#!/usr/bin/python


"""Run a command until it succeeds.

Lars Wirzenius <liw@liw.fi>
"""


import optparse
import subprocess
import sys
import time


def do_until(options, argv):
    while True:
        if options.verbose:
            sys.stderr.write("do-until: executing: %s\n" % " ".join(argv))
        if options.no_act:
            sys.stderr.write("do-until: not running command, pretending it "
                             "works anyway\n")
            break
        else:
            p = subprocess.Popen(argv)
            p.communicate()
            if p.returncode == 0:
                break
        sys.stderr.write("do-until: command failed, "
                         "trying again in %d second(s)\n" % options.sleep)
        time.sleep(options.sleep)


def parse_args(args):
    parser = optparse.OptionParser()
    parser.add_option("-n", "--no-act", action="store_true",
                      help="Do not run command, just pretend to do it, and "
                           "pretend that it succeeds.")
    parser.add_option("-v", "--verbose", action="store_true",
                      help="Print command before executing it.")
    parser.add_option("--sleep", type="int", default=1, metavar="SECS",
                      help="Wait SECS seconds before re-trying a command. "
                           "(Default is %default.)")
    
    options, argv = parser.parse_args(args)

    return options, argv


def main():
    try:
        options, argv = parse_args(sys.argv[1:])
        if argv:
            do_until(options, argv)
    except KeyboardInterrupt:
        sys.exit(1)


if __name__ == "__main__":
    main()