#! perl
#CONVERSION: NONE

use List::Util;

sub set_stack {
   my ($map, $x, $y, $as) = @_;

   $_->insert_ob_in_map_at ($map, $_, cf::INS_ON_TOP, $x, $y)
      for @$as;
}

sub on_move {
   my ($event, $who) = @_;

   # on first call (there is no initialiser callback), initialise
   my $self = $who->{map_grid_move} ||= {
      x1 => $who->x,
      y1 => $who->y,
      split /(?:\s+|=)/, $event->options,
   };

   my ($x1, $y1) = ($self->{x1}, $self->{y1});

   # this is horribly ugly code.. why can't there be a simple function to just move objects,
   # instead of having 20+ of them that all crash in different ways.

   if (0.5 <= rand) {
      # horizontal

      my $y = $y1 + int rand $self->{height};

      my @ass = map [grep $_->remove || 1, $who->map->at ($_, $y)], $x1 .. $x1 + $self->{width} - 1;

      if (0.5 <= rand) {
         my $as = pop @ass; unshift @ass, $as;
      } else {
         my $as = shift @ass; push @ass, $as;
      }

      set_stack $who->map, $_, $y, $ass[$_ - $x1] for $x1 .. $x1 + $self->{width} - 1;
      
   } else {
      # vertical

      my $x = $x1 + int rand $self->{width};

      my @ass = map [grep $_->remove || 1, $who->map->at ($x, $_)], $y1 .. $y1 + $self->{height} - 1;

      if (0.5 <= rand) {
         my $as = pop @ass; unshift @ass, $as;
      } else {
         my $as = shift @ass; push @ass, $as;
      }

      set_stack $who->map, $x, $_, $ass[$_ - $y1] for $y1 .. $y1 + $self->{height} - 1;
      
   }

   1
}