#include <Rcpp.h>
// Copyright (c) 2003-2007  INRIA Sophia-Antipolis (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
//
// $URL: https://github.com/CGAL/cgal/blob/v5.6.1/Surface_mesher/include/CGAL/IO/Complex_2_in_triangulation_3_file_writer.h $
// $Id: Complex_2_in_triangulation_3_file_writer.h 580a1ef 2020-05-22T15:31:50+02:00 Mael Rouxel-Labbé
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s)     : Steve Oudot, Laurent Rineau

#ifndef CGAL_IO_COMPLEX_2_IN_TRIANGULATION_3_FILE_WRITER_H
#define CGAL_IO_COMPLEX_2_IN_TRIANGULATION_3_FILE_WRITER_H

#include <CGAL/license/Surface_mesher.h>

#include <CGAL/disable_warnings.h>

#define CGAL_C2T3_USE_FILE_WRITER_OFF

#include <CGAL/IO/OFF.h>

#include <CGAL/Polyhedron_3.h>
#include <CGAL/Polyhedron_incremental_builder_3.h>

#include <iomanip>
#include <stack>
#include <set>

namespace CGAL { namespace Surface_mesher {
  template < class Tr>
  typename Tr::size_type number_of_facets_on_surface(const Tr& T);

  template <class Triangulation>
  class Write_to_OFF_file
  {
    CGAL::File_writer_OFF off;
    std::ostream& os;

    typedef Triangulation Tr;
  public:
    Write_to_OFF_file(std::ostream& os,  bool verbose)
      : off(verbose), os(os)
    {
    }

    bool write_header(const typename Tr::size_type number_of_vertices,
                      const typename Tr::size_type number_of_facets)
    {
      off.header().set_no_comments(true);
      off.write_header(os,
                       number_of_vertices,
                       0, // fake number of halfedges, not used.
                       number_of_facets);
      return os.good();
    }

    bool write_vertex(const typename Tr::Vertex_handle& v)
    {
      const typename Tr::Point& p = v->point();
      off.write_vertex(p.x(), p.y(), p.z());
      return os.good();
    }

    bool begin_facets()
    {
      off.write_facet_header();
      return os.good();
    }

    bool write_facet(const int index1,
                     const int index2,
                     const int index3)
    {
      off.write_facet_begin(3);
      off.write_facet_vertex_index(index1);
      off.write_facet_vertex_index(index2);
      off.write_facet_vertex_index(index3);
      off.write_facet_end();
      return os.good();
    }

    bool write_footer()
    {
      off.write_footer();
      return os.good();
    }
  }; // end class Write_to_OFF_file

  template <class Triangulation, class HDS>
  class Write_to_HDS
  {
    CGAL::Polyhedron_incremental_builder_3<HDS> builder;

    typedef Triangulation Tr;
  public:
    Write_to_HDS(HDS& hds)
      : builder(hds)
    {
    }

    bool write_header(const typename Tr::size_type number_of_vertices,
                      const typename Tr::size_type number_of_facets)
    {
      builder.begin_surface(number_of_vertices,
                            number_of_facets);
      return !builder.error();
    }

    bool write_vertex(const typename Tr::Vertex_handle& v)
    {
      const typename Tr::Point& p = v->point();
      builder.add_vertex(p);
      return !builder.error();
    }

    bool begin_facets()
    {
      return !builder.error();
    }

    bool write_facet(const int index1,
                     const int index2,
                     const int index3)
    {
      int indices[3];
      indices[0]=index1;
      indices[1]=index2;
      indices[2]=index3;
      builder.add_facet(indices+0, indices+3);
      return !builder.error();
    }

    bool write_footer()
    {
      builder.end_surface();
      return builder.error();
    }
  }; // end class Write_to_HDS

  enum IO_option { NO_OPTION = 0,
                   IO_ORIENT_SURFACE = 1,
                   IO_VERBOSE = 2 };

  } // end namespace Surface_mesher

template <class C2t3>
bool output_surface_facets_to_off (std::ostream& os,
                                   const C2t3& c2t3,
                                   int options =
                                   Surface_mesher::IO_ORIENT_SURFACE)
{
  using CGAL::Surface_mesher::number_of_facets_on_surface;

  typedef typename C2t3::Triangulation Tr;
  typedef typename Tr::Finite_facets_iterator Finite_facets_iterator;
  typedef typename Tr::Finite_vertices_iterator Finite_vertices_iterator;
  typedef typename Tr::Facet Facet;
  typedef typename Tr::Edge Edge;
  typedef typename Tr::Vertex_handle Vertex_handle;

  // Header.
  const Tr& tr = c2t3.triangulation();

  bool success = true;

  Surface_mesher::Write_to_OFF_file<Tr>
    off(os, (options & Surface_mesher::IO_VERBOSE) != 0);

  success &= off.write_header(tr.number_of_vertices(),
                              c2t3.number_of_facets());

  CGAL_assertion(c2t3.number_of_facets() == number_of_facets_on_surface(tr));

  // Finite vertices coordinates.
  std::map<Vertex_handle, int> V;
  int inum = 0;
  for(Finite_vertices_iterator vit = tr.finite_vertices_begin();
      vit != tr.finite_vertices_end();
      ++vit)
  {
    V[vit] = inum++;
    success &= off.write_vertex(vit);
  }

  success &= off.begin_facets();

  if((options & Surface_mesher::IO_ORIENT_SURFACE) == 0)
  {
    for( Finite_facets_iterator fit = tr.finite_facets_begin();
         fit != tr.finite_facets_end(); ++fit)
    {
      const typename Tr::Cell_handle cell = fit->first;
      const int& index = fit->second;
      if (cell->is_facet_on_surface(index)==true)
      {
        const int index1 = V[cell->vertex(tr.vertex_triple_index(index, 0))];
        const int index2 = V[cell->vertex(tr.vertex_triple_index(index, 1))];
        const int index3 = V[cell->vertex(tr.vertex_triple_index(index, 2))];
        success &= off.write_facet(index1, index2, index3);
      }
    }
  }
  else // if facets must be oriented
  {

    Finite_facets_iterator fit = tr.finite_facets_begin();
    std::set<Facet> oriented_set;
    std::stack<Facet> stack;

    typename Tr::size_type number_of_facets = c2t3.number_of_facets();

    CGAL_assertion_code(typename Tr::size_type nb_facets = 0; )

      while (oriented_set.size() != number_of_facets)
      {
        while ( fit->first->is_facet_on_surface(fit->second) == false ||
                oriented_set.find(*fit) != oriented_set.end() ||

                oriented_set.find(c2t3.opposite_facet(*fit)) !=
                oriented_set.end() )
        {
          ++fit;
        }
        oriented_set.insert(*fit);
        stack.push(*fit);
        while(! stack.empty() )
        {
          Facet f = stack.top();
          stack.pop();
          for(int ih = 0 ; ih < 3 ; ++ih) {
            const int i1  = tr.vertex_triple_index(f.second, tr. cw(ih));
            const int i2  = tr.vertex_triple_index(f.second, tr.ccw(ih));

            const typename C2t3::Face_status face_status
              = c2t3.face_status(Edge(f.first, i1, i2));
            if(face_status == C2t3::REGULAR) {
              Facet fn = c2t3.neighbor(f, ih);
              if (oriented_set.find(fn) == oriented_set.end()) {
                if(oriented_set.find(c2t3.opposite_facet(fn)) == oriented_set.end())
                {
                  oriented_set.insert(fn);
                  stack.push(fn);
                }
                else {
                  success = false; // non-orientable
                }
              }
            }
            else if(face_status != C2t3::BOUNDARY) {
              success = false; // non manifold, thus non-orientable
            }
          } // end "for each neighbor of f"
        } // end "stack non empty"
      } // end "oriented_set not full"

    for(typename std::set<Facet>::const_iterator fit =
          oriented_set.begin();
        fit != oriented_set.end();
        ++fit)
    {
      const typename Tr::Cell_handle cell = fit->first;
      const int& index = fit->second;
      const int index1 = V[cell->vertex(tr.vertex_triple_index(index, 0))];
      const int index2 = V[cell->vertex(tr.vertex_triple_index(index, 1))];
      const int index3 = V[cell->vertex(tr.vertex_triple_index(index, 2))];
      success &= off.write_facet(index1, index2, index3);
      CGAL_assertion_code(++nb_facets);
    }

    CGAL_assertion(nb_facets == number_of_facets);
  } // end if(facets must be oriented)

  success &= off.write_footer();
  return success;
}

//   typedef CGAL::Polyhedron_3<Gt> Polyhedron_3;
//   typedef typename Polyhedron_3::HalfedgeDS HalfedgeDS;

//   Polyhedron_3 p;

//   struct Build_polyhedron : public CGAL::Modifier_base<HalfedgeDS>{
//     const C2t3& c2t3;
//     const Tr& tr;
//     Build_polyhedron(const C2t3& c2t3) : c2t3(c2t3), tr(c2t3.triangulation()) {};
//     void operator()( HalfedgeDS& hds) {
//       CGAL::Polyhedron_incremental_builder_3<HalfedgeDS> builder(hds, true);
//       const typename Tr::size_type number_of_facets = c2t3.number_of_facets();
//       builder.begin_surface(tr.number_of_vertices(),
//                             number_of_facets);
//       {
//         // Finite vertices coordinates.
//         std::map<Vertex_handle, int> V;
//         int inum = 0;
//         for(Finite_vertices_iterator vit = tr.finite_vertices_begin();
//             vit != tr.finite_vertices_end();
//             ++vit)
//         {
//           V[vit] = inum++;
//           Point p = static_cast<Point>(vit->point());
//           builder.add_vertex(p);
//         }
//         Finite_facets_iterator fit = tr.finite_facets_begin();
//         std::set<Facet> oriented_set;
//         std::stack<Facet> stack;

//         CGAL_assertion_code(typename Tr::size_type nb_facets = 0; )

//         while (oriented_set.size() != number_of_facets) {
//           while ( fit->first->is_facet_on_surface(fit->second) == false ||
//                   oriented_set.find(*fit) != oriented_set.end() ||

//                   oriented_set.find(c2t3.opposite_facet(*fit)) !=
//                   oriented_set.end() ) {
//             ++fit;
//           }
//           oriented_set.insert(*fit);
//           stack.push(*fit);
//           while(! stack.empty() ) {
//             Facet f = stack.top();
//             stack.pop();
//             for(int ih = 0 ; ih < 3 ; ++ih) {
//               const int i1  = tr.vertex_triple_index(f.second, tr. cw(ih));
//               const int i2  = tr.vertex_triple_index(f.second, tr.ccw(ih));
//               if( c2t3.face_status(Edge(f.first, i1, i2)) == C2t3::REGULAR ) {
//                 Facet fn = c2t3.neighbor(f, ih);
//                 if (oriented_set.find(fn) == oriented_set.end() &&
//                     oriented_set.find(c2t3.opposite_facet(fn)) == oriented_set.end())
//                 {
//                   oriented_set.insert(fn);
//                   stack.push(fn);
//                 }
//               } // end "if the edge is regular"
//             } // end "for each neighbor of f"
//           } // end "stack non empty"
//         } // end "oriented_set not full"

//         for(typename std::set<Facet>::const_iterator fit =
//               oriented_set.begin();
//             fit != oriented_set.end();
//             ++fit)
//         {
//           int indices[3];
//           int index = 0;
//           for (int i=0; i<3; i++)
//             indices[index++] =
//               V[fit->first->vertex(tr.vertex_triple_index(fit->second, i))];
//           builder.add_facet(indices+0, indices+3);
//           CGAL_assertion_code(++nb_facets);
//         }
//         CGAL_assertion(nb_facets == number_of_facets);
// //         for( Finite_facets_iterator fit = tr.finite_facets_begin();
// //              fit != tr.finite_facets_end(); ++fit)
// //           if ((*fit).first->is_facet_on_surface((*fit).second)==true)
// //           {
// //             int indices[3];
// //             int index = 0;
// //             for (int i=0; i<3; i++)
// //               Rcpp::Rcerr << ( indices[index++] = V[(*fit).first->vertex(tr.vertex_triple_index(fit->second, i))] ) << ", ";
// //             Rcpp::Rcerr << "\n";
// //             if( builder.test_facet(indices+0, indices+3) )
// //               builder.add_facet(indices+0, indices+3);
// //             else
// //             {
// //               builder.begin_facet();
// //               builder.add_vertex_to_facet(indices[2]);
// //               builder.add_vertex_to_facet(indices[1]);
// //               builder.add_vertex_to_facet(indices[0]);
// //               builder.end_facet();
// //             }
// //             CGAL_assertion_code(++nb_facets);
// //           }
//       }
//       builder.end_surface();
//     }
//   } build_polyhedron(c2t3);

//   p.delegate( build_polyhedron );
//   os << p;
// }

// only if cells have is_in_domain() method.
template < class Tr>
void
output_oriented_surface_facets_to_off (std::ostream& os, const Tr & T) {
  using CGAL::Surface_mesher::number_of_facets_on_surface;

  typedef typename Tr::Finite_facets_iterator Finite_facets_iterator;
  typedef typename Tr::Finite_vertices_iterator Finite_vertices_iterator;
  typedef typename Tr::Vertex_handle Vertex_handle;
  typedef typename Tr::Point Point;

  // Header.


  os << "OFF \n"
     << T.number_of_vertices() << " " <<
    number_of_facets_on_surface (T) <<
    " " << 0 << "\n";

  os << std::setprecision(20);

  // Finite vertices coordinates.
  std::map<Vertex_handle, int> V;
  int inum = 0;
  for( Finite_vertices_iterator
      vit = T.finite_vertices_begin(); vit != T.finite_vertices_end(); ++vit) {
    V[vit] = inum++;
    Point p = static_cast<Point>(vit->point());
    os << p.x() << " " << p.y() << " " << p.z() << "\n";
  }

  // Finite facets indices.
  for( Finite_facets_iterator fit = T.finite_facets_begin();
       fit != T.finite_facets_end(); ++fit)
    if ((*fit).first->is_facet_on_surface((*fit).second)==true)
      {
        typename Tr::Facet f = *fit;
        typename Tr::Facet opposite = T.mirror_facet(f);
        CGAL_assertion (f.first->is_in_domain() !=
                        opposite.first->is_in_domain());
        if(!f.first->is_in_domain())
          f = T.mirror_facet(f);
        os << "3 "
           << V[f.first->vertex(T.vertex_triple_index(f.second,0))] << " "
           << V[f.first->vertex(T.vertex_triple_index(f.second,1))] << " "
           << V[f.first->vertex(T.vertex_triple_index(f.second,2))] << " "
           << "\n"; // without color.
      }
}

// only if cells have is_in_domain() method.
template < class Tr>
void
output_surface_facets_to_ghs   (std::ostream& os_points,
                                std::ostream& os_faces,
                                const Tr & T) {
  typedef typename Tr::Finite_facets_iterator Finite_facets_iterator;
  typedef typename Tr::Finite_vertices_iterator Finite_vertices_iterator;
  typedef typename Tr::Vertex_handle Vertex_handle;
  typedef typename Tr::Point Point;
  typedef typename Tr::Facet Facet;

  // Header.


  os_points << T.number_of_vertices() << "\n";

  os_points << std::setprecision(20);

  // Finite vertices coordinates.
  std::map<Vertex_handle, int> V;
  int inum = 1;
  for( Finite_vertices_iterator
      vit = T.finite_vertices_begin(); vit != T.finite_vertices_end(); ++vit) {
    V[vit] = inum++;
    Point p = static_cast<Point>(vit->point());
    os_points << p.x() << " " << p.y() << " " << p.z() << " 0\n";
  }

  os_faces << number_of_facets_on_surface(T) << "\n";
  // Finite facets indices.
  for( Finite_facets_iterator fit = T.finite_facets_begin();
       fit != T.finite_facets_end(); ++fit)
    if ((*fit).first->is_facet_on_surface((*fit).second)==true)
      {
        Facet f = *fit;
        if(!f.first->is_in_domain())
          f = T.mirror_facet(f);
        os_faces
          << "3 "
          << V[f.first->vertex(T.vertex_triple_index(f.second,0))] << " "
          << V[f.first->vertex(T.vertex_triple_index(f.second,1))] << " "
          << V[f.first->vertex(T.vertex_triple_index(f.second,2))] << " "
          << "0 0 0 0\n";
      }
}

template < class Tr>
int number_of_facets_in_domain(const Tr& T) {
  int result=0;
  for (typename Tr::Finite_facets_iterator fit = T.finite_facets_begin();
       fit != T.finite_facets_end(); ++fit) {
    typename Tr::Cell_handle neighb = fit->first->neighbor (fit->second);
    if ((fit->first->is_in_domain () || neighb->is_in_domain()) &&
        !fit->first->is_facet_on_surface (fit->second))
      ++result;
  }
  return result;
}

template < class Tr>
void
output_interior_facets_to_off (std::ostream& os, const Tr & T) {
  typedef typename Tr::Finite_facets_iterator Finite_facets_iterator;
  typedef typename Tr::Finite_vertices_iterator Finite_vertices_iterator;
  typedef typename Tr::Vertex_handle Vertex_handle;

  // Header.


  os << "OFF \n"
     << T.number_of_vertices() << " " <<
    number_of_facets_in_domain (T) <<
    " " << 0 << "\n";

  os << std::setprecision(20);

  // Finite vertices coordinates.
  std::map<Vertex_handle, int> V;
  int inum = 0;
  for( Finite_vertices_iterator
      vit = T.finite_vertices_begin(); vit != T.finite_vertices_end(); ++vit) {
    V[vit] = inum++;
    os << vit->point() << "\n";
  }

  // Finite facets indices.
  for( Finite_facets_iterator fit = T.finite_facets_begin();
       fit != T.finite_facets_end(); ++fit){
    typename Tr::Cell_handle neighb = fit->first->neighbor (fit->second);
    if ((fit->first->is_in_domain () || neighb->is_in_domain()) &&
        !fit->first->is_facet_on_surface (fit->second))
      {
        os << "3 ";
        for (int i=0; i<4; i++)
          if (i != (*fit).second)
            os << V[(*fit).first->vertex(i)] << " ";

        os << "\n"; // without color.
      }
  }
}

} // end namespace CGAL

#include <CGAL/enable_warnings.h>

#endif  // CGAL_IO_COMPLEX_2_IN_TRIANGULATION_3_FILE_WRITER_H

