#!/bin/bash
########################################
## Rings buzzer (console beep) like crazy until keypress
## Usage: alarm [-t#] [message]
##   If the first parameter begins with ONE dash, the number it contains
##   will be the beep interval in seconds.
##   Any other parameters are considered a message to display.
##   You can change the action performed on the interval by setting $BEEP
## Default: alarm -t0.5 'ALARM, ALARM!! PRESS A KEY! '
## 
## alarm 0.4, Copyright (c) 2002-8 by Adam Katz <scriptsATkhopiscom>, GPL2+
########################################
# This script requires bash, sleep, and date.
# GNU sleep allows decimal intervals, GNU date is more efficient.
# A carriage return is required for older versions of bash.

# just in case you've got your own beep program (like the Debian one)
if [ -z "$BEEPER" ]
  then which beep >/dev/null 2>&1 && BEEPER=beep || BEEPER="printf \a"
fi

# toggle all LEDs to be more annoying (uncomment the three for just scroll lock)
function BEEP() {
nice -n19 xset led 3
"$BEEPER"
nice -n19 xset -led 3
}

# helper for non-GNU date
# doesn't mimic %s, but it does give the day's time in seconds
function ngDATE() {
  # hash notation forces base 10, since a leading 0 sets octal mode
  let "HOUR=10#`date +%H`"
  let "MIN=10#`date +%M`"
  let "SEC=10#`date +%S`"
  echo $((HOUR*3600+MIN*60+SEC))
  unset HOUR MIN SEC
}

# determine if date understands %s, seconds since 1970 UTC
# (currently a GNU-only ability)
if date --help 2>&1 |grep "seconds since.*1970" >/dev/null
  then DATE='date +%s'
  else DATE=ngDATE
fi

# helper that beeps like crazy on given interval ($1, defaults to 0.01)
function ALARM() {
BEEP
# look for interval parameter
[ -n "$1" ] && T="${@//[-=a-zA-Z]/}" # T=`echo $1|sed s/[-a-zA-Z]//g`
[ -z "$T" ] && T='0.5'
# if sleep can't handle decimals, truncate (provide for non-GNU sleep)
if ! sleep --help 2>&1 |grep floating >/dev/null; then
  T="${1/%.*/}"                      # T=`echo $T|sed "s/\..*$//"`
  # T is now empty if it started with a decimal point. fix:
  [ -z "$T" ] && T=0
fi  
case $TERM in 
  # try to determine if we can print to the window's titlebar
  xterm* | vt100* |rxvt* |Eterm* )
    began=`$DATE`
    w="seconds ago, interval of $T seconds"
    while true
    do 
      [ "$T" = 0 ] || sleep $T
      # get current date as a number
      now=`$DATE`
      BEEP
      printf "\033]0;ALARM: started $((now-began)) $w\007"
    done
    ;;
  # default case (just beep)
  *)
    while true
    do
      sleep $T
      BEEP
    done
    ;;
esac
} # note - this function needs to be killed to stop


if [ -n "$1" ] 
then
  echo $1|grep "^-*help" >/dev/null && \
    grep '^## ' `which $0 2>/dev/null || echo $0`|sed 's/^..//' && exit 0  # --help
  # look for beep interval, take it out of $@
  echo $1|grep "^-[\.0-9A-Za-z]" >/dev/null && T=$1 && shift
fi
# ensure read likes the -n# parameter
read --help 2>&1 |grep "\-n " >/dev/null && \
  nchar="-n1" && akey="A KEY" || akey="ENTER"
[ "$@" ] && echo -n "$@" || printf "ALARM, ALARM!! PRESS $akey! "

ALARM $T&

PID="$!" # the most recent bg'd process (ALARM)
trap "kill -9 $PID 2>&1|true; exit 0" 0 1 2 5 9 15 # stop alarm on exit or break

# get keypress
read $nchar nothing
# if a letter was pressed, there was no linefeed.  fix:
[ -n "$nothing" ] && printf "\n"

exit 0