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.observable;

import java.util.concurrent.*;
import java.util.concurrent.atomic.*;

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

import static io.reactivex.internal.util.ExceptionHelper.timeoutMessage;

public final class ObservableTimeoutTimed<T> extends AbstractObservableWithUpstream<T, T> {
    final long timeout;
    final TimeUnit unit;
    final Scheduler scheduler;
    final ObservableSource<? extends T> other;

    public ObservableTimeoutTimed(Observable<T> source,
            long timeout, TimeUnit unit, Scheduler scheduler, ObservableSource<? extends T> other) {
        super(source);
        this.timeout = timeout;
        this.unit = unit;
        this.scheduler = scheduler;
        this.other = other;
    }

    @Override
    protected void subscribeActual(Observer<? super T> observer) {
        if (other == null) {
            TimeoutObserver<T> parent = new TimeoutObserver<T>(observer, timeout, unit, scheduler.createWorker());
            observer.onSubscribe(parent);
            parent.startTimeout(0L);
            source.subscribe(parent);
        } else {
            TimeoutFallbackObserver<T> parent = new TimeoutFallbackObserver<T>(observer, timeout, unit, scheduler.createWorker(), other);
            observer.onSubscribe(parent);
            parent.startTimeout(0L);
            source.subscribe(parent);
        }
    }

    static final class TimeoutObserver<T> extends AtomicLong
    implements Observer<T>, Disposable, TimeoutSupport {

        private static final long serialVersionUID = 3764492702657003550L;

        final Observer<? super T> downstream;

        final long timeout;

        final TimeUnit unit;

        final Scheduler.Worker worker;

        final SequentialDisposable task;

        final AtomicReference<Disposable> upstream;

        TimeoutObserver(Observer<? super T> actual, long timeout, TimeUnit unit, Scheduler.Worker worker) {
            this.downstream = actual;
            this.timeout = timeout;
            this.unit = unit;
            this.worker = worker;
            this.task = new SequentialDisposable();
            this.upstream = new AtomicReference<Disposable>();
        }

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

        @Override
        public void onNext(T t) {
            long idx = get();
            if (idx == Long.MAX_VALUE || !compareAndSet(idx, idx + 1)) {
                return;
            }

            task.get().dispose();

            downstream.onNext(t);

            startTimeout(idx + 1);
        }

        void startTimeout(long nextIndex) {
            task.replace(worker.schedule(new TimeoutTask(nextIndex, this), timeout, unit));
        }

        @Override
        public void onError(Throwable t) {
            if (getAndSet(Long.MAX_VALUE) != Long.MAX_VALUE) {
                task.dispose();

                downstream.onError(t);

                worker.dispose();
            } else {
                RxJavaPlugins.onError(t);
            }
        }

        @Override
        public void onComplete() {
            if (getAndSet(Long.MAX_VALUE) != Long.MAX_VALUE) {
                task.dispose();

                downstream.onComplete();

                worker.dispose();
            }
        }

        @Override
        public void onTimeout(long idx) {
            if (compareAndSet(idx, Long.MAX_VALUE)) {
                DisposableHelper.dispose(upstream);

                downstream.onError(new TimeoutException(timeoutMessage(timeout, unit)));

                worker.dispose();
            }
        }

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

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

    static final class TimeoutTask implements Runnable {

        final TimeoutSupport parent;

        final long idx;

        TimeoutTask(long idx, TimeoutSupport parent) {
            this.idx = idx;
            this.parent = parent;
        }

        @Override
        public void run() {
            parent.onTimeout(idx);
        }
    }

    static final class TimeoutFallbackObserver<T> extends AtomicReference<Disposable>
    implements Observer<T>, Disposable, TimeoutSupport {

        private static final long serialVersionUID = 3764492702657003550L;

        final Observer<? super T> downstream;

        final long timeout;

        final TimeUnit unit;

        final Scheduler.Worker worker;

        final SequentialDisposable task;

        final AtomicLong index;

        final AtomicReference<Disposable> upstream;

        ObservableSource<? extends T> fallback;

        TimeoutFallbackObserver(Observer<? super T> actual, long timeout, TimeUnit unit,
                Scheduler.Worker worker, ObservableSource<? extends T> fallback) {
            this.downstream = actual;
            this.timeout = timeout;
            this.unit = unit;
            this.worker = worker;
            this.fallback = fallback;
            this.task = new SequentialDisposable();
            this.index = new AtomicLong();
            this.upstream = new AtomicReference<Disposable>();
        }

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

        @Override
        public void onNext(T t) {
            long idx = index.get();
            if (idx == Long.MAX_VALUE || !index.compareAndSet(idx, idx + 1)) {
                return;
            }

            task.get().dispose();

            downstream.onNext(t);

            startTimeout(idx + 1);
        }

        void startTimeout(long nextIndex) {
            task.replace(worker.schedule(new TimeoutTask(nextIndex, this), timeout, unit));
        }

        @Override
        public void onError(Throwable t) {
            if (index.getAndSet(Long.MAX_VALUE) != Long.MAX_VALUE) {
                task.dispose();

                downstream.onError(t);

                worker.dispose();
            } else {
                RxJavaPlugins.onError(t);
            }
        }

        @Override
        public void onComplete() {
            if (index.getAndSet(Long.MAX_VALUE) != Long.MAX_VALUE) {
                task.dispose();

                downstream.onComplete();

                worker.dispose();
            }
        }

        @Override
        public void onTimeout(long idx) {
            if (index.compareAndSet(idx, Long.MAX_VALUE)) {
                DisposableHelper.dispose(upstream);

                ObservableSource<? extends T> f = fallback;
                fallback = null;

                f.subscribe(new FallbackObserver<T>(downstream, this));

                worker.dispose();
            }
        }

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

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

    static final class FallbackObserver<T> implements Observer<T> {

        final Observer<? super T> downstream;

        final AtomicReference<Disposable> arbiter;

        FallbackObserver(Observer<? super T> actual, AtomicReference<Disposable> arbiter) {
            this.downstream = actual;
            this.arbiter = arbiter;
        }

        @Override
        public void onSubscribe(Disposable d) {
            DisposableHelper.replace(arbiter, d);
        }

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

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

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

    interface TimeoutSupport {

        void onTimeout(long idx);

    }
}