#!/usr/bin/python
#
# do-until - run a command until it succeeds
# Copyright (C) 2008, 2011  Lars Wirzenius
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


'''Run a command until it succeeds.'''


import cliapp
import subprocess
import sys
import time


class DoUntil(cliapp.Application):

    def add_settings(self):
        self.settings.boolean(['no-act', 'n'],
             'Do not run command, just pretend to do it, '
                 'and pretend that it succeeds.')
        self.settings.boolean(['verbose', 'v'],
                             'Print command before executing it.')
        self.settings.integer(['sleep'],
            'Wait SECS seconds before re-trying a command. '
                '(Default is %default.)',
            default=1)
        self.settings.integer(['max-tries'],
            'Try at most COUNT times, with 0 meaning forever. '
                '(Default is %default.)',
            default=0)

    def process_args(self, argv):
        tries = 0
        max_tries = self.settings['max-tries']
        while max_tries == 0 or tries < max_tries:
            tries += 1
            if self.settings['verbose']:
                sys.stderr.write('do-until: attempt #%d: %s\n' % 
                                 (tries, ' '.join(argv)))
            if self.settings['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: attempt %d failed, '
                             'trying again in %d second(s)\n' % 
                                (tries, self.settings['sleep']))
            time.sleep(self.settings['sleep'])


if __name__ == '__main__':
    DoUntil().run()