Copyright (c) 2016-present, RxJava Contributors.
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
http://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.
/**
 * Copyright (c) 2016-present, RxJava Contributors.
 *
 * 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
 *
 * http://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 io.reactivex.internal.operators.flowable;

import java.util.concurrent.atomic.*;

import org.reactivestreams.*;

import io.reactivex.*;
import io.reactivex.exceptions.Exceptions;
import io.reactivex.functions.Function;
import io.reactivex.internal.functions.ObjectHelper;
import io.reactivex.internal.subscriptions.*;
import io.reactivex.processors.*;
import io.reactivex.subscribers.SerializedSubscriber;

public final class FlowableRepeatWhen<T> extends AbstractFlowableWithUpstream<T, T> {
    final Function<? super Flowable<Object>, ? extends Publisher<?>> handler;

    public FlowableRepeatWhen(Flowable<T> source,
            Function<? super Flowable<Object>, ? extends Publisher<?>> handler) {
        super(source);
        this.handler = handler;
    }

    @Override
    public void subscribeActual(Subscriber<? super T> s) {

        SerializedSubscriber<T> z = new SerializedSubscriber<T>(s);

        FlowableProcessor<Object> processor = UnicastProcessor.<Object>create(8).toSerialized();

        Publisher<?> when;

        try {
            when = ObjectHelper.requireNonNull(handler.apply(processor), "handler returned a null Publisher");
        } catch (Throwable ex) {
            Exceptions.throwIfFatal(ex);
            EmptySubscription.error(ex, s);
            return;
        }

        WhenReceiver<T, Object> receiver = new WhenReceiver<T, Object>(source);

        RepeatWhenSubscriber<T> subscriber = new RepeatWhenSubscriber<T>(z, processor, receiver);

        receiver.subscriber = subscriber;

        s.onSubscribe(subscriber);

        when.subscribe(receiver);

        receiver.onNext(0);
    }

    static final class WhenReceiver<T, U>
    extends AtomicInteger
    implements FlowableSubscriber<Object>, Subscription {

        private static final long serialVersionUID = 2827772011130406689L;

        final Publisher<T> source;

        final AtomicReference<Subscription> upstream;

        final AtomicLong requested;

        WhenSourceSubscriber<T, U> subscriber;

        WhenReceiver(Publisher<T> source) {
            this.source = source;
            this.upstream = new AtomicReference<Subscription>();
            this.requested = new AtomicLong();
        }

        @Override
        public void onSubscribe(Subscription s) {
            SubscriptionHelper.deferredSetOnce(upstream, requested, s);
        }

        @Override
        public void onNext(Object t) {
            if (getAndIncrement() == 0) {
                for (;;) {
                    if (upstream.get() == SubscriptionHelper.CANCELLED) {
                        return;
                    }

                    source.subscribe(subscriber);

                    if (decrementAndGet() == 0) {
                        break;
                    }
                }
            }
        }

        @Override
        public void onError(Throwable t) {
            subscriber.cancel();
            subscriber.downstream.onError(t);
        }

        @Override
        public void onComplete() {
            subscriber.cancel();
            subscriber.downstream.onComplete();
        }

        @Override
        public void request(long n) {
            SubscriptionHelper.deferredRequest(upstream, requested, n);
        }

        @Override
        public void cancel() {
            SubscriptionHelper.cancel(upstream);
        }
    }

    abstract static class WhenSourceSubscriber<T, U> extends SubscriptionArbiter implements FlowableSubscriber<T> {

        private static final long serialVersionUID = -5604623027276966720L;

        protected final Subscriber<? super T> downstream;

        protected final FlowableProcessor<U> processor;

        protected final Subscription receiver;

        private long produced;

        WhenSourceSubscriber(Subscriber<? super T> actual, FlowableProcessor<U> processor,
                Subscription receiver) {
            super(false);
            this.downstream = actual;
            this.processor = processor;
            this.receiver = receiver;
        }

        @Override
        public final void onSubscribe(Subscription s) {
            setSubscription(s);
        }

        @Override
        public final void onNext(T t) {
            produced++;
            downstream.onNext(t);
        }

        protected final void again(U signal) {
            setSubscription(EmptySubscription.INSTANCE);
            long p = produced;
            if (p != 0L) {
                produced = 0L;
                produced(p);
            }
            receiver.request(1);
            processor.onNext(signal);
        }

        @Override
        public final void cancel() {
            super.cancel();
            receiver.cancel();
        }
    }

    static final class RepeatWhenSubscriber<T> extends WhenSourceSubscriber<T, Object> {

        private static final long serialVersionUID = -2680129890138081029L;

        RepeatWhenSubscriber(Subscriber<? super T> actual, FlowableProcessor<Object> processor,
                Subscription receiver) {
            super(actual, processor, receiver);
        }

        @Override
        public void onError(Throwable t) {
            receiver.cancel();
            downstream.onError(t);
        }

        @Override
        public void onComplete() {
            again(0);
        }
    }
}