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


BRIGHTNESS_DEV="$(find /sys/class/backlight/*/ -name brightness -print -quit)"
BRIGHTNESS_PATH="${BRIGHTNESS_DEV%/brightness}"

MIN=0
MAX=$(<$(find /sys/class/backlight/*/ -name max_brightness -print -quit))
STEP=$(( ${MAX} / 10 ))

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

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

getBrightness() {
  echo $(<${BRIGHTNESS_DEV})
}

setBrightness() {
  echo "${1}" > ${BRIGHTNESS_DEV}
  set_setting system.brightness "$(( ${1} / ${STEP} ))"
}

stepUp() {
  MYBRIGHTNESS=$(getBrightness)
  NEWBRIGHTNESS=$((${MYBRIGHTNESS}+${STEP}))
  if (( ${NEWBRIGHTNESS} > ${MAX} ))
  then
    NEWBRIGHTNESS=${MAX}
  fi
  setBrightness ${NEWBRIGHTNESS}
}

stepDown() {
  MYBRIGHTNESS=$(getBrightness)
  NEWBRIGHTNESS=$((${MYBRIGHTNESS}-${STEP}))
  if (( ${NEWBRIGHTNESS} < ${MIN} ))
  then
    NEWBRIGHTNESS=${MIN}
  fi
  setBrightness ${NEWBRIGHTNESS}
}

case ${1} in
        "up")
          stepUp
        ;;
        "down")
          stepDown
        ;;
        "device")
          echo ${BRIGHTNESS_DEV}
        ;;
        "path")
          echo ${BRIGHTNESS_PATH}
        ;;
        "set")
           setBrightness "$(( ${STEP} * ${2} ))"
        ;;
        *)
          echo $(getBrightness)
        ;;
esac