/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.servicecomb.http.client.task;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.TimeUnit;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class AbstractTask {
  public class BackOffSleepTask implements Task {
    final long base = 3000;

    final long max = 10 * 60 * 10000;

    long waitTime;

    Task nextTask;

    public BackOffSleepTask(int failedCount, Task nextTask) {
      this.waitTime = failedCount * failedCount * base;
      this.nextTask = nextTask;
    }

    public BackOffSleepTask(long waitTime, Task nextTask) {
      this.waitTime = waitTime;
      this.nextTask = nextTask;
    }

    @Override
    public void execute() {
      long time = Math.min(max, waitTime);
      try {
        Thread.sleep(time);
      } catch (InterruptedException e) {
        LOGGER.error("unexpected interrupt during sleep", e);
      }
      startTask(nextTask);
    }
  }

  private static final Logger LOGGER = LoggerFactory.getLogger(AbstractTask.class);

  protected ExecutorService taskPool;

  private volatile boolean running = true;

  protected AbstractTask(String taskName) {
    initTaskPool(taskName);
    Runtime.getRuntime().addShutdownHook(new Thread(taskName + "-shutdown-hook") {
      @Override
      public void run() {
        AbstractTask.this.stop();
      }
    });
  }

  protected void initTaskPool(String taskName) {
    this.taskPool = Executors.newSingleThreadExecutor((task) ->
        new Thread(task, taskName));
  }

  protected void startTask(Task task) {
    if (!running) {
      return;
    }

    try {
      this.taskPool.execute(() -> {
        try {
          task.execute();
        } catch (Throwable e) {
          LOGGER.error("unexpected error execute task {}", task.getClass().getName(), e);
        }
      });
    } catch (RejectedExecutionException e) {
      LOGGER.error("execute task rejected {}", task.getClass().getName(), e);
    }
  }

  public void stop() {
    try {
      running = false;
      this.taskPool.shutdown();
      this.taskPool.awaitTermination(10, TimeUnit.SECONDS);
    } catch (InterruptedException e) {
      LOGGER.warn("tasks not shutdown in time {}", e.getMessage());
    }
  }
}
