import { Subscription } from '../Subscription';
import { OperatorFunction, ObservableInput, ObservedValueOf } from '../types';
import { operate } from '../util/lift';
import { innerFrom } from '../observable/from';
import { OperatorSubscriber } from './OperatorSubscriber';
/**
* Converts a higher-order Observable into a first-order Observable by dropping
* inner Observables while the previous inner Observable has not yet completed.
*
* Flattens an Observable-of-Observables by dropping the
* next inner Observables while the current inner is still executing.
*
* 
*
* `exhaust` subscribes to an Observable that emits Observables, also known as a
* higher-order Observable. Each time it observes one of these emitted inner
* Observables, the output Observable begins emitting the items emitted by that
* inner Observable. So far, it behaves like {@link mergeAll}. However,
* `exhaust` ignores every new inner Observable if the previous Observable has
* not yet completed. Once that one completes, it will accept and flatten the
* next inner Observable and repeat this process.
*
* ## Example
* Run a finite timer for each click, only if there is no currently active timer
* ```ts
* import { fromEvent, interval } from 'rxjs';
* import { exhaustAll, map, take } from 'rxjs/operators';
*
* const clicks = fromEvent(document, 'click');
* const higherOrder = clicks.pipe(
* map((ev) => interval(1000).pipe(take(5))),
* );
* const result = higherOrder.pipe(exhaustAll());
* result.subscribe(x => console.log(x));
* ```
*
* @see {@link combineLatestAll}
* @see {@link concatAll}
* @see {@link switchAll}
* @see {@link switchMap}
* @see {@link mergeAll}
* @see {@link exhaustMap}
* @see {@link zipAll}
*
* @return A function that returns an Observable that takes a source of
* Observables and propagates the first Observable exclusively until it
* completes before subscribing to the next.
*/
export function exhaustAll>(): OperatorFunction> {
return operate((source, subscriber) => {
let isComplete = false;
let innerSub: Subscription | null = null;
source.subscribe(
new OperatorSubscriber(
subscriber,
(inner) => {
if (!innerSub) {
innerSub = innerFrom(inner).subscribe(
new OperatorSubscriber(subscriber, undefined, () => {
innerSub = null;
isComplete && subscriber.complete();
})
);
}
},
() => {
isComplete = true;
!innerSub && subscriber.complete();
}
)
);
});
}