import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/do';
import 'rxjs/add/operator/publishReplay';
import { Subscriber } from 'rxjs/Subscriber';
import { MonoTypeOperatorFunction } from 'rxjs/interfaces';
import { Subscription, TeardownLogic } from 'rxjs/Subscription';
import { Operator } from 'rxjs/Operator';

export function debugUnsubscribe<T>(text: string,
                                    thisArg?: any): MonoTypeOperatorFunction<T> {
  return function debugUnsubscribeFunction(source: Observable<T>): Observable<T> {
    return source.lift(new DebugUnsubscribeOperator(text, thisArg));
  };
}


class DebugUnsubscribeOperator<T> implements Operator<T, T> {

  constructor(private text: string, private source: Observable<T>) {
  }

  call(subscriber: Subscriber<T>, source: any): TeardownLogic {

    const {text} = this;

    const debugUnsubscribeSubscriber = new DebugUnsubscribeSubscriber(subscriber, source, text);

    console.log('subscribing', text);

    const subscription = source.subscribe(debugUnsubscribeSubscriber);

    (<any> debugUnsubscribeSubscriber).sub = debugUnsubscribeSubscriber;

    return subscription;
  }
}

class DebugUnsubscribeSubscriber<T> extends Subscriber<T> {
  private sub: Subscription;

  constructor(destination: Subscriber<T>,
              private source: Observable<T>,
              private text: string) {
    super(destination);
  }

  protected _unsubscribe() {
    const {sub, text} = this;
    if (sub) {
      sub.unsubscribe();
    }
    console.log('unsubscribing', text, sub ? 'sucess' : 'fail');
  }
}