#!/usr/bin/env bash

PID_PATH="$HOME/.cache/my-battery-watcher.pid";
[[ ! -f "$PID_PATH" ]] && touch $PID_PATH;

battery_component() { cat "/sys/class/power_supply/BAT0/$1"; }

get_level() { battery_component capacity; }
get_state() { battery_component status; }

LOW_BATTERY="30";
CRITICAL_BATTERY="10";

DELAY=1;
LOW_DELAY=240;
CRITICAL_DELAY=60;

oldpid=$(cat $PID_PATH);
cmd=${1:-"start"};

if [[ ! -z "$oldpid" ]] || [[ "$cmd" == "stop" ]]; then
  kill $oldpid;
fi;

# :: Min -> Max -> Number -> Bool
between() { test "$3" -gt "$1" && test "$3" -le "$2"; }

if [[ "$cmd" == "start" ]]; then
  while true; do
    battery_level=$(get_level);
    state=$(get_state);

    if [[ "$state" == "Discharging" ]]; then
      if (between $CRITICAL_BATTERY $LOW_BATTERY $battery_level); then
        notify-send "Please charge this shit. Battery is at $battery_level%" -u normal;
        sleep $LOW_DELAY;
      fi

      if (between 0 $CRITICAL_BATTERY $battery_level); then
        notify-send "HOLY SHIT DUDE. I'M DYING. Battery is at $battery_level%" -u critical;
        sleep $CRITICAL_DELAY;
      fi
    fi

    sleep $DELAY;
  done &

  echo $! > $PID_PATH;
fi;