start

#!/usr/bin/env perl

use v5.38;
use autodie;
use HTTP::Cookies;
use LWP::UserAgent;
use File::Path qw(make_path);
use File::Basename qw(dirname);

sub slurp ($file_name)
{
	local $/;
	open my $fh, '<', $file_name;
	my $content = readline $fh;

	chomp $content;
	return $content;
}

my $year = shift || die 'requires year';
my $day = shift;
my @days;
if ($day && $day =~ m{ \A (\d+) (?: \.\. (\d+))? \z }x) {
	my $day_from = $1;
	my $day_to = $2 || $day_from;
	@days = $day_from .. $day_to;
}

die 'requires day number(s)'
	if !@days;

foreach my $day (@days) {
	my $solution_content = <<~PERL;
	package Day${day}::Solution;

	use class;

	with 'Solution';

	sub part_1 (\$self)
	{
		...
	}

	sub part_2 (\$self)
	{
		...
	}
	PERL

	my $fetch_input = sub {
		my $jar = HTTP::Cookies->new;
		$jar->set_cookie(0, session => slurp('.session'), '/', 'adventofcode.com', 443, 0, 0, 9999, 0);

		say 'Fetching input data...';
		my $ua = LWP::UserAgent->new(cookie_jar => $jar, timeout => 10);
		my $response = $ua->get("https://adventofcode.com/${year}/day/${day}/input");
		if (!$response->is_success) {
			die $response->status_line;
		}

		return $response->decoded_content;
	};

	my %new_files = (
		"${year}/input/day${day}.txt" => $fetch_input,
		"${year}/test/day${day}.txt" => '',
		"${year}/test/expected/day${day}_part1.txt" => '',
		"${year}/test/expected/day${day}_part2.txt" => '',
		"${year}/lib/Day${day}/Solution.pm" => $solution_content,
	);

	foreach my $file_name (keys %new_files) {
		my $content = $new_files{$file_name};
		make_path dirname $file_name;

		next if -e $file_name;
		$content = $content->()
			if ref $content eq 'CODE';

		say "Creating $file_name...";
		open my $fh, '>', $file_name;
		print {$fh} $content;
	}

	say "Done with day $day";
}

say 'All done!';