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/*
 * Licensed to Metamarkets Group Inc. (Metamarkets) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. Metamarkets 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 io.druid.java.util.common.concurrent;

import com.google.common.base.Preconditions;
import com.google.common.base.Strings;
import com.google.common.util.concurrent.ThreadFactoryBuilder;

import javax.annotation.Nullable;
import javax.validation.constraints.NotNull;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 */
public class Execs
{
  /**
   * Returns an ExecutorService which is terminated and shutdown from the beginning and not able to accept any tasks.
   */
  public static ExecutorService dummy()
  {
    return DummyExecutorService.INSTANCE;
  }

  public static ExecutorService singleThreaded(@NotNull String nameFormat)
  {
    return singleThreaded(nameFormat, null);
  }

  public static ExecutorService singleThreaded(@NotNull String nameFormat, @Nullable Integer priority)
  {
    return Executors.newSingleThreadExecutor(makeThreadFactory(nameFormat, priority));
  }

  public static ExecutorService multiThreaded(int threads, @NotNull String nameFormat)
  {
    return multiThreaded(threads, nameFormat, null);
  }

  public static ExecutorService multiThreaded(int threads, @NotNull String nameFormat, @Nullable Integer priority)
  {
    return Executors.newFixedThreadPool(threads, makeThreadFactory(nameFormat, priority));
  }

  public static ScheduledExecutorService scheduledSingleThreaded(@NotNull String nameFormat)
  {
    return scheduledSingleThreaded(nameFormat, null);
  }

  public static ScheduledExecutorService scheduledSingleThreaded(@NotNull String nameFormat, @Nullable Integer priority)
  {
    return Executors.newSingleThreadScheduledExecutor(makeThreadFactory(nameFormat, priority));
  }

  public static ThreadFactory makeThreadFactory(@NotNull String nameFormat)
  {
    return makeThreadFactory(nameFormat, null);
  }

  public static ThreadFactory makeThreadFactory(@NotNull String nameFormat, @Nullable Integer priority)
  {
    final ThreadFactoryBuilder builder = new ThreadFactoryBuilder()
        .setDaemon(true)
        .setNameFormat(nameFormat);
    if (priority != null) {
      builder.setPriority(priority);
    }

    return builder.build();
  }

  public static Thread makeThread(String name, Runnable runnable, boolean isDaemon)
  {
    Preconditions.checkArgument(!Strings.isNullOrEmpty(name), "name null/empty");
    Preconditions.checkNotNull(runnable, "null runnable");

    Thread t = new Thread(runnable);
    t.setName(name);
    t.setDaemon(isDaemon);
    return t;
  }

  /**
   * @param nameFormat nameformat for threadFactory
   * @param capacity   maximum capacity after which the executorService will block on accepting new tasks
   *
   * @return ExecutorService which blocks accepting new tasks when the capacity reached
   */
  public static ExecutorService newBlockingSingleThreaded(final String nameFormat, final int capacity)
  {
    return newBlockingSingleThreaded(nameFormat, capacity, null);
  }

  public static ExecutorService newBlockingSingleThreaded(
      final String nameFormat,
      final int capacity,
      final Integer priority
  )
  {
    final BlockingQueue queue;
    if (capacity > 0) {
      queue = new ArrayBlockingQueue<>(capacity);
    } else {
      queue = new SynchronousQueue<>();
    }
    return new ThreadPoolExecutor(
        1, 1, 0L, TimeUnit.MILLISECONDS, queue, makeThreadFactory(nameFormat, priority),
        new RejectedExecutionHandler()
        {
          @Override
          public void rejectedExecution(Runnable r, ThreadPoolExecutor executor)
          {
            try {
              executor.getQueue().put(r);
            }
            catch (InterruptedException e) {
              throw new RejectedExecutionException("Got Interrupted while adding to the Queue", e);
            }
          }
        }
    );
  }
}