// Copyright (c) 1997  INRIA Sophia-Antipolis (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1.1/TDS_2/include/CGAL/Triangulation_ds_face_2.h $
// $Id: include/CGAL/Triangulation_ds_face_2.h 08b27d3db14 $
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s)     : Mariette Yvinec

#ifndef CGAL_TRIANGULATION_DS_FACE_2_H
#define CGAL_TRIANGULATION_DS_FACE_2_H

#include <CGAL/license/TDS_2.h>


#include <CGAL/basic.h>
#include <CGAL/Triangulation_utils_2.h>

namespace CGAL {

template < class Fb >
class  Triangulation_ds_face_2
  : public Fb
{
public:
  typedef typename Fb::Triangulation_data_structure Tds;
  typedef typename Tds::Vertex             Vertex;
  typedef typename Tds::Face               Face;
  typedef typename Tds::Vertex_handle      Vertex_handle;
  typedef typename Tds::Face_handle        Face_handle;

public :
  // creators
  Triangulation_ds_face_2()
    : Fb()
  {}

  Triangulation_ds_face_2(Vertex_handle v0, Vertex_handle v1, Vertex_handle v2)
    :  Fb(v0,v1,v2)
  {}

  Triangulation_ds_face_2(Vertex_handle v0, Vertex_handle v1, Vertex_handle v2,
                          Face_handle n0, Face_handle n1, Face_handle n2)
    :  Fb(v0,v1,v2,n0,n1,n2)
  {}

  Triangulation_ds_face_2( const Face& f)
    : Fb(f)
    {}

  static int ccw(int i) {return Triangulation_cw_ccw_2::ccw(i);}
  static int  cw(int i) {return Triangulation_cw_ccw_2::cw(i);}

  Vertex_handle mirror_vertex(int i) const;
  int mirror_index(int i) const;

  bool is_valid(bool verbose = false, int level = 0) const;

};

template < class Fb >
inline
typename Triangulation_ds_face_2<Fb>::Vertex_handle
Triangulation_ds_face_2<Fb>::
mirror_vertex(int i) const
{
  CGAL_precondition ( this->neighbor(i) != Face_handle()
                      && this->dimension() >= 1);
  //return neighbor(i)->vertex(neighbor(i)->index(this->handle()));
  return this->neighbor(i)->vertex(mirror_index(i));
}

template < class Fb >
inline int
Triangulation_ds_face_2<Fb>::
mirror_index(int i) const
{
  // return the index of opposite vertex in neighbor(i);
  CGAL_precondition (this->neighbor(i) != Face_handle() &&
                     this->dimension() >= 1);
  if (this->dimension() == 1) {
    return 1 - (this->neighbor(i)->index(this->vertex(1-i)));
  }
  return this->ccw( this->neighbor(i)->index(this->vertex(this->ccw(i))));
}


template < class Fb >
bool
Triangulation_ds_face_2<Fb>::
is_valid(bool verbose, int level) const
{
  bool result = Fb::is_valid(verbose, level);
  for(int i = 0; i <= this->dimension(); i++) {
    Face_handle n = this->neighbor(i);
    // the strange formulation in case dimension()==2
    // is used to handle the cases of TDS allowing
    // two faces with two common edges
    int in;
    if (this->dimension() == 0) in = 0;
    else in = mirror_index(i);
    result = result && ( this == &*(n->neighbor(in)) );
    switch(this->dimension()) {
    case 0 :
      break;
    case 1 :
      result = result &&  in == 1-i;
      result = result && ( this->vertex(1-i) == n->vertex(1-in));
      break;
    case 2 :
      result = result && ( this->vertex(cw(i))  == n->vertex(ccw(in)))
                      && ( this->vertex(ccw(i)) == n->vertex(cw(in)));
      break;
    }
  }
  return result;
}


} //namespace CGAL

#endif //CGAL_TRIANGULATION_DS_FACE_2_H
