/*
 * 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.rsgroup;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Optional;
import java.util.function.Predicate;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.NamespaceDescriptor;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.TableDescriptor;
import org.apache.hadoop.hbase.master.ClusterSchema;
import org.apache.hadoop.hbase.master.MasterServices;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Helper class for RSGroup implementation
 */
@InterfaceAudience.Private
public final class RSGroupUtil {

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

  public static final String RS_GROUP_ENABLED = "hbase.balancer.rsgroup.enabled";

  private RSGroupUtil() {
  }

  public static boolean isRSGroupEnabled(Configuration conf) {
    return conf.getBoolean(RS_GROUP_ENABLED, false);
  }

  public static void enableRSGroup(Configuration conf) {
    conf.setBoolean(RS_GROUP_ENABLED, true);
  }

  public static List<TableName> listTablesInRSGroup(MasterServices master, String groupName)
    throws IOException {
    List<TableName> tables = new ArrayList<>();
    boolean isDefaultGroup = RSGroupInfo.DEFAULT_GROUP.equals(groupName);
    for (TableDescriptor td : master.getTableDescriptors().getAll().values()) {
      // no config means in default group
      if (
        RSGroupUtil.getRSGroupInfo(master, master.getRSGroupInfoManager(), td.getTableName())
          .map(g -> g.getName().equals(groupName)).orElse(isDefaultGroup)
      ) {
        tables.add(td.getTableName());
      }
    }
    return tables;
  }

  /**
   * Will try to get the rsgroup from {@link TableDescriptor} first, and then try to get the rsgroup
   * from the {@link NamespaceDescriptor}. If still not present, return empty.
   */
  public static Optional<RSGroupInfo> getRSGroupInfo(MasterServices master,
    RSGroupInfoManager manager, TableName tableName) throws IOException {
    TableDescriptor td = master.getTableDescriptors().get(tableName);
    if (td == null) {
      return Optional.empty();
    }
    // RSGroup information determined by client.
    Optional<String> optGroupNameOfTable = td.getRegionServerGroup();
    if (optGroupNameOfTable.isPresent()) {
      RSGroupInfo group = manager.getRSGroup(optGroupNameOfTable.get());
      if (group != null) {
        return Optional.of(group);
      }
    }
    // for backward compatible, where we may still have table configs in the RSGroupInfo after
    // upgrading when migrating is still on-going.
    RSGroupInfo groupFromOldRSGroupInfo = manager.getRSGroupForTable(tableName);
    if (groupFromOldRSGroupInfo != null) {
      return Optional.of(groupFromOldRSGroupInfo);
    }
    // RSGroup information determined by administrator.
    String groupDeterminedByAdmin = manager.determineRSGroupInfoForTable(tableName);
    RSGroupInfo groupInfo = null;
    if (groupDeterminedByAdmin != null) {
      groupInfo = manager.getRSGroup(groupDeterminedByAdmin);
    }
    if (groupInfo != null) {
      return Optional.of(groupInfo);
    }
    // Finally, we will try to fall back to namespace as rsgroup if exists
    ClusterSchema clusterSchema = master.getClusterSchema();
    if (clusterSchema == null) {
      if (TableName.isMetaTableName(tableName)) {
        LOG.info("Can not get the namespace rs group config for meta table, since the"
          + " meta table is not online yet, will use default group to assign meta first");
      } else {
        LOG.warn("ClusterSchema is null, can only use default rsgroup, should not happen?");
      }
      return Optional.empty();
    }
    NamespaceDescriptor nd = clusterSchema.getNamespace(tableName.getNamespaceAsString());
    String groupNameOfNs = nd.getConfigurationValue(RSGroupInfo.NAMESPACE_DESC_PROP_GROUP);
    if (groupNameOfNs == null) {
      return Optional.empty();
    }
    return Optional.ofNullable(manager.getRSGroup(groupNameOfNs));
  }

  /**
   * Fill the tables field for {@link RSGroupInfo}, for backward compatibility.
   */
  @SuppressWarnings("deprecation")
  public static RSGroupInfo fillTables(RSGroupInfo rsGroupInfo, Collection<TableDescriptor> tds) {
    RSGroupInfo newRsGroupInfo = new RSGroupInfo(rsGroupInfo);
    Predicate<TableDescriptor> filter;
    if (rsGroupInfo.getName().equals(RSGroupInfo.DEFAULT_GROUP)) {
      filter = td -> {
        Optional<String> optGroupName = td.getRegionServerGroup();
        return !optGroupName.isPresent() || optGroupName.get().equals(RSGroupInfo.DEFAULT_GROUP);
      };
    } else {
      filter = td -> {
        Optional<String> optGroupName = td.getRegionServerGroup();
        return optGroupName.isPresent() && optGroupName.get().equals(newRsGroupInfo.getName());
      };
    }
    tds.stream().filter(filter).map(TableDescriptor::getTableName)
      .forEach(newRsGroupInfo::addTable);
    return newRsGroupInfo;
  }
}