#!/usr/bin/env python3

import itertools
import json
import os
import sys
import logging

import yaml
import schema
import click
import ovh
import dns.resolver
import dns.rdatatype

from schema import And, Optional, Use, Schema

logger = logging.getLogger('ovhdns')

config_schema = Schema({
    'ovh': {
        'application_key': Use(str),
        'application_secret': Use(str),
        'consumer_key': Use(str),
        'endpoint': Use(str),
    },
    'zone': Use(str),
    'subdomain': Use(str),
    Optional('field_type', default='A'): And(Use(str), Use(str.upper), dns.rdatatype.RdataType.make),
    Optional('logging', default={'level': ':WARNING,ovhdns:INFO'}): {
        Optional('level', default=':WARNING,ovhdns:INFO'): Use(str),
    },
    Optional('ttl', default=None): Use(lambda i: int(i) if i is not None else None),
})

def get_opendns_ips():
    ips = []
    for addr, typ in itertools.product(
        ['resolver1.opendns.com', 'resolver2.opendns.com'],
        ['A', 'AAAA'],
    ):
        ips += [r.to_text() for r in dns.resolver.resolve(addr, typ)]
    return ips

def get_my_ips():
    resolver = dns.resolver.Resolver(configure=False)
    resolver.nameservers = get_opendns_ips()
    return [r.to_text() for r in resolver.resolve('myip.opendns.com')]


def get_records(client, config):
    zone = config['zone']
    records = client.get(f'/domain/zone/{zone}/record')
    records = [
        client.get(f'/domain/zone/{zone}/record/{id}')
        for id in records
    ]
    return records

def init_logging():
    logging.getLogger().addHandler(
        logging.StreamHandler(),
    )

def set_logging_level(level: str):
    levels = {
        'NOTSET': logging.NOTSET,
        'DEBUG': logging.DEBUG,
        'INFO': logging.INFO,
        'WARNING': logging.WARNING,
        'WARN': logging.WARNING,
        'ERROR': logging.ERROR,
        'CRITICAL': logging.CRITICAL,
    }

    log_levels = [x.split(':') for x in level.split(',')]
    for module, level in log_levels:
        module = module.strip() if module else None
        level = level.strip().upper()
        if level not in levels:
            raise ValueError(f'invalid log level, allowed values: {repr(set(levels.keys()))}')
        logging.getLogger(module).setLevel(levels[level])

def load_config(file):
    if file == '-':
        config = yaml.safe_load(sys.stdin)
    else:
        if os.stat(file).st_mode & 0o777 & ~0o600:
            raise Exception('refusing to load insecure configuration file, file must have permission 0o600')
        with open(file) as fp:
            config = yaml.safe_load(fp)
    return config_schema.validate(config)

@click.command()
@click.option('--config', '-c', envvar='OVHDNS_CONFIG', default='-', help='The configuration file')
@click.option('--level', '-l', envvar='OVHDNS_LEVEL', default=None, help='The log level for the application')
@click.option('--force-refresh', '-f', envvar='OVHDNS_FORCE_REFRESH', is_flag=True, help='Force zone refresh even if deemed not needed')
def main(config, level, force_refresh):
    init_logging()
    config = load_config(config)
    if level:
        config['logging']['level'] = level
    config = config_schema.validate(config)
    set_logging_level(config['logging']['level'])

    ovh_client = ovh.Client(
        **config['ovh'],
    )
    records = [
        r
        for r in get_records(ovh_client, {'zone': 'redxef.at'})
        if r['fieldType'] == config['field_type']
        and r['zone'] == config['zone']
        and r['subDomain'] == config['subdomain']
    ]
    logger.info('found matching records: %s', records)
    if len(records) > 1:
        logger.error('found more than one record, don\'t know which to pick')
        sys.exit(1)

    my_ips = get_my_ips()
    need_refresh = False
    if len(records) == 1:
        logger.info('record already present, updating if needed')
        if my_ips[0] == records[0]['target']:
            logger.info('ip is up-to-date, skipping update')
        else:
            need_refresh = True
            ovh_client.put(
                f'/domain/zone/{config["zone"]}/record/{records[0]["id"]}',
                target=my_ips[0],
                ttl=config['ttl'],
            )
            logger.info('updated record, new ip is %s', my_ips[0])

    else:
        logger.info('record not already present, creating new one')
        need_refresh = True
        ovh_client.post(
            f'/domain/zone/{config["zone"]}/record/',
            subDomain=config['subdomain'],
            target=my_ips[0],
            fieldType=config['field_type'],
            ttl=config['ttl'],
        )
        logger.info('created new record, ip is %s', my_ips[0])

    if need_refresh or force_refresh:
        ovh_client.post(f'/domain/zone/{config["zone"]}/refresh')
        logger.info('refreshed zone')
    else:
        logger.info('zone refresh skipped')
    sys.exit(0)

if __name__ == '__main__':
    main()