#!/bin/bash

## config

full=80
low=20

############################

red='%{F#f00}'
green='%{F#0f0}'
end='%{F-}'

bat="$(cat /sys/class/power_supply/BAT0/capacity)"
ac="$(cat /sys/class/power_supply/AC/online)"
declare -a ramp
ramp=(          )

# display in red when under $low and no charger is connected
[ "$bat" -gt "$low" ] || [ "$ac" -eq 1 ] || color="$red"
# display in green when over $full and a charger is connected
[ "$bat" -lt "$full" ] || [ "$ac" -eq 0 ] || color="$green"

let "icon_index = $bat / (${#ramp[@]} - 1)"
[ $icon_index -lt ${#ramp[@]} ] || icond_index=10
icon="${ramp[$icon_index]}"
[ "$ac" -eq 0 ] || charge=""

echo "${color}${icon}${charge} ${bat}%"