import { Subject } from './Subject';
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import { SchedulerLike } from './types';
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import { queue } from './scheduler/queue';
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import { Subscriber } from './Subscriber';
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import { Subscription } from './Subscription';
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import { ObserveOnSubscriber } from './operators/observeOn';
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import { ObjectUnsubscribedError } from './util/ObjectUnsubscribedError';
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import { SubjectSubscription } from './SubjectSubscription';
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/**
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* A variant of Subject that "replays" or emits old values to new subscribers.
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* It buffers a set number of values and will emit those values immediately to
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* any new subscribers in addition to emitting new values to existing subscribers.
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*
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* @class ReplaySubject<T>
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*/
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export class ReplaySubject<T> extends Subject<T> {
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private _events: (ReplayEvent<T> | T)[] = [];
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private _bufferSize: number;
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private _windowTime: number;
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private _infiniteTimeWindow: boolean = false;
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constructor(bufferSize: number = Number.POSITIVE_INFINITY,
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windowTime: number = Number.POSITIVE_INFINITY,
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private scheduler?: SchedulerLike) {
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super();
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this._bufferSize = bufferSize < 1 ? 1 : bufferSize;
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this._windowTime = windowTime < 1 ? 1 : windowTime;
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if (windowTime === Number.POSITIVE_INFINITY) {
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this._infiniteTimeWindow = true;
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this.next = this.nextInfiniteTimeWindow;
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} else {
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this.next = this.nextTimeWindow;
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}
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}
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private nextInfiniteTimeWindow(value: T): void {
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if (!this.isStopped) {
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const _events = this._events;
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_events.push(value);
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// Since this method is invoked in every next() call than the buffer
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// can overgrow the max size only by one item
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if (_events.length > this._bufferSize) {
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_events.shift();
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}
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}
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super.next(value);
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}
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private nextTimeWindow(value: T): void {
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if (!this.isStopped) {
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this._events.push(new ReplayEvent(this._getNow(), value));
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this._trimBufferThenGetEvents();
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}
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super.next(value);
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}
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/** @deprecated This is an internal implementation detail, do not use. */
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_subscribe(subscriber: Subscriber<T>): Subscription {
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// When `_infiniteTimeWindow === true` then the buffer is already trimmed
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const _infiniteTimeWindow = this._infiniteTimeWindow;
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const _events = _infiniteTimeWindow ? this._events : this._trimBufferThenGetEvents();
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const scheduler = this.scheduler;
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const len = _events.length;
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let subscription: Subscription;
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if (this.closed) {
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throw new ObjectUnsubscribedError();
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} else if (this.isStopped || this.hasError) {
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subscription = Subscription.EMPTY;
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} else {
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this.observers.push(subscriber);
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subscription = new SubjectSubscription(this, subscriber);
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}
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if (scheduler) {
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subscriber.add(subscriber = new ObserveOnSubscriber<T>(subscriber, scheduler));
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}
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if (_infiniteTimeWindow) {
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for (let i = 0; i < len && !subscriber.closed; i++) {
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subscriber.next(<T>_events[i]);
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}
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} else {
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for (let i = 0; i < len && !subscriber.closed; i++) {
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subscriber.next((<ReplayEvent<T>>_events[i]).value);
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}
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}
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if (this.hasError) {
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subscriber.error(this.thrownError);
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} else if (this.isStopped) {
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subscriber.complete();
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}
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return subscription;
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}
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_getNow(): number {
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return (this.scheduler || queue).now();
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}
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private _trimBufferThenGetEvents(): ReplayEvent<T>[] {
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const now = this._getNow();
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const _bufferSize = this._bufferSize;
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const _windowTime = this._windowTime;
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const _events = <ReplayEvent<T>[]>this._events;
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const eventsCount = _events.length;
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let spliceCount = 0;
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// Trim events that fall out of the time window.
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// Start at the front of the list. Break early once
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// we encounter an event that falls within the window.
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while (spliceCount < eventsCount) {
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if ((now - _events[spliceCount].time) < _windowTime) {
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break;
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}
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spliceCount++;
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}
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if (eventsCount > _bufferSize) {
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spliceCount = Math.max(spliceCount, eventsCount - _bufferSize);
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}
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if (spliceCount > 0) {
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_events.splice(0, spliceCount);
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}
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return _events;
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}
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}
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class ReplayEvent<T> {
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constructor(public time: number, public value: T) {
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}
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}
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