// Copyright (c) 2015  GeometryFactory (France).  All rights reserved.
//
// This file is part of CGAL (www.cgal.org)
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1/BGL/include/CGAL/boost/graph/copy_face_graph.h $
// $Id: include/CGAL/boost/graph/copy_face_graph.h b26b07a1242 $
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s)     : Andreas Fabri

#ifndef CGAL_BOOST_GRAPH_COPY_FACE_GRAPH_H
#define CGAL_BOOST_GRAPH_COPY_FACE_GRAPH_H

#include <CGAL/config.h>
#include <CGAL/iterator.h>
#include <CGAL/Kernel_traits.h>
#include <CGAL/Cartesian_converter.h>

#include <CGAL/boost/graph/Euler_operations.h>
#include <CGAL/boost/graph/iterator.h>
#include <CGAL/boost/graph/helpers.h>
#include <CGAL/Named_function_parameters.h>
#include <CGAL/boost/graph/named_params_helper.h>
#include <CGAL/property_map.h>

#include <unordered_map>

namespace CGAL {

namespace internal {

template <typename SourceMesh, typename TargetMesh,
          typename V2V, typename H2H, typename F2F,
          typename Src_vpm, typename Tgt_vpm>
void copy_face_graph_impl(const SourceMesh& sm, TargetMesh& tm,
                          V2V v2v, H2H h2h, F2F f2f,
                          Src_vpm sm_vpm, Tgt_vpm tm_vpm )
{
  typedef typename boost::graph_traits<SourceMesh>::vertex_descriptor sm_vertex_descriptor;
  typedef typename boost::graph_traits<TargetMesh>::vertex_descriptor tm_vertex_descriptor;

  typedef typename boost::graph_traits<SourceMesh>::face_descriptor sm_face_descriptor;
  typedef typename boost::graph_traits<TargetMesh>::face_descriptor tm_face_descriptor;

  typedef typename boost::graph_traits<SourceMesh>::halfedge_descriptor sm_halfedge_descriptor;
  typedef typename boost::graph_traits<TargetMesh>::halfedge_descriptor tm_halfedge_descriptor;

  typedef typename boost::graph_traits<SourceMesh>::edge_descriptor sm_edge_descriptor;
  typedef typename boost::graph_traits<TargetMesh>::edge_descriptor tm_edge_descriptor;

  Cartesian_converter<typename Kernel_traits<typename boost::property_traits<Src_vpm>::value_type>::type,
                      typename Kernel_traits<typename boost::property_traits<Tgt_vpm>::value_type>::type >
    conv;

  typedef CGAL::dynamic_halfedge_property_t<tm_halfedge_descriptor> Dyn_h_tag;
  typename boost::property_map<SourceMesh, Dyn_h_tag >::const_type hs_to_ht = get(Dyn_h_tag(), sm);

  std::vector<tm_halfedge_descriptor> tm_border_halfedges;
  std::vector<sm_halfedge_descriptor> sm_border_halfedges;

  const tm_face_descriptor tm_null_face = boost::graph_traits<TargetMesh>::null_face();
  const tm_vertex_descriptor tm_null_vertex = boost::graph_traits<TargetMesh>::null_vertex();

  reserve(tm, static_cast<typename boost::graph_traits<TargetMesh>::vertices_size_type>(internal::exact_num_vertices(tm)+internal::exact_num_vertices(sm)),
              static_cast<typename boost::graph_traits<TargetMesh>::edges_size_type>(internal::exact_num_edges(tm)+internal::exact_num_edges(sm)),
              static_cast<typename boost::graph_traits<TargetMesh>::faces_size_type>(internal::exact_num_faces(tm)+internal::exact_num_faces(sm)) );

  //insert halfedges and create each vertex when encountering its halfedge
  std::vector<tm_edge_descriptor> new_edges;
  std::vector<tm_halfedge_descriptor> new_vertices;
  new_edges.reserve(internal::exact_num_edges(sm));
  new_vertices.reserve(internal::exact_num_vertices(sm));
  for(sm_edge_descriptor sm_e : edges(sm))
  {
    tm_edge_descriptor tm_e = add_edge(tm);
    new_edges.push_back(tm_e);
    sm_halfedge_descriptor sm_h = halfedge(sm_e, sm), sm_h_opp = opposite(sm_h, sm);
    tm_halfedge_descriptor tm_h = halfedge(tm_e, tm), tm_h_opp = opposite(tm_h, tm);

    // set next pointers to itself (in case previous garbage is present)
    set_next( tm_h, tm_h, tm );
    set_next( tm_h_opp, tm_h_opp, tm );

    put(hs_to_ht, sm_h, tm_h);
    put(hs_to_ht, sm_h_opp, tm_h_opp);
    *h2h++=std::make_pair(sm_h, tm_h);
    *h2h++=std::make_pair(sm_h_opp, tm_h_opp);

    if ( is_border(sm_h, sm) ){
      tm_border_halfedges.push_back( tm_h );
      sm_border_halfedges.push_back( sm_h );
      set_face(tm_h, tm_null_face, tm);
      CGAL_assertion(next(tm_h, tm) == tm_h );
    }

    if( is_border(sm_h_opp, sm) ){
      tm_border_halfedges.push_back( tm_h_opp );
      sm_border_halfedges.push_back( sm_h_opp );
      set_face(tm_h_opp, tm_null_face, tm);
      CGAL_assertion(next(tm_h_opp, tm) == tm_h_opp );
    }

    //create a copy of interior vertices only once
    sm_vertex_descriptor sm_h_src = source(sm_h,sm), sm_h_tgt = target(sm_h,sm);
    if ( halfedge(sm_h_tgt,sm)==sm_h )
    {
      tm_vertex_descriptor tm_h_tgt = add_vertex(tm);
      *v2v++=std::make_pair(sm_h_tgt, tm_h_tgt);
      set_halfedge(tm_h_tgt, tm_h, tm);
      new_vertices.push_back(tm_h);
      set_target(tm_h, tm_h_tgt, tm);
      put(tm_vpm, tm_h_tgt, conv(get(sm_vpm, sm_h_tgt)));
    }
    else
      set_target(tm_h, tm_null_vertex, tm);
    if ( halfedge(sm_h_src,sm)==sm_h_opp )
    {
      tm_vertex_descriptor tm_h_src = add_vertex(tm);
      *v2v++=std::make_pair(sm_h_src, tm_h_src);
      set_halfedge(tm_h_src, tm_h_opp, tm);
      new_vertices.push_back(tm_h_opp);
      set_target(tm_h_opp, tm_h_src, tm);
      put(tm_vpm, tm_h_src, conv(get(sm_vpm, sm_h_src)));
    }
    else
      set_target(tm_h_opp, tm_null_vertex, tm);
  }
  //create faces and connect halfedges
  for(sm_face_descriptor sm_f : faces(sm))
  {
    tm_face_descriptor tm_f = add_face(tm);
    *f2f++=std::make_pair(sm_f, tm_f);

    sm_halfedge_descriptor sm_h_i=halfedge(sm_f, sm);
    tm_halfedge_descriptor tm_h_prev = get(hs_to_ht, prev(sm_h_i, sm));
    set_halfedge(tm_f, tm_h_prev, tm);

    CGAL_precondition(*halfedges_around_face(sm_h_i, sm).first == sm_h_i);
    for(sm_halfedge_descriptor sm_h : halfedges_around_face(sm_h_i, sm))
    {
      tm_halfedge_descriptor tm_h = get(hs_to_ht, sm_h);
      set_next(tm_h_prev, tm_h, tm);
      set_face(tm_h, tm_f, tm);
      tm_h_prev=tm_h;
    }
  }

  // update next/prev of tm border halfedges
  std::size_t nb_border_hedges = tm_border_halfedges.size();
  for (std::size_t i=0; i< nb_border_hedges; ++i)
  {
    tm_halfedge_descriptor tm_h = tm_border_halfedges[i];

    if ( next(tm_h, tm) != tm_h )
      continue; //already set

    tm_halfedge_descriptor tm_h_prev = tm_h;
    CGAL_precondition(*halfedges_around_face(sm_border_halfedges[i], sm).first == sm_border_halfedges[i]);
    for(sm_halfedge_descriptor sm_h :
                  halfedges_around_face(next(sm_border_halfedges[i], sm), sm))
    {
      CGAL_assertion(next(tm_h_prev, tm) == tm_h_prev);
      tm_h = get(hs_to_ht, sm_h);
      set_next(tm_h_prev, tm_h, tm);
      tm_h_prev=tm_h;
    }
  }
  // update halfedge vertex of all but the vertex halfedge
  for(tm_halfedge_descriptor h : new_vertices)
  {
    tm_vertex_descriptor v = target(h, tm);
    tm_halfedge_descriptor next_around_vertex=h;
    do{
      next_around_vertex=opposite(next(next_around_vertex, tm), tm);
      set_target(next_around_vertex, v, tm);
    }while(h != next_around_vertex);
  }

  // detect if there are some non-manifold umbrellas and fix missing halfedge target pointers
  std::map<sm_vertex_descriptor, std::vector<tm_halfedge_descriptor>> nm_umbrella_map;
  typedef typename std::vector<tm_edge_descriptor>::iterator edge_iterator;
  for (edge_iterator it=new_edges.begin(); it!=new_edges.end(); ++it)
  {
    if (target(*it, tm) == tm_null_vertex || source(*it, tm) == tm_null_vertex)
    {
      // create and fill a map from target halfedge to source halfedge
      typedef CGAL::dynamic_halfedge_property_t<sm_halfedge_descriptor> Dyn_th_tag;
      typename boost::property_map<TargetMesh, Dyn_th_tag >::type ht_to_hs = get(Dyn_th_tag(), tm);
      for (sm_halfedge_descriptor hs : halfedges(sm))
        put(ht_to_hs, get(hs_to_ht, hs), hs);

      for(; it!=new_edges.end(); ++it)
      {
        tm_halfedge_descriptor nh_t = halfedge(*it, tm);
        for (int i=0; i<2; ++i)
        {
          if (target(nh_t, tm) == tm_null_vertex)
          {
            // we recover tm_v using the halfedge associated to the target vertex of
            // the halfedge in sm corresponding to nh_t. This is working because we
            // set the vertex halfedge pointer to the "same" halfedges.

            sm_vertex_descriptor vs = target(get(ht_to_hs, nh_t), sm);
            sm_halfedge_descriptor hs = halfedge(vs, sm);
            if (hs == boost::graph_traits<SourceMesh>::null_halfedge())
            {  // special case for Face_filtered_graph with a non-manifold input with not all umbrellas selected
              nm_umbrella_map[vs].push_back(nh_t);
            }
            else
            {
              tm_vertex_descriptor tm_v = target( get(hs_to_ht, hs), tm);
              for(tm_halfedge_descriptor ht : halfedges_around_target(nh_t, tm))
                set_target(ht, tm_v, tm);
            }
          }
          nh_t = opposite(nh_t, tm);
        }
      }
      break;
    }
  }

  for (const auto& vs_and_hts : nm_umbrella_map)
  {
    sm_vertex_descriptor v_sm = vs_and_hts.first;
    tm_vertex_descriptor v_tm = add_vertex(tm);
    *v2v++=std::make_pair(v_sm, v_tm);
    set_halfedge(v_tm, vs_and_hts.second.front(), tm);
    put(tm_vpm, v_tm, conv(get(sm_vpm, v_sm)));

    for (tm_halfedge_descriptor h_tm : vs_and_hts.second)
      set_target(h_tm, v_tm, tm);
  }
}

} // end of namespace internal

/*!
  \ingroup PkgBGLHelperFct

  copies a source model of `FaceListGraph` into a target model of a
  `FaceListGraph`. `OutputIterators` can be provided to produce a
  mapping between source and target elements. The target graph is not
  cleared.

  \tparam SourceMesh a model of `FaceListGraph`.
          The descriptor types `boost::graph_traits<SourceMesh>::%vertex_descriptor`
          and `boost::graph_traits<SourceMesh>::%face_descriptor` must be
          models of `Hashable`.
  \tparam TargetMesh a model of `FaceListGraph`
  \tparam NamedParameters1 a sequence of \ref bgl_namedparameters "Named Parameters"
  \tparam NamedParameters2 a sequence of \ref bgl_namedparameters "Named Parameters"

  The types `sm_vertex_descriptor` and `sm_face_descriptor` must be models of the concept `Hashable`.

  \param sm the source mesh
  \param tm the target mesh
  \param np1 an optional sequence of \ref bgl_namedparameters "Named Parameters" among the ones listed below

  \cgalNamedParamsBegin
    \cgalParamNBegin{vertex_point_map}
      \cgalParamDescription{a property map associating points to the vertices of `sm`}
      \cgalParamType{a class model of `ReadWritePropertyMap` with `boost::graph_traits<SourceMesh>::%vertex_descriptor`
                     as key type and `%Point_3` as value type}
      \cgalParamDefault{`boost::get(CGAL::vertex_point, sm)`}
      \cgalParamExtra{If this parameter is omitted, an internal property map for `CGAL::vertex_point_t`
                      must be available in `SourceMesh`.}
    \cgalParamNEnd

    \cgalParamNBegin{vertex_to_vertex_output_iterator}
      \cgalParamDescription{an `OutputIterator` containing the pairs source-vertex, target-vertex.}
      \cgalParamType{a class model of `OutputIterator` accepting
                     `std::pair<`boost::graph_traits<SourceMesh>::%vertex_descriptor, `boost::graph_traits<TargetMesh>::%vertex_descriptor>`}
      \cgalParamDefault{`Emptyset_iterator`}
      \cgalParamExtra{If this parameter is given, then `vertex_to_vertex_map` cannot be used.}
    \cgalParamNEnd

    \cgalParamNBegin{halfedge_to_halfedge_output_iterator}
      \cgalParamDescription{an `OutputIterator` containing the pairs source-halfedge, target-halfedge.}
      \cgalParamType{a class model of `OutputIterator` accepting
                     `std::pair<`boost::graph_traits<SourceMesh>::%halfedge_descriptor, `boost::graph_traits<TargetMesh>::%halfedge_descriptor>`}
      \cgalParamDefault{`Emptyset_iterator`}
      \cgalParamExtra{If this parameter is given, then `halfedge_to_halfedge_map` cannot be used.}
    \cgalParamNEnd

    \cgalParamNBegin{face_to_face_output_iterator}
      \cgalParamDescription{an `OutputIterator` containing the pairs source-face, target-face.}
      \cgalParamType{a class model of `OutputIterator` accepting
                     `std::pair<`boost::graph_traits<SourceMesh>::%face_descriptor, `boost::graph_traits<TargetMesh>::%face_descriptor>`}
      \cgalParamDefault{`Emptyset_iterator`}
      \cgalParamExtra{If this parameter is given, then `face_to_face_map` cannot be used.}
    \cgalParamNEnd

    \cgalParamNBegin{vertex_to_vertex_map}
      \cgalParamDescription{a property map storing for each vertex of a source mesh the corresponding vertex of another mesh}
      \cgalParamType{a class model of `ReadWritePropertyMap` with
                     `boost::graph_traits<SourceMesh>::%vertex_descriptor` as key type and
                     `boost::graph_traits<TargetMesh>::%vertex_descriptor` as value type.}
      \cgalParamDefault{unused}
      \cgalParamExtra{A typical use case is mapping the vertices from a source mesh
                      to its copy's after a `copy_face_graph()` operation.}
    \cgalParamNEnd

    \cgalParamNBegin{halfedge_to_halfedge_map}
      \cgalParamDescription{a property map storing for each halfedge of a source mesh the corresponding halfedge of another mesh}
      \cgalParamType{a class model of `ReadWritePropertyMap` with
                     `boost::graph_traits<SourceMesh>::%halfedge_descriptor` as key type and
                     `boost::graph_traits<TargetMesh>::%halfedge_descriptor` as value type}
      \cgalParamDefault{unused}
      \cgalParamExtra{A typical use case is mapping the halfedges from a source mesh to its copy's
                      after a `copy_face_graph()`operation.}
    \cgalParamNEnd

    \cgalParamNBegin{face_to_face_map}
      \cgalParamDescription{a property map storing for each face of a source mesh the corresponding face of another mesh}
      \cgalParamType{a class model of `ReadWritePropertyMap` with
                     `boost::graph_traits<SourceMesh>::%face_descriptor` as key type and
                     `boost::graph_traits<TargetMesh>::%face_descriptor` as value type}
      \cgalParamDefault{unused}
      \cgalParamExtra{A typical use case is mapping the faces from a source mesh to its copy's
                      after a `copy_face_graph()` operation}
    \cgalParamNEnd
  \cgalNamedParamsEnd

  \param np2 an optional sequence of \ref bgl_namedparameters "Named Parameters" among the ones listed below

  \cgalNamedParamsBegin
    \cgalParamNBegin{vertex_point_map}
      \cgalParamDescription{a property map associating points to the vertices of `tm`}
      \cgalParamType{a class model of `ReadWritePropertyMap` with `boost::graph_traits<TargetMesh>::%vertex_descriptor`
                     as key type and `%Point_3` as value type}
      \cgalParamDefault{`boost::get(CGAL::vertex_point, tm)`}
      \cgalParamExtra{If this parameter is omitted, an internal property map for `CGAL::vertex_point_t`
                      must be available in `TargetMesh`.}
    \cgalParamNEnd
  \cgalNamedParamsEnd

  The points from `sm` to `tm` are converted using
  `CGAL::Cartesian_converter<SourceKernel, TargetKernel>`.
  `SourceKernel` and `TargetKernel` are deduced using `CGAL::Kernel_traits`
  from the value types of the vertex point maps.

  Other properties are not copied.
*/
template <typename SourceMesh, typename TargetMesh,
          typename NamedParameters1 = parameters::Default_named_parameters,
          typename NamedParameters2 = parameters::Default_named_parameters
          >
void copy_face_graph(const SourceMesh& sm, TargetMesh& tm,
                     const NamedParameters1& np1 =  parameters::default_values(),
                     const NamedParameters2& np2 = parameters::default_values()
                     )
{
  using parameters::choose_parameter;
  using parameters::get_parameter;

  internal::copy_face_graph_impl(sm, tm,
                            choose_parameter(get_parameter(np1, internal_np::vertex_to_vertex_output_iterator),
                                             impl::make_functor(get_parameter(np1, internal_np::vertex_to_vertex_map))),
                            choose_parameter(get_parameter(np1, internal_np::halfedge_to_halfedge_output_iterator),
                                             impl::make_functor(get_parameter(np1, internal_np::halfedge_to_halfedge_map))),
                            choose_parameter(get_parameter(np1, internal_np::face_to_face_output_iterator),
                                             impl::make_functor(get_parameter(np1, internal_np::face_to_face_map))),
                            choose_parameter(get_parameter(np1, internal_np::vertex_point),
                                             get(vertex_point, sm)),
                            choose_parameter(get_parameter(np2, internal_np::vertex_point),
                                             get(vertex_point, tm)));
}

} // namespace CGAL

#endif //  CGAL_BOOST_GRAPH_COPY_FACE_GRAPH_H

