#!/usr/bin/python3
#
#

import sys
import os.path
import argparse
import configparser
import getpass
import pprint  # For some verbose output

try:
  import requests as _
except ImportError:
  sys.stderr.write("ERROR: requests package appears to be missing.\n"
                   "       Please use 'pip3 install requests'\n")
  sys.exit(1)
try:
  import namecheap
except ImportError:
  sys.stderr.write("ERROR: PyNamecheap package appears to be missing.\n"
                   "       Please use 'pip3 install PyNamecheap'\n")
  sys.exit(1)

# Configuration file, in the user's home directory.
CONFIG_FNAME = '.namecheap'

# Bump this higher if the retries still don't get through
DEFAULT_ATTEMPTS = 4

# Name of the TXT challenge record.
ACME_CHALLENGE = '_acme-challenge'


def main(args):
    cfg = configparser.ConfigParser()
    fname = os.path.join(os.path.expanduser('~'), CONFIG_FNAME)
    cfg.read(fname)

    ### just let the cfg[] fail, rather than fancy error
    domain = (args.domain
              or os.environ.get('CERTBOT_DOMAIN',
                                cfg.get('certbot', 'domain', fallback=None)))

    ### fail ungracefully if validation isn't present
    validation = args.validation or os.environ['CERTBOT_VALIDATION']

    assert domain and validation
    print('DOMAIN:', domain)
    print('VALIDATION:', validation)

    creds = cfg['credentials']

    if args.prompt_key:
        api_key = getpass.getpass('API key: ')
    else:
        api_key = creds['api_key']

    api = namecheap.Api(creds['username'], api_key,
                        creds['username'], creds['ip_address'],
                        sandbox=False, debug=args.api_debug,
                        attempts_count=args.attempts)

    add_validation(api, domain, validation, args.verbose, args.dry_run)


def add_validation(api, domain, validation, verbose=False, dry_run=False):
    hosts = api.domains_dns_getHosts(domain)
    print(f'INFO: domain "{domain}" has {len(hosts)} records')
    if verbose:
        print('HOSTS:')
        pprint.pprint(hosts)

    # Fix the record keys, since getHosts and setHosts uses different keys.
    # NOTE: this method is destructive, and alters the records we pass.
    for record in hosts:
        api._elements_names_fix(record)

    # Add or alter the challenge TXT record.
    for record in hosts:
        if record['HostName'] == ACME_CHALLENGE:
            record['Address'] = validation
            print('INFO: updated challenge record to:', validation)
            break
    else:
        hosts.append({
            'HostName': ACME_CHALLENGE,
            'RecordType': 'TXT',
            'Address': validation,
            })
        print('INFO: added challenge record to:', validation)

    if verbose:
        print('NEW HOSTS:')
        pprint.pprint(hosts)

    if not dry_run:
        api.domains_dns_setHosts(domain, hosts)
        print(f'SETHOSTS: wrote {len(hosts)} records.')


if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument('-v', '--verbose', action='store_true',
                        help='Verbose output of the script operation.')
    parser.add_argument('--api-debug', action='store_true',
                        help='Verbose output for API exchanges with Namecheap.')
    parser.add_argument('--attempts', default=DEFAULT_ATTEMPTS, type=int,
                        help='How many attempts for a successful API operations.')
    parser.add_argument('--domain',
                        help='Domain for certificate generation,'
                             ' overriding the CERTBOT_DOMAIN environment variable')
    parser.add_argument('--validation',
                        help='Validation code for certificate generation,'
                             ' overriding the CERTBOT_VALIDATION environment variable')
    parser.add_argument('--prompt-key', action='store_true',
                        help='Prompt for the API key, rather than look on-disk.')
    parser.add_argument('-n', '--dry-run', action='store_true',
                        help='Perform as much as possible, without changing data.')

    args = parser.parse_args()
    print('ARGS:', args)
    main(args)