async init()

in src/auth/auth-core.ts [357:437]
65 lines of code
25 McCabe index (conditional complexity)

  async init(): Promise<string | null | undefined> {
    this._storage?.onTokenChange(async token => {
      const isGuest = this.user ? this.user.guest : false;

      if (isGuest && !token) {
        return;
      }

      if (!token) {
        this.logout();
      } else {
        try {
          await this._detectUserChange(token.accessToken);
        } catch (error) {
          if (!(error instanceof Error)) {
            throw error;
          }
          if (this._canShowDialogs()) {
            this._showAuthDialog({nonInteractive: true, error});
          }
        }
      }
    });

    this._domainStorage.onMessage(DOMAIN_USER_CHANGED_EVENT, (message: UserChange | null) => {
      const {userID, serviceID} = message || {};
      if (serviceID === this.config.clientId) {
        return;
      }
      if (this.user && userID === this.user.id) {
        return;
      }
      this.forceTokenUpdate();
    });

    let state: AuthState | undefined;

    try {
      // Look for token or error in hash
      state = await this._checkForAuthResponse();
    } catch (error) {
      return error instanceof Error ? this.handleInitError(error) : undefined;
    }

    // Return endless promise in the background to avoid service start
    if (state && state.nonRedirect) {
      return new Promise(noop);
    }

    try {
      // Check if there is a valid token
      await this._tokenValidator?.validateToken();

      // Checking if there is a message left by another app on this domain
      const message = await this._domainStorage._messagesStorage.get<UserChange>(
        `domain-message-${DOMAIN_USER_CHANGED_EVENT}`,
      );
      if (message) {
        const {userID, serviceID} = message;
        if (serviceID !== this.config.clientId && (!userID || this.user?.id !== userID)) {
          this.forceTokenUpdate();
        }
      }

      // Access token appears to be valid.
      // We may resolve restoreLocation URL now
      if (!state) {
        // Check if we have requested to restore state anyway
        state = await this._checkForStateRestoration();
      }
      this._initDeferred?.resolve?.(state && state.restoreLocation);
      return state?.restoreLocation;
    } catch (error) {
      if (Auth.storageIsUnavailable) {
        this._initDeferred?.resolve?.(); // No way to handle if cookies are disabled
        await this.requestUser(); // Someone may expect user to be loaded as a part of token validation
        return null;
      }
      return error instanceof Error ? this.handleInitValidationError(error) : undefined;
    }
  }