import { Operator } from '../Operator';
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import { Subscriber } from '../Subscriber';
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import { Observable } from '../Observable';
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import { Subscription } from '../Subscription';
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import { OperatorFunction } from '../types';
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import { SimpleOuterSubscriber, innerSubscribe, SimpleInnerSubscriber } from '../innerSubscribe';
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/**
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* Buffers the source Observable values, using a factory function of closing
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* Observables to determine when to close, emit, and reset the buffer.
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*
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* <span class="informal">Collects values from the past as an array. When it
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* starts collecting values, it calls a function that returns an Observable that
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* tells when to close the buffer and restart collecting.</span>
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*
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* 
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*
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* Opens a buffer immediately, then closes the buffer when the observable
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* returned by calling `closingSelector` function emits a value. When it closes
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* the buffer, it immediately opens a new buffer and repeats the process.
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*
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* ## Example
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*
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* Emit an array of the last clicks every [1-5] random seconds
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*
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* ```ts
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* import { fromEvent, interval } from 'rxjs';
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* import { bufferWhen } from 'rxjs/operators';
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*
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* const clicks = fromEvent(document, 'click');
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* const buffered = clicks.pipe(bufferWhen(() =>
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* interval(1000 + Math.random() * 4000)
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* ));
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* buffered.subscribe(x => console.log(x));
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* ```
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*
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*
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* @see {@link buffer}
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* @see {@link bufferCount}
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* @see {@link bufferTime}
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* @see {@link bufferToggle}
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* @see {@link windowWhen}
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*
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* @param {function(): Observable} closingSelector A function that takes no
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* arguments and returns an Observable that signals buffer closure.
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* @return {Observable<T[]>} An observable of arrays of buffered values.
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* @method bufferWhen
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* @owner Observable
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*/
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export function bufferWhen<T>(closingSelector: () => Observable<any>): OperatorFunction<T, T[]> {
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return function (source: Observable<T>) {
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return source.lift(new BufferWhenOperator(closingSelector));
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};
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}
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class BufferWhenOperator<T> implements Operator<T, T[]> {
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constructor(private closingSelector: () => Observable<any>) {
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}
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call(subscriber: Subscriber<T[]>, source: any): any {
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return source.subscribe(new BufferWhenSubscriber(subscriber, this.closingSelector));
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}
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}
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/**
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* We need this JSDoc comment for affecting ESDoc.
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* @ignore
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* @extends {Ignored}
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*/
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class BufferWhenSubscriber<T> extends SimpleOuterSubscriber<T, any> {
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private buffer?: T[];
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private subscribing: boolean = false;
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private closingSubscription?: Subscription;
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constructor(destination: Subscriber<T[]>, private closingSelector: () => Observable<any>) {
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super(destination);
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this.openBuffer();
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}
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protected _next(value: T) {
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this.buffer!.push(value);
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}
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protected _complete() {
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const buffer = this.buffer;
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if (buffer) {
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this.destination.next!(buffer);
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}
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super._complete();
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}
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/** @deprecated This is an internal implementation detail, do not use. */
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_unsubscribe() {
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this.buffer = undefined;
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this.subscribing = false;
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}
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notifyNext(): void {
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this.openBuffer();
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}
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notifyComplete(): void {
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if (this.subscribing) {
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this.complete();
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} else {
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this.openBuffer();
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}
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}
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openBuffer() {
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let { closingSubscription } = this;
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if (closingSubscription) {
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this.remove(closingSubscription);
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closingSubscription.unsubscribe();
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}
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const buffer = this.buffer;
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if (this.buffer) {
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this.destination.next!(buffer);
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}
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this.buffer = [];
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let closingNotifier;
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try {
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const { closingSelector } = this;
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closingNotifier = closingSelector();
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} catch (err) {
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return this.error(err);
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}
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closingSubscription = new Subscription();
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this.closingSubscription = closingSubscription;
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this.add(closingSubscription);
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this.subscribing = true;
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closingSubscription.add(innerSubscribe(closingNotifier, new SimpleInnerSubscriber(this)));
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this.subscribing = false;
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}
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}
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