import { Observable } from '../Observable';
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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 { ObservableInput, OperatorFunction, ObservedValueOf } from '../types';
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import { map } from './map';
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import { from } from '../observable/from';
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import { SimpleOuterSubscriber, SimpleInnerSubscriber, innerSubscribe } from '../innerSubscribe';
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/* tslint:disable:max-line-length */
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export function mergeMap<T, O extends ObservableInput<any>>(project: (value: T, index: number) => O, concurrent?: number): OperatorFunction<T, ObservedValueOf<O>>;
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/** @deprecated resultSelector no longer supported, use inner map instead */
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export function mergeMap<T, O extends ObservableInput<any>>(project: (value: T, index: number) => O, resultSelector: undefined, concurrent?: number): OperatorFunction<T, ObservedValueOf<O>>;
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/** @deprecated resultSelector no longer supported, use inner map instead */
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export function mergeMap<T, R, O extends ObservableInput<any>>(project: (value: T, index: number) => O, resultSelector: (outerValue: T, innerValue: ObservedValueOf<O>, outerIndex: number, innerIndex: number) => R, concurrent?: number): OperatorFunction<T, R>;
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/* tslint:enable:max-line-length */
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/**
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* Projects each source value to an Observable which is merged in the output
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* Observable.
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*
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* <span class="informal">Maps each value to an Observable, then flattens all of
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* these inner Observables using {@link mergeAll}.</span>
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*
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* 
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*
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* Returns an Observable that emits items based on applying a function that you
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* supply to each item emitted by the source Observable, where that function
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* returns an Observable, and then merging those resulting Observables and
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* emitting the results of this merger.
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*
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* ## Example
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* Map and flatten each letter to an Observable ticking every 1 second
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* ```ts
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* import { of, interval } from 'rxjs';
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* import { mergeMap, map } from 'rxjs/operators';
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*
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* const letters = of('a', 'b', 'c');
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* const result = letters.pipe(
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* mergeMap(x => interval(1000).pipe(map(i => x+i))),
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* );
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* result.subscribe(x => console.log(x));
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*
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* // Results in the following:
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* // a0
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* // b0
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* // c0
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* // a1
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* // b1
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* // c1
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* // continues to list a,b,c with respective ascending integers
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* ```
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*
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* @see {@link concatMap}
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* @see {@link exhaustMap}
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* @see {@link merge}
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* @see {@link mergeAll}
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* @see {@link mergeMapTo}
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* @see {@link mergeScan}
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* @see {@link switchMap}
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*
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* @param {function(value: T, ?index: number): ObservableInput} project A function
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* that, when applied to an item emitted by the source Observable, returns an
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* Observable.
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* @param {number} [concurrent=Number.POSITIVE_INFINITY] Maximum number of input
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* Observables being subscribed to concurrently.
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* @return {Observable} An Observable that emits the result of applying the
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* projection function (and the optional deprecated `resultSelector`) to each item
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* emitted by the source Observable and merging the results of the Observables
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* obtained from this transformation.
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*/
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export function mergeMap<T, R, O extends ObservableInput<any>>(
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project: (value: T, index: number) => O,
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resultSelector?: ((outerValue: T, innerValue: ObservedValueOf<O>, outerIndex: number, innerIndex: number) => R) | number,
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concurrent: number = Number.POSITIVE_INFINITY
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): OperatorFunction<T, ObservedValueOf<O>|R> {
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if (typeof resultSelector === 'function') {
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// DEPRECATED PATH
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return (source: Observable<T>) => source.pipe(
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mergeMap((a, i) => from(project(a, i)).pipe(
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map((b: any, ii: number) => resultSelector(a, b, i, ii)),
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), concurrent)
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);
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} else if (typeof resultSelector === 'number') {
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concurrent = resultSelector;
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}
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return (source: Observable<T>) => source.lift(new MergeMapOperator(project, concurrent));
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}
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export class MergeMapOperator<T, R> implements Operator<T, R> {
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constructor(private project: (value: T, index: number) => ObservableInput<R>,
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private concurrent: number = Number.POSITIVE_INFINITY) {
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}
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call(observer: Subscriber<R>, source: any): any {
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return source.subscribe(new MergeMapSubscriber(
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observer, this.project, this.concurrent
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));
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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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export class MergeMapSubscriber<T, R> extends SimpleOuterSubscriber<T, R> {
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private hasCompleted: boolean = false;
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private buffer: T[] = [];
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private active: number = 0;
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protected index: number = 0;
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constructor(destination: Subscriber<R>,
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private project: (value: T, index: number) => ObservableInput<R>,
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private concurrent: number = Number.POSITIVE_INFINITY) {
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super(destination);
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}
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protected _next(value: T): void {
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if (this.active < this.concurrent) {
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this._tryNext(value);
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} else {
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this.buffer.push(value);
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}
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}
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protected _tryNext(value: T) {
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let result: ObservableInput<R>;
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const index = this.index++;
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try {
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result = this.project(value, index);
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} catch (err) {
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this.destination.error!(err);
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return;
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}
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this.active++;
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this._innerSub(result);
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}
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private _innerSub(ish: ObservableInput<R>): void {
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const innerSubscriber = new SimpleInnerSubscriber(this);
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const destination = this.destination as Subscription;
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destination.add(innerSubscriber);
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const innerSubscription = innerSubscribe(ish, innerSubscriber);
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// The returned subscription will usually be the subscriber that was
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// passed. However, interop subscribers will be wrapped and for
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// unsubscriptions to chain correctly, the wrapper needs to be added, too.
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if (innerSubscription !== innerSubscriber) {
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destination.add(innerSubscription);
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}
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}
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protected _complete(): void {
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this.hasCompleted = true;
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if (this.active === 0 && this.buffer.length === 0) {
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this.destination.complete!();
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}
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this.unsubscribe();
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}
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notifyNext(innerValue: R): void {
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this.destination.next!(innerValue);
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}
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notifyComplete(): void {
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const buffer = this.buffer;
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this.active--;
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if (buffer.length > 0) {
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this._next(buffer.shift()!);
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} else if (this.active === 0 && this.hasCompleted) {
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this.destination.complete!();
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}
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}
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}
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/**
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* @deprecated renamed. Use {@link mergeMap}
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*/
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export const flatMap = mergeMap;
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