use lib '.';
use 5.36.0;

use Part1;

package Part2;

use List::AllUtils qw/ uniq /;
use Math::Vector::Real;
use Algorithm::Combinatorics qw(permutations variations variations_with_repetition);
use Grid;

sub find_antinodes($grid,@group) {
    my %antinodes;
    my $iter = variations(\@group,2);
    while( my $p = $iter->next ) {
        my( $x, $y) = @$p;
        my $delta = $y - $x;
        $y = V(@$y);

        while( $grid->is_inside(@$y) ) {
            $antinodes{$y}++;
            $y+=$delta;
        }
    }
    return keys %antinodes;
}

sub solve ($grid) {
    my %groups;

    $grid->foreach( sub($l,$r,$content) {
        return if $content eq '.';
        my $g = ( $groups{$content} //= [] );
        push @$g, V($l,$r);
    });

    my %antinodes;

    for my $group ( values %groups ) {
        $antinodes{$_}++ for find_antinodes($grid,@$group);
    }

    return scalar keys %antinodes;
}

1;