#!/usr/bin/perl -w
use strict;
use File::Find;
use File::Copy;

use Getopt::Long;

my %g_config;
GetOptions ( \%g_config,
             qw(
                 dir=s
               )
) || Usage();

if (!defined $g_config{dir}) {
    &Usage();
}

my $modified = 0;

print "Adding pragma once...\n";
find (\&RecurseFiles, $g_config{dir});

print "Done. $modified files modified.\n";


sub RecurseFiles {
    if ($_ =~ /\.h$/) {
        &AddPragmaOnce ($_, $File::Find::name);
    }
}

sub AddPragmaOnce {
    my ($filename, $fullname) = @_;

    my $added = 0;
    my $tmpname = $filename.".tmp";
    open (FIN, "<$filename") or die "Can't open $filename for read.";
    open (FOUT, ">$tmpname") or die "Can't open $tmpname for write.";
    while (my $line = <FIN>) {
        if (!$added && $line =~ /\w+/) {
            print FOUT "#pragma once\n";
            $added = 1;
        }
        print FOUT "$line";
    }
    close FOUT or die;
    close FIN or die;

    if ($added) {
        copy ($tmpname, $filename) or die;
        $modified++;
    }
    unlink $tmpname or die;
}

sub Usage {
  print STDERR "Usage: $0 -dir directory\n";
  print STDERR "\n";
  exit(1);
}