/*   
  separating-group-spanner.cc --  implement Separating_group_spanner
  
  source file of the GNU LilyPond music typesetter
  
  (c) 1998--2004 Han-Wen Nienhuys <hanwen@cs.uu.nl>
  
 */

#include "separating-group-spanner.hh"
#include "separation-item.hh"
#include "paper-column.hh"
#include "output-def.hh"
#include "dimensions.hh"
#include "group-interface.hh"

void
Separating_group_spanner::find_rods (Item * r, SCM next, Real padding)
{

  /*
    This is an inner loop: look for the first normal (unbroken) Left
    grob.  This looks like an inner loop (ie. quadratic total), but in
    most cases, the interesting L will just be the first entry of
    NEXT, making it linear in most of the cases.
  */
  if (Separation_item::width (r).is_empty ())
    return; 


  for (; scm_is_pair (next); next = scm_cdr (next))
    {
      Item *l = dynamic_cast<Item*> (unsmob_grob (scm_car ( next)));
      Item *lb = l->find_prebroken_piece (RIGHT);

      if (lb)
	{
	  Interval li (Separation_item::width (lb));
	  Interval ri (Separation_item::conditional_width (r, lb));
	  if (!li.is_empty () && !ri.is_empty ())
	    {
	      Rod rod;

	      rod.item_l_drul_[LEFT] = lb;
	      rod.item_l_drul_[RIGHT] = r;

	      rod.distance_ = li[RIGHT] - ri[LEFT] + padding;
	      rod.add_to_cols ();
	    }
	}

      Interval li (Separation_item::width (l));
      Interval ri (Separation_item::conditional_width (r, l));
      if (!li.is_empty () && !ri.is_empty ())
	{
	  Rod rod;

	  rod.item_l_drul_[LEFT] =l;
	  rod.item_l_drul_[RIGHT]=r;

	  rod.distance_ = li[RIGHT] - ri[LEFT] + padding;
	
	  rod.add_to_cols ();
	  break;
	}

      /*
	this grob doesn't cause a constraint. We look further until we
	find one that does.
      */

    }
}

MAKE_SCHEME_CALLBACK (Separating_group_spanner,set_spacing_rods,1);
SCM
Separating_group_spanner::set_spacing_rods (SCM smob)
{
  Grob*me = unsmob_grob (smob);

  /*
    Ugh: padding is added doubly, also for SeparationItem
   */
  Real padding = robust_scm2double (me->get_property ("padding"), 0.1);
  
  for (SCM s = me->get_property ("elements"); scm_is_pair (s) && scm_is_pair (scm_cdr (s)); s = scm_cdr (s))
    {
      /*
	Order of elements is reversed!
       */
      SCM elt = scm_car (s);
      Item *r = unsmob_item (elt);

      if (!r)
	continue;

      Item *rb
	= dynamic_cast<Item*> (r->find_prebroken_piece (LEFT));
      
      find_rods (r, scm_cdr (s), padding);
      if (rb)
	find_rods (rb, scm_cdr (s), padding);
    }

  return SCM_UNSPECIFIED ;
}

void
Separating_group_spanner::add_spacing_unit (Grob* me ,Item*i)
{
  Pointer_group_interface::add_grob (me, ly_symbol2scm ("elements"), i);
  me->add_dependency (i);
}





ADD_INTERFACE (Separating_group_spanner,"separation-spanner-interface",
	       "A spanner that calculates spacing constraints (\"rods\") "
	       "using the @code{separation-item-interface} grobs in @code{elements}.",
	       "elements padding");
