// Copyright (c) 2015  GeometryFactory (France).  All rights reserved.
//
// This file is part of CGAL (www.cgal.org)
//
// $URL$
// $Id$
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
//
// Author(s)     : Andreas Fabri
//                 Mael Rouxel-Labbé

#ifndef CGAL_BGL_IO_OBJ_H
#define CGAL_BGL_IO_OBJ_H

#include <CGAL/boost/graph/IO/Generic_facegraph_builder.h>
#include <CGAL/IO/OBJ.h>

#include <CGAL/assertions.h>
#include <CGAL/boost/graph/Euler_operations.h>
#include <CGAL/boost/graph/Named_function_parameters.h>
#include <CGAL/boost/graph/named_params_helper.h>

#include <fstream>
#include <iostream>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>

namespace CGAL {

////////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////
/// Read

namespace IO {
namespace internal {

// Use CRTP to gain access to the protected members without getters/setters.
template <typename FaceGraph, typename Point>
class OBJ_builder
  : public Generic_facegraph_builder<FaceGraph, Point, OBJ_builder<FaceGraph, Point> >
{
  typedef OBJ_builder<FaceGraph, Point>                                         Self;
  typedef Generic_facegraph_builder<FaceGraph, Point, Self>                     Base;

  typedef typename Base::Point_container                                        Point_container;
  typedef typename Base::Face                                                   Face;
  typedef typename Base::Face_container                                         Face_container;

public:
  OBJ_builder(std::istream& is_) : Base(is_) { }

  // Implementation of the two functions required by the generic builder
  bool read(std::istream& input, Point_container& points, Face_container& faces)
  {
    return read_OBJ(input, points, faces);
  }
};

} // namespace internal
} // namespace IO

/*!
  \ingroup PkgBGLIOFct

  reads the graph `g` from the stream `in` in the OBJ format.

  \returns `true` if the resulting mesh is valid.

  \pre The data must represent a 2-manifold

  \see \ref IOStreamOBJ
*/
template <typename FaceGraph, typename CGAL_BGL_NP_TEMPLATE_PARAMETERS>
bool read_OBJ(std::istream& in,
              FaceGraph& g,
              const CGAL_BGL_NP_CLASS& np)
{
  typedef typename CGAL::GetVertexPointMap<FaceGraph, CGAL_BGL_NP_CLASS>::type  VPM;
  typedef typename boost::property_traits<VPM>::value_type                      Point;

  IO::internal::OBJ_builder<FaceGraph, Point> builder(in);
  return builder(g, np);
}

/*!
  \ingroup PkgBGLIOFct

  reads the graph `g` from data in the OFF format. Ignores comment lines which start with a hash,
  and lines with whitespace.

  \sa Overloads of this function for specific models of the concept `FaceGraph`.

  \pre The data must represent a 2-manifold

  \attention The graph `g` is not cleared, and the data from the stream are added.

  \see \ref IOStreamOFF
*/
template <typename FaceGraph, typename CGAL_BGL_NP_TEMPLATE_PARAMETERS>
bool read_OBJ(const char* fname,
              FaceGraph& g,
              const CGAL_BGL_NP_CLASS& np)
{
  std::ifstream in(fname);
  return read_OBJ(in, g, np);
}

template <typename FaceGraph, typename CGAL_BGL_NP_TEMPLATE_PARAMETERS>
bool read_OBJ(const std::string& fname,
              FaceGraph& g,
              const CGAL_BGL_NP_CLASS& np)
{
  return read_OBJ(fname.c_str(), g, np);
}

template <typename FaceGraph>
bool read_OBJ(std::istream& is, FaceGraph& g) { return read_OBJ(is, g, parameters::all_default()); }
template <typename FaceGraph>
bool read_OBJ(const char* fname, FaceGraph& g) { return read_OBJ(fname, g, parameters::all_default()); }
template <typename FaceGraph>
bool read_OBJ(const std::string& fname, FaceGraph& g) { return read_OBJ(fname, g, parameters::all_default()); }

////////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////
/// Write

/*!
 \ingroup PkgBGLIOFct

  writes the graph `g` in the OBJ format.

  \returns `true` if writing was successful.

  \see \ref IOStreamOBJ
*/
template <typename FaceGraph, typename CGAL_BGL_NP_TEMPLATE_PARAMETERS>
bool write_OBJ(std::ostream& os,
               const FaceGraph& g,
               const CGAL_BGL_NP_CLASS& np)
{
  typedef typename boost::graph_traits<FaceGraph>::vertex_descriptor                  vertex_descriptor;
  typedef typename boost::graph_traits<FaceGraph>::vertices_size_type                 vertices_size_type;
  typedef typename boost::graph_traits<FaceGraph>::face_descriptor                    face_descriptor;

  typedef typename CGAL::GetVertexPointMap<FaceGraph, CGAL_BGL_NP_CLASS>::const_type  VPM;
  typedef typename boost::property_traits<VPM>::reference                             Point_ref;

  VPM vpm = parameters::choose_parameter(parameters::get_parameter(np, internal_np::vertex_point),
                                         get_const_property_map(CGAL::vertex_point, g));

  if(!os.good())
    return false;

  CGAL::File_writer_wavefront writer;
  writer.write_header(os, num_vertices(g), num_halfedges(g), num_faces(g));

  boost::container::flat_map<vertex_descriptor, vertices_size_type> index_map;
  vertices_size_type id = 0;

  for(vertex_descriptor v : vertices(g))
  {
    Point_ref p = get(vpm, v);
    writer.write_vertex(::CGAL::to_double(p.x()),
                        ::CGAL::to_double(p.y()),
                        ::CGAL::to_double(p.z()));
    index_map[v] = id++;
  }

  writer.write_facet_header();
  for(face_descriptor f : faces(g))
  {
    CGAL::Halfedge_around_face_circulator<FaceGraph> hc(halfedge(f, g), g);
    CGAL::Halfedge_around_face_circulator<FaceGraph> hc_end = hc;

    const std::size_t n = circulator_size(hc);
    CGAL_assertion(n >= 3);

    writer.write_facet_begin(n);
    do
    {
      writer.write_facet_vertex_index(index_map[target(*hc, g)]);
      ++hc;
    }
    while(hc != hc_end);

    writer.write_facet_end();
  }
  writer.write_footer();

  return os.good();
}

/*!
\ingroup PkgBGLIOFct

 writes the graph `g` in the OFF format into a file named `fname`.

 \sa Overloads of this function for specific models of the concept `FaceGraph`.

 \see \ref IOStreamOFF
*/
template <typename FaceGraph, typename CGAL_BGL_NP_TEMPLATE_PARAMETERS>
bool write_OBJ(const char* fname,
               const FaceGraph& g,
               const CGAL_BGL_NP_CLASS& np)
{
  std::ofstream out(fname);
  return write_OBJ(out, g, np);
}

template <typename FaceGraph, typename CGAL_BGL_NP_TEMPLATE_PARAMETERS>
bool write_OBJ(const std::string& fname, const FaceGraph& g, const CGAL_BGL_NP_CLASS& np)
{
  return write_OBJ(fname.c_str(), g, np);
}

template <typename FaceGraph>
bool write_OBJ(std::ostream& os, const FaceGraph& g) { return write_OBJ(os, g, parameters::all_default()); }
template <typename FaceGraph>
bool write_OBJ(const char* fname, const FaceGraph& g) { return write_OBJ(fname, g, parameters::all_default()); }
template <typename FaceGraph>
bool write_OBJ(const std::string& fname, const FaceGraph& g) { return write_OBJ(fname, g, parameters::all_default()); }

} // namespace CGAL

#endif // CGAL_BGL_IO_OBJ_H