import { mergeMap } from './mergeMap';
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import { ObservableInput, OperatorFunction, ObservedValueOf } from '../types';
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import { isFunction } from '../util/isFunction';
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/* tslint:disable:max-line-length */
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export function concatMap<T, O extends ObservableInput<any>>(
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project: (value: T, index: number) => O
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): OperatorFunction<T, ObservedValueOf<O>>;
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/** @deprecated The `resultSelector` parameter will be removed in v8. Use an inner `map` instead. Details: https://rxjs.dev/deprecations/resultSelector */
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export function concatMap<T, O extends ObservableInput<any>>(
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project: (value: T, index: number) => O,
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resultSelector: undefined
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): OperatorFunction<T, ObservedValueOf<O>>;
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/** @deprecated The `resultSelector` parameter will be removed in v8. Use an inner `map` instead. Details: https://rxjs.dev/deprecations/resultSelector */
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export function concatMap<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
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): 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, in a serialized fashion waiting for each one to complete before
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* merging the next.
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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 concatAll}.</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 (so-called "inner") Observable. Each new inner Observable is
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* concatenated with the previous inner Observable.
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*
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* __Warning:__ if source values arrive endlessly and faster than their
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* corresponding inner Observables can complete, it will result in memory issues
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* as inner Observables amass in an unbounded buffer waiting for their turn to
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* be subscribed to.
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*
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* Note: `concatMap` is equivalent to `mergeMap` with concurrency parameter set
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* to `1`.
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*
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* ## Example
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*
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* For each click event, tick every second from 0 to 3, with no concurrency
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*
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* ```ts
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* import { fromEvent, concatMap, interval, take } from 'rxjs';
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*
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* const clicks = fromEvent(document, 'click');
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* const result = clicks.pipe(
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* concatMap(ev => interval(1000).pipe(take(4)))
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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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* // (results are not concurrent)
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* // For every click on the "document" it will emit values 0 to 3 spaced
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* // on a 1000ms interval
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* // one click = 1000ms-> 0 -1000ms-> 1 -1000ms-> 2 -1000ms-> 3
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* ```
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*
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* @see {@link concat}
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* @see {@link concatAll}
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* @see {@link concatMapTo}
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* @see {@link exhaustMap}
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* @see {@link mergeMap}
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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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* @return A function that returns an Observable that emits the result of
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* applying the projection function (and the optional deprecated
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* `resultSelector`) to each item emitted by the source Observable and taking
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* values from each projected inner Observable sequentially.
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*/
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export function concatMap<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
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): OperatorFunction<T, ObservedValueOf<O> | R> {
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return isFunction(resultSelector) ? mergeMap(project, resultSelector, 1) : mergeMap(project, 1);
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}
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