/*
    * 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.maven.surefire.junitcore.pc;
  
  import java.util.Collection;
  import java.util.concurrent.ConcurrentLinkedQueue;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.LinkedBlockingQueue;
  import java.util.concurrent.ThreadFactory;
  import java.util.concurrent.ThreadPoolExecutor;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.maven.plugin.surefire.log.api.ConsoleLogger;
  import org.apache.maven.surefire.api.util.internal.DaemonThreadFactory;
  import org.junit.runner.Description;
  import org.junit.runners.model.RunnerScheduler;
  
  /**
   * Used to execute tests annotated with net.jcip.annotations.NotThreadSafe.
   * <br>
   *
   * @author <a href="mailto:tibordigana@apache.org">Tibor Digana (tibor17)</a>
   * @see ParallelComputerBuilder
   * @since 2.18
   */
  final class SingleThreadScheduler {
      private final ConsoleLogger logger;
  
      private final ExecutorService pool = newPool();
  
      private final Scheduler master;
  
      private static ExecutorService newPool() {
          ThreadFactory tf = DaemonThreadFactory.newDaemonThreadFactory("maven-surefire-plugin@NotThreadSafe");
          return new ThreadPoolExecutor(1, 1, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>(), tf);
      }
  
      SingleThreadScheduler(ConsoleLogger logger) {
          this.logger = logger;
          SchedulingStrategy strategy = SchedulingStrategies.createParallelSharedStrategy(logger, pool);
          master = new Scheduler(logger, null, strategy);
      }
  
      RunnerScheduler newRunnerScheduler() {
          SchedulingStrategy strategy = SchedulingStrategies.createParallelSharedStrategy(logger, pool);
          return new Scheduler(logger, null, master, strategy);
      }
  
      /**
       * @see Scheduler#describeStopped(boolean)
       */
      ShutdownResult describeStopped(boolean shutdownNow) {
          ShutdownResult shutdownResult = master.describeStopped(shutdownNow);
          return new ShutdownResult(
                  copyExisting(shutdownResult.getTriggeredTests()), copyExisting(shutdownResult.getIncompleteTests()));
      }
  
      /**
       * @see Scheduler#shutdownThreadPoolsAwaitingKilled()
       */
      boolean shutdownThreadPoolsAwaitingKilled() {
          return master.shutdownThreadPoolsAwaitingKilled();
      }
  
      private Collection<Description> copyExisting(Collection<Description> descriptions) {
          Collection<Description> activeChildren = new ConcurrentLinkedQueue<>(descriptions);
          ParallelComputerUtil.removeUnusedDescriptions(activeChildren);
          return activeChildren;
      }
  }