/*
 * Copyright 2022 DeNA Co., Ltd.
 *
 * 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 packetproxy.quic.utils;


import java.time.Duration;
import java.time.Instant;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;

public class ScheduledTimer {

    private final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);
    private final Runnable onTimeout;
    private ScheduledFuture<?> future;

    public ScheduledTimer(Runnable onTimeout) {
        this.onTimeout = onTimeout;
        this.future = null;
    }

    public synchronized void update(Instant time) {
        if (time == Instant.MAX) {
            this.cancel();
        } else {
            long delay = Duration.between(Instant.now(), time).toMillis();
            this.future = this.scheduler.schedule(this.onTimeout, delay, TimeUnit.MILLISECONDS);
        }
    }

    public synchronized void cancel() {
        if (this.future != null) {
            this.future.cancel(false);
        }
    }

}
