fetch method

Implementation

@override
Future<IpGeoLocation> fetch({IpAddress? ip}) async {
  Log.debug('fetch(ip: $ip) with $_language', '$runtimeType');

  Mutex? mutex = _guards[ip];
  if (mutex == null) {
    mutex = Mutex();
    _guards[ip] = mutex;
  }

  return await mutex.protect(() async {
    IpAddress? address = ip;

    if (address == null) {
      _ip ??= await _geoProvider.current();
      address = _ip;
    }

    if (address == null) {
      throw Exception('Unreachable');
    }

    final local = await _geoLocal.read(address, language: _language);
    if (local != null) {
      // Consider the persisted result as obsolete, if 30 days has passed
      // since it was persisted.
      if (local.updatedAt.val.difference(DateTime.now()).abs().inDays < 30) {
        return local.value;
      }
    }

    final response = await _geoProvider.get(address, language: _language);
    _geoLocal.upsert(address, response, language: _language);

    return response;
  });
}