use lib qw/ . /;
use lib qw! ../../perl-lib !;

use 5.36.0;
use AoC::Puzzle;

package Part1;

use Moo;

use AoC::Grid;
use List::AllUtils qw/ sum /;

extends 'AoC::Puzzle';

has '+input', default => sub ($self) {
    AoC::Grid->new( string => $self->file_slurp );
};

sub trailhead_score ( $self, $x, $y ) {

    my $grid = $self->input;
    my %endpoints;

    my @points = ( [ $x, $y, 0 ] );

    while ( my $p = shift @points ) {
        if ( $p->[2] == 9 ) {
            $endpoints{ join ':', @$p }++;
            next;
        }
        my $v = $p->[2] + 1;
        push @points,
          map  { [ @$_, $v ] }
          grep { $grid->get(@$_) == $v }
          $grid->ortho_neighbors( $p->@[ 0, 1 ] );
    }

    return $self->trailhead_score_resolution(%endpoints);
}

sub trailhead_score_resolution ( $self, %endpoints ) {
    return scalar keys %endpoints;
}

sub solve ($self) {
    my @points;

    $self->input->foreach(
        sub ( $x, $y, $v ) {
            push @points, [ $x, $y ] if $v == 0;
        }
    );

    return sum map { $self->trailhead_score(@$_) } @points;
}

1;