#!/usr/bin/env bash

set -o nounset
set -o pipefail

export DBUS_SESSION_BUS_ADDRESS="unix:path=/run/user/1000/bus"
export DISPLAY=:0

# Battery percentage at which to notify.
BATTERY_DISCHARGING=$(acpi -b | grep "Battery 0" | grep -c "Discharging")
BATTERY_LEVEL=$(acpi -b | grep "Battery 0" | grep -P -o '[0-9]+(?=%)')
WARNING_LEVEL=20

# Use two files to store whether we've shown a notification or not (to prevent multiple notifications).
EMPTY_FILE=/tmp/battery-empty
FULL_FILE=/tmp/battery-full

# Reset notifications if the computer is charging/discharging.
if [ "$BATTERY_DISCHARGING" -eq 1 ] && [ -f $FULL_FILE ]; then
  rm $FULL_FILE
elif [ "$BATTERY_DISCHARGING" -eq 0 ] && [ -f $EMPTY_FILE ]; then
  rm $EMPTY_FILE
fi

# If the battery is charging and is full (and has not shown notification yet).
if [ "$BATTERY_LEVEL" -gt 95 ] && [ "$BATTERY_DISCHARGING" -eq 0 ] && [ ! -f $FULL_FILE ]; then
  notify-send "Battery Charged" "Battery is fully charged." -r 9991
  touch $FULL_FILE
# If the battery is low and is not charging (and has not shown notification yet).
elif [ "$BATTERY_LEVEL" -le $WARNING_LEVEL ] && [ "$BATTERY_DISCHARGING" -eq 1 ] && [ ! -f $EMPTY_FILE ]; then
  notify-send "Low Battery" "${BATTERY_LEVEL}% of battery remaining." -u critical -r 9991 -t 0
  touch $EMPTY_FILE
fi