/*
    * 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.api.runorder;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * @author Kristian Rosenvold
   */
  public class ThreadedExecutionScheduler {
      private final int numThreads;
  
      private final int runTime[];
  
      private final List<Class<?>>[] lists;
  
      @SuppressWarnings("unchecked")
      public ThreadedExecutionScheduler(int numThreads) {
          this.numThreads = numThreads;
          runTime = new int[numThreads];
          lists = new List[numThreads];
          for (int i = 0; i < numThreads; i++) {
              lists[i] = new ArrayList<>();
          }
      }
  
      public void addTest(PrioritizedTest prioritizedTest) {
          final int leastBusySlot = findLeastBusySlot();
          runTime[leastBusySlot] += prioritizedTest.getTotalRuntime();
          //noinspection unchecked
          lists[leastBusySlot].add(prioritizedTest.getClazz());
      }
  
      public List<Class<?>> getResult() {
          List<Class<?>> result = new ArrayList<>();
          int index = 0;
          boolean added;
          do {
              added = false;
              for (int i = 0; i < numThreads; i++) {
                  if (lists[i].size() > index) {
                      result.add(lists[i].get(index));
                      added = true;
                  }
              }
              index++;
          } while (added);
          return result;
      }
  
      private int findLeastBusySlot() {
          int leastBusy = 0;
          int minRuntime = runTime[0];
          for (int i = 1; i < numThreads; i++) {
              if (runTime[i] < minRuntime) {
                  leastBusy = i;
                  minRuntime = runTime[i];
              }
          }
          return leastBusy;
      }
  }