#!/usr/bin/perl
use urpm;
use urpm::msg;

sub main {
	
	my %options;
	$options{restrict_group} = 0;
	$options{group} = 'System/Libraries';
	
	my $usage = N("usage: %s [options]
where [options] are from
", $0) . N("   -h|--help      - print this help message.
") . N("   -g [group]     - restrict results to given group.
") . N("                    defaults is %s.
", $options{group});

	my $group;
	
	while ($_ = shift @_) {
		/^-g$/ and do {
			$options{restrict_group}=1;
			$group=shift @_;
			$group and $options{group}=$group;
			next;
		};
		die $usage;
	}

	
	my @packages;
	{
		my $db = URPM::DB::open or die;
		$db->traverse(sub {
			my ($p) = @_;
			$p->pack_header;
			push @packages, $p;
		});
	}

	foreach my $pkg (@packages) {
		next if $options{restrict_group} && $pkg->group !~ /$options{group}/i;
		$l{$pkg->name} = 1;
		push @{$provides{$_}}, $pkg->name foreach $pkg->provides_nosense;
	}

	foreach my $pkg (@packages) {
		delete @l{grep { $_ ne $pkg->name } @{$provides{$_} || []}} foreach $pkg->requires_nosense;
	}

	print "$_\n" foreach sort keys %l;
}

main(@ARGV);