battery check script

#!/usr/bin/python3

'''
Script for checking laptop battery state and displaying warnings

Needs python3, acpi and gxmessage to be installed
'''

import subprocess, re
from time import sleep

# seconds of sleep time between battery checks
sleep_time = 60

# actions
# play_sound='aplay /home/marek/temps/alarm.wav'
# empty_action='/sbin/shutdown -h now'

# states of battery life
s_ok = 0  #  > 30 min
s_30 = 1  # <= 30 min
s_15 = 2  # <= 15 min
s_10 = 3  # <= 10 min
s_05 = 4  # <=  5 min

# main state
state = s_ok

def getstate():
    '''getstate() -> state, minutes_left
    return the battery state and battery minutes left'''
    battery_info = subprocess.getoutput('acpi -b')
    battery_state = re.search(r'^Battery \d: (.+), \d+%', battery_info).groups()[0]

    if battery_state.lower() == 'discharging':
        time_left = int(re.search(r'(\d+:\d+)', battery_info).groups()[0].replace(':', ''))
        if time_left <= 5:
            return s_05, time_left
        elif time_left <= 10:
            return s_10, time_left
        elif time_left <= 15:
            return s_15, time_left
        elif time_left <= 30:
            return s_30, time_left
    return s_ok, None

def printwarning(minutes):
    '''prints battery state warning'''
    subprocess.getoutput('gxmessage -center -title "{M} min battery left" -buttons ok:0 -default ok "{M} minutes of computer battery left..."'.format(M=minutes))

if __name__ == '__main__':
    while True:
        prevstate = state
        state, time = getstate()
        if prevstate < state or state == s_05:
            printwarning(time)
        sleep(sleep_time)