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+import { ReplaySubject } from '../ReplaySubject';
+import { MonoTypeOperatorFunction, SchedulerLike } from '../types';
+import { share } from './share';
+
+export interface ShareReplayConfig {
+  bufferSize?: number;
+  windowTime?: number;
+  refCount: boolean;
+  scheduler?: SchedulerLike;
+}
+
+export function shareReplay<T>(config: ShareReplayConfig): MonoTypeOperatorFunction<T>;
+export function shareReplay<T>(bufferSize?: number, windowTime?: number, scheduler?: SchedulerLike): MonoTypeOperatorFunction<T>;
+
+/**
+ * Share source and replay specified number of emissions on subscription.
+ *
+ * This operator is a specialization of `replay` that connects to a source observable
+ * and multicasts through a `ReplaySubject` constructed with the specified arguments.
+ * A successfully completed source will stay cached in the `shareReplay`ed observable forever,
+ * but an errored source can be retried.
+ *
+ * ## Why use `shareReplay`?
+ *
+ * You generally want to use `shareReplay` when you have side-effects or taxing computations
+ * that you do not wish to be executed amongst multiple subscribers.
+ * It may also be valuable in situations where you know you will have late subscribers to
+ * a stream that need access to previously emitted values.
+ * This ability to replay values on subscription is what differentiates {@link share} and `shareReplay`.
+ *
+ * ## Reference counting
+ *
+ * By default `shareReplay` will use `refCount` of false, meaning that it will _not_ unsubscribe the
+ * source when the reference counter drops to zero, i.e. the inner `ReplaySubject` will _not_ be unsubscribed
+ * (and potentially run for ever).
+ * This is the default as it is expected that `shareReplay` is often used to keep around expensive to setup
+ * observables which we want to keep running instead of having to do the expensive setup again.
+ *
+ * As of RXJS version 6.4.0 a new overload signature was added to allow for manual control over what
+ * happens when the operators internal reference counter drops to zero.
+ * If `refCount` is true, the source will be unsubscribed from once the reference count drops to zero, i.e.
+ * the inner `ReplaySubject` will be unsubscribed. All new subscribers will receive value emissions from a
+ * new `ReplaySubject` which in turn will cause a new subscription to the source observable.
+ *
+ * ## Examples
+ *
+ * Example with a third subscriber coming late to the party
+ *
+ * ```ts
+ * import { interval, take, shareReplay } from 'rxjs';
+ *
+ * const shared$ = interval(2000).pipe(
+ *   take(6),
+ *   shareReplay(3)
+ * );
+ *
+ * shared$.subscribe(x => console.log('sub A: ', x));
+ * shared$.subscribe(y => console.log('sub B: ', y));
+ *
+ * setTimeout(() => {
+ *   shared$.subscribe(y => console.log('sub C: ', y));
+ * }, 11000);
+ *
+ * // Logs:
+ * // (after ~2000 ms)
+ * // sub A: 0
+ * // sub B: 0
+ * // (after ~4000 ms)
+ * // sub A: 1
+ * // sub B: 1
+ * // (after ~6000 ms)
+ * // sub A: 2
+ * // sub B: 2
+ * // (after ~8000 ms)
+ * // sub A: 3
+ * // sub B: 3
+ * // (after ~10000 ms)
+ * // sub A: 4
+ * // sub B: 4
+ * // (after ~11000 ms, sub C gets the last 3 values)
+ * // sub C: 2
+ * // sub C: 3
+ * // sub C: 4
+ * // (after ~12000 ms)
+ * // sub A: 5
+ * // sub B: 5
+ * // sub C: 5
+ * ```
+ *
+ * Example for `refCount` usage
+ *
+ * ```ts
+ * import { Observable, tap, interval, shareReplay, take } from 'rxjs';
+ *
+ * const log = <T>(name: string, source: Observable<T>) => source.pipe(
+ *   tap({
+ *     subscribe: () => console.log(`${ name }: subscribed`),
+ *     next: value => console.log(`${ name }: ${ value }`),
+ *     complete: () => console.log(`${ name }: completed`),
+ *     finalize: () => console.log(`${ name }: unsubscribed`)
+ *   })
+ * );
+ *
+ * const obs$ = log('source', interval(1000));
+ *
+ * const shared$ = log('shared', obs$.pipe(
+ *   shareReplay({ bufferSize: 1, refCount: true }),
+ *   take(2)
+ * ));
+ *
+ * shared$.subscribe(x => console.log('sub A: ', x));
+ * shared$.subscribe(y => console.log('sub B: ', y));
+ *
+ * // PRINTS:
+ * // shared: subscribed <-- reference count = 1
+ * // source: subscribed
+ * // shared: subscribed <-- reference count = 2
+ * // source: 0
+ * // shared: 0
+ * // sub A: 0
+ * // shared: 0
+ * // sub B: 0
+ * // source: 1
+ * // shared: 1
+ * // sub A: 1
+ * // shared: completed <-- take(2) completes the subscription for sub A
+ * // shared: unsubscribed <-- reference count = 1
+ * // shared: 1
+ * // sub B: 1
+ * // shared: completed <-- take(2) completes the subscription for sub B
+ * // shared: unsubscribed <-- reference count = 0
+ * // source: unsubscribed <-- replaySubject unsubscribes from source observable because the reference count dropped to 0 and refCount is true
+ *
+ * // In case of refCount being false, the unsubscribe is never called on the source and the source would keep on emitting, even if no subscribers
+ * // are listening.
+ * // source: 2
+ * // source: 3
+ * // source: 4
+ * // ...
+ * ```
+ *
+ * @see {@link publish}
+ * @see {@link share}
+ * @see {@link publishReplay}
+ *
+ * @param configOrBufferSize Maximum element count of the replay buffer or {@link ShareReplayConfig configuration}
+ * object.
+ * @param windowTime Maximum time length of the replay buffer in milliseconds.
+ * @param scheduler Scheduler where connected observers within the selector function
+ * will be invoked on.
+ * @return A function that returns an Observable sequence that contains the
+ * elements of a sequence produced by multicasting the source sequence within a
+ * selector function.
+ */
+export function shareReplay<T>(
+  configOrBufferSize?: ShareReplayConfig | number,
+  windowTime?: number,
+  scheduler?: SchedulerLike
+): MonoTypeOperatorFunction<T> {
+  let bufferSize: number;
+  let refCount = false;
+  if (configOrBufferSize && typeof configOrBufferSize === 'object') {
+    ({ bufferSize = Infinity, windowTime = Infinity, refCount = false, scheduler } = configOrBufferSize);
+  } else {
+    bufferSize = (configOrBufferSize ?? Infinity) as number;
+  }
+  return share<T>({
+    connector: () => new ReplaySubject(bufferSize, windowTime, scheduler),
+    resetOnError: true,
+    resetOnComplete: false,
+    resetOnRefCountZero: refCount,
+  });
+}