// Copyright (c) 2003-2004  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/Mesh_2/include/CGAL/Delaunay_mesh_area_criteria_2.h $
// $Id: Delaunay_mesh_area_criteria_2.h 0779373 2020-03-26T13:31:46+01:00 Sébastien Loriot
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s)     : Laurent RINEAU

#ifndef CGAL_DELAUNAY_MESH_AREA_CRITERIA_2_H
#define CGAL_DELAUNAY_MESH_AREA_CRITERIA_2_H

#include <CGAL/license/Mesh_2.h>


#include <CGAL/Delaunay_mesh_size_criteria_2.h>

namespace CGAL {

template <class Tr>
class Delaunay_mesh_area_criteria_2
  : public virtual Delaunay_mesh_criteria_2<Tr>,
    private Delaunay_mesh_size_criteria_2<Tr>
/* This class "is a" Delaunay_mesh_criteria_2<Tr> and is implemented by
   Delaunay_mesh_size_criteria_2<Tr>. Delaunay_mesh_criteria_2<Tr> is a
   virtual base class of Delaunay_mesh_size_criteria_2<Tr>. */
{
  typedef typename Tr::Geom_traits Geom_traits;

protected:
  Geom_traits traits;
public:
  typedef Delaunay_mesh_criteria_2<Tr> Base;
  typedef Delaunay_mesh_size_criteria_2<Tr> Private_base;

  typedef typename Delaunay_mesh_size_criteria_2<Tr>::Quality Quality;

  Delaunay_mesh_area_criteria_2(const double aspect_bound = 0.125,
                                const double area_bound = 0,
                                const Geom_traits& traits = Geom_traits())
    : Private_base(aspect_bound, area_bound, traits), traits(traits) {}

  inline
  double area_bound() const { return this->sizebound; }

  inline
  void set_area_bound(const double ab) { this->sizebound = ab; }

  class Is_bad: public Private_base::Is_bad
  {
  public:
    typedef typename Private_base::Is_bad Is_bad_base;

    typedef typename Tr::Point Point_2;
    typedef typename Tr::Triangle Triangle_2;
    typedef typename Tr::Face_handle Face_handle;

    Is_bad(const double aspect_bound,
           const double area_bound,
           const Geom_traits& traits)
      : Is_bad_base(aspect_bound, area_bound, traits) {}

    Mesh_2::Face_badness operator()(Quality q)
    {
      return Is_bad_base::operator()(q);
    }

    Mesh_2::Face_badness operator()(const Face_handle& fh,
                                    Quality& q) const
    {
      typedef typename Tr::Geom_traits Geom_traits;

      typedef typename Geom_traits::Point_2 Point_2;
      typedef typename Geom_traits::Triangle_2 Triangle_2;
      typedef typename Geom_traits::Compute_area_2 Compute_area_2;
      typedef typename Geom_traits::Compute_squared_distance_2
        Compute_squared_distance_2;

      Geom_traits geom_traits;

      Compute_area_2 area_2 = geom_traits.compute_area_2_object();
      Compute_squared_distance_2 squared_distance =
        geom_traits.compute_squared_distance_2_object();

      const Point_2& pa = fh->vertex(0)->point();
      const Point_2& pb = fh->vertex(1)->point();
      const Point_2& pc = fh->vertex(2)->point();

      Triangle_2 t = geom_traits.construct_triangle_2_object()(pa,pb,pc);
      double area = CGAL::to_double(area_2(t));
      area=area*area; // squared area

      double
        a = CGAL::to_double(squared_distance(pb, pc)),
        b = CGAL::to_double(squared_distance(pc, pa)),
        c = CGAL::to_double(squared_distance(pa, pb));

      double min_sine; // squared minimum sine

      if(a<b)
        if(a<c)
          min_sine = area/(b*c);
        else
          min_sine = area/(a*b);
      else
        if(b<c)
          min_sine = area/(a*c);
        else
          min_sine = area/(a*b);

      q.first = min_sine;
      q.second = area;

      if( this->squared_size_bound != 0 &&
          area > this->squared_size_bound )
        return Mesh_2::IMPERATIVELY_BAD;
      else
        if( min_sine < this->B )
          return Mesh_2::BAD;
        else
          return Mesh_2::NOT_BAD;
    };
  }; // end class Is_bad

  Is_bad is_bad_object() const
  { return Is_bad(this->bound(), area_bound(), traits); }
};

} //end namespace

#endif

