import { Observable } from '../Observable';
import { multicast } from './multicast';
import { Subject } from '../Subject';

function shareSubjectFactory() {
  return new Subject();
}

/**
 * Returns a new Observable that multicasts (shares) the original Observable. As long as there is at least one
 * Subscriber this Observable will be subscribed and emitting data. When all subscribers have unsubscribed it will
 * unsubscribe from the source Observable. Because the Observable is multicasting it makes the stream `hot`.
 * This is an alias for .publish().refCount().
 *
 * <img src="./img/share.png" width="100%">
 *
 * @return {Observable<T>} an Observable that upon connection causes the source Observable to emit items to its Observers
 * @method share
 * @owner Observable
 */
export function share<T>(this: Observable<T>): Observable<T> {
  return multicast.call(this, shareSubjectFactory).refCount();
};