#!/usr/bin/python2
# We need to force py2 until M2Crypto is ported:
# https://gitlab.com/m2crypto/m2crypto/issues/114
# pylint: disable=invalid-name

"""Renew Let's Encrypt certs!

To generate a new set of certs:
$ certbot certonly --webroot \\
    --webroot-path /var/www/wh0rd/ -d wh0rd.org -d www.wh0rd.org \\
    --webroot-path /var/www/rss/ -d rss.wh0rd.org
"""

from __future__ import print_function

import argparse
try:
    import configparser
except ImportError:
    import ConfigParser as configparser
try:
    from cStringIO import StringIO
except ImportError:
    from io import StringIO
import datetime
import logging
import logging.handlers
import M2Crypto
import os
import pytz
import subprocess
import sys


LE_BASE = '/etc/letsencrypt'


def get_parser():
    """Return an ArgumentParser() for this module."""
    parser = argparse.ArgumentParser(description=__doc__,
                                     formatter_class=argparse.RawTextHelpFormatter)
    parser.add_argument('-n', '--dry-run', default=False,
                        action='store_true',
                        help='Do not actually update certs')
    parser.add_argument('--cronjob', default=False,
                        action='store_true',
                        help='Exit non-zero if no certs were changed')
    return parser


def setup_logging(debug=False, syslog=None):
    """Setup the logging module just the way we like it."""
    if syslog is None:
        syslog = not os.isatty(sys.stdin.fileno())

    if syslog:
        handler = logging.handlers.SysLogHandler(address='/dev/log')
    else:
        handler = logging.StreamHandler(stream=sys.stdout)

    fmt = '%(asctime)s: %(levelname)-7s: %(message)s'

    datefmt = '%a, %d %b %Y %H:%M:%S letsencrypt'

    level = logging.DEBUG if debug else logging.INFO

    formatter = logging.Formatter(fmt, datefmt)
    handler.setFormatter(formatter)

    logger = logging.getLogger()
    logger.addHandler(handler)
    logger.setLevel(level)


def load_cert(path):
    """Load the cert at |path|"""
    with open(path) as f:
        data = f.read()
        return M2Crypto.X509.load_cert_string(data)


def load_live_cert(domain):
    """Load the live cert for |domain|"""
    path = os.path.join(LE_BASE, 'live', domain, 'cert.pem')
    return load_cert(path)


def load_conf(domain):
    """Load the LE config file for |domain|"""
    path = os.path.join(LE_BASE, 'renewal', domain + '.conf')
    # The config file format is almost enough for the configparser.
    # We need to insert a section header for the first few items.
    fp = StringIO()
    fp.write('[globals]\n')
    fp.write(open(path).read())
    fp.seek(0)

    conf = configparser.RawConfigParser()
    conf.readfp(fp)
    return conf


def process_domain(domain, dry_run=False):
    """Update |domain|'s certs as needed."""
    ret = 0

    logging.info('%s: checking', domain)

    conf = load_conf(domain)
    webroot_path = conf.get('[webroot_map', domain)

    cert_path = os.path.realpath(conf.get('globals', 'cert'))

    cert = load_cert(cert_path)
    stamp = cert.get_not_after()
    now = pytz.timezone('UTC').localize(datetime.datetime.now())
    delta = stamp.get_datetime() - now
    logging.info('%s: expires in %2s days', domain, delta.days)

    cmd = [
        'certbot',
        'certonly', '--webroot',
        '--webroot-path', webroot_path,
        '-d', domain,
    ]
    san = cert.get_ext('subjectAltName').get_value()
    domains = [x.strip()[4:] for x in san.split(',')]
    domains.remove(domain)
    for d in domains:
        cmd += ['-d', d]
    if delta.days < 30:
        logging.info('%s: renewing', domain)
        logging.info('%s: %s', domain, cmd)
        if not dry_run:
            subprocess.check_call(cmd)
            ret = 1
        # Try to revoke the old one.
        cmd = ['certbot', 'revoke', '--cert-path', cert_path]
        logging.info('%s: revoking old cert', domain)
        logging.info('%s: %s', domain, cmd)
        if not dry_run:
            subprocess.check_call(cmd)
    else:
        logging.info('%s: up-to-date!', domain)

    return ret


def main(argv):
    """The main() entry point!"""
    parser = get_parser()
    opts = parser.parse_args(argv)
    setup_logging()

    cnt = 0
    domains = [x[:-5] for x in os.listdir('/etc/letsencrypt/renewal')]
    for domain in domains:
        cnt += process_domain(domain, dry_run=opts.dry_run)

    if opts.cronjob:
        if cnt:
            return 0
        else:
            return 1


if __name__ == '__main__':
    sys.exit(main(sys.argv[1:]))