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.flowable;

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

import org.reactivestreams.*;

import io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.exceptions.MissingBackpressureException;
import io.reactivex.internal.disposables.*;
import io.reactivex.internal.subscriptions.SubscriptionHelper;

public final class FlowableTimer extends Flowable<Long> {
    final Scheduler scheduler;
    final long delay;
    final TimeUnit unit;
    public FlowableTimer(long delay, TimeUnit unit, Scheduler scheduler) {
        this.delay = delay;
        this.unit = unit;
        this.scheduler = scheduler;
    }

    @Override
    public void subscribeActual(Subscriber<? super Long> s) {
        TimerSubscriber ios = new TimerSubscriber(s);
        s.onSubscribe(ios);

        Disposable d = scheduler.scheduleDirect(ios, delay, unit);

        ios.setResource(d);
    }

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

        private static final long serialVersionUID = -2809475196591179431L;

        final Subscriber<? super Long> downstream;

        volatile boolean requested;

        TimerSubscriber(Subscriber<? super Long> downstream) {
            this.downstream = downstream;
        }

        @Override
        public void request(long n) {
            if (SubscriptionHelper.validate(n)) {
                requested = true;
            }
        }

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

        @Override
        public void run() {
            if (get() != DisposableHelper.DISPOSED) {
                if (requested) {
                    downstream.onNext(0L);
                    lazySet(EmptyDisposable.INSTANCE);
                    downstream.onComplete();
                } else {
                    lazySet(EmptyDisposable.INSTANCE);
                    downstream.onError(new MissingBackpressureException("Can't deliver value due to lack of requests"));
                }
            }
        }

        public void setResource(Disposable d) {
            DisposableHelper.trySet(this, d);
        }
    }
}