#!/usr/bin/perl

use strict;

MAIN:{
	my $encstr = "# -*- coding: ISO8859-1 -*-\n";
	local *FILE;

	foreach my $fn (@ARGV) {
		open(FILE, "<", $fn)
			or die("$fn: $!\n");
		my @lines = <FILE>;
		close(FILE);

		my $interpreter = "";
		if ($lines[0] =~ m/^\#!/) {
			($interpreter = shift(@lines)) =~
			    s|!\s+/usr/bin/env\s+python|!$ENV{'PYTHON_CMD'}|;
		}
		if ($lines[0] =~ m/^\#.*-\*-.*coding/) {
			# leave untouched
		} else {
			unshift(@lines, $encstr);
		}

		open(FILE, ">", "$fn.new")
			or die("$fn.new: $!\n");
		print(FILE $interpreter, @lines);
		close(FILE);
		link("$fn", "$fn.orig");
		rename("$fn.new", "$fn");
	}
}