#!/usr/bin/perl

use FileHandle;
use IPC::Open3;

require "timelocal.pl";

@mname = ("Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec");
%mnum  = ("Jan", 0, "Feb", 1, "Mar", 2, "Apr", 3, "May", 4, "Jun", 5,
          "Jul", 6, "Aug", 7, "Sep", 8, "Oct", 9, "Nov",10, "Dec",11);

$username = getpwuid($>)
  or die "$zero: who are you?? getpwuid($>) failed\n";

die <<USAGE unless $#ARGV > 0;
usage: $0 datetime message...

datetime can be any string containing 12 digits:
 4 digits year
 2 digits month
 2 digits day of month
 2 digits hour
 2 digits minutes
for example: 1998-12-30-19:30

all arguments after the first become your message text.
USAGE

$date = shift;
$message = "@ARGV";

($year,$mon,$mday,$hour,$min,$sec)
    = $date =~ /^\D*(\d{4})\D*(\d{2})\D*(\d{2})\D*(\d{2})\D*(\d{2})/
    or die "What date is that?  $date\nTry YYYY-MM-DD-HH:MM (or just YYYYMMDDHHMM)\n";

$time = timelocal($sec,$min,$hour,$mday,$mon-1,$year-1900);
die "That time is in the past or doesn't make sense: $time\n" if $time < time;

$dateformat .= "%02d:%02d %s %02d, %04d";

($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime($time);
$pagetime = sprintf $dateformat, $hour,$min, $mname[$mon],$mday,$year+1900;

($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time);
$currtime = sprintf $dateformat, $hour,$min, $mname[$mon],$mday,$year+1900;

$atr = new FileHandle;
$atw = new FileHandle;
$ate = new FileHandle;
$atpid = open3($atw, $atr, $ate, "/bin/at $pagetime");
print $atw "echo '$message' | /usr/ucb/Mail -s 'alarm set on $currtime' ${username}-beep\n";
close $atw;
print <$atr>;
close $atr;

while(<$ate>)
{ next if /^commands will be executed using \S+sh$/;
  next if ($atjob,$atdate) = /^job (\S+) at (.+\d)\s*$/;
  print;
}
close $ate;

print <<SUBMITTED if $atjob;
Alarm successfully submitted.

Job Number: $atjob
 Date/Time: $atdate
   Message: $message

To cancel this alarm, use: at -r $atjob
SUBMITTED