#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Surface_mesh.h>

#include <CGAL/Polygon_mesh_processing/corefinement.h>
#include <CGAL/Polygon_mesh_processing/IO/polygon_mesh_io.h>
#include <CGAL/Polygon_mesh_processing/remesh.h>

#include <CGAL/boost/graph/selection.h>

#include <fstream>
#include <iostream>
#include <iterator>
#include <vector>

typedef CGAL::Exact_predicates_inexact_constructions_kernel   K;

typedef CGAL::Surface_mesh<K::Point_3>                        Mesh;
typedef boost::graph_traits<Mesh>::halfedge_descriptor        halfedge_descriptor;
typedef boost::graph_traits<Mesh>::edge_descriptor            edge_descriptor;
typedef boost::graph_traits<Mesh>::face_descriptor            face_descriptor;

namespace PMP = CGAL::Polygon_mesh_processing;
namespace params = CGAL::parameters;

struct Vector_pmap_wrapper
{
  std::vector<bool>& vect;
  Vector_pmap_wrapper(std::vector<bool>& v) : vect(v) {}
  friend bool get(const Vector_pmap_wrapper& m, face_descriptor f)
  {
    return m.vect[f];
  }
  friend void put(const Vector_pmap_wrapper& m, face_descriptor f, bool b)
  {
    m.vect[f]=b;
  }
};

int main(int argc, char* argv[])
{
  const std::string filename1 = (argc > 1) ? argv[1] : CGAL::data_file_path("meshes/blobby.off");
  const std::string filename2 = (argc > 2) ? argv[2] : CGAL::data_file_path("meshes/eight.off");

  Mesh mesh1, mesh2;
  if (!PMP::IO::read_polygon_mesh(filename1, mesh1) || !PMP::IO::read_polygon_mesh(filename2, mesh2))
  {
    std::cerr << "Invalid input." << std::endl;
    return 1;
  }

  // create a property on edges to indicate whether they are constrained
  Mesh::Property_map<edge_descriptor,bool> is_constrained_map =
    mesh1.add_property_map<edge_descriptor,bool>("e:is_constrained", false).first;

  // update mesh1 to contain the mesh bounding the difference
  // of the two input volumes.
  bool valid_difference =
    PMP::corefine_and_compute_difference(mesh1,
                                         mesh2,
                                         mesh1,
                                         params::default_values(), // default parameters for mesh1
                                         params::default_values(), // default parameters for mesh2
                                         params::edge_is_constrained_map(is_constrained_map));

  if (valid_difference)
  {
    std::cout << "Difference was successfully computed\n";
    CGAL::IO::write_polygon_mesh("difference.off", mesh1, CGAL::parameters::stream_precision(17));
  }
  else
  {
    std::cout << "Difference could not be computed\n";
    return 1;
  }

  // collect faces incident to a constrained edge
  std::vector<face_descriptor> selected_faces;
  std::vector<bool> is_selected(num_faces(mesh1), false);
  for (edge_descriptor e : edges(mesh1))
    if (is_constrained_map[e])
    {
      // insert all faces incident to the target vertex
      for (halfedge_descriptor h : halfedges_around_target(halfedge(e,mesh1),mesh1))
      {
        if (!is_border(h, mesh1) )
        {
          face_descriptor f = face(h, mesh1);
          if (!is_selected[f])
          {
            selected_faces.push_back(f);
            is_selected[f] = true;
          }
        }
      }
    }

  // increase the face selection
  CGAL::expand_face_selection(selected_faces, mesh1, 2,
                              Vector_pmap_wrapper(is_selected),
                              std::back_inserter(selected_faces));

  std::cout << selected_faces.size() << " faces were selected for the remeshing step\n";

  // remesh the region around the intersection polylines
  PMP::isotropic_remeshing(selected_faces, 0.02, mesh1,
                           params::edge_is_constrained_map(is_constrained_map));

  CGAL::IO::write_polygon_mesh("difference_remeshed.off", mesh1, CGAL::parameters::stream_precision(17));

  return 0;
}
