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

  Copyright (C) 1999--2020 Han-Wen Nienhuys <hanwen@xs4all.nl>

  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/>.
*/

#include "staff-symbol-referencer.hh"

#include "staff-symbol.hh"
#include "grob.hh"
#include "output-def.hh"

bool
Staff_symbol_referencer::on_line (Grob *me, int pos)
{
  Grob *st = get_staff_symbol (me);
  return st ? Staff_symbol::on_line (st, pos) : false;
}

bool
Staff_symbol_referencer::on_staff_line (Grob *me, int pos)
{
  Grob *st = get_staff_symbol (me);
  return st ? Staff_symbol::on_line (st, pos, false) : false;
}

Grob *
Staff_symbol_referencer::get_staff_symbol (Grob *me)
{
  if (has_interface<Staff_symbol> (me))
    return me;

  SCM st = get_object (me, "staff-symbol");
  return unsmob<Grob> (st);
}

Real
Staff_symbol_referencer::staff_space (Grob *me)
{
  Grob *st = get_staff_symbol (me);
  if (st)
    return Staff_symbol::staff_space (st);
  return 1.0;
}

Real
Staff_symbol_referencer::line_thickness (Grob *me)
{
  Grob *st = get_staff_symbol (me);
  if (st)
    return Staff_symbol::get_line_thickness (st);
  return me->layout ()->get_dimension (ly_symbol2scm ("line-thickness"));
}

Real
Staff_symbol_referencer::get_position (Grob *me)
{
  return internal_get_position (me, false);
}

Real
Staff_symbol_referencer::pure_get_position (Grob *me)
{
  return internal_get_position (me, true);
}

Real
Staff_symbol_referencer::internal_get_position (Grob *me, bool pure)
{
  Real p = 0.0;
  Grob *st = get_staff_symbol (me);
  Grob *c = st ? me->common_refpoint (st, Y_AXIS) : 0;
  if (st && c)
    {
      Real y = (pure
                ? me->pure_relative_y_coordinate (c, 0, INT_MAX)
                : me->relative_coordinate (c, Y_AXIS))
               - st->relative_coordinate (c, Y_AXIS);
      Real space = Staff_symbol::staff_space (st);
      p = (space == 0) ? 0 : 2.0 * y / space;
      return p;
    }
  else if (!st)
    return me->relative_coordinate (me->get_y_parent (), Y_AXIS) * 2;
  return from_scm<double> (get_property (me, "staff-position"), p);
}

Interval
Staff_symbol_referencer::extent_in_staff (Grob *me)
{
  Grob *st = get_staff_symbol (me);
  Grob *c = st ? me->common_refpoint (st, Y_AXIS) : 0;

  Interval retval;
  if (st && c)
    {
      retval = me->extent (c, Y_AXIS)
               - st->relative_coordinate (c, Y_AXIS);
    }

  return retval;
}

int
Staff_symbol_referencer::get_rounded_position (Grob *me)
{
  return int (rint (get_position (me)));
}

int
Staff_symbol_referencer::pure_get_rounded_position (Grob *me)
{
  return int (rint (pure_get_position (me)));
}

MAKE_SCHEME_CALLBACK (Staff_symbol_referencer, callback, 1);
SCM
Staff_symbol_referencer::callback (SCM smob)
{
  Grob *me = unsmob<Grob> (smob);

  SCM pos = get_property (me, "staff-position");
  Real off = 0.0;
  if (scm_is_number (pos))
    {
      Real space = Staff_symbol_referencer::staff_space (me);
      off = scm_to_double (pos) * space / 2.0;
    }

  return to_scm (off);
}

/*  This sets the position relative to the center of the staff symbol.

The function is hairy, because it can be called in two situations:

1. There is no staff yet; we must set staff-position

2. There is a staff, and perhaps someone even applied a
translate_axis (). Then we must compensate for the translation

In either case, we set a callback to be sure that our new position
will be extracted from staff-position */

void
Staff_symbol_referencer::set_position (Grob *me, Real p)
{
  internal_set_position (me, p, false);
}

void
Staff_symbol_referencer::pure_set_position (Grob *me, Real p)
{
  internal_set_position (me, p, true);
}

void
Staff_symbol_referencer::internal_set_position (Grob *me, Real p, bool pure)
{
  Grob *st = get_staff_symbol (me);
  Real oldpos = 0.0;
  if (st && me->common_refpoint (st, Y_AXIS))
    {
      oldpos = pure ? pure_get_position (me) : get_position (me);
    }

  Real ss = Staff_symbol_referencer::staff_space (me);
  me->translate_axis ((p - oldpos) * ss * 0.5, Y_AXIS);
}

Interval
Staff_symbol_referencer::staff_span (Grob *me)
{
  Interval result;
  if (me)
    if (Grob *symb = get_staff_symbol (me))
      result = Staff_symbol::line_span (symb);
  return result;
}

Real
Staff_symbol_referencer::staff_radius (Grob *me)
{
  /*
    line_span is measured in pitch steps, not in staff spaces
  */
  return staff_span (me).length () / 4.0;
}

int
compare_position (Grob *const &a, Grob *const &b)
{
  return sign (Staff_symbol_referencer::get_position ((Grob *)a)
               - Staff_symbol_referencer::get_position ((Grob *) b));
}

bool
position_less (Grob *const &a, Grob *const &b)
{
  return Staff_symbol_referencer::get_position (a)
         < Staff_symbol_referencer::get_position (b);
}

bool
pure_position_less (Grob *const &a, Grob *const &b)
{
  return Staff_symbol_referencer::pure_get_position (a)
         < Staff_symbol_referencer::pure_get_position (b);
}

ADD_INTERFACE (Staff_symbol_referencer,
               "An object whose Y@tie{}position is meant relative to a staff"
               " symbol.  These usually"
               " have @code{Staff_symbol_referencer::callback} in their"
               " @code{Y-offset-callbacks}.",

               /* properties */
               "staff-position "
              );
