Process MAM message

device-client.js

/**
  * Retrieves and processes MAM messages by dispatching the type of message to
  * its handler.
  *
  * @function processMamMessage
  * @returns {undefined}
  */
async processMamMessage() {
  const IS_PAIRED = (typeof this.root !== 'undefined');
  if (!IS_PAIRED) {
    logger.info('IOTA MAM: No root received (device not paired)');
    return;
  }
  logger.info(`IOTA MAM: Fetching from root ${DeviceClient.formatTrytes(this.root)}`);
  try {
    const mode = 'private';
    const mamMsg = await this.mam.fetchSingle(this.root, mode);
    if (typeof mamMsg === 'undefined') {
      // no message, you can try again later, keep root
      logger.info('No new MAM message');
      return;
    }
    const { nextRoot, message } = mamMsg;
    switch (message.type) {
      case AUTHORIZED_TYPE: {
        this.processAuthorizedMessage(message);
        break;
      }
      case AUTHORIZATION_REVOKED_TYPE: {
        this.processAuthorizationRevokedMessage(message);
        break;
      }
      case DEVICE_ADDED_TYPE: {
        this.authorizedServiceProviders.clear();
        break;
      }
      case DEVICE_DELETED_TYPE: {
        this.authorizedServiceProviders.clear();
        break;
      }
      default: {
        logger.info(`Unknown MAM msg type: ${message.type}`);
      }
    }
    logger.info(`IOTA MAM: Setting root to ${DeviceClient.formatTrytes(nextRoot)}`);
    this.root = nextRoot;
  } catch (err) {
    logger.error(`In processMamMessage: ${err}`);
  }
}