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import { Observable } from '../Observable';
import { OperatorFunction } from '../types';
import { Subject } from '../Subject';
import { Subscriber } from '../Subscriber';
import { OuterSubscriber } from '../OuterSubscriber';
import { InnerSubscriber } from '../InnerSubscriber';
import { subscribeToResult } from '../util/subscribeToResult';
import { Operator } from '../Operator';
/**
* Branch out the source Observable values as a nested Observable whenever
* `windowBoundaries` emits.
*
* <span class="informal">It's like {@link buffer}, but emits a nested Observable
* instead of an array.</span>
*
* 
*
* Returns an Observable that emits windows of items it collects from the source
* Observable. The output Observable emits connected, non-overlapping
* windows. It emits the current window and opens a new one whenever the
* Observable `windowBoundaries` emits an item. Because each window is an
* Observable, the output is a higher-order Observable.
*
* ## Example
* In every window of 1 second each, emit at most 2 click events
* ```javascript
* const clicks = fromEvent(document, 'click');
* const interval = interval(1000);
* const result = clicks.pipe(
* window(interval),
* map(win => win.take(2)), // each window has at most 2 emissions
* mergeAll(), // flatten the Observable-of-Observables
* );
* result.subscribe(x => console.log(x));
* ```
* @see {@link windowCount}
* @see {@link windowTime}
* @see {@link windowToggle}
* @see {@link windowWhen}
* @see {@link buffer}
*
* @param {Observable<any>} windowBoundaries An Observable that completes the
* previous window and starts a new window.
* @return {Observable<Observable<T>>} An Observable of windows, which are
* Observables emitting values of the source Observable.
* @method window
* @owner Observable
*/
export function window<T>(windowBoundaries: Observable<any>): OperatorFunction<T, Observable<T>> {
return function windowOperatorFunction(source: Observable<T>) {
return source.lift(new WindowOperator(windowBoundaries));
};
}
class WindowOperator<T> implements Operator<T, Observable<T>> {
constructor(private windowBoundaries: Observable<any>) {
}
call(subscriber: Subscriber<Observable<T>>, source: any): any {
const windowSubscriber = new WindowSubscriber(subscriber);
const sourceSubscription = source.subscribe(windowSubscriber);
if (!sourceSubscription.closed) {
windowSubscriber.add(subscribeToResult(windowSubscriber, this.windowBoundaries));
}
return sourceSubscription;
}
}
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
class WindowSubscriber<T> extends OuterSubscriber<T, any> {
private window: Subject<T> = new Subject<T>();
constructor(destination: Subscriber<Observable<T>>) {
super(destination);
destination.next(this.window);
}
notifyNext(outerValue: T, innerValue: any,
outerIndex: number, innerIndex: number,
innerSub: InnerSubscriber<T, any>): void {
this.openWindow();
}
notifyError(error: any, innerSub: InnerSubscriber<T, any>): void {
this._error(error);
}
notifyComplete(innerSub: InnerSubscriber<T, any>): void {
this._complete();
}
protected _next(value: T): void {
this.window.next(value);
}
protected _error(err: any): void {
this.window.error(err);
this.destination.error(err);
}
protected _complete(): void {
this.window.complete();
this.destination.complete();
}
/** @deprecated This is an internal implementation detail, do not use. */
_unsubscribe() {
this.window = null;
}
private openWindow(): void {
const prevWindow = this.window;
if (prevWindow) {
prevWindow.complete();
}
const destination = this.destination;
const newWindow = this.window = new Subject<T>();
destination.next(newWindow);
}
}
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