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

  Copyright (C) 2011--2020 Mike Solomon <mike@mikesolomon.org>

  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 "grob.hh"
#include "item.hh"
#include "pointer-group-interface.hh"
#include "pure-from-neighbor-interface.hh"
#include "engraver.hh"

#include "translator.icc"

#include <algorithm>
#include <map>

using std::vector;

class Pure_from_neighbor_engraver : public Engraver
{
  vector<Grob *> pure_relevants_;
  vector<Grob *> need_pure_heights_from_neighbors_;

public:
  TRANSLATOR_DECLARATIONS (Pure_from_neighbor_engraver);
protected:
  void acknowledge_pure_from_neighbor (Grob_info);
  void acknowledge_item (Grob_info);
  void finalize () override;
};

Pure_from_neighbor_engraver::Pure_from_neighbor_engraver (Context *c)
  : Engraver (c)
{
}

void
Pure_from_neighbor_engraver::acknowledge_item (Grob_info i)
{
  if (Item *item = dynamic_cast<Item *> (i.grob ()))
    {
      if (!has_interface<Pure_from_neighbor_interface> (item))
        pure_relevants_.push_back (item);
    }
}

bool
in_same_column (Grob *g1, Grob *g2)
{
  return (g1->spanned_rank_interval ()[LEFT]
          == g2->spanned_rank_interval ()[LEFT])
         && (g1->spanned_rank_interval ()[RIGHT]
             == g2->spanned_rank_interval ()[RIGHT])
         && (g1->spanned_rank_interval ()[LEFT]
             == g1->spanned_rank_interval ()[RIGHT]);
}

void
Pure_from_neighbor_engraver::acknowledge_pure_from_neighbor (Grob_info i)
{
  Item *item = dynamic_cast<Item *> (i.grob ());
  need_pure_heights_from_neighbors_.push_back (item);
}

void
Pure_from_neighbor_engraver::finalize ()
{
  if (!need_pure_heights_from_neighbors_.size ())
    return;

  vector_sort (need_pure_heights_from_neighbors_, Grob::less);
  vector_sort (pure_relevants_, Grob::less);

  /*
    first, clump need_pure_heights_from_neighbors into
    vectors of grobs that have the same column.
  */

  vsize l = 0;
  vector<vector<Grob *> > need_pure_heights_from_neighbors;
  do
    {
      vector<Grob *> temp;
      temp.push_back (need_pure_heights_from_neighbors_[l]);
      for (;
           (l < need_pure_heights_from_neighbors_.size () - 1
            && ((need_pure_heights_from_neighbors_[l]
                 ->spanned_rank_interval ()[LEFT])
                == (need_pure_heights_from_neighbors_[l + 1]
                    ->spanned_rank_interval ()[LEFT])));
           l++)
        temp.push_back (need_pure_heights_from_neighbors_[l + 1]);
      need_pure_heights_from_neighbors.push_back (temp);
      l++;
    }
  while (l < need_pure_heights_from_neighbors_.size ());

  /*
    then, loop through the pure_relevants_ list, adding the items
    to the elements of need_pure_heights_from_neighbors_ on either side.
  */

  int pos[2] = { -1, 0};
  for (vsize i = 0; i < pure_relevants_.size (); i++)
    {
      while (pos[1] < (int) need_pure_heights_from_neighbors.size ()
             && (pure_relevants_[i]->spanned_rank_interval ()[LEFT]
                 > (need_pure_heights_from_neighbors[pos[1]][0]
                    ->spanned_rank_interval ()[LEFT])))
        {
          pos[0] = pos[1];
          pos[1]++;
        }
      for (int j = 0; j < 2; j++)
        if (pos[j] >= 0 && pos[j]
            < (int) need_pure_heights_from_neighbors.size ())
          for (vsize k = 0;
               k < need_pure_heights_from_neighbors[pos[j]].size ();
               k++)
            if (!in_same_column (need_pure_heights_from_neighbors[pos[j]][k],
                                 pure_relevants_[i]))
              Pointer_group_interface::add_grob
              (need_pure_heights_from_neighbors[pos[j]][k],
               ly_symbol2scm ("neighbors"),
               pure_relevants_[i]);
    }

  need_pure_heights_from_neighbors_.clear ();
  pure_relevants_.clear ();
}

void
Pure_from_neighbor_engraver::boot ()
{
  ADD_ACKNOWLEDGER (Pure_from_neighbor_engraver, item);
  ADD_ACKNOWLEDGER (Pure_from_neighbor_engraver, pure_from_neighbor);
}

ADD_TRANSLATOR (Pure_from_neighbor_engraver,
                /* doc */
                "Coordinates items that get their pure heights from their neighbors.",

                /* create */
                "",

                /* read */
                "",

                /* write */
                ""
               );
