#!/usr/bin/env perl

use strict;
use utf8;
use Getopt::Std;
use Tie::File;

$::VERSION = "1.0.0";

getopts("ne", \my %opts);

my $metavar;
if (defined $opts{n}) {
    # "new" post
    $metavar = "created";
} elsif (defined $opts{e}) {
    # "edited" post
    $metavar = "modified";
} else {
    die "Neither -n[ew] nor -e[dited] are defined!";
}

my $timestamp = time;

my $fname = shift @ARGV;
tie my @fharr, 'Tie::File', $fname or die $!;

my $done = 0;
for (@fharr) {
    if (s/^$metavar=.+/$metavar=$timestamp/) {
        print "$fname:$.: Overwriting existing \`$metavar\'\n";
        $done++;
    }
    if (s/^(--.+?--)$/$metavar=$timestamp\n$1/) {
        print "$fname:$.: Inserting new \`$metavar\'\n";
        $done++;
    }
    last if ($done);
}

if (!$done) {
    print "$fname: No content and no \`$metavar\', inserting at end\n";
    push @fharr, "$metavar=$timestamp";
}

untie @fharr;