulator incident_facets (const Edge& e) {
    typename Edge_facet_counter::iterator it = 
      edge_facet_counter.find(make_ordered_pair(e.first->vertex(e.second),
                                                e.first->vertex(e.third)));
    
    if( it == edge_facet_counter.end() )
      return Facet_circulator();
    else
    {
      // position the circulator on the first element of the facets list
      Facets& lof = it->second.second;
      return Facet_circulator(&lof);
    }
  }

  /** @TODO: document this class in the
      SurfaceMeshComplex_2InTriangulation_3 concept.
   */
  template <typename OutputIterator>
  OutputIterator incident_facets(const Vertex_handle v, OutputIterator it)
  {
    // TODO: review this function (Laurent Rineau)

    // We assume that for the generated facets the Cell_handle is smaller than the opposite one
    tr.incident_facets(v,
                  CGAL::filter_output_iterator(it, 
                                               Facet_not_in_complex(this)));
    return it;
  }

  // Setting functions

  void set_in_complex (const Facet& f) {
    set_in_complex (f.first, f.second);
  }

  void set_in_complex (const Cell_handle c, const int i) {
    change_in_complex_status<true, false>(c, i);
  }

  template <bool in_complex, bool force_modification>
  void change_in_complex_status(const Cell_handle c, const int i)
  {
    // if not already in the complex
    if ( force_modification || 
         (in_complex ? 
          face_status (c, i) == NOT_IN_COMPLEX
          : face_status (c, i) != NOT_IN_COMPLEX) )
    {
      if(in_complex) 
        ++m_number_of_facets;
      else
        --m_number_of_facets;

      Facet f = canonical_facet(c, i);

      c->set_facet_on_surface(i, in_complex);

      switch( tr.dimension() )
      {
      case 3:
        {
          const Cell_handle& c2 = c->neighbor(i);
          const int& i2 = c2->index(c);
          c2->set_facet_on_surface(i2, in_complex);
        }
        break;
      case 2:
        break;
      default:
        CGAL_assertion(false);
      }

      const int dimension_plus_1 = tr.dimension() + 1;

      // update c2t3 for edges of f
      // We consider only pairs made by vertices without i
      for (int j = 0; j < dimension_plus_1; j++) {
        for (int k = j + 1; k < dimension_plus_1; k++) {
          if ( (i != j) && (i != k) ){

            const std::pair<Vertex_handle, Vertex_handle> e = 
              make_ordered_pair(c->vertex(j),
                                c->vertex(k));

            if(in_complex)
            {
              (edge_facet_counter[e]).first++;
              (edge_facet_counter[e]).second.push_back(f); // @TODO: beurk.
                                                           // Recode this!
            }
            else 
            {
              typename Edge_facet_counter::iterator it =
                edge_facet_counter.find(e);

              CGAL_assertion( it != edge_facet_counter.end() );
              
	      if(--(it->second.first) > 0)
                it->second.second.remove(f);
              else
                edge_facet_counter.erase(it);
            }              
          }
        }
      }

      // update c2t3 for vertices of f
      for (int j = 0; j < dimension_plus_1; j++) {
        if (j != i)
          c->vertex(j)->invalidate_c2t3_cache();
      }
    }
  }

  void remove_from_complex (const Facet& f) {
    remove_from_complex (f.first, f.second);
  }

  void remove_from_complex (const Cell_handle c, const int i) {
    change_in_complex_status<false, false>(c, i);
  }

  Facet_iterator facets_begin(){
    return CGAL::filter_iterator(tr.finite_facets_end(),
                                 Iterator_not_in_complex(this),
                                 tr.finite_facets_begin());
  }

  Facet_iterator facets_end(){
    return CGAL::filter_iterator(tr.finite_facets_end(),
                                 Iterator_not_in_complex(this));
  }

  
  Edge_iterator edges_begin(){
    return CGAL::filter_iterator(tr.finite_edges_end(),
                                 Iterator_not_in_complex(this),
                                 tr.finite_edges_begin());
  }

  Edge_iterator edges_end(){
    return CGAL::filter_iterator(tr.finite_edges_end(),
                                 Iterator_not_in_complex(this));
  }

  Vertex_iterator vertices_begin(){
    return CGAL::filter_iterator(tr.finite_vertices_end(),
                                 Vertex_not_in_complex(this),
                                 tr.finite_vertices_begin());
  }

  Vertex_iterator vertices_end(){
    return CGAL::filter_iterator(tr.finite_vertices_end(),
                                 Vertex_not_in_complex(this));
  }

  Boundary_edges_iterator boundary_edges_begin() {
    return CGAL::filter_iterator(tr.finite_edges_end(),
                                 Iterator_not_on_boundary(this),
                                 tr.finite_edges_begin()); 
  }

  Boundary_edges_iterator boundary_edges_end() {
    return CGAL::filter_iterator(tr.finite_edges_end(),
                                 Iterator_not_on_boundary(this)); 
  }

#ifdef CGAL_MESH_3_IO_H
  static
  std::string io_signature()
  {
    return Get_io_signature<Tr>()();
  }
#endif
}; // end Complex_2_in_triangulation_3

template < class Tr >
std::istream & 
operator>> (std::istream& is, Complex_2_in_triangulation_3<Tr>& c2t3)
{
  c2t3.clear();
  is >> c2t3.triangulation();

  // restore datas of c2t3
  for(typename Tr::Finite_facets_iterator fit = 
        c2t3.triangulation().finite_facets_begin();
      fit != c2t3.triangulation().finite_facets_end();
      ++fit)
    if(fit->first->is_facet_on_surface(fit->second))
      c2t3.template change_in_complex_status<true, true>(fit->first, fit->second);

  return is;
}

template < class Tr>
std::ostream & 
operator<< (std::ostream& os, const Complex_2_in_triangulation_3<Tr> &c2t3)
{
  return os << c2t3.triangulation();
}

} // end namespace CGAL

#endif // CGAL_COMPLEX_2_IN_TRIANGULATION_3_H