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.maybe;

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;
import io.reactivex.plugins.RxJavaPlugins;

Relays the main source's event unless the other Publisher signals an item first or just completes
at which point the resulting Maybe is completed.
Type parameters:
<T> – the value type
<U> – the other's value type/**
 * Relays the main source's event unless the other Publisher signals an item first or just completes
 * at which point the resulting Maybe is completed.
 *
 * @param <T> the value type
 * @param <U> the other's value type
 */
public final class MaybeTakeUntilPublisher<T, U> extends AbstractMaybeWithUpstream<T, T> {

    final Publisher<U> other;

    public MaybeTakeUntilPublisher(MaybeSource<T> source, Publisher<U> other) {
        super(source);
        this.other = other;
    }

    @Override
    protected void subscribeActual(MaybeObserver<? super T> observer) {
        TakeUntilMainMaybeObserver<T, U> parent = new TakeUntilMainMaybeObserver<T, U>(observer);
        observer.onSubscribe(parent);

        other.subscribe(parent.other);

        source.subscribe(parent);
    }

    static final class TakeUntilMainMaybeObserver<T, U>
    extends AtomicReference<Disposable> implements MaybeObserver<T>, Disposable {

        private static final long serialVersionUID = -2187421758664251153L;

        final MaybeObserver<? super T> downstream;

        final TakeUntilOtherMaybeObserver<U> other;

        TakeUntilMainMaybeObserver(MaybeObserver<? super T> downstream) {
            this.downstream = downstream;
            this.other = new TakeUntilOtherMaybeObserver<U>(this);
        }

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

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

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

        @Override
        public void onSuccess(T value) {
            SubscriptionHelper.cancel(other);
            if (getAndSet(DisposableHelper.DISPOSED) != DisposableHelper.DISPOSED) {
                downstream.onSuccess(value);
            }
        }

        @Override
        public void onError(Throwable e) {
            SubscriptionHelper.cancel(other);
            if (getAndSet(DisposableHelper.DISPOSED) != DisposableHelper.DISPOSED) {
                downstream.onError(e);
            } else {
                RxJavaPlugins.onError(e);
            }
        }

        @Override
        public void onComplete() {
            SubscriptionHelper.cancel(other);
            if (getAndSet(DisposableHelper.DISPOSED) != DisposableHelper.DISPOSED) {
                downstream.onComplete();
            }
        }

        void otherError(Throwable e) {
            if (DisposableHelper.dispose(this)) {
                downstream.onError(e);
            } else {
                RxJavaPlugins.onError(e);
            }
        }

        void otherComplete() {
            if (DisposableHelper.dispose(this)) {
                downstream.onComplete();
            }
        }

        static final class TakeUntilOtherMaybeObserver<U>
        extends AtomicReference<Subscription> implements FlowableSubscriber<U> {

            private static final long serialVersionUID = -1266041316834525931L;

            final TakeUntilMainMaybeObserver<?, U> parent;

            TakeUntilOtherMaybeObserver(TakeUntilMainMaybeObserver<?, U> parent) {
                this.parent = parent;
            }

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

            @Override
            public void onNext(Object value) {
                SubscriptionHelper.cancel(this);
                parent.otherComplete();
            }

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

            @Override
            public void onComplete() {
                parent.otherComplete();
            }
        }
    }

}