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.AtomicReference;

import org.reactivestreams.*;

import io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.internal.disposables.DisposableHelper;
import io.reactivex.internal.subscriptions.SubscriptionHelper;

Subscribe to a main Flowable first, then when it completes normally, subscribe to a Completable
and terminate when it terminates.
History: 2.1.10 - experimental
Type parameters:
<T> – the element type of the main source and output type
Since:
2.2/**
 * Subscribe to a main Flowable first, then when it completes normally, subscribe to a Completable
 * and terminate when it terminates.
 * <p>History: 2.1.10 - experimental
 * @param <T> the element type of the main source and output type
 * @since 2.2
 */
public final class FlowableConcatWithCompletable<T> extends AbstractFlowableWithUpstream<T, T> {

    final CompletableSource other;

    public FlowableConcatWithCompletable(Flowable<T> source, CompletableSource other) {
        super(source);
        this.other = other;
    }

    @Override
    protected void subscribeActual(Subscriber<? super T> s) {
        source.subscribe(new ConcatWithSubscriber<T>(s, other));
    }

    static final class ConcatWithSubscriber<T>
    extends AtomicReference<Disposable>
    implements FlowableSubscriber<T>, CompletableObserver, Subscription {

        private static final long serialVersionUID = -7346385463600070225L;

        final Subscriber<? super T> downstream;

        Subscription upstream;

        CompletableSource other;

        boolean inCompletable;

        ConcatWithSubscriber(Subscriber<? super T> actual, CompletableSource other) {
            this.downstream = actual;
            this.other = other;
        }

        @Override
        public void onSubscribe(Subscription s) {
            if (SubscriptionHelper.validate(upstream, s)) {
                this.upstream = s;
                downstream.onSubscribe(this);
            }
        }

        @Override
        public void onSubscribe(Disposable d) {
            DisposableHelper.setOnce(this, d);
        }

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

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

        @Override
        public void onComplete() {
            if (inCompletable) {
                downstream.onComplete();
            } else {
                inCompletable = true;
                upstream = SubscriptionHelper.CANCELLED;
                CompletableSource cs = other;
                other = null;
                cs.subscribe(this);
            }
        }

        @Override
        public void request(long n) {
            upstream.request(n);
        }

        @Override
        public void cancel() {
            upstream.cancel();
            DisposableHelper.dispose(this);
        }
    }
}