/*
 * 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;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertTrue;

import java.util.List;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.MiniHBaseCluster;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.RegionInfo;
import org.apache.hadoop.hbase.testclassification.MasterTests;
import org.apache.hadoop.hbase.testclassification.MediumTests;
import org.apache.hadoop.hbase.util.JVMClusterUtil;
import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Tag(MasterTests.TAG)
@Tag(MediumTests.TAG)
public class TestRoundRobinAssignmentOnRestart extends AbstractTestRestartCluster {

  private static final Logger LOG =
    LoggerFactory.getLogger(TestRoundRobinAssignmentOnRestart.class);

  @Override
  protected boolean splitWALCoordinatedByZk() {
    return true;
  }

  private final int regionNum = 10;
  private final int rsNum = 2;

  /**
   * This tests retaining assignments on a cluster restart
   */
  @Test
  public void test() throws Exception {
    UTIL.startMiniCluster(rsNum);
    // Turn off balancer
    UTIL.getMiniHBaseCluster().getMaster().getMasterRpcServices().synchronousBalanceSwitch(false);
    LOG.info("\n\nCreating tables");
    for (TableName TABLE : TABLES) {
      UTIL.createMultiRegionTable(TABLE, FAMILY, regionNum);
    }
    // Wait until all regions are assigned
    for (TableName TABLE : TABLES) {
      UTIL.waitTableEnabled(TABLE);
    }
    UTIL.waitUntilNoRegionsInTransition(60000);

    MiniHBaseCluster cluster = UTIL.getHBaseCluster();
    List<JVMClusterUtil.RegionServerThread> threads = cluster.getLiveRegionServerThreads();
    assertEquals(2, threads.size());

    ServerName testServer = threads.get(0).getRegionServer().getServerName();
    int port = testServer.getPort();
    List<RegionInfo> regionInfos =
      cluster.getMaster().getAssignmentManager().getRegionsOnServer(testServer);
    LOG.debug("RegionServer {} has {} regions", testServer, regionInfos.size());
    assertTrue(regionInfos.size() >= (TABLES.length * regionNum / rsNum));

    // Restart 1 regionserver
    cluster.stopRegionServer(testServer);
    cluster.waitForRegionServerToStop(testServer, 60000);
    cluster.getConf().setInt(HConstants.REGIONSERVER_PORT, port);
    cluster.startRegionServer();

    HMaster master = UTIL.getMiniHBaseCluster().getMaster();
    List<ServerName> localServers = master.getServerManager().getOnlineServersList();
    ServerName newTestServer = null;
    for (ServerName serverName : localServers) {
      if (serverName.getAddress().equals(testServer.getAddress())) {
        newTestServer = serverName;
        break;
      }
    }
    assertNotNull(newTestServer);

    // Wait until all regions are assigned
    for (TableName TABLE : TABLES) {
      UTIL.waitTableAvailable(TABLE);
    }
    UTIL.waitUntilNoRegionsInTransition(60000);

    List<RegionInfo> newRegionInfos =
      cluster.getMaster().getAssignmentManager().getRegionsOnServer(newTestServer);
    LOG.debug("RegionServer {} has {} regions", newTestServer, newRegionInfos.size());
    assertTrue(newRegionInfos.size() < regionInfos.size(),
      "Should not retain all regions when restart");
  }
}
