Fixing Android SMS timestamps

#!/usr/bin/python

from xml.dom.minidom import parse

import os
import sys
import time

START_TIMESTAMP_SECS = 1294290000000
HOUR_TO_MILLISECS = 60 * 60 * 1000
RECEIVED, SENT = (1, 2)

def format_time(timestamp_in_ms):
    return time.strftime("%a, %d %b %Y %H:%M:%S",
            time.gmtime(timestamp_in_ms / 1000))

def convert_est_to_utc(timestamp_in_ms):
    return timestamp_in_ms + (5 * HOUR_TO_MILLISECS)

def replace_timestamps(document):
    smses = document.getElementsByTagName('sms')
    for sms in smses:
        received = int(sms.getAttribute('type')) == RECEIVED
        date = int(sms.getAttribute('date'))

        if received and date > START_TIMESTAMP_SECS:
            sms.setAttribute('date', unicode(convert_est_to_utc(date)))

def main():
    if (len(sys.argv) < 2):
        sys.exit('Usage: %s sms_file' % os.path.basename(__file__))

    sms_file = sys.argv[1]

    document = parse(sms_file)
    replace_timestamps(document)
    print(document.toprettyxml(encoding='utf-8'))


if __name__ == '__main__':
    main()