#!/usr/bin/perl

use strict;
use warnings;

foreach my $fn (@ARGV) {
    my $ofn = $fn . '.new';

    open IN, '<', $fn
        or die "Cannot open " . $fn;
    open OUT, '>', $ofn
        or die "Cannot create " . $ofn;

    my $last_line = '';

    while(<IN>) {
        s/zorder="3"/zorder="11"/
            if $last_line =~ /\[water\]/;

        print OUT $_;

        $last_line = $_;
    }

    close IN;
    close OUT;

    rename $ofn, $fn
        or die "Could not replace " . $fn;
}