// Copyright (c) 2000  Utrecht University (The Netherlands),
// ETH Zurich (Switzerland), Freie Universitaet Berlin (Germany),
// INRIA Sophia-Antipolis (France), Martin-Luther-University Halle-Wittenberg
// (Germany), Max-Planck-Institute Saarbruecken (Germany), RISC Linz (Austria),
// and Tel-Aviv University (Israel).  All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; version 2.1 of the License.
// See the file LICENSE.LGPL 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.
//
// $Source$
// $Revision$ $Date$
// $Name$
//
// Author(s)     : Andreas Fabri, Herve Bronnimann

#ifndef CGAL_CARTESIAN_VECTOR_2_H
#define CGAL_CARTESIAN_VECTOR_2_H

#include <CGAL/Origin.h>
#include <CGAL/Twotuple.h>

CGAL_BEGIN_NAMESPACE

template < class R_ >
class VectorC2
{
  typedef typename R_::FT                   FT;
  typedef typename R_::Point_2              Point_2;
  typedef typename R_::Vector_2             Vector_2;
  typedef typename R_::Segment_2            Segment_2;
  typedef typename R_::Ray_2                Ray_2;
  typedef typename R_::Line_2               Line_2;
  typedef typename R_::Direction_2          Direction_2;
  typedef typename R_::Aff_transformation_2 Aff_transformation_2;

  typedef Twotuple<FT>	                           Rep;
  typedef typename R_::template Handle<Rep>::type  Base;

  Base base;

public:
  typedef R_                                     R;

  VectorC2() {}

  VectorC2(const Null_vector &n)
  { *this = R().construct_vector_2_object()(n); }

  VectorC2(const Point_2 &a, const Point_2 &b)
  { *this = R().construct_vector_2_object()(a, b); }

  VectorC2(const Segment_2 &s)
  { *this = R().construct_vector_2_object()(s); }

  VectorC2(const Ray_2 &r)
  { *this = R().construct_vector_2_object()(r); }

  VectorC2(const Line_2 &l)
  { *this = R().construct_vector_2_object()(l); }

  VectorC2(const FT &x, const FT &y)
    : base(x, y) {}

  VectorC2(const FT &hx, const FT &hy, const FT &hw)
  {
    if (hw != FT(1))
      base = Rep(hx/hw, hy/hw);
    else
      base = Rep(hx, hy);
  }

  const FT & x() const
  {
      return get(base).e0;
  }
  const FT & y() const
  {
      return get(base).e1;
  }

  const FT & hx() const
  {
      return x();
  }
  const FT & hy() const
  {
      return y();
  }
  FT hw() const
  {
      return FT(1);
  }

  const FT & cartesian(int i) const;
  const FT & operator[](int i) const;
  FT homogeneous(int i) const;

  int dimension() const
  {
      return 2;
  }

  Vector_2 operator+(const VectorC2 &w) const;
  Vector_2 operator-(const VectorC2 &w) const;
  Vector_2 operator-() const;
  FT squared_length() const;
  Vector_2 operator/(const FT &c) const;
  Direction_2 direction() const;

  Vector_2 perpendicular(const Orientation &o) const;
  Vector_2 transform(const Aff_transformation_2 &t) const
  {
    return t.transform(*this);
  }
};

template < class R >
CGAL_KERNEL_INLINE
bool 
operator==(const VectorC2<R> &v, const VectorC2<R> &w)
{
  return w.x() == v.x() && w.y() == v.y();
}

template < class R >
inline
bool 
operator!=(const VectorC2<R> &v, const VectorC2<R> &w)
{
  return !(v == w);
}

template < class R >
inline
bool
operator==(const VectorC2<R> &v, const Null_vector &)
{
  return CGAL_NTS is_zero(v.x()) && CGAL_NTS is_zero(v.y());
}

template < class R >
inline
bool
operator==(const Null_vector &n, const VectorC2<R> &v)
{
  return v == n;
}

template < class R >
inline
bool
operator!=(const VectorC2<R> &v, const Null_vector &n)
{
  return !(v == n);
}

template < class R >
inline
bool
operator!=(const Null_vector &n, const VectorC2<R> &v)
{
  return !(v == n);
}

template < class R >
CGAL_KERNEL_INLINE
const typename VectorC2<R>::FT &
VectorC2<R>::cartesian(int i) const
{
  CGAL_kernel_precondition( (i == 0) || (i == 1) );
  return (i == 0) ? x() : y();
}

template < class R >
inline
const typename VectorC2<R>::FT &
VectorC2<R>::operator[](int i) const
{
  return cartesian(i);
}

template < class R >
CGAL_KERNEL_INLINE
typename VectorC2<R>::FT 
VectorC2<R>::homogeneous(int i) const
{
  return (i == 2) ? FT(1) : cartesian(i);
}

template < class R >
CGAL_KERNEL_INLINE
typename VectorC2<R>::Vector_2
VectorC2<R>::operator+(const VectorC2<R> &w) const
{
  return VectorC2<R>(x() + w.x(), y() + w.y());
}

template < class R >
CGAL_KERNEL_INLINE
typename VectorC2<R>::Vector_2
VectorC2<R>::operator-(const VectorC2<R> &w) const
{
  return VectorC2<R>(x() - w.x(), y() - w.y());
}

template < class R >
inline
typename VectorC2<R>::Vector_2
VectorC2<R>::operator-() const
{
  return R().construct_opposite_vector_2_object()(*this);
}

template < class R >
CGAL_KERNEL_INLINE
typename VectorC2<R>::FT
VectorC2<R>::squared_length() const
{
  return CGAL_NTS square(x()) + CGAL_NTS square(y());
}

template < class R >
CGAL_KERNEL_INLINE
typename VectorC2<R>::Vector_2
VectorC2<R>::
operator/(const typename VectorC2<R>::FT &c) const
{
  return VectorC2<R>( x()/c, y()/c);
}

template < class R >
inline
typename VectorC2<R>::Direction_2
VectorC2<R>::direction() const
{
  return Direction_2(x(), y());
}

template < class R >
CGAL_KERNEL_MEDIUM_INLINE
typename VectorC2<R>::Vector_2
VectorC2<R>::perpendicular(const Orientation &o) const
{
  CGAL_kernel_precondition( o != COLLINEAR );
  if (o == COUNTERCLOCKWISE)
    return VectorC2<R>(-y(), x());
  else
    return VectorC2<R>(y(), -x());
}

#ifndef CGAL_NO_OSTREAM_INSERT_VECTORC2
template < class R >
std::ostream &
operator<<(std::ostream &os, const VectorC2<R> &v)
{
    switch(os.iword(IO::mode)) {
    case IO::ASCII :
        return os << v.x() << ' ' << v.y();
    case IO::BINARY :
        write(os, v.x());
        write(os, v.y());
        return os;
    default:
        return os << "VectorC2(" << v.x() << ", " << v.y() << ')';
    }
}
#endif // CGAL_NO_OSTREAM_INSERT_VECTORC2

#ifndef CGAL_NO_ISTREAM_EXTRACT_VECTORC2
template < class R >
std::istream &
operator>>(std::istream &is, VectorC2<R> &p)
{
    typename R::FT x, y;
    switch(is.iword(IO::mode)) {
    case IO::ASCII :
        is >> x >> y;
        break;
    case IO::BINARY :
        read(is, x);
        read(is, y);
        break;
    default:
        std::cerr << "" << std::endl;
        std::cerr << "Stream must be in ascii or binary mode" << std::endl;
        break;
    }
    if (is)
	p = VectorC2<R>(x, y);
    return is;
}
#endif // CGAL_NO_ISTREAM_EXTRACT_VECTORC2

CGAL_END_NAMESPACE

#endif // CGAL_CARTESIAN_VECTOR_2_H