#!/usr/bin/perl -w
# vim:sw=4:et
# Author: Dirk Mueller

use strict;

my $diffname = $ARGV[0];
my $specname = $ARGV[1];

if (!defined($diffname) || ! -f $diffname) {

    print "$0: <diffname>\n";
    exit 1;
}

sub find_specfile()
{
    opendir(D, ".");
    my @specs = grep { /\.spec$/ } readdir(D);
    closedir(D);

    # choose the one with the shortest name (heuristic)
    $specname = ( sort { length($a) - length($b) } @specs)[0];

}

if (!defined($specname) || ! -f $specname) {
    &find_specfile();
}


open(S, '<', $specname) or die;

my $ifdef_level = 0;
my $in_prep = 0;
my $in_global = 1;
my $last_patch_in_prep_index = 0;
my $last_patch_in_global_index = 0;
my $already_found_patch = 0;
my @c = ();
my $index = 0;

# first read the specfile, parse useful information
while(<S>)
{

    if(/^\s*%\s*endif/) {
        $ifdef_level--;
        $last_patch_in_prep_index = $index if ($in_prep && $ifdef_level == 0);
    }
    die if ($ifdef_level < 0);
    $ifdef_level++ if(/^\s*%\s*if/);

    if ($ifdef_level == 0 && !$in_prep && $in_global
        && /^\%(?:prep|build|install|package|description|doc)/) {
        $in_global = 0;
    }

    if (!$in_prep && /^%prep/i) {
        $in_prep = 1;
        die if ($in_global);
    }

    if ($in_prep
        && /^%setup\b/) {
        $last_patch_in_prep_index = $index;
    }

    if ($in_prep
        && /^\%(?:build|install|package|description|doc)/) {
        $in_prep = 0;
    }

    die if (($in_prep + $in_global) > 1);

    if ($in_global && /^Patch(?:\d+)?:/) {
        $last_patch_in_global_index = $index;
    }

    if ($in_global && $ifdef_level == 0 && /^Source(?:\d+)?:/) {
        $last_patch_in_global_index = $index;
    }

    if ($in_global && /^Patch.*?:\s+$diffname/) {
        $already_found_patch = 1;
    }

    if ($in_prep && $ifdef_level == 0 && /^\%patch/) {
        $last_patch_in_prep_index = $index;
    }
    push(@c, $_);
    $index++;
}
close(S);

exit 0 if ($already_found_patch);

print "Adding patch $diffname to $specname\n";

die if ($ifdef_level > 0);
die if ($in_global || $in_prep);
die if ($last_patch_in_prep_index == 0);
die if ($last_patch_in_global_index == 0);

#print "adding Patch: $diffname to line $last_patch_in_global_index\n";
#print "adding %patch to line $last_patch_in_prep_index\n";

# determine patch number
my $patchnum = 0;
$patchnum = $1+1 if ($c[$last_patch_in_global_index] =~ /Patch(\d+):/);
$patchnum = 1 if ($c[$last_patch_in_global_index] =~ /Patch:/);

# determine strip level
my $striplevel = "";
open(P, '<', $diffname) or die;
while(<P>) {
    $striplevel = " -p1" if (m/^--- a/ or m/^--- [^\/]+-\d+\./);
    last if (/^--- /);

}
close(P);


splice @c, $last_patch_in_prep_index+1, 0, ("\%patch$patchnum$striplevel\n");
splice @c, $last_patch_in_global_index+1, 0,
    (sprintf "Patch%s:%s%s\n", $patchnum, ' ' x (10-length($patchnum)), $diffname);

open(O, '>', "$specname.new") or die;
print O @c;
close(O);

system("diff", "-u", $specname, "$specname.new");
rename("$specname.new", $specname);