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.atomic.AtomicBoolean;

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

public final class ObservableUnsubscribeOn<T> extends AbstractObservableWithUpstream<T, T> {
    final Scheduler scheduler;
    public ObservableUnsubscribeOn(ObservableSource<T> source, Scheduler scheduler) {
        super(source);
        this.scheduler = scheduler;
    }

    @Override
    public void subscribeActual(Observer<? super T> t) {
        source.subscribe(new UnsubscribeObserver<T>(t, scheduler));
    }

    static final class UnsubscribeObserver<T> extends AtomicBoolean implements Observer<T>, Disposable {

        private static final long serialVersionUID = 1015244841293359600L;

        final Observer<? super T> downstream;
        final Scheduler scheduler;

        Disposable upstream;

        UnsubscribeObserver(Observer<? super T> actual, Scheduler scheduler) {
            this.downstream = actual;
            this.scheduler = scheduler;
        }

        @Override
        public void onSubscribe(Disposable d) {
            if (DisposableHelper.validate(this.upstream, d)) {
                this.upstream = d;
                downstream.onSubscribe(this);
            }
        }

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

        @Override
        public void onError(Throwable t) {
            if (get()) {
                RxJavaPlugins.onError(t);
                return;
            }
            downstream.onError(t);
        }

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

        @Override
        public void dispose() {
            if (compareAndSet(false, true)) {
                scheduler.scheduleDirect(new DisposeTask());
            }
        }

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

        final class DisposeTask implements Runnable {
            @Override
            public void run() {
                upstream.dispose();
            }
        }
    }
}