/**
    * 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.NavigableMap;
  import java.util.TreeMap;
  
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.ServerName;
  
  /**
   * Class used to hold the current state of the cluster and how balanced it is.
   */
  public class ClusterLoadState {
    private final Map<ServerName, List<HRegionInfo>> clusterState;
    private final NavigableMap<ServerAndLoad, List<HRegionInfo>> serversByLoad;
    private boolean emptyRegionServerPresent = false;
    private int numRegions = 0;
    private int numServers = 0;
  
    public ClusterLoadState(Map<ServerName, List<HRegionInfo>> clusterState) {
      this.numRegions = 0;
      this.numServers = clusterState.size();
      this.clusterState = clusterState;
      serversByLoad = new TreeMap<ServerAndLoad, List<HRegionInfo>>();
      // Iterate so we can count regions as we build the map
      for (Map.Entry<ServerName, List<HRegionInfo>> server : clusterState.entrySet()) {
        List<HRegionInfo> regions = server.getValue();
        int sz = regions.size();
        if (sz == 0) emptyRegionServerPresent = true;
        numRegions += sz;
        serversByLoad.put(new ServerAndLoad(server.getKey(), sz), regions);
      }
    }
  
    Map<ServerName, List<HRegionInfo>> getClusterState() {
      return clusterState;
    }
  
    NavigableMap<ServerAndLoad, List<HRegionInfo>> getServersByLoad() {
      return serversByLoad;
    }
  
    boolean isEmptyRegionServerPresent() {
      return emptyRegionServerPresent;
    }
  
    int getNumRegions() {
      return numRegions;
    }
  
    int getNumServers() {
      return numServers;
    }
  
    float getLoadAverage() {
      return (float) numRegions / numServers;
    }
  
    int getMaxLoad() {
      return getServersByLoad().lastKey().getLoad();
    }
  
    int getMinLoad() {
      return getServersByLoad().firstKey().getLoad();
    }
  
  }