#! /bin/bash
#    Path: ${HOME}/bin/brightness.sh
#  Author: Alexander Brunhirl
#    Date: 15.09.2015
# Version: 0.1
########################################

[ ${UID} != 0 ] && echo -e "\033[1;31mERROR:\033[0m Need to be run as root!" >&2 && exit 1
backlight="/sys/class/backlight/intel_backlight"
[ ! -d "${backlight}" ] && echo -e "\033[1;31mERROR:\033[0m No such file or directory: ${backlight}">&2 && exit 1

function main() {
    actual=$(cat ${backlight}/actual_brightness)
    if [ ${actual} == ${1} ]; then
        echo "Already the expected brightness (${actual})"
        exit 0
    else
        echo ${1} > ${backlight}/brightness
        echo "Brightness set to $(cat ${backlight}/actual_brightness)"
        exit 0
    fi
}

function usage() {
    echo -e "Usage: $(basename ${0}) <1..10>\n
\033[1mDESCRIPTION:\033[0m
This script set the monitor brightness. The values are between 1 for the lowest
brightness and 10 for the highest.\n
\033[1mEXIT STATUS:\033[0m
 0 if OK,
 1 if minor problems.\n"
exit 0
}

[ -e ${1} ] && echo -e "\033[1;31mERROR:\033[0m Missing parameter\nRun \`$(basename ${0}) --help\` for more informations" >&2 && exit 1

case ${1} in
    -h|--help) usage
    ;;
    1) main 465
    ;;
    2) main 930
    ;;
    3) main 1395
    ;;
    4) main 1860
    ;;
    5) main 2325
    ;;
    6) main 2790
    ;;
    7) main 3255
    ;;
    8) main 3720
    ;;
    9) main 4185
    ;;
    10) main 4650
    ;;
    *) echo -e "\033[1;31mERROR:\033[0m Unknown brightness\nRun \`$(basename ${0}) --help\` for more informations" >&2 && exit 1
    ;;
esac