import { Observable, ObservableInput } from '../Observable';
import { FromObservable } from '../observable/FromObservable';
import { Operator } from '../Operator';
import { Subscriber } from '../Subscriber';
import { isArray } from '../util/isArray';
import { OuterSubscriber } from '../OuterSubscriber';
import { InnerSubscriber } from '../InnerSubscriber';
import { subscribeToResult } from '../util/subscribeToResult';

/* tslint:disable:max-line-length */
export function onErrorResumeNext<T, R>(this: Observable<T>, v: ObservableInput<R>): Observable<R>;
export function onErrorResumeNext<T, T2, T3, R>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>): Observable<R>;
export function onErrorResumeNext<T, T2, T3, T4, R>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>): Observable<R>;
export function onErrorResumeNext<T, T2, T3, T4, T5, R>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>): Observable<R>;
export function onErrorResumeNext<T, T2, T3, T4, T5, T6, R>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, v6: ObservableInput<T6>): Observable<R> ;
export function onErrorResumeNext<T, R>(this: Observable<T>, ...observables: Array<ObservableInput<any> | ((...values: Array<any>) => R)>): Observable<R>;
export function onErrorResumeNext<T, R>(this: Observable<T>, array: ObservableInput<any>[]): Observable<R>;
/* tslint:enable:max-line-length */

/**
 * When any of the provided Observable emits an complete or error notification, it immediately subscribes to the next one
 * that was passed.
 *
 * <span class="informal">Execute series of Observables no matter what, even if it means swallowing errors.</span>
 *
 * <img src="./img/onErrorResumeNext.png" width="100%">
 *
 * `onErrorResumeNext` is an operator that accepts a series of Observables, provided either directly as
 * arguments or as an array. If no single Observable is provided, returned Observable will simply behave the same
 * as the source.
 *
 * `onErrorResumeNext` returns an Observable that starts by subscribing and re-emitting values from the source Observable.
 * When its stream of values ends - no matter if Observable completed or emitted an error - `onErrorResumeNext`
 * will subscribe to the first Observable that was passed as an argument to the method. It will start re-emitting
 * its values as well and - again - when that stream ends, `onErrorResumeNext` will proceed to subscribing yet another
 * Observable in provided series, no matter if previous Observable completed or ended with an error. This will
 * be happening until there is no more Observables left in the series, at which point returned Observable will
 * complete - even if the last subscribed stream ended with an error.
 *
 * `onErrorResumeNext` can be therefore though of as version of {@link concat} operator, which is more permissive
 * when it comes to the errors emitted by its input Observables. While `concat` subscribes to the next Observable
 * in series only if previous one successfully completed, `onErrorResumeNext` subscribes even if it ended with
 * an error.
 *
 * Note that you do not get any access to errors emitted by the Observables. In particular do not
 * expect these errors to appear in error callback passed to {@link subscribe}. If you want to take
 * specific actions based on what error was emitted by an Observable, you should try out {@link catch} instead.
 *
 *
 * @example <caption>Subscribe to the next Observable after map fails</caption>
 * Rx.Observable.of(1, 2, 3, 0)
 *   .map(x => {
 *       if (x === 0) { throw Error(); }
         return 10 / x;
 *   })
 *   .onErrorResumeNext(Rx.Observable.of(1, 2, 3))
 *   .subscribe(
 *     val => console.log(val),
 *     err => console.log(err),          // Will never be called.
 *     () => console.log('that\'s it!')
 *   );
 *
 * // Logs:
 * // 10
 * // 5
 * // 3.3333333333333335
 * // 1
 * // 2
 * // 3
 * // "that's it!"
 *
 * @see {@link concat}
 * @see {@link catch}
 *
 * @param {...ObservableInput} observables Observables passed either directly or as an array.
 * @return {Observable} An Observable that emits values from source Observable, but - if it errors - subscribes
 * to the next passed Observable and so on, until it completes or runs out of Observables.
 * @method onErrorResumeNext
 * @owner Observable
 */

export function onErrorResumeNext<T, R>(this: Observable<T>, ...nextSources: Array<ObservableInput<any> |
                                                       Array<ObservableInput<any>> |
                                                       ((...values: Array<any>) => R)>): Observable<R> {
  if (nextSources.length === 1 && isArray(nextSources[0])) {
    nextSources = <Array<Observable<any>>>nextSources[0];
  }

  return this.lift(new OnErrorResumeNextOperator<T, R>(nextSources));
}

/* tslint:disable:max-line-length */
export function onErrorResumeNextStatic<R>(v: ObservableInput<R>): Observable<R>;
export function onErrorResumeNextStatic<T2, T3, R>(v2: ObservableInput<T2>, v3: ObservableInput<T3>): Observable<R>;
export function onErrorResumeNextStatic<T2, T3, T4, R>(v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>): Observable<R>;
export function onErrorResumeNextStatic<T2, T3, T4, T5, R>(v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>): Observable<R>;
export function onErrorResumeNextStatic<T2, T3, T4, T5, T6, R>(v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, v6: ObservableInput<T6>): Observable<R>;

export function onErrorResumeNextStatic<R>(...observables: Array<ObservableInput<any> | ((...values: Array<any>) => R)>): Observable<R>;
export function onErrorResumeNextStatic<R>(array: ObservableInput<any>[]): Observable<R>;
/* tslint:enable:max-line-length */

export function onErrorResumeNextStatic<T, R>(...nextSources: Array<ObservableInput<any> |
                                                              Array<ObservableInput<any>> |
                                                              ((...values: Array<any>) => R)>): Observable<R> {
  let source: ObservableInput<any> = null;

  if (nextSources.length === 1 && isArray(nextSources[0])) {
    nextSources = <Array<ObservableInput<any>>>nextSources[0];
  }
  source = nextSources.shift();

  return new FromObservable(source, null).lift(new OnErrorResumeNextOperator<T, R>(nextSources));
}

class OnErrorResumeNextOperator<T, R> implements Operator<T, R> {
  constructor(private nextSources: Array<ObservableInput<any>>) {
  }

  call(subscriber: Subscriber<R>, source: any): any {
    return source.subscribe(new OnErrorResumeNextSubscriber(subscriber, this.nextSources));
  }
}

class OnErrorResumeNextSubscriber<T, R> extends OuterSubscriber<T, R> {
  constructor(protected destination: Subscriber<T>,
              private nextSources: Array<ObservableInput<any>>) {
    super(destination);
  }

  notifyError(error: any, innerSub: InnerSubscriber<T, any>): void {
    this.subscribeToNextSource();
  }

  notifyComplete(innerSub: InnerSubscriber<T, any>): void {
    this.subscribeToNextSource();
  }

  protected _error(err: any): void {
    this.subscribeToNextSource();
  }

  protected _complete(): void {
    this.subscribeToNextSource();
  }

  private subscribeToNextSource(): void {
    const next = this.nextSources.shift();
    if (next) {
      this.add(subscribeToResult(this, next));
    } else {
      this.destination.complete();
    }
  }
}
