round() { awk -v n=$1 -v d=$2 'BEGIN{print int((n+d/2)/d) * d}'; }

# e.g. 7h
est_time=$(upower -i /org/freedesktop/UPower/devices/DisplayDevice | awk '/time to empty:/ {print $4substr($5, 1, 1)}')
# charging / discharging / pending-charge / ???
chg_state=$(upower -i /org/freedesktop/UPower/devices/DisplayDevice | awk '/state:/ {print $2}')
# e.g. 69.420%
percentage_raw=$(upower -i /org/freedesktop/UPower/devices/DisplayDevice | awk '/percentage:/ {print $2}')
# rounded to integer
percentage_int=$(printf "%.0f%" "${percentage_raw%%%}")

# when battery is low, highlight the widget
if [[ $percentage_int -le "10" ]]; then 
	printf "#[bg=red,fg=brightwhite]";
elif [[ $percentage_int -le "15" ]]; then
	printf "#[bg=brightyellow]";
fi

printf " "; # left padding

# battery icon
if [[ $chg_state == "charging" ]]; then
	printf "󰂄"
else
	case "$(round "$percentage_int" 10)" in
		"10") printf "󰁺";;
		"20") printf "󰁻";;
		"30") printf "󰁼";;
		"40") printf "󰁽";;
		"50") printf "󰁾";;
		"60") printf "󰁿";;
		"70") printf "󰂀";;
		"80") printf "󰂁";;
		"90") printf "󰂂";;
		"100") printf "󰁹";;
	esac
fi

printf " "; #bat-percent gap

printf "%s%%" "$percentage_int";

# this is only shown when on battery
if [[ $est_time ]]; then
	printf " "; #percent-estimage gap
	printf " $est_time"
fi

printf " "; # right padding
printf "#[default]"; # reset style