i3blocks Battery Script

#!/bin/bash

POW=$(upower -i /org/freedesktop/UPower/devices/battery_BAT0 | grep -o '[0-9]*%' -m 1)
PO=${POW::-1}

case $PO in
    [76-100]*)
        tput setaf 2; echo $POW
        tput sgr0
        ;;
    [50-75]*)
        tput setaf 2; echo $POW
        tput sgr0
        ;;
    [26-49]*)
        tput setaf 3; echo $POW
        tput sgr0
        ;;
    [11-25]*)
        tput setaf 3; echo $POW
        tput sgr0
        ;;
    [0-10]*)
        tput setaf 1; echo $POW
        tput sgr0
        ;;
esac