/*
  rest-collision.cc -- implement Rest_collision

  source file of the GNU LilyPond music typesetter

  (c) 1997--2007 Han-Wen Nienhuys <hanwen@xs4all.nl>
*/

#include "rest-collision.hh"

#include <cmath>		// ceil.
using namespace std;

#include "directional-element-interface.hh"
#include "duration.hh"
#include "international.hh"
#include "note-column.hh"
#include "output-def.hh"
#include "pointer-group-interface.hh"
#include "rest.hh"
#include "rhythmic-head.hh"
#include "staff-symbol-referencer.hh"
#include "stem.hh"
#include "grob.hh"
#include "warn.hh"

MAKE_SCHEME_CALLBACK (Rest_collision, force_shift_callback, 1);
SCM
Rest_collision::force_shift_callback (SCM smob)
{
  Grob *them = unsmob_grob (smob);
  if (Note_column::has_rests (them))
    {
      Grob *collision = unsmob_grob (them->get_object ("rest-collision"));

      if (collision)
	{
	  (void) collision->get_property ("positioning-done");
	}
    }
  return scm_from_double (0.0);
}

MAKE_SCHEME_CALLBACK_WITH_OPTARGS (Rest_collision, force_shift_callback_rest, 2, 1, "");
SCM
Rest_collision::force_shift_callback_rest (SCM rest, SCM offset)
{
  Grob *rest_grob = unsmob_grob (rest);
  Grob *parent = rest_grob->get_parent (X_AXIS);

  /*
    translate REST; we need the result of this translation later on,
    while the offset probably still is 0/calculation-in-progress.
   */
  if (scm_is_number (offset))
    rest_grob->translate_axis (scm_to_double (offset), Y_AXIS);
  
  if (Note_column::has_interface (parent))
    force_shift_callback (parent->self_scm ());

  return scm_from_double (0.0);
}

void
Rest_collision::add_column (Grob *me, Grob *p)
{
  Pointer_group_interface::add_grob (me, ly_symbol2scm ("elements"), p);

  /*
    only add callback for the rests, since we don't move anything
    else.

    (not?)
  */
  add_offset_callback (p, Rest_collision::force_shift_callback_proc, Y_AXIS);
  p->set_object ("rest-collision", me->self_scm ());

  Grob *rest = unsmob_grob (p->get_object ("rest"));
  if (rest)
    {
      chain_offset_callback (rest,
			     Rest_collision::force_shift_callback_rest_proc, Y_AXIS);
    }
}

/*
  TODO: look at horizontal-shift to determine ordering between rests
  for more than two voices.
*/
MAKE_SCHEME_CALLBACK (Rest_collision, calc_positioning_done, 1);
SCM
Rest_collision::calc_positioning_done (SCM smob)
{
  Grob *me = unsmob_grob (smob);

  me->set_property ("positioning-done", SCM_BOOL_T);

  extract_grob_set (me, "elements", elts);

  vector<Grob*> rests;
  vector<Grob*> notes;

  for (vsize i = 0; i < elts.size (); i++)
    {
      Grob *e = elts[i];
      if (unsmob_grob (e->get_object ("rest")))
	rests.push_back (e);
      else
	notes.push_back (e);
    }

  /*
    handle rest-rest and rest-note collisions

    [todo]
    * decide not to print rest if too crowded?
    */

  /*
    no partners to collide with
  */
  if (rests.size () + notes.size () < 2)
    return SCM_BOOL_T;

  Real staff_space = Staff_symbol_referencer::staff_space (me);
  /*
    only rests
  */
  if (!notes.size ())
    {

      /*
	This is incomplete: in case of an uneven number of rests, the
	center one should be centered on the staff.
      */
      Drul_array<vector<Grob*> > ordered_rests;
      for (vsize i = 0; i < rests.size (); i++)
	{
	  Grob *r = Note_column::get_rest (rests[i]);

	  Direction d = get_grob_direction (r);
	  if (d)
	    ordered_rests[d].push_back (rests[i]);
	  else
	    rests[d]->warning (_ ("cannot resolve rest collision: rest direction not set"));
	}

      Direction d = LEFT;
      do
	vector_sort (ordered_rests[d], Note_column::shift_less);
      while (flip (&d) != LEFT)
	;

      do
	{
	  if (ordered_rests[d].size () < 1)
	    {
	      if (ordered_rests[-d].size () > 1)
		ordered_rests[-d][0]->warning (_ ("too many colliding rests"));

	      return SCM_BOOL_T;
	    }
	}
      while (flip (&d) != LEFT);

      Grob *common = common_refpoint_of_array (ordered_rests[DOWN], me, Y_AXIS);
      common = common_refpoint_of_array (ordered_rests[UP], common, Y_AXIS);

      Real diff
	= (ordered_rests[DOWN].back ()->extent (common, Y_AXIS)[UP]
	   - ordered_rests[UP].back ()->extent (common, Y_AXIS)[DOWN]) / staff_space;

      if (diff > 0)
	{
	  int amount_down = (int) ceil (diff / 2);
	  diff -= amount_down;
	  Note_column::translate_rests (ordered_rests[DOWN].back (),
					-2 * amount_down);
	  if (diff > 0)
	    Note_column::translate_rests (ordered_rests[UP].back (),
					  2 * int (ceil (diff)));
	}

      do
	{
	  for (vsize i = ordered_rests[d].size () -1; i-- > 0;)
	    {
	      Real last_y = ordered_rests[d][i + 1]->extent (common, Y_AXIS)[d];
	      Real y = ordered_rests[d][i]->extent (common, Y_AXIS)[-d];

	      Real diff = d * ((last_y - y) / staff_space);
	      if (diff > 0)
		Note_column::translate_rests (ordered_rests[d][i], d * (int) ceil (diff) * 2);
	    }
	}
      while (flip (&d) != LEFT);
    }
  else
    {
      /*
	Rests and notes.
      */
      if (rests.size () > 1)
	warning (_ ("too many colliding rests"));
      Grob *rcol = 0;
      Direction dir = CENTER;

      for (vsize i = rests.size (); !rcol && i--;)
	if (Note_column::dir (rests[i]))
	  {
	    rcol = rests[i];
	    dir = Note_column::dir (rcol);
	  }

      if (!rcol)
	return SCM_BOOL_T;

      Grob *rest = Note_column::get_rest (rcol);
      Grob *common = common_refpoint_of_array (notes, rcol, Y_AXIS);

      Interval restdim = rcol->extent (common, Y_AXIS);
      if (restdim.is_empty ())
	return SCM_BOOL_T;

      Real staff_space = Staff_symbol_referencer::staff_space (rcol);
      Real minimum_dist = robust_scm2double (me->get_property ("minimum-distance"), 1.0) * staff_space;

      Interval notedim;
      for (vsize i = 0; i < notes.size (); i++)
	notedim.unite (notes[i]->extent (common, Y_AXIS));


      Real y = dir * max (0.0,
			  -dir * restdim[-dir] + dir * notedim[dir]  + minimum_dist);
      
      int stafflines = Staff_symbol_referencer::line_count (me);
      if (!stafflines)
	{
	  programming_error ("no staff line count");
	  stafflines = 5;
	}

      // move discretely by half spaces.
      int discrete_y = dir * int (ceil (y / (0.5 * dir * staff_space)));

      // move by whole spaces inside the staff.
      if (fabs (Staff_symbol_referencer::get_position (rest)
		+ discrete_y) < stafflines + 1)
	{
	  discrete_y = dir * int (ceil (dir * discrete_y / 2.0) * 2.0);
	}

      Note_column::translate_rests (rcol, discrete_y);
    }
  return SCM_BOOL_T;
}

ADD_INTERFACE (Rest_collision,
	       "Move around ordinary rests (not multi-measure-rests) to avoid "
	       "conflicts.",

	       /* properties */
	       "minimum-distance "
	       "positioning-done "
	       "elements");

