#!/bin/sh

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

case "$1" in
	'-u')
		case "$brightness" in
			0) echo 1;;
			1) echo "$step";;
			*) echo "$((brightness+step))";;
		esac
	;;
	'-d')
		case "$brightness" in
			1) echo 0;;
			"$step") echo 1;;
			*) echo "$((brightness-step))";;
		esac
	;;
	*) exit 1;;
esac > /sys/class/backlight/intel_backlight/brightness