#!/usr/bin/env nix-shell
#!nix-shell -i bash

full=$(cat /sys/class/power_supply/axp20x-battery/charge_full_design)
rate=$(cat /sys/class/power_supply/axp20x-battery/current_now)
perc=$(cat /sys/class/power_supply/axp20x-battery/capacity)
perc_left=$((100 - $perc))
# these icons come from sxmo; they only render in nerdfonts
bat_dis="󱊢"
bat_chg="󱊥"

fmt_minutes() {
  if [[ $2 -gt 1440 ]]; then
    echo "∞"  # more than 1d
  else
    hr=$(($2 / 60))
    hr_in_min=$(($hr * 60))
    min=$(($2 - $hr_in_min))
    printf "%s %dh%02dm" "$1" "$hr" "$min"
  fi
}

if [[ $rate -lt 0 ]]; then
  # discharging
  fmt_minutes "$bat_dis" $(($full * 60 * $perc / (-100 * $rate)))
elif [[ $rate -gt 0 ]]; then
  # charging
  fmt_minutes "$bat_chg" $(($full * 60 * $perc_left / (100 * $rate)))
else
  echo "󱊢 N/A"
fi