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

import io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.internal.disposables.DisposableHelper;
import io.reactivex.plugins.RxJavaPlugins;

Switches to the fallback Maybe if the other MaybeSource signals a success or completes, or
signals TimeoutException if fallback is null.
Type parameters:
<T> – the main value type
<U> – the other value type/**
 * Switches to the fallback Maybe if the other MaybeSource signals a success or completes, or
 * signals TimeoutException if fallback is null.
 * 
 * @param <T> the main value type
 * @param <U> the other value type
 */
public final class MaybeTimeoutMaybe<T, U> extends AbstractMaybeWithUpstream<T, T> {

    final MaybeSource<U> other;

    final MaybeSource<? extends T> fallback;

    public MaybeTimeoutMaybe(MaybeSource<T> source, MaybeSource<U> other, MaybeSource<? extends T> fallback) {
        super(source);
        this.other = other;
        this.fallback = fallback;
    }

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

        other.subscribe(parent.other);

        source.subscribe(parent);
    }

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

        private static final long serialVersionUID = -5955289211445418871L;

        final MaybeObserver<? super T> downstream;

        final TimeoutOtherMaybeObserver<T, U> other;

        final MaybeSource<? extends T> fallback;

        final TimeoutFallbackMaybeObserver<T> otherObserver;

        TimeoutMainMaybeObserver(MaybeObserver<? super T> actual, MaybeSource<? extends T> fallback) {
            this.downstream = actual;
            this.other = new TimeoutOtherMaybeObserver<T, U>(this);
            this.fallback = fallback;
            this.otherObserver = fallback != null ? new TimeoutFallbackMaybeObserver<T>(actual) : null;
        }

        @Override
        public void dispose() {
            DisposableHelper.dispose(this);
            DisposableHelper.dispose(other);
            TimeoutFallbackMaybeObserver<T> oo = otherObserver;
            if (oo != null) {
                DisposableHelper.dispose(oo);
            }
        }

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

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

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

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

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

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

        public void otherComplete() {
            if (DisposableHelper.dispose(this)) {
                if (fallback == null) {
                    downstream.onError(new TimeoutException());
                } else {
                    fallback.subscribe(otherObserver);
                }
            }
        }
    }

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

        private static final long serialVersionUID = 8663801314800248617L;

        final TimeoutMainMaybeObserver<T, U> parent;

        TimeoutOtherMaybeObserver(TimeoutMainMaybeObserver<T, U> parent) {
            this.parent = parent;
        }

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

        @Override
        public void onSuccess(Object value) {
            parent.otherComplete();
        }

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

        @Override
        public void onComplete() {
            parent.otherComplete();
        }
    }
    static final class TimeoutFallbackMaybeObserver<T>
    extends AtomicReference<Disposable>
    implements MaybeObserver<T> {

        private static final long serialVersionUID = 8663801314800248617L;

        final MaybeObserver<? super T> downstream;

        TimeoutFallbackMaybeObserver(MaybeObserver<? super T> downstream) {
            this.downstream = downstream;
        }

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

        @Override
        public void onSuccess(T value) {
            downstream.onSuccess(value);
        }

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

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