#!/bin/bash
# SPDX-License-Identifier: GPL-2.0-or-later
# Copyright (C) 2020-present Fewtarius

BRIGHTNESS_DEV="$(ls /sys/class/backlight | head -n 1)"

MIN=1
MAX=$(cat /sys/class/backlight/${BRIGHTNESS_DEV}/max_brightness)
if [ "${MAX}" = 255 ]
then
  STEP=17
else
  STEP=6
fi

if [[ -n "$2" ]]; then
  STEP=$2
fi

# Ensure set_setting exists in all contexts
if ! type set_setting  &>/dev/null
then
  source /etc/profile
fi

if [ ! -f /sys/class/backlight/${BRIGHTNESS_DEV}/brightness ]
then
  echo "ERROR: There is no BRIGHTNESS object to manage."
  exit 1
fi

stepUp() {
  getBrightness
  MYBRIGHTNESS=$?
  NEWBRIGHTNESS=$((${MYBRIGHTNESS}+${STEP}))
  if (( ${NEWBRIGHTNESS} > ${MAX} ))
  then
    NEWBRIGHTNESS=${MAX}
  fi
  echo "${NEWBRIGHTNESS}" > /sys/class/backlight/${BRIGHTNESS_DEV}/brightness
  set_setting system.brightness ${NEWBRIGHTNESS}
}

stepDown() {
  getBrightness
  MYBRIGHTNESS=$?
  NEWBRIGHTNESS=$((${MYBRIGHTNESS}-${STEP}))
  if (( ${NEWBRIGHTNESS} < ${MIN} ))
  then
    NEWBRIGHTNESS=${MIN}
  fi
  echo "${NEWBRIGHTNESS}" > /sys/class/backlight/${BRIGHTNESS_DEV}/brightness
  set_setting system.brightness ${NEWBRIGHTNESS}
}
getBrightness() {
  local BRIGHTNESS=$(cat /sys/class/backlight/${BRIGHTNESS_DEV}/brightness)
  return ${BRIGHTNESS}
}


case ${1} in
        "up")
	  stepUp ${BRIGHTNESS}
        ;;
        "down")
          stepDown ${BRIGHTNESS}
        ;;
        "device")
          echo ${BRIGHTNESS_DEV}
        ;;
        *)
	  getBrightness
	  echo $?
	;;
esac