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

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

Signals a 0L after the specified delay. /**
 * Signals a {@code 0L} after the specified delay.
 */
public final class SingleTimer extends Single<Long> {

    final long delay;
    final TimeUnit unit;
    final Scheduler scheduler;

    public SingleTimer(long delay, TimeUnit unit, Scheduler scheduler) {
        this.delay = delay;
        this.unit = unit;
        this.scheduler = scheduler;
    }

    @Override
    protected void subscribeActual(final SingleObserver<? super Long> observer) {
        TimerDisposable parent = new TimerDisposable(observer);
        observer.onSubscribe(parent);
        parent.setFuture(scheduler.scheduleDirect(parent, delay, unit));
    }

    static final class TimerDisposable extends AtomicReference<Disposable> implements Disposable, Runnable {

        private static final long serialVersionUID = 8465401857522493082L;
        final SingleObserver<? super Long> downstream;

        TimerDisposable(final SingleObserver<? super Long> downstream) {
            this.downstream = downstream;
        }

        @Override
        public void run() {
            downstream.onSuccess(0L);
        }

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

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

        void setFuture(Disposable d) {
            DisposableHelper.replace(this, d);
        }
    }
}