#!/usr/bin/perl

use strict;
use warnings;

use Getopt::Long;

sub usage {
	print "Usage: $0 [--test]\n";
	print "Reads list of kernels to keep from /etc/zypp/zypp.conf:multiversion.kernels\n";
	print "kernels can be given as <version>, latest(-N), running, oldest(+N).\n";
}

# arch/flavor => version-release => [ subpackages ]
my %kernels;

my @keep_spec;
my ($want_running, $running_version, $running_flavor);

# do not actually delete anything
my $test_only;

# undocumented debugging options
my ($fake_config, $fake_rpm_qa, $fake_uname_r, $fake_uname_m);

sub get_config_line {
	my $file = "/etc/zypp/zypp.conf";

	if ($fake_config) {
		return $fake_config;
	}
	if (!-e $file) {
		print STDERR "$0: /etc/zypp/zypp.conf does not exist, exiting.\n";
		exit 0;
	}
	open(my $fh, '<', $file) or die "$0: $file: $!\n";
	while (<$fh>) {
		chomp;
		next unless /^\s*multiversion\.kernels\b/;
		s/^[^=]*=\s*//;
		close($fh);
		return $_;
	}
	close($fh);
	return "";
}

sub load_config {
	my @kernels;

	@kernels = split(/,\s*/, get_config_line());
	for my $kernel (@kernels) {
		if ($kernel =~ /^\s*(latest|oldest|running)(\s*[-+]\s*\d+)?\s*$/) {
			my $new = { whence => $1, offset => $2 || 0 };
			$new->{offset} =~ s/\s*//g;
			if ($new->{whence} eq "running") {
				$want_running = 1;
			}
			push (@keep_spec, $new);
		} elsif ($kernel =~ /^\d+\.\d+/) {
			my $new = { version => $kernel };
			push (@keep_spec, $new);
		} elsif ($kernel =~ /^\s*$/) {
			next;
		} else {
			print STDERR "$0: Ignoring unknow kernel specification in\n";
			print STDERR "/etc/zypp/zypp.conf:multiversion.kernels: $kernel\n";
		}
	}
}

sub add_package {
	my ($name, $vr, $arch) = @_;
	(my $flavor = $name) =~ s/^kernel-//;

	#print STDERR "add_package: $name $vr $arch\n";
	if ($name eq "kernel-firmware" || $name eq "kernel-coverage") {
		return;
	}
	# Put all subpackages into the same group, except for
	# kernel-source-{vanilla,rt}, which are packages on their own
	if ($flavor !~ /^source/) {
		$flavor =~ s/-.*//; # XXX: No dashes in flavor names
	}
	# kernel-devel is a subpackage of kernel-source
	$flavor =~ s/^devel/source/;
	$kernels{"$arch/$flavor"} ||= {};
	$kernels{"$arch/$flavor"}{$vr} ||= [];
	push(@{$kernels{"$arch/$flavor"}{$vr}}, "$name-$vr.$arch");
}

sub load_packages {
	my $pipe;

	if ($fake_rpm_qa) {
		open($pipe, '<', $fake_rpm_qa) or die "$fake_rpm_qa: $!\n";
	} else {
		open($pipe, '-|', 'rpm', '-qa', '--qf',
			'%{n} %{v}-%{r} %{arch}\n', 'kernel-*') or die "rpm: $!\n";
	}
	while (<$pipe>) {
		chomp;
		my ($name, $vr, $arch) = split;
		add_package($name, $vr, $arch);
	}
	close($pipe)
}

sub sort_versions {
	my @versions = @_;

	pipe (my $read, my $write);
	my $pid = fork();
	if (!defined($pid)) {
		die "Cannot fork: $!\n";
	} elsif ($pid == 0) {
		# child
		close($read);
		open STDOUT, '>&', $write;
		open(my $fh, '|-', "/usr/lib/rpm/rpmsort") or die "/usr/lib/rpm/rpmsort: $!\n";
		print $fh join("\n", @versions), "\n";
		close($fh);
		die "rpmsort failed ($?)\n" if $? != 0;

		exit 0;
	}
	# parent
	close($write);
	@versions = <$read>;
	chomp @versions;
	close($read);
	waitpid($pid, 0);
	die "rpmsort failed ($?)\n" if $? != 0;

	return @versions;
}

# return true if VER1 == VER2 or VER1 == (VER2 minus rebuild counter)
sub version_match {
	my ($ver1, $ver2) = @_;

	return 1 if $ver1 eq $ver2;

	# copied from kernel-source/rpm/kernel-spec-macros
	$ver2 =~ s/\.[0-9]+($|\.[^.]*[^.0-9][^.]*$)/$1/;
	return $ver1 eq $ver2;
}

sub list_old_versions {
	my ($flavor) = @_;

	my $is_source = $flavor =~ /\/(source|syms)/;
	my $kernels = $kernels{$flavor};
	my @versions = sort_versions(keys(%$kernels));
	my %idx = (
		oldest => 0,
		latest => scalar(@versions) - 1,
	);
	if ($want_running && ($running_flavor eq $flavor || $is_source)) {
		for (my $i = scalar(@versions) - 1; $i >= 0; $i--) {
			if (version_match($running_version, $versions[$i])) {
				$idx{running} = $i;
				last;
			}
		}
		if (!exists($idx{running}) && !$is_source) {
			print STDERR "$0: Running kernel $running_version-$running_flavor not installed.\n";
			print "NOT removing any packages for flavor $flavor.\n";
			return;
		}
	}
	my %delete = map { $_ => 1 } @versions;
	for my $keep (@keep_spec) {
		if ($keep->{version}) {
			for my $ver (@versions) {
				if (version_match($keep->{version}, $ver)) {
					$delete{$ver} = 0;
				}
			}
		} elsif ($keep->{whence}) {
			next unless exists($idx{$keep->{whence}});
			my $idx = $idx{$keep->{whence}};
			$idx += $keep->{offset};
			next unless $idx >= 0 && $idx < scalar(@versions);
			$delete{$versions[$idx]} = 0;
		} else {
			die "??";
		}
	}
	return grep { $delete{$_} } @versions;
}

sub package_exists {
	my ($version, $archs, $flavors) = @_;

	for my $arch (@$archs) {
		for my $flavor (@$flavors) {
			my $config = "$arch/$flavor";
			if (exists($kernels{$config})
				&& exists($kernels{$config}->{$version})) {
					return 1;
			}
		}
	}
	return 0;
}

sub list_old_packages {
	my (@packages, @archs, @flavors);
	my (@syms_flavors, @binary_flavors, @source_configs);

	# there are some inter-dependencies among the kernel packages,
	# so we have to be careful
	my %t = map { s:/.*::; $_ => 1 } keys(%kernels);
	@archs = sort(keys(%t));
	%t = map { s:.*/::; $_ => 1 } keys(%kernels);
	@flavors = sort(keys(%t));
	@syms_flavors = grep { /^syms/ } @flavors;
	@binary_flavors = grep { !/^(source|syms)/ } @flavors;
	@source_configs = grep { /\/source/ } sort(keys(%kernels));

	for my $arch (@archs) {
		for my $flavor (@syms_flavors) {
			my $config = "$arch/$flavor";
			next unless exists($kernels{$config});
			my @versions = list_old_versions($config);
			for my $ver (@versions) {
				push(@packages, @{$kernels{$config}->{$ver}});
				delete($kernels{$config}->{$ver});
			}
		}
		for my $flavor (@binary_flavors) {
			my $config = "$arch/$flavor";
			next unless exists($kernels{$config});
			my @versions = list_old_versions($config);
			for my $ver (@versions) {
				my @pacs = @{$kernels{$config}->{$ver}};
				my $remove_all = 1;
				# do not remove kernel-$flavor-devel-$ver
				# if kernel-syms-$ver still exists
				if (grep { /-devel$/ } @pacs) {
					my $syms = "syms";
					if ($flavor =~ /^rt/) {
						$syms = "syms-rt";
					}
					if (exists($kernels{$syms}->{$ver})) {
						$remove_all = 0;
						@pacs = grep { !/-devel$/ }
							@pacs;
					}
				}
				push(@packages, @pacs);
				if ($remove_all) {
					delete($kernels{$config}->{$ver});
				}
			}
		}
	}
	for my $config (@source_configs) {
		my @versions = list_old_versions($config);
		for my $ver (@versions) {
			# Remove kernel-{devel,source} only if no other package
			# of the same version exists
			next if package_exists($ver, \@archs, \@binary_flavors);
			push(@packages, @{$kernels{$config}->{$ver}});
		}
	}
	return @packages;
}

sub remove_packages {
	my @packages = @_;

	while (1) {
		pipe(my $read, my $write);
		my $pid = fork();
		if (!defined($pid)) {
			die "Cannot fork: $!\n";
		} elsif($pid == 0) {
			# child
			close($read);
			open STDOUT, '>&', $write;
			open STDERR, '>&', $write;
			$ENV{LC_ALL} = "C";
			my @cmd = qw(rpm -e);
			push(@cmd, "--test") if $test_only;
			exec(@cmd, @packages) or die "rpm: $!\n";
		}
		# parent
		close($write);
		my @out = <$read>;
		chomp @out;
		close($read);
		waitpid($pid, 0);
		if ($? == 0) {
			print "Removed:\n    ", join("\n    ", @packages), "\n";
			return 1;
		}
		my ($retry, @problems);
		my %old_packages = map { $_ => 1 } @packages;
		my %new_packages;
		for (@out) {
			if (/ is needed by \(installed\) (kgraft-patch-.*|.*-kmp-.*)/ &&
					!$old_packages{$1}) {
				push(@packages, $1) unless $new_packages{$1};
				$new_packages{$1} = 1;
				$retry = 1;
			} else {
				push(@problems, $_);
			}
		}
		if (!$retry) {
			print STDERR join("\n", @problems), "\n";
			print STDERR "$0: giving up.\n";
			return 0;
		}
	}
}

if (!GetOptions(
		"h|help" => sub { usage(); exit; },
		"--test" => \$test_only,
		"--fake-config=s" => \$fake_config,
		"--fake-rpm-qa=s" => \$fake_rpm_qa,
		"--fake-uname-r=s" => \$fake_uname_r,
		"--fake-uname-m=s" => \$fake_uname_m)) {
	usage();
	exit 1;
}
load_config();
if (!@keep_spec) {
	print STDERR "$0: multiversion.kernels not configured in /etc/zypp/zypp.conf, exiting.\n";
	exit 0;
}

load_packages();
if ($want_running) {
	$running_version = $fake_uname_r ? $fake_uname_r : `uname -r`;
	chomp($running_version);
	($running_flavor = $running_version) =~ s/.*-//;
	$running_version =~ s/-[^-]*$//;
	(my $release = $running_version) =~ s/.*-//;
	$running_version =~ s/-[^-]*$//;

	# copied from kernel-source/rpm/mkspec
	$running_version =~ s/\.0-rc/.rc/;
	$running_version =~ s/-rc\d+//;
	$running_version =~ s/-/./g;

	$running_version .= "-$release";

	my $arch = $fake_uname_m ? $fake_uname_m : `uname -m`;
	chomp($arch);
	$arch =~ s/^i.86$/i586/;
	$running_flavor = "$arch/$running_flavor";
}
my @remove = list_old_packages();
if (!@remove) {
	print STDERR "$0: Nothing to do.\n";
	exit 0;
}
if (remove_packages(@remove)) {
	exit 0;
}
exit 1;