import { async } from '../scheduler/async';
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import { isDate } from '../util/isDate';
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import { Operator } from '../Operator';
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import { Subscriber } from '../Subscriber';
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import { Subscription } from '../Subscription';
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import { Notification } from '../Notification';
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import { Observable } from '../Observable';
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import { MonoTypeOperatorFunction, PartialObserver, SchedulerAction, SchedulerLike, TeardownLogic } from '../types';
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/**
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* Delays the emission of items from the source Observable by a given timeout or
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* until a given Date.
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*
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* <span class="informal">Time shifts each item by some specified amount of
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* milliseconds.</span>
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*
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* 
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*
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* If the delay argument is a Number, this operator time shifts the source
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* Observable by that amount of time expressed in milliseconds. The relative
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* time intervals between the values are preserved.
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*
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* If the delay argument is a Date, this operator time shifts the start of the
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* Observable execution until the given date occurs.
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*
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* ## Examples
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* Delay each click by one second
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* ```ts
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* import { fromEvent } from 'rxjs';
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* import { delay } from 'rxjs/operators';
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*
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* const clicks = fromEvent(document, 'click');
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* const delayedClicks = clicks.pipe(delay(1000)); // each click emitted after 1 second
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* delayedClicks.subscribe(x => console.log(x));
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* ```
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*
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* Delay all clicks until a future date happens
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* ```ts
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* import { fromEvent } from 'rxjs';
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* import { delay } from 'rxjs/operators';
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*
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* const clicks = fromEvent(document, 'click');
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* const date = new Date('March 15, 2050 12:00:00'); // in the future
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* const delayedClicks = clicks.pipe(delay(date)); // click emitted only after that date
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* delayedClicks.subscribe(x => console.log(x));
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* ```
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*
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* @see {@link debounceTime}
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* @see {@link delayWhen}
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*
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* @param {number|Date} delay The delay duration in milliseconds (a `number`) or
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* a `Date` until which the emission of the source items is delayed.
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* @param {SchedulerLike} [scheduler=async] The {@link SchedulerLike} to use for
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* managing the timers that handle the time-shift for each item.
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* @return {Observable} An Observable that delays the emissions of the source
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* Observable by the specified timeout or Date.
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* @method delay
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* @owner Observable
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*/
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export function delay<T>(delay: number|Date,
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scheduler: SchedulerLike = async): MonoTypeOperatorFunction<T> {
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const absoluteDelay = isDate(delay);
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const delayFor = absoluteDelay ? (+delay - scheduler.now()) : Math.abs(<number>delay);
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return (source: Observable<T>) => source.lift(new DelayOperator(delayFor, scheduler));
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}
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class DelayOperator<T> implements Operator<T, T> {
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constructor(private delay: number,
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private scheduler: SchedulerLike) {
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}
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call(subscriber: Subscriber<T>, source: any): TeardownLogic {
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return source.subscribe(new DelaySubscriber(subscriber, this.delay, this.scheduler));
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}
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}
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interface DelayState<T> {
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source: DelaySubscriber<T>;
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destination: PartialObserver<T>;
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scheduler: SchedulerLike;
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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 DelaySubscriber<T> extends Subscriber<T> {
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private queue: Array<DelayMessage<T>> = [];
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private active: boolean = false;
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private errored: boolean = false;
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private static dispatch<T>(this: SchedulerAction<DelayState<T>>, state: DelayState<T>): void {
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const source = state.source;
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const queue = source.queue;
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const scheduler = state.scheduler;
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const destination = state.destination;
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while (queue.length > 0 && (queue[0].time - scheduler.now()) <= 0) {
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queue.shift().notification.observe(destination);
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}
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if (queue.length > 0) {
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const delay = Math.max(0, queue[0].time - scheduler.now());
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this.schedule(state, delay);
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} else {
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this.unsubscribe();
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source.active = false;
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}
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}
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constructor(destination: Subscriber<T>,
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private delay: number,
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private scheduler: SchedulerLike) {
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super(destination);
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}
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private _schedule(scheduler: SchedulerLike): void {
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this.active = true;
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const destination = this.destination as Subscription;
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destination.add(scheduler.schedule<DelayState<T>>(DelaySubscriber.dispatch, this.delay, {
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source: this, destination: this.destination, scheduler: scheduler
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}));
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}
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private scheduleNotification(notification: Notification<T>): void {
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if (this.errored === true) {
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return;
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}
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const scheduler = this.scheduler;
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const message = new DelayMessage(scheduler.now() + this.delay, notification);
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this.queue.push(message);
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if (this.active === false) {
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this._schedule(scheduler);
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}
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}
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protected _next(value: T) {
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this.scheduleNotification(Notification.createNext(value));
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}
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protected _error(err: any) {
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this.errored = true;
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this.queue = [];
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this.destination.error(err);
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this.unsubscribe();
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}
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protected _complete() {
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this.scheduleNotification(Notification.createComplete());
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this.unsubscribe();
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}
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}
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class DelayMessage<T> {
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constructor(public readonly time: number,
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public readonly notification: Notification<T>) {
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}
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}
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