/*
    * 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.plugins.invoker;
  
  import java.util.Comparator;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.Callable;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import java.util.stream.Collectors;
  
  import org.apache.maven.plugins.invoker.model.BuildJob;
  
  /**
   * Execute build jobs with parallel.
   *
   * @author Slawomir Jaranowski
   */
  class JobExecutor {
      interface ThrowableJobConsumer {
          void accept(BuildJob t) throws Throwable;
      }
  
      private final List<BuildJob> jobs;
      private final int threadsCount;
  
      JobExecutor(List<BuildJob> jobs, int threadsCount) {
          this.jobs = jobs;
          this.threadsCount = threadsCount;
      }
  
      public void forEach(ThrowableJobConsumer jobConsumer) {
          // group and sort jobs by ordinal
          Map<Integer, List<BuildJob>> groupedJobs = jobs.stream()
                  .sorted(Comparator.comparing(BuildJob::getOrdinal).reversed())
                  .collect(Collectors.groupingBy(BuildJob::getOrdinal, LinkedHashMap::new, Collectors.toList()));
  
          ExecutorService executorService = Executors.newFixedThreadPool(threadsCount);
  
          groupedJobs.forEach((key, value) -> {
              // prepare list of callable tasks
              List<Callable<Void>> callableJobs = value.stream()
                      .map(buildJob -> (Callable<Void>) () -> {
                          try {
                              jobConsumer.accept(buildJob);
                          } catch (Throwable e) {
                              buildJob.setResult(BuildJob.Result.ERROR);
                              buildJob.setFailureMessage(String.valueOf(e));
                          }
                          return null;
                      })
                      .collect(Collectors.toList());
  
              try {
                  executorService.invokeAll(callableJobs);
              } catch (InterruptedException e) {
                  Thread.currentThread().interrupt();
                  throw new RuntimeException(e);
              }
          });
  
          // all task are finished here
          executorService.shutdownNow();
      }
  }