#!/bin/ksh
# @(#) mbiff.ksh 1.2 95/08/25
# mbiff: turn mail notification on or off.    
# 92/02/15 john h. dubois iii (john@armory.com)
# 92/03/25 rcvalert broken under 3.2v4; use mailalert instead
#          (modified so that alertprog is only given once so it can be changed)
# 92/09/26 Remove ksh dependence
# 93/12/04 Changed name from notify to mbiff; notify is a tcsh builtin
# 94/07/14 exec alertprog to avoid needless shell fork.
#          Put user name on mailalert cmd line for efficiency.
# 95/02/04 Added 'status' command.

alertprog=/usr/local/bin/mailalert
expression="^\*[ 	][ 	]*-[ 	].*[ 	](exec )?$alertprog"

# status: returns zero if mail notification is enabled; nonzero if not.
status() {
    egrep "$expression" $HOME/.maildelivery > /dev/null 2>&1
}

function help {
    echo \
"$name: Turn immediate mail notification on or off.  If immediate mail
notification is on, any time that a mail message is received for you while
you are logged in a message will be printed to your screen regardless of what
you are doing.
Usage: $name [on|off|status]
$name          tells you whether notification is on or off.
$name status   prints a more terse notification status.
$name on       turns on immediate notification of new mail.
$name off      turns off immediate notification of new mail.

Notification status does not change between logins (when you turn
it on or off, it will remain on or off until you change it again)."
    exit 0
}

if [[ "${0##*/}" = biff ]]; then
    echo 'Use "mbiff" to turn on immediate notification of new mail.'
    name=mbiff
    help
fi

name=${0##*/}

cd
case "$1" in
on)
    if status; then
	echo "Immediate mail notification was already on."
    else
	# preserve old .maildelivery permissions
	[ -f .maildelivery ]
	hasmaildelivery=$?
	[ $hasmaildelivery = 0 ] && /bin/cp .maildelivery .maildelivery-
	# put alert line at top of .maildelivery
	echo \
"*	-	pipe	R	exec $alertprog $USER" > .maildelivery
	[ $hasmaildelivery = 0 ] && cat .maildelivery- >> .maildelivery
	echo "Immediate mail notification is now on."
    fi
    ;;
off)
    if status; then
	# preserve old .maildelivery permissions
	/bin/cp .maildelivery .maildelivery-
	egrep -v "$expression" .maildelivery- > .maildelivery
	echo "Immediate mail notification is now off."
    else
	echo "Immediate mail notification was already off."
    fi
    ;;
status)
    if status; then
	echo "on"
    else
	echo "off"
    fi
    ;;
"")
    if status; then
	echo "Immediate mail notification is on."
    else
	echo "Immediate mail notification is off."
    fi
    ;;
*)
    help
    ;;
esac