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

#include <CGAL/Polygon_mesh_processing/triangulate_faces.h>
#include <CGAL/Polygon_mesh_processing/IO/polygon_mesh_io.h>

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

#include <iostream>
#include <string>

typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
typedef Kernel::Point_3                                     Point;
typedef CGAL::Surface_mesh<Point>                           Mesh;

namespace PMP = CGAL::Polygon_mesh_processing;

int main(int argc, char* argv[])
{
  const std::string filename = (argc > 1) ? argv[1] : CGAL::data_file_path("meshes/P.off");
  const char* outfilename = (argc > 2) ? argv[2] : "P_tri.off";

  Mesh mesh;
  if(!PMP::IO::read_polygon_mesh(filename, mesh))
  {
    std::cerr << "Error: Invalid input." << std::endl;
    return EXIT_FAILURE;
  }

  if(is_empty(mesh))
  {
    std::cerr << "Warning: empty file?" << std::endl;
    return EXIT_SUCCESS;
  }

  if(!CGAL::is_triangle_mesh(mesh))
    std::cout << "Input mesh is not triangulated." << std::endl;
  else
    std::cout << "Input mesh is triangulated." << std::endl;

  PMP::triangulate_faces(mesh);

  // Confirm that all faces are triangles.
  for(boost::graph_traits<Mesh>::face_descriptor f : faces(mesh))
  {
    if(!CGAL::is_triangle(halfedge(f, mesh), mesh))
      std::cerr << "Error: non-triangular face left in mesh." << std::endl;
  }

  CGAL::IO::write_polygon_mesh(outfilename, mesh, CGAL::parameters::stream_precision(17));

  return EXIT_SUCCESS;
}
