/*
    * 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.giraph.worker;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import com.google.common.base.Preconditions;
  
  import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap;
  
  /**
   * Information about all workers, their WorkerInfo values, and indices.
   */
  public class AllWorkersInfo {
    /** List of workers in current superstep, sorted by task id */
    private final List<WorkerInfo> workerInfos;
    /** My worker index */
    private final int myWorkerIndex;
    /** Map of taskId to worker index */
    private final Int2IntOpenHashMap taskIdToIndex;
  
    /**
     * Constructor
     * @param workers Ordered list of workers
     * @param myWorker My worker
     */
    public AllWorkersInfo(List<WorkerInfo> workers, WorkerInfo myWorker) {
      workerInfos = new ArrayList<>(workers);
  
      taskIdToIndex = new Int2IntOpenHashMap(workerInfos.size());
      taskIdToIndex.defaultReturnValue(-1);
      for (int i = 0; i < workerInfos.size(); i++) {
        int task = workerInfos.get(i).getTaskId();
        if (i > 0) {
          Preconditions.checkState(
              task > workerInfos.get(i - 1).getTaskId(), "Tasks not ordered");
        }
        Preconditions.checkState(task >= 0, "Task not specified, %d", task);
        int old = taskIdToIndex.put(task, i);
        Preconditions.checkState(old == -1,
            "Task with %d id found twice (positions %d and %d)",
            task, i, old);
      }
  
      myWorkerIndex = getWorkerIndex(myWorker);
    }
  
    /**
     * List of WorkerInfos
     *
     * @return List of WorkerInfos
     */
    public List<WorkerInfo> getWorkerList() {
      return workerInfos;
    }
  
    /**
     * Get number of workers
     *
     * @return Number of workers
     */
    public int getWorkerCount() {
      return workerInfos.size();
    }
  
    /**
     * Get index for this worker
     *
     * @return Index of this worker
     */
    public int getMyWorkerIndex() {
      return myWorkerIndex;
    }
  
    /**
     * For every worker this method returns unique number
     * between 0 and N, where N is the total number of workers.
     * This number stays the same throughout the computation.
     * TaskID may be different from this number and task ID
     * is not necessarily continuous
     * @param workerInfo worker info object
     * @return worker number
     */
   public int getWorkerIndex(WorkerInfo workerInfo) {
     return taskIdToIndex.get(workerInfo.getTaskId());
   }
 }