// Copyright (c) 2003,2004,2005,2006  INRIA Sophia-Antipolis (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1/Segment_Delaunay_graph_2/include/CGAL/Segment_Delaunay_graph_2/Is_degenerate_edge_C2.h $
// $Id: include/CGAL/Segment_Delaunay_graph_2/Is_degenerate_edge_C2.h b26b07a1242 $
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s)     : Menelaos Karavelas <mkaravel@iacm.forth.gr>

#ifndef CGAL_SEGMENT_DELAUNAY_GRAPH_2_IS_DEGENERATE_EDGE_C2_H
#define CGAL_SEGMENT_DELAUNAY_GRAPH_2_IS_DEGENERATE_EDGE_C2_H

#include <CGAL/license/Segment_Delaunay_graph_2.h>


#include <CGAL/Segment_Delaunay_graph_2/Are_same_points_C2.h>
#include <CGAL/Segment_Delaunay_graph_2/Voronoi_vertex_C2.h>

namespace CGAL {

namespace SegmentDelaunayGraph_2 {

//-----------------------------------------------------------------------------

template<class K, class Method_tag>
class Is_degenerate_edge_C2
{
public:
  typedef typename K::Site_2      Site_2;
  typedef typename K::Boolean     Boolean;

private:
  typedef Voronoi_vertex_C2<K,Method_tag>  Voronoi_vertex_2;
  typedef Are_same_points_C2<K>            Are_same_points_2;

  bool is_endpoint(const Site_2& p, const Site_2& s) const
  {
    CGAL_precondition( p.is_point() && s.is_segment() );
    Are_same_points_2 same_points;

    return
      same_points(p, s.source_site()) || same_points(p, s.target_site());
  }

public:
  Boolean operator()(const Site_2& p, const Site_2& q,
                     const Site_2& r, const Site_2& s) const
  {
    Voronoi_vertex_2 vpqr(p, q, r);
    if ( vpqr.incircle_no_easy(s) == POSITIVE ) { return false; }

    Voronoi_vertex_2 vqps(q, p, s);
    if ( vqps.incircle_no_easy(r) == POSITIVE ) { return false; }

    return true;
  }

};


//-----------------------------------------------------------------------------

} //namespace SegmentDelaunayGraph_2

} //namespace CGAL

#endif // CGAL_SEGMENT_DELAUNAY_GRAPH_2_IS_DEGENERATE_EDGE_C2_H

