u-wave / core / 12200196837

class LostConnection extends EventEmitter {

  #logger;

  /**

   * @param {import('../Uwave.js').default} uw

   * @param {import('../schema.js').User} user

   * @param {string} sessionID

   */

  constructor(uw, user, sessionID, timeout = 30) {

    super();

    this.uw = uw;

    this.user = user;

    this.sessionID = sessionID;

    this.timeout = timeout;

    this.#logger = uw.logger.child({

      ns: 'uwave:sockets', connectionType: 'LostConnection', userID: this.user.id, sessionID,

    });

    this.initQueued();

    this.setTimeout(timeout);

  }

  /**

   * @private

   */

  get key() {

    return `http-api:disconnected:${this.sessionID}`;

  }

  /**

   * @private

   */

  get messagesKey() {

    return `http-api:disconnected:${this.sessionID}:messages`;

  }

  /**

   * @private

   */

  initQueued() {

    // We expire the keys after timeout*10, because a server restart near the

    // end of the timeout might mean that someone fails to reconnect. This way

    // we can ensure that everyone still gets the full `timeout` duration to

    // reconnect after a server restart, while also not filling up Redis with

    // messages to users who left and will never return.

    this.uw.redis.multi()

      .set(this.key, 'true', 'EX', this.timeout * 10)

      .ltrim(this.messagesKey, 0, 0)

      .expire(this.messagesKey, this.timeout * 10)

      .exec();

  }

  /**

   * @param {number} timeout

   * @private

   */

  setTimeout(timeout) {

    this.removeTimer = setTimeout(() => {

      this.close();

      this.uw.redis.del(this.key, this.messagesKey);

    }, timeout * 1000);

  }

  /**

   * @param {string} command

   * @param {import('type-fest').JsonValue} data

   */

  send(command, data) {

    this.#logger.info({ command, data }, 'queue command');

    this.uw.redis.rpush(

      this.messagesKey,

      JSON.stringify({ command, data }),

    );

  }

  close() {

    this.#logger.info('close');

    this.emit('close');

  }

  removed() {

    if (this.removeTimer) {

      clearTimeout(this.removeTimer);

    }

  }

  toString() {

    return `Lost { user: ${this.user.id} ${this.user.username} }`;

  }

}