Function applySubscriberEndpoint

app/src/API/Handlers/MqttHandler.cpp:493–530

* @brief Applies endpoint + credential + topic fields to the subscriber. */

 * @brief Applies endpoint + credential + topic fields to the subscriber.
 */
[[nodiscard]] static std::optional<QString> applySubscriberEndpoint(IO::Drivers::MQTT* d,
                                                                    const QJsonObject& params)
{
  if (params.contains(QStringLiteral("hostname"))) {
    const auto host = params.value(QStringLiteral("hostname")).toString();
    if (host.trimmed().isEmpty())
      return QStringLiteral("hostname must not be empty");

    d->setHostname(host);
  }

  if (params.contains(QStringLiteral("port"))) {
    const int port = params.value(QStringLiteral("port")).toInt(-1);
    if (!portIsValid(port))
      return QStringLiteral("port must be in [1, 65535] (got %1)").arg(port);

    d->setPort(static_cast<quint16>(port));
  }

  if (params.contains(QStringLiteral("clientId")))
    d->setClientId(params.value(QStringLiteral("clientId")).toString());

  const bool hasUser = params.contains(QStringLiteral("username"));
  const bool hasPass = params.contains(QStringLiteral("password"));
  if (hasPass && !hasUser)
    return QStringLiteral("Setting 'password' requires 'username' in the same call");

  if (hasUser)
    d->setUsername(params.value(QStringLiteral("username")).toString());

  if (hasPass)
    d->setPassword(params.value(QStringLiteral("password")).toString());

  if (params.contains(QStringLiteral("topicFilter")))
    d->setTopicFilter(params.value(QStringLiteral("topicFilter")).toString());

  return std::nullopt;
}

/**
 * @brief Applies session + TLS fields to the subscriber.