/*
  This file is part of LilyPond, the GNU music typesetter.

  Copyright (C) 1996--2020 Han-Wen Nienhuys

  LilyPond is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  LilyPond is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef OFFSET_HH
#define OFFSET_HH

#include "axis.hh"
#include "std-string.hh"
#include "real.hh"

/*
  This is a mixture a 2D vector. Sometimes it can
  also be convenient to think of 2D vectors as complex numbers
  (ie. x + i y). The naming of some methods reflects that.
*/
class Offset
{
public:
  Real coordinate_a_[NO_AXES];

  Real &operator [] (Axis i)
  {
    return coordinate_a_[i];
  }

  Real operator [] (Axis i) const
  {
    return coordinate_a_[i];
  }

  Offset &operator += (Offset o)
  {
    (*this)[X_AXIS] += o[X_AXIS];
    (*this)[Y_AXIS] += o[Y_AXIS];
    return *this;
  }

  Offset operator - () const
  {
    Offset o = *this;

    o[X_AXIS] = -o[X_AXIS];
    o[Y_AXIS] = -o[Y_AXIS];
    return o;
  }

  Offset &operator -= (Offset o)
  {
    (*this)[X_AXIS] -= o[X_AXIS];
    (*this)[Y_AXIS] -= o[Y_AXIS];

    return *this;
  }

  Offset &scale (Offset o)
  {
    (*this)[X_AXIS] *= o[X_AXIS];
    (*this)[Y_AXIS] *= o[Y_AXIS];

    return *this;
  }

  Offset &operator /= (Real a)
  {
    (*this) *= 1 / a;
    return *this;
  }

  Offset &operator *= (Real a)
  {
    (*this)[X_AXIS] *= a;
    (*this)[Y_AXIS] *= a;

    return *this;
  }

  Offset (Real ix, Real iy)
  {
    coordinate_a_[X_AXIS] = ix;
    coordinate_a_[Y_AXIS] = iy;
  }

  Offset ()
  {
    coordinate_a_[X_AXIS] = coordinate_a_[Y_AXIS] = 0.0;
  }

  std::string to_string () const;

  Offset &mirror (Axis a)
  {
    coordinate_a_[a] = -coordinate_a_[a];
    return *this;
  }
  Offset direction () const;
  Offset swapped () const;

  Real angle_degrees () const;
  Real length () const;
  bool is_sane () const;
  Offset operator *= (Offset z2);

  /*
    Gets an orthogonal vector with same size to orig, pointing left
    (in the complex domain, a multiplication by i)
  */
  Offset normal () const
  {
    return Offset (-coordinate_a_[Y_AXIS], coordinate_a_[X_AXIS]);
  }
};

#include "arithmetic-operator.hh"
IMPLEMENT_ARITHMETIC_OPERATOR (Offset, +);
IMPLEMENT_ARITHMETIC_OPERATOR (Offset, -);
IMPLEMENT_ARITHMETIC_OPERATOR (Offset, *);

Offset complex_multiply (Offset, Offset);
Offset offset_directed (Real);

inline Offset
Offset::operator *= (Offset z2)
{
  *this = complex_multiply (*this, z2);
  return *this;
}

inline Offset
operator * (Real o1, Offset o2)
{
  o2 *= o1;
  return o2;
}

inline Offset
operator / (Offset o1, Real a)
{
  o1 /= a;
  return o1;
}

inline Offset
operator * (Offset o1, Real o2)
{
  o1 *= o2;
  return o1;
}

inline Offset
mirror (Offset o, Axis a)
{
  o.mirror (a);
  return o;
}

inline
Real
dot_product (Offset o1, Offset o2)
{
  return o1[X_AXIS] * o2[X_AXIS] + o1[Y_AXIS] * o2[Y_AXIS];
}

inline
Real
cross_product (Offset o1, Offset o2)
{
  return o1[X_AXIS] * o2[Y_AXIS] - o1[Y_AXIS] * o2[X_AXIS];
}

#endif /* OFFSET_HH */
