#!/usr/bin/env perl
use strict;
use warnings;

my $lineno = 0;
my $status = 0;

sub err {
    my ($msg) = @_;

    print STDERR "Error on line $lineno (actual line $.): ". $msg ."\n";
    $status = 1;
}

open(my $commitfile, "<", $ARGV[0]) or die "Couldn't open $ARGV[0]";

while (<$commitfile>) {
    next if /^#/;                 # Discard comments
    next if $lineno == 0 && /^$/; # Discard leading empty lines
    $lineno++;                    # Start at 1, so increment first

    if ($lineno == 1) {
        err "Not capitalized" if /^[^[:upper:]]/;
        err "Longer than 50 characters" if /^.{51,}/;
        next;
    }

    err "Should be empty" if $lineno == 2 && /.+/;
    err "Longer than 72 characters" if /^.{73,}/;
}

close $commitfile;
exit $status;