#!/usr/bin/perl

=head1 NAME

rdeps - List ProteanOS package reverse dependencies

=cut

use strict;
use warnings;
no indirect;
use autovivification;
use English qw(-no_match_vars);

use LWP::Simple;
use POSIX qw(strftime);

my $SOURCE_URL = 'http://git.proteanos.com/depsdot/depsdot.git/';
my $BASE_URL = 'http://files.proteanos.com/pub/proteanos/feeds/dev/trunk';
my @DEP_FIELDS = qw(Build-Depends Depends Recommends Suggests Pre-Depends);

my @rdeps;

sub read_list
{
	my ($list, $dep, $is_src) = @_;

	foreach my $para (split(m{\n\n}, get($list))) {
		my $package = undef;
		my $source = undef;
		my @deps;
		foreach my $line (split(m{\n}, $para)) {
			my ($name, $value) = split(m{\s*:\s*}, $line);
			if ($name eq 'Package') {
				$package = $value;
			}
			if ($name eq 'Source') {
				$source = $value;
			}
			if (grep(m{^\Q$name\E$}, @DEP_FIELDS)) {
				push(@deps, split(m{\s*,\s*}, $value));
			}
		}
		next if not defined($source);
		map({ $_ =~ s{[\s(].*$}{}; } @deps);  # Vim: )
		if (grep(m{^\Q$dep\E$}, @deps) and not
				grep(m{^\Q$source\E$}, @rdeps)) {
			push(@rdeps, $source);
		}
	}

	return;
}

sub usage
{
	my ($fh) = @_;

	$fh->printf("Usage: %s <pkg>\n", $PROGRAM_NAME);

	return;
}

sub main
{
	my $dep;
	my @manifest;

	if ($#ARGV lt 0) {
		usage(*STDERR);
		return 1;
	}
	$dep = $ARGV[0];

	@manifest = split(m{\n}, get($BASE_URL . '/Manifest'));
	foreach my $aps (@manifest) {
		read_list($BASE_URL . '/' . $aps . '/Packages', $dep,
			($aps =~ m{^src/}));
	}
	STDOUT->print(join("\n", sort(@rdeps)));

	return 0;
}

exit(main());

__END__

=head1 SYNOPSIS

B<rdeps>

=head1 DESCRIPTION

B<rdeps> lists the source packages providing build- and run-time dependencies of
a ProteanOS binary package.

=head1 OUTPUT

B<rdeps> writes a list of source packages to standard output.

=head1 COPYRIGHT

Copyright (C) 2019-2020 Patrick McDermott

This program 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.

This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.

=cut