#!/usr/bin/env sh

######################################################################
# @author      : swytch
# @file        : sbacklight
# @license     : GPLv3
# @created     : Wednesday May 20, 2020 18:22:36 CEST
#
# @description : control screen brightness
######################################################################


## You need write privileges on /sys/.../brightness
## This can be achieved via a `udev` rule (see ~/.config/root)

current=$(cat /sys/class/backlight/intel_backlight/brightness)
max=$(cat /sys/class/backlight/intel_backlight/max_brightness)
step=$(expr $max / 20)

[ "$1" = "dec" ] && new=$(expr $current - $step)
[ "$1" = "inc" ] && new=$(expr $current + $step)
[ "$1" = "set" ] && new=$(expr $2 \* $step)
case "$1" in
        "dec") new=$(expr $current - $step);;
        "inc") new=$(expr $current + $step);;
        "set") new=$(expr $2 \* $step);;
        *) exit
esac

[ $new -gt $max ] && new=$max
[ $new -lt 0 ] && new=0

echo $new > /sys/class/backlight/intel_backlight/brightness