private reportEnqueuedEventsWhenClientIsReady()

in src/client/src/analytics_client/analytics_client.ts [281:333]
33 lines of code
2 McCabe index (conditional complexity)

  private reportEnqueuedEventsWhenClientIsReady() {
    // Observer that will emit when both events occur: the OptInConfig is set + a shipper has been registered
    const configReceivedAndShipperReceivedObserver$ = combineLatest([
      this.optInConfigWithReplay$,
      merge([
        this.shipperRegistered$,
        // Merging shipperRegistered$ with the optInConfigWithReplay$ when optedIn is false, so that we don't need to wait for the shipper if opted-in === false
        this.optInConfigWithReplay$.pipe(filter((cfg) => cfg?.isOptedIn() === false)),
      ]),
    ]);

    // Flush the internal queue when we get any optInConfig and, at least, 1 shipper
    this.internalEventQueue$
      .pipe(
        // Take until will close the observer once we reach the condition below
        takeUntil(configReceivedAndShipperReceivedObserver$),

        // Accumulate the events until we can send them
        buffer(configReceivedAndShipperReceivedObserver$),

        // Minimal delay only to make this chain async and let the optIn operation to complete first.
        delay(0),

        // Re-emit the context to make sure all the shippers got it (only if opted-in)
        tap(() => {
          if (this.optInConfig$.value?.isOptedIn()) {
            this.context$.next(this.context$.value);
          }
        }),

        // Minimal delay only to make this chain async and let
        // the context update operation to complete first.
        delay(0),

        // Flatten the array of events
        concatMap((events) => from(events)),

        // Discard opted-out events
        filter((event) => this.optInConfig$.value?.isEventTypeOptedIn(event.event_type) === true),

        // Let's group the requests per eventType for easier batching
        groupBy((event) => event.event_type),
        mergeMap((groupedObservable) =>
          groupedObservable.pipe(
            bufferCount(1000), // Batching up-to 1000 events per event type for backpressure reasons
            map((events) => ({ eventType: groupedObservable.key, events }))
          )
        )
      )
      .subscribe(({ eventType, events }) => {
        this.sendToShipper(eventType, events);
      });
  }