#!/bin/bash

#    set the keyboard brigthness on a Apple MacBook computer
#    Copyright (C) 2006  Ludovic Rousseau <ludovic.rousseau@free.fr>
#
#    This program is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License along
#    with this program; if not, write to the Free Software Foundation, Inc.,
#    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

#set -v
#set -x
BRIGHTNESS=/sys/class/leds/smc\:kbd_backlight/brightness
value=$(cat $BRIGHTNESS)

if [ -z "$1" ]; then
	echo $value
	exit
fi

if [ "$1" = "-h" ]; then
	echo "Usage: $0 [-h|arg|+arg|-arg]"
	echo
	echo "Change the keyboard brigthness to:"
	echo "  arg"
	echo "  or current value + arg"
	echo "  or current value - arg"
	echo
	echo "Without argument it return the current value"
	exit
fi

if [ $(expr match "$1" "[+-]")  = "1" ]; then
	value=$((value$1))
else
	value=$1
fi

if [ $value -lt 0 ]; then
	value=0
fi

echo $value > $BRIGHTNESS
cat $BRIGHTNESS