// Copyright (c) 1997-2000
// Utrecht University (The Netherlands),
// ETH Zurich (Switzerland),
// INRIA Sophia-Antipolis (France),
// Max-Planck-Institute Saarbruecken (Germany),
// and Tel-Aviv University (Israel).  All rights reserved.
//
// This file is part of CGAL (www.cgal.org)
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1.1/Kernel_d/include/CGAL/Kernel_d/Pair_d.h $
// $Id: include/CGAL/Kernel_d/Pair_d.h 08b27d3db14 $
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s)     : Michael Seel <seel@mpi-sb.mpg.de>
#ifndef CGAL_PAIR_D_H
#define CGAL_PAIR_D_H

#include <CGAL/basic.h>
#include <CGAL/Handle_for.h>

namespace CGAL {

template <class R> class Segment_d;
template <class R> class Ray_d;
template <class R> class Line_d;

template <class R>
class Pair_d
{
  typedef Pair_d<R> Self;
  typedef typename R::Point_d Point_d;
  typedef typename R::Vector_d Vector_d;
  typedef typename R::Direction_d Direction_d;
  Point_d _p[2];

  friend class Line_d<R>;
  friend class Ray_d<R>;
  friend class Segment_d<R>;

/* Any line object in $d$ - space is defined by two points |_p1| and |_p2|
respectively. There exists an orientation from _p1 to _p2. */

public:
Pair_d(int d = 0) { _p[0]=_p[1]=Point_d(d); }

Pair_d(const Point_d& p, const Point_d& q)
{ CGAL_assertion_msg((p.dimension() == q.dimension()),
  "Pair_d::constructor: source and target must have the same dimension.");
  _p[0]=p; _p[1]=q;
}

bool is_degenerate() const
{ return (_p[0] == _p[1]); }

Vector_d vector() const
{ return (_p[1] - _p[0]); }

Direction_d direction() const
{ return vector().direction(); }

void read(std::istream& is)
{
  switch( IO::get_mode(is) ) {
    case CGAL::IO::ASCII :
      is >> _p[0] >> _p[1]; break;
    case CGAL::IO::BINARY :
      CGAL::read(is, _p[0]); CGAL::read(is, _p[1]); break;
    default:
    CGAL_error_msg("\nStream must be in ASCII or binary mode\n");
  }
}

void print(std::ostream& os, const char* _name) const
{
  switch( IO::get_mode(os) ) {
    case CGAL::IO::ASCII :
      os << _p[0] << " " <<  _p[1]; break;
    case CGAL::IO::BINARY :
      CGAL::write(os, _p[0]); CGAL::write(os, _p[1]); break;
    default :
      os << _name << "(" << _p[0] << ", " << _p[1] << ")"; break;
  }
}

}; // Pair_d<R>

} //namespace CGAL
#endif //CGAL_PAIR_D_H
