#!/usr/bin/env python3

import logging
from ipaddress import ip_address
from json import loads
from subprocess import check_output, run


DOMAIN = '${domain}'

# <%text>
logging.basicConfig(level=logging.INFO)
LOG = logging.getLogger('DynDNS checker')
try:
    iproute = loads(check_output(['ip', '-json', 'address', 'show', 'scope', 'global']))
    resolved_ipv4 = check_output(['dig', '+short', DOMAIN, 'A']).decode().strip()
    resolved_ipv6 = check_output(['dig', '+short', DOMAIN, 'AAAA']).decode().strip()

    LOG.info(f'resolved ipv4 is "{resolved_ipv4}"')
    LOG.info(f'resolved ipv6 is "{resolved_ipv6}"')

    needs_changing = False

    for iface in iproute:
        if not iface['ifname'].startswith('ppp'):
            LOG.debug(f'ignoring {iface["ifname"]}')
            continue

        LOG.info(f'working on {iface["ifname"]}')
        for ip in iface['addr_info']:
            try:
                addr = ip_address(ip['local'])

                LOG.info(f'{iface["ifname"]} has ip {addr.compressed}')

                if (
                    (addr.version == 4 and addr.compressed != resolved_ipv4)
                    or (addr.version == 6 and addr.compressed != resolved_ipv6)
                ):
                    needs_changing = True
            except Exception:
                continue

    if needs_changing:
        LOG.warning('addresses have changed, calling update script!')
        run(['/etc/ppp/ip-up.d/dyndns'])
    else:
        LOG.info('everything is fine')
except Exception as e:
    logging.exception(e)

# </%text>