import time, datetime, subprocess, math, sys, os

def say(s, cmd):
    """
    Runs a command with the specified string s. 'cmd' should be a
    command line to be run in the default shell using a string template
    to specify where the string to speak should be placed and can
    include pipes if necessary (i.e. for the festival command line
    utility).
    """

    nullfile = open(os.devnull, 'w') # null file to suppress stdout
    subprocess.Popen(cmd % s, stdout=nullfile, shell=True)

def seconds_until(dt):
    return time.mktime(dt.timetuple()) - time.time()

def countdown_to(target_time, only_if_below=10, end_statement=None, say_cmd='say "%s"'):
    said = set()
    while True:
        i = int(math.ceil(seconds_until(target_time)))
        if i < 0:
            if end_statement:
                say(end_statement, say_cmd)
            break
        if i <= only_if_below and i not in said:
            said.add(i)
            say(i, say_cmd)
        sys.stdout.write('%s. ' % i)
        sys.stdout.flush()
        time.sleep(0.1)

if __name__ == '__main__':
    countdown_to(
        datetime.datetime(2010, 1, 1, 0, 0, 0),
        10,
        'Happy new year!',
        'echo "%s" | festival --tts'
    )