#! /bin/sh

# Yell if they are trying to lock remotely. This won't work.
# Even if it does, it's wrong.
if [ "${SSH_TTY}" ] && [ -z "${STY}" ] ; then
	echo "You're doing it wrong. Don't try to lock a remote computer."
	exit 1
fi

# Graphically locking on Macs is simple.
# If we're not in screen, attempt to graphically lock it.
if [ `uname -s` = 'Darwin' ] && [ -z "${STY}" ] ; then
	/System/Library/CoreServices/Menu\ Extras/User.menu/Contents/Resources/CGSession -suspend
	exit
fi

# Handle non-graphical locking
if [ -z "${DISPLAY}" ] ; then
	if [ -z "${STY}" ] ; then # not running screen
		if ( command -v vlock >/dev/null 2>/dev/null ) ; then
			vlock
			exit
		else
			echo "You don't have vlock. Maybe try locking in screen."
		fi
	else
		echo "You are in screen. Use 'C-a x' to lock"
	fi
	exit 1
fi

# Try to lock sanely on X11.
# Certain combinations of desktop managers and locking programs
# allow new sessions to be started.
KDE_LOCK='kdesktop_lock --forcelock || krunner_lock --forcelock || /usr/libexec/kde4/krunner_lock --forcelock || /usr/lib/kde4/libexec/krunner_lock --forcelock'
GNOME_LOCK='gnome-screensaver-command --lock'
XSCREEN_LOCK='xscreensaver-command -lock || xlock'

if ( ps -e | grep gdm >/dev/null 2>/dev/null ) ; then
	# looks like Gnome. They probably want gnome-screensaver.
	# start gnome-screensaver to ensure it's running
	gnome-screensaver >/dev/null 2>/dev/null
	eval $GNOME_LOCK 2>/dev/null && exit
elif ( ps -e | grep kdm >/dev/null 2>/dev/null ) ; then
	# looks like some version of KDE. They probably want kde's screensaver.
	eval $KDE_LOCK 2>/dev/null && exit
elif ( ps -e | grep xdm >/dev/null 2>/dev/null ) ; then
	xscreensaver & >/dev/null 2>/dev/null
	eval $XSCREEN_LOCK 2>/dev/null && exit
fi

echo "Could not decide what desktop manager you are using."
echo "Trying fallback locking."
eval $KDE_LOCK 2>/dev/null && exit
gnome-screensaver >/dev/null 2>/dev/null
eval $GNOME_LOCK 2>/dev/null
xscreensaver & >/dev/null 2>/dev/null
eval $XSCREEN_LOCK 2>/dev/null && exit

echo "Could not lock your screen."
exit 1