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.single;

import java.util.concurrent.CancellationException;
import java.util.concurrent.atomic.AtomicReference;

import org.reactivestreams.*;

import io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.internal.disposables.*;
import io.reactivex.internal.subscriptions.SubscriptionHelper;
import io.reactivex.plugins.RxJavaPlugins;

Signals the events of the source Single or signals a CancellationException if the
other Publisher signalled first.
Type parameters:
<T> – the main value type
<U> – the other value type/**
 * Signals the events of the source Single or signals a CancellationException if the
 * other Publisher signalled first.
 * @param <T> the main value type
 * @param <U> the other value type
 */
public final class SingleTakeUntil<T, U> extends Single<T> {

    final SingleSource<T> source;

    final Publisher<U> other;

    public SingleTakeUntil(SingleSource<T> source, Publisher<U> other) {
        this.source = source;
        this.other = other;
    }

    @Override
    protected void subscribeActual(SingleObserver<? super T> observer) {
        TakeUntilMainObserver<T> parent = new TakeUntilMainObserver<T>(observer);
        observer.onSubscribe(parent);

        other.subscribe(parent.other);

        source.subscribe(parent);
    }

    static final class TakeUntilMainObserver<T>
    extends AtomicReference<Disposable>
    implements SingleObserver<T>, Disposable {

        private static final long serialVersionUID = -622603812305745221L;

        final SingleObserver<? super T> downstream;

        final TakeUntilOtherSubscriber other;

        TakeUntilMainObserver(SingleObserver<? super T> downstream) {
            this.downstream = downstream;
            this.other = new TakeUntilOtherSubscriber(this);
        }

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

        @Override
        public boolean isDisposed() {
            return DisposableHelper.isDisposed(get());
        }

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

        @Override
        public void onSuccess(T value) {
            other.dispose();

            Disposable a = getAndSet(DisposableHelper.DISPOSED);
            if (a != DisposableHelper.DISPOSED) {
                downstream.onSuccess(value);
            }
        }

        @Override
        public void onError(Throwable e) {
            other.dispose();

            Disposable a = get();
            if (a != DisposableHelper.DISPOSED) {
                a = getAndSet(DisposableHelper.DISPOSED);
                if (a != DisposableHelper.DISPOSED) {
                    downstream.onError(e);
                    return;
                }
            }
            RxJavaPlugins.onError(e);
        }

        void otherError(Throwable e) {
            Disposable a = get();
            if (a != DisposableHelper.DISPOSED) {
                a = getAndSet(DisposableHelper.DISPOSED);
                if (a != DisposableHelper.DISPOSED) {
                    if (a != null) {
                        a.dispose();
                    }
                    downstream.onError(e);
                    return;
                }
            }
            RxJavaPlugins.onError(e);
        }
    }

    static final class TakeUntilOtherSubscriber
    extends AtomicReference<Subscription>
    implements FlowableSubscriber<Object> {

        private static final long serialVersionUID = 5170026210238877381L;

        final TakeUntilMainObserver<?> parent;

        TakeUntilOtherSubscriber(TakeUntilMainObserver<?> parent) {
            this.parent = parent;
        }

        @Override
        public void onSubscribe(Subscription s) {
            SubscriptionHelper.setOnce(this, s, Long.MAX_VALUE);
        }

        @Override
        public void onNext(Object t) {
            if (SubscriptionHelper.cancel(this)) {
                parent.otherError(new CancellationException());
            }
        }

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

        @Override
        public void onComplete() {
            if (get() != SubscriptionHelper.CANCELLED) {
                lazySet(SubscriptionHelper.CANCELLED);
                parent.otherError(new CancellationException());
            }
        }

        public void dispose() {
            SubscriptionHelper.cancel(this);
        }
    }
}