/**
    *
    * 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.hadoop.hbase.master.balancer;
  
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.ServerName;
  
  /**
   * This class contains the mapping information between each region and
   * its favored region server list. Used by {@link FavoredNodeLoadBalancer} set
   * of classes and from unit tests (hence the class is public)
   *
   * All the access to this class is thread-safe.
   */
  @InterfaceAudience.Private
  public class FavoredNodesPlan {
    private static final Log LOG = LogFactory.getLog(
        FavoredNodesPlan.class.getName());
  
    /** the map between each region and its favored region server list */
    private Map<HRegionInfo, List<ServerName>> favoredNodesMap;
  
    public static enum Position {
      PRIMARY,
      SECONDARY,
      TERTIARY;
    };
  
    public FavoredNodesPlan() {
      favoredNodesMap = new ConcurrentHashMap<HRegionInfo, List<ServerName>>();
    }
  
    /**
     * Add an assignment to the plan
     * @param region
     * @param servers
     */
    public synchronized void updateFavoredNodesMap(HRegionInfo region,
        List<ServerName> servers) {
      if (region == null || servers == null || servers.size() ==0)
        return;
      this.favoredNodesMap.put(region, servers);
    }
  
    /**
     * @param region
     * @return the list of favored region server for this region based on the plan
     */
    public synchronized List<ServerName> getFavoredNodes(HRegionInfo region) {
      return favoredNodesMap.get(region);
    }
  
    /**
     * Return the position of the server in the favoredNodes list. Assumes the
     * favoredNodes list is of size 3.
     * @param favoredNodes
     * @param server
     * @return position
     */
    public static Position getFavoredServerPosition(
        List<ServerName> favoredNodes, ServerName server) {
      if (favoredNodes == null || server == null ||
          favoredNodes.size() != FavoredNodeAssignmentHelper.FAVORED_NODES_NUM) {
        return null;
      }
      for (Position p : Position.values()) {
        if (ServerName.isSameHostnameAndPort(favoredNodes.get(p.ordinal()),server)) {
          return p;
        }
      }
      return null;
    }
  
    /**
     * @return the mapping between each region to its favored region server list
     */
   public synchronized Map<HRegionInfo, List<ServerName>> getAssignmentMap() {
     return this.favoredNodesMap;
   }
 
   /**
    * Add an assignment to the plan
    * @param region
    * @param servers
    */
   public synchronized void updateAssignmentPlan(HRegionInfo region,
       List<ServerName> servers) {
     if (region == null || servers == null || servers.size() ==0)
       return;
     this.favoredNodesMap.put(region, servers);
     LOG.info("Update the assignment plan for region " +
         region.getRegionNameAsString() + " ; favored nodes " +
         FavoredNodeAssignmentHelper.getFavoredNodesAsString(servers));
   }
 
   @Override
   public boolean equals(Object o) {
     if (this == o) {
       return true;
     }
     if (o == null) {
       return false;
     }
     if (getClass() != o.getClass()) {
       return false;
     }
     // To compare the map from objec o is identical to current assignment map.
     Map<HRegionInfo, List<ServerName>> comparedMap=
       ((FavoredNodesPlan)o).getAssignmentMap();
 
     // compare the size
     if (comparedMap.size() != this.favoredNodesMap.size())
       return false;
 
     // compare each element in the assignment map
     for (Map.Entry<HRegionInfo, List<ServerName>> entry :
       comparedMap.entrySet()) {
       List<ServerName> serverList = this.favoredNodesMap.get(entry.getKey());
       if (serverList == null && entry.getValue() != null) {
         return false;
       } else if (serverList != null && !serverList.equals(entry.getValue())) {
         return false;
       }
     }
     return true;
   }
 
   @Override
   public int hashCode() {
     return favoredNodesMap.hashCode();
   }
 }