#!/usr/bin/perl

use strict;
use warnings;

use File::Copy;
use Getopt::Long;

my $dir = ".";
my $rpmrelease;
my $patches="";

GetOptions(
	"patches=s" => \$patches,
	"release=s" => \$rpmrelease
) or die "Usage: $0 [--release <release>] [--patches <dir>]\n";

# flavor -> [supported archs]
my %flavor_archs = parse_config_conf();
# subset to include in kernel-syms
my %syms_flavor_archs = parse_config_conf("syms");

# template name -> template body
my %templates = read_spec_templates();

# config.sh variables
my %vars = parse_config_sh();
my ($srcversion, $variant, $vanilla_only) =
	($vars{'SRCVERSION'}, $vars{'VARIANT'}, $vars{'VANILLA_ONLY'});
$vanilla_only ||= "0";

# package name -> [summary, description]
my %binary_descriptions = parse_descriptions();

$patches="--patches $patches" if $patches;
my $patchversion = `$dir/compute-PATCHVERSION.sh $patches`;
chomp $patchversion;
my $rpmversion = $patchversion;
# stuff the -rcX tag into the rpm version if possible;
$rpmversion =~ s/\.0-rc/.rc/;
$rpmversion =~ s/-rc\d+//;
$rpmversion =~ s/-/./g;

if (defined($rpmrelease)) {
	# convince abuild that we really want this release number
	xopen(my $fh, '>', "$dir/get_release_number.sh");
	print $fh "#!/bin/sh\n";
	print $fh "echo \"$rpmrelease.0\"\n";
	close($fh);
	chmod(0755, "$dir/get_release_number.sh");
} else {
	$rpmrelease = "0";
}
$rpmrelease =~ s/-/./g;

my $sources = join("", $templates{source} =~ /\nSource\d+:[^\n]*/mg);
# Find all SourceN: foo.tar.bz2 lines and generate the NoSource:
# lines and the %setup line
my @tarballs = ($sources =~ /\nSource(\d+):[^\n]*\.tar\.bz2/mg);
my $nosource = join("\n", map { "NoSource:       $_" } @tarballs);
# Source0 (the linux tarball) is unpacked manually
@tarballs = grep { $_ > 0 } @tarballs;
my $unpack_patches = join(" ", map { "-a $_" } @tarballs);
# List of scripts to automatically chmod +x before build
my $scripts = join(",", grep { is_script($_) }
			($sources =~ /\nSource\d+:\s*([^\s]*)/mg));

my $tarball_url;
if ($srcversion =~ /^(\d+)(?:\.\d+)*(-rc\d+)?$/) {
	$tarball_url = "http://www.kernel.org/pub/linux/kernel/v$1.x/";
	$tarball_url .= "testing/" if $2;
} else {
	# kernel.org has no tarballs for  linux-next or vanilla snapshots
	$tarball_url = "";
}

my %macros = (
	VARIANT => $variant,
	VANILLA_ONLY => $vanilla_only,
	SRCVERSION => $srcversion,
	PATCHVERSION => $patchversion,
	RPMVERSION => $rpmversion,
	TARBALL_URL => $tarball_url,
	RELEASE => $rpmrelease,
	SOURCES => $sources,
	NOSOURCE => $nosource,
	UNPACK_PATCHES => $unpack_patches,
	SCRIPTS => $scripts,
	YEAR => (localtime time)[5] + 1900,
);

# binary spec files
for my $flavor (sort keys(%flavor_archs)) {
	my ($summary, $description);
	if (!exists($binary_descriptions{"kernel-$flavor"})) {
		print STDERR "warning: no description for kernel-$flavor found\n";
		$summary = "The Linux Kernel";
		$description = "The Linux Kernel.";
	} else {
		$summary = $binary_descriptions{"kernel-$flavor"}->[0];
		$description = $binary_descriptions{"kernel-$flavor"}->[1];
	}

	do_spec('binary', "kernel-$flavor.spec", %macros,
		FLAVOR => $flavor,
		SUMMARY => $summary,
		DESCRIPTION => $description,
		ARCHS => join(" ", arch2rpm(@{$flavor_archs{$flavor}})),
		PROVIDES_OBSOLETES => provides_obsoletes($flavor, @{$flavor_archs{$flavor}}),
	);
}
# kernel-source.spec
do_spec('source', "kernel-source$variant.spec", %macros);

# kernel-docs.spec
do_spec('docs', "kernel-docs$variant.spec", %macros);

# kernel-syms.spec
{
	my $requires = "";
	my %all_archs;
	for my $flavor (sort keys(%syms_flavor_archs)) {
		next if $flavor eq "vanilla";
		my @archs = arch2rpm(@{$syms_flavor_archs{$flavor}});
		$all_archs{$_} = 1 for @archs;
		$requires .= "%ifarch @archs\n";
		$requires .= "Requires:       kernel-$flavor-devel = \%version-\%source_rel\n";
		$requires .= "%endif\n";
	}
	chomp $requires;
	if (keys(%all_archs)) {
		do_spec('syms', "kernel-syms$variant.spec", %macros,
			REQUIRES => $requires,
			ARCHS => join(" ", sort(keys(%all_archs))));
	}
}

exit 0;



sub parse_config_conf {
	my @symbols = @_;
	my $symbols = join(' ', @symbols);
	my %res;

	for my $arch (split(/\s+/, `$dir/arch-symbols --list`)) {
		my @flavors = `$dir/guards $arch $symbols < $dir/config.conf`;
		next if @flavors == 0;
		chomp @flavors;
		@flavors = map { s/.*\///; $_ } @flavors;
		for my $flavor (@flavors) {
			$res{$flavor} ||= [];
			push(@{$res{$flavor}}, $arch);
		}
	}
	for my $flavor (keys(%res)) {
		$res{$flavor} = [sort @{$res{$flavor}}];
	}
	return %res;
}

sub read_spec_templates {
	my %res;

	for my $template (qw(binary source syms docs)) {
		xopen(my $fh, '<', "$dir/kernel-$template.spec.in");
		local $/ = undef;
		$res{$template} = <$fh>;
		close($fh);
	}
	return %res;
}

# return a hash of config.sh variables
sub parse_config_sh {
	my %res;

	xopen(my $fh, '<', "$dir/config.sh");
	while (<$fh>) {
		chomp;
		if (/^\s*([A-Z_]+)=(.*)/) {
			$res{$1} = $2;
		}
	}
	close($fh);
	return %res;
}

sub parse_descriptions {
	my %res;
	my $current;
	my $blank = "";
	# 0 - expect summary, 1 - eating blank lines, 2 - reading description
	my $state = 0;

	xopen(my $fh, '<', "$dir/package-descriptions");
	while (<$fh>) {
		next if /^\s*#/;

		if (/^==+\s+([^\s]+)\s+==+\s*$/) {
			my $package = $1;
			if ($current) {
				chomp $current->[1];
			}
			$current = ["", ""];
			$res{$package} = $current;
			$state = 0;
			next;
		}
		if (/^$/) {
			if ($state == 2) {
				$blank .= $_;
			}
			next;
		}
		# non-blank line and not === package ===
		if ($state == 0) {
			chomp;
			$current->[0] = $_;
			$state = 1;
		} elsif ($state == 1) {
			$current->[1] = $_;
			$blank = "";
			$state = 2;
		} else {
			$current->[1] .= $blank;
			$blank = "";
			$current->[1] .= $_;
		}
	}
	if ($current) {
		chomp $current->[1];
	}
	close($fh);
	return %res;
}

sub is_script {
	my $script = shift;

	return undef if $script =~ /\.(tar\.(gz|bz2)|in|conf)$/;
	return undef if $script =~ /^README/;
	return 1 if $script =~ /\.pl$/;
	open(my $fh, '<', $script) or return undef;
	sysread($fh, my $shebang, 2);
	close($fh);
	return 1 if $shebang eq "#!";
	return undef;
}

sub arch2rpm {
	if (wantarray) {
		return map { _arch2rpm($_) } @_;
	}
	return _arch2rpm($_[0]);
}
sub _arch2rpm {
	my $arch = shift;
	return "\%ix86" if $arch eq "i386";
	return "aarch64" if $arch eq "arm64";
	return $arch;
}

sub provides_obsoletes {
	my $flavor = shift;
	my @archs = @_;
	my $res = "";

	for my $arch (@archs) {
		my @packs = `$dir/guards $arch $flavor <$dir/old-packages.conf`;
		chomp @packs;
		next if (!@packs);
		my $rpmarch = arch2rpm($arch);
		chomp $rpmarch;
		$res .= "\%ifarch $rpmarch\n";
		$res .= "Provides:       @packs\n";
		$res .= "Obsoletes:      @packs\n";
		$res .= "\%endif\n";
	}
	chomp $res;
	return $res;
}

sub do_spec {
	my $template = shift;
	my $specfile = shift;
	my %macros = @_;

	my $text = $templates{$template};
	my $prev_text;
	do {
		$prev_text = $text;
		for my $m (keys %macros) {
			$text =~ s/\@$m\@/$macros{$m}/g;
		}
	} while ($prev_text ne $text);
	print "$specfile\n";
	xopen(my $fh, '>', "$dir/$specfile");
	print $fh $text;
	close($fh);

	return if $specfile eq "kernel-source$variant.spec";
	my $changesfile = $specfile;
	$changesfile =~ s/\.spec$//;
	$changesfile .= ".changes";
	copy("$dir/kernel-source$variant.changes", $changesfile);
}

sub xopen {
        open($_[0], $_[1], $_[2]) or die "$_[2]: $!\n";
}