#!/bin/zsh

tail -f ~/.config/xob/xobpipe | xob -s volume &
if [[ $# -eq 2 ]]; then
  CHANGE=$1
  TARGET_FILE=$2
elif [[ $# -eq 3 ]]; then
  CHANGE=`expr 0 - $2`
  TARGET_FILE=$3
else
  echo "Improper usage. To increase a value in a file,\nupdate-bl [change] [target_file]."
  echo "To decrease a value in a file,\nupdate-bl --decrease [change] [target_file]."
fi

OLDNUM=`cut -f1 $TARGET_FILE`
NEWNUM=`expr $OLDNUM + $CHANGE`

if [[ $NEWNUM -le 100 && $NEWNUM -ge 0 ]]; then
  sed -i "s/$OLDNUM/$NEWNUM/g" $TARGET_FILE
  brightnessctl set $NEWNUM%
  echo $NEWNUM >> ~/.config/xob/xobpipe
fi