#!/usr/bin/env bash

DDC_UTIL=$(which ddcutil)
STEP="10"
FUNCTION="$DDC_UTIL setvcp 10"
PROG_NAME="$(basename $0)"

usage() {
    printf "Usage: %s (-d | --decrease=NUM | -i | --increase=NUM)\n" $PROG_NAME > /dev/stderr
}

while [[ $# -gt 0 ]]; do
    case $1 in
        -d)
            FUNCTION="$FUNCTION -"
            ;;
        -i)
            FUNCTION="$FUNCTION +"
            ;;
        --decrease=*)
            FUNCTION="$FUNCTION -"
            STEP=$(echo $1 | sed "s/--decrease=//g")
            ;;
        --increase=*)
            FUNCTION="$FUNCTION +"
            STEP=$(echo $1 | sed "s/--increase=//g")
            ;;
        --help)
            usage
            exit 1
            ;;
        *)
            printf "Error: Unknown Flag '%s'.\n" $1 > /dev/stderr
            usage
            exit 1
            ;;
    esac

    shift
done

FUNCTION="$FUNCTION $STEP"

$FUNCTION