// Copyright (c) 2001-2004  ENS of Paris (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you may redistribute it under
// the terms of the Q Public License version 1.0.
// See the file LICENSE.QPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL$
// $Id$
// 
//
// Author(s)     : Pierre Angelier, Michel Pocchiola

#ifndef SHORTEST_PATH_POLYGON_TRAITS_H
#define SHORTEST_PATH_POLYGON_TRAITS_H

#include <CGAL/Visibility_complex_polygon_traits.h>


CGAL_BEGIN_NAMESPACE

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

template < class _R , class _E >
class Shortest_path_polygon_traits 
    : public Visibility_complex_polygon_traits<_R>
{
public:
    // -------------------------------------------------------------------------
    typedef Visibility_complex_polygon_traits<_R> Base;
    typedef typename Base::R                      R;
    typedef typename Base::Disk                   Disk;
    typedef typename Base::Bitangent_2            Bitangent_2;
    typedef typename Base::Arc_2                  Arc_2;
    typedef typename Base::Point_2                Point_2;
    typedef _E                                    Exact_NT;       
    // -------------------------------------------------------------------------
private:
    // -------------------------------------------------------------------------
    typedef Simple_cartesian<Exact_NT>            EK;
    typedef typename EK::Point_2                  Exact_point_2;
    typedef typename Arc_2::Vertex_const_iterator Arc_const_iterator;
    // -------------------------------------------------------------------------
public:
    // -------------------------------------------------------------------------
    Disk make_convex_from_point(const Point_2& p) 
    {
	Disk c;
	c.push_back(p);
	return c;
    }
    bool is_vertex(const Disk& c) { return c.size() == 1; }

    Exact_NT length(const Arc_2& a, 
		    const Bitangent_2& inf, const Bitangent_2& sup) const 
    {
	// Arc reduced to one point : length is 0
	if (*a.begin() == sup.source() || *a.begin() == sup.target()) 
	    return 0;
	// Arc containing at least two points : length is > 0
	Arc_const_iterator it  = a.begin();
	Arc_const_iterator its = it; ++its;
	Exact_NT l = 0;
	while (*its != sup.source() && *its != sup.target()) {
	    l = l + distance(*it,*its);
	    it = its; ++its;
	}
	l = l + distance(*it,*its);
	return l;
    }
    Exact_NT length(const Bitangent_2& b) const 
	{ return distance(b.source(),b.target()); }
    // -------------------------------------------------------------------------
private:
    // -------------------------------------------------------------------------
    Exact_point_2 make_exact(const Point_2& p) const
    {
	Exact_NT px = static_cast<Exact_NT>(CGAL::to_double(p.x()));
	Exact_NT py = static_cast<Exact_NT>(CGAL::to_double(p.y()));
	return Exact_point_2(px,py);
    }
    Exact_NT distance(const Point_2& p, const Point_2& q) const 
    {
	return CGAL_NTS sqrt(EK().compute_squared_distance_2_object()(make_exact(p),make_exact(q)));
    }
    // -------------------------------------------------------------------------
};

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

CGAL_END_NAMESPACE

#endif // SHORTEST_PATH_POLYGON_TRAITS_H