#!/usr/bin/perl

# Run the command into PS
# Run gv with the -watch option
# go into a loop watching the file and rerun command whenever the file
# has changed.

use POSIX ":sys_wait_h";

$usage = "usage: $0 comand -args -args file [file ...]\n";

foreach $file (@ARGV) {
	next unless -f $file;
	push(@files, $file);
}
die $usage unless $#files > -1;
$cmd = "@ARGV > PS.$ENV{USER}";
$gv = "gv -spartan -antialias PS.$ENV{USER}";
$gv = "gv --spartan --antialias --media=letter PS.$ENV{USER}";

system "$cmd";
$pid = fork;
if ($pid == 0) {
	exec $gv;
	die $gv;
}
# Read all the files looking for .so's so we catch the implied list.
# I dunno if groff catches nested .so's but we don't.
foreach $file (@files) {
	$stat{$file} = (stat($file))[9];
	open(F, $file);
	while (<F>) {
		next unless /^\.so\s+(.*)\s*$/;
		$stat{$1} = (stat($1))[9];
	}
	close(F);
}
while (1) {
	select(undef, undef, undef, .2);
	$kid = waitpid($pid,&WNOHANG);
	exit 0 if (kill(0, $pid) != 1);
	$doit = 0;
	foreach $f (keys %stat) {
		if ($stat{$f} != (stat($f))[9]) {
			$stat{$f} = (stat($f))[9];
			$doit = 1;
		}
	}
	if ($doit) {
		system $cmd;
		kill(1, $pid);
	}
}