#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""API client to core-networks"""

import requests
import os
import json
import urlparse
import configparser
import sys
import logging
import tldextract
import codecs

from time import sleep


def setup_logger():
    # seup logging
    logger = logging.getLogger("certbot_dns_corenetworks")
    logging.basicConfig(level=logging.INFO)
    # silence logging from requests module
    logging.getLogger('requests').setLevel(logging.CRITICAL)

    # create console handler
    ch = logging.StreamHandler()
    ch.setLevel(logging.INFO)

    formatter = logging.Formatter(
        '%(asctime)s - %(name)s - %(levelname)s: %(message)s', datefmt='%Y-%m-%d,%H:%M:%S')
    ch.setFormatter(formatter)
    # add handler to logger
    logger.addHandler(ch)
    logger.propagate = False
    return logger


def set_log_level(config):
    try:
        loglevel = str(config.get('LOG', 'LEVEL')).upper()
    except (configparser.NoSectionError, configparser.NoOptionError) as e:
        logger.error("Config error: %s" % (e))
        sys.exit(1)

    if loglevel == 'INFO':
        level = logging.INFO
    elif loglevel == 'ERROR':
        level = logging.ERROR
    elif loglevel == 'DEBUG':
        level = logging.DEBUG
    else:
        level = logging.INFO

    logger = logging.getLogger('certbot_dns_corenetworks')
    logger.setLevel(level)
    for handler in logger.handlers:
        handler.setLevel(level)


def load_config(logger):
    config_path = os.path.join(os.path.expanduser("~"), ".certbot_dns_corenetworks", "config.ini")

    if os.path.isfile(config_path):
        config = configparser.ConfigParser()
        config.read(config_path)
    else:
        logger.error("Configfile " + config_path + " not present.")
        sys.exit(1)

    return config


def write_backup(filename, name, value, logger):
    data = {}
    data["name"] = name
    data["data"] = value

    with codecs.open(filename, 'w', encoding='utf8') as f:
        f.write(json.dumps(data, sort_keys=True, indent=4, ensure_ascii=False))


def get_auth_token(config, logger):
    data = {}

    try:
        data["login"] = config.get('API', 'USER')
        data["password"] = config.get('API', 'PASSWORD')
        json_data = json.dumps(data)

        host = config.get('API', 'HOST')
    except (configparser.NoSectionError, configparser.NoOptionError) as e:
        logger.error("Config error: %s" % (e))
        sys.exit(1)

    url = urlparse.urljoin(host, os.path.join("auth", "token"))

    try:
        r = requests.post(url, data=json_data)
        r.raise_for_status()
    except requests.exceptions.HTTPError as e:
        logger.error(e)
        sys.exit(1)

    return r


def get_zone(config, logger):
    try:
        host = config.get('API', 'HOST')
        zone = config.get('DNS', 'ZONE')
        token = config.get('API', 'TOKEN')
    except (configparser.NoSectionError, configparser.NoOptionError) as e:
        logger.error("Config error: %s" % (e))
        sys.exit(1)

    url = urlparse.urljoin(host, os.path.join("dnszones", zone))
    headers = {"Authorization": "Bearer %s" % (token)}

    try:
        r = requests.get(url, headers=headers)
        r.raise_for_status()
    except requests.exceptions.HTTPError, e:
        logger.error(e)
        sys.exit(1)

    return r


def set_record(config, logger):
    filename = '/tmp/CERTBOT_%s.json' % (os.environ['CERTBOT_DOMAIN'])
    if os.path.isfile(filename):
        logger.error("File '%s' exists. There seems to be an existing DNS record." % (filename))
        sys.exit(1)

    try:
        host = config.get('API', 'HOST')
        zone = config.get('DNS', 'ZONE')
        token = config.get('API', 'TOKEN')
    except (configparser.NoSectionError, configparser.NoOptionError) as e:
        logger.error("Config error: %s" % (e))
        sys.exit(1)

    url = urlparse.urljoin(host, os.path.join("dnszones", zone, "records/"))
    headers = {"Authorization": "Bearer %s" % (token)}

    try:
        custom_cache_extract = tldextract.TLDExtract(
            cache_file=os.path.join(os.path.expanduser("~"), "tld_set"))
        subdomain = custom_cache_extract(os.environ['CERTBOT_DOMAIN']).subdomain
        record_name = "_acme-challenge.%s" % (os.environ['CERTBOT_DOMAIN'])
        if subdomain:
            certbot_domain = "_acme-challenge.%s" % (subdomain)
        else:
            certbot_domain = "_acme-challenge"
        certbot_validation = os.environ['CERTBOT_VALIDATION']
    except KeyError, e:
        logger.error("Environment Variable %s not set" % (e))
        sys.exit(1)

    data = {}
    data["name"] = certbot_domain
    data["ttl"] = 120
    data["type"] = "TXT"
    data["data"] = certbot_validation
    json_data = json.dumps(data)

    try:
        r = requests.post(url, headers=headers, data=json_data)
        r.raise_for_status()
    except requests.exceptions.HTTPError, e:
        logger.error(e)
        sys.exit(1)

    write_backup(filename, certbot_domain, certbot_validation, logger)

    return r


def dns_commit(config, logger):
    try:
        host = config.get('API', 'HOST')
        zone = config.get('DNS', 'ZONE')
        token = config.get('API', 'TOKEN')
    except (configparser.NoSectionError, configparser.NoOptionError) as e:
        logger.error("Config error: %s" % (e))
        sys.exit(1)

    url = urlparse.urljoin(host, os.path.join("dnszones", zone, "records", "commit"))
    headers = {"Authorization": "Bearer %s" % (token)}

    try:
        r = requests.post(url, headers=headers)
        r.raise_for_status()
    except requests.exceptions.HTTPError, e:
        logger.error(e)
        sys.exit(1)

    return r


def main():
    """Main logic entrypoint"""

    logger = setup_logger()
    config = load_config(logger)
    set_log_level(config)

    # get auth token
    logger.info("Try to get auth token")
    r_token = get_auth_token(config, logger)
    config.set('API', 'TOKEN', r_token.json()["token"])
    logger.info("Authentication successful")

    # verify dns zone
    r_zone = get_zone(config, logger)

    try:
        zone_name = config.get('DNS', 'ZONE')
    except (configparser.NoSectionError, configparser.NoOptionError) as e:
        logger.error("Config error: %s" % (e))
        sys.exit(1)

    zone_active = r_zone.json()["active"]

    if zone_active:
        logger.info("Zone '%s' verified (active)" % (zone_name))
    else:
        logger.error("Zone '%s' verified (not active)" % (zone_name))
        sys.exit(1)

    # add txt record
    logger.info("Try to set TXT record for dns challenge")
    z_record = set_record(config, logger)
    # commit changes
    z_commit = dns_commit(config, logger)
    logger.info("Set TXT record successful")

    logger.info("Sleep to propagate over changes to DNS")
    sleep(30)


if __name__ == "__main__":
    main()