/*
 * Copyright (c) 2011-2017 Pivotal Software Inc, All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package reactor.core.publisher;

import java.util.Objects;
import java.util.function.Function;

import org.reactivestreams.Publisher;
import org.reactivestreams.Subscriber;
import reactor.core.CoreSubscriber;

Repeats a source when a companion sequence signals an item in response to the main's
completion signal

If the companion sequence signals when the main source is active, the repeat attempt
is suppressed and any terminal signal will terminate the main source with the same
signal immediately.
Type parameters:
<T> – the source value type
See Also:
Reactive-Streams-Commons/**
 * Repeats a source when a companion sequence signals an item in response to the main's
 * completion signal
 * <p>
 * <p>If the companion sequence signals when the main source is active, the repeat attempt
 * is suppressed and any terminal signal will terminate the main source with the same
 * signal immediately.
 *
 * @param <T> the source value type
 *
 * @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
 */
final class MonoRepeatWhen<T> extends FluxFromMonoOperator<T, T> {

	final Function<? super Flux<Long>, ? extends Publisher<?>> whenSourceFactory;

	MonoRepeatWhen(Mono<? extends T> source,
			Function<? super Flux<Long>, ? extends Publisher<?>> whenSourceFactory) {
		super(source);
		this.whenSourceFactory =
				Objects.requireNonNull(whenSourceFactory, "whenSourceFactory");
	}

	@Override
	public CoreSubscriber<? super T> subscribeOrReturn(CoreSubscriber<? super T> actual) {
		FluxRepeatWhen.RepeatWhenOtherSubscriber other =
				new FluxRepeatWhen.RepeatWhenOtherSubscriber();

		CoreSubscriber<T> serial = Operators.serialize(actual);

		FluxRepeatWhen.RepeatWhenMainSubscriber<T> main =
				new FluxRepeatWhen.RepeatWhenMainSubscriber<>(serial, other.completionSignal, source);
		other.main = main;

		serial.onSubscribe(main);

		Publisher<?> p;

		try {
			p = Objects.requireNonNull(whenSourceFactory.apply(other),
					"The whenSourceFactory returned a null Publisher");
		}
		catch (Throwable e) {
			actual.onError(Operators.onOperatorError(e, actual.currentContext()));
			return null;
		}

		p.subscribe(other);

		if (!main.cancelled) {
			return main;
		}
		else {
			return null;
		}
	}

	@Override
	public Object scanUnsafe(Attr key) {
		if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
		return super.scanUnsafe(key);
	}
}