content: /*
   * Copyright (C) 2016-2023 ActionTech.
   * based on code by MyCATCopyrightHolder Copyright (c) 2013, OpenCloudDB/MyCAT.
   * License: http://www.gnu.org/licenses/gpl.html GPL version 2 or higher.
   */
  package com.actiontech.dble.server.response;
  
  import com.actiontech.dble.DbleServer;
  import com.actiontech.dble.backend.mysql.PacketUtil;
  import com.actiontech.dble.config.Fields;
  import com.actiontech.dble.config.ServerConfig;
  import com.actiontech.dble.config.model.user.ShardingUserConfig;
  import com.actiontech.dble.config.model.user.UserConfig;
  import com.actiontech.dble.config.model.user.UserName;
  import com.actiontech.dble.net.mysql.*;
  import com.actiontech.dble.services.mysqlsharding.ShardingService;
  import com.actiontech.dble.util.StringUtil;
  
  import java.nio.ByteBuffer;
  import java.util.Map;
  import java.util.Set;
  import java.util.TreeSet;
  
  /**
   * @author mycat
   */
  public final class ShowDatabases {
      private ShowDatabases() {
      }
  
      private static final int FIELD_COUNT = 1;
      private static final ResultSetHeaderPacket HEADER = PacketUtil.getHeader(FIELD_COUNT);
      private static final FieldPacket[] FIELDS = new FieldPacket[FIELD_COUNT];
      private static final EOFPacket EOF = new EOFPacket();
  
  
      public static void response(ShardingService shardingService) {
  
          HEADER.setPacketId(shardingService.nextPacketId());
          FIELDS[0] = PacketUtil.getField("DATABASE", Fields.FIELD_TYPE_VAR_STRING);
          FIELDS[0].setPacketId(shardingService.nextPacketId());
          EOF.setPacketId(shardingService.nextPacketId());
  
          ByteBuffer buffer = shardingService.allocate();
          // writeDirectly header
          buffer = HEADER.write(buffer, shardingService, true);
  
  
          // writeDirectly fields
          for (FieldPacket field : FIELDS) {
              buffer = field.write(buffer, shardingService, true);
          }
  
          // writeDirectly eof
          buffer = EOF.write(buffer, shardingService, true);
  
          // writeDirectly rows
          ServerConfig conf = DbleServer.getInstance().getConfig();
          Map<UserName, UserConfig> users = conf.getUsers();
          UserConfig user = users == null ? null : users.get(shardingService.getUser());
          if (user != null) {
              ShardingUserConfig shardingUser = (ShardingUserConfig) user;
              TreeSet<String> schemaSet = new TreeSet<>();
              Set<String> schemaList = shardingUser.getSchemas();
              if (schemaList == null || schemaList.size() == 0) {
                  schemaSet.addAll(conf.getSchemas().keySet());
              } else {
                  schemaSet.addAll(schemaList);
              }
              for (String name : schemaSet) {
                  RowDataPacket row = new RowDataPacket(FIELD_COUNT);
                  row.add(StringUtil.encode(name, shardingService.getCharset().getResults()));
                  row.setPacketId(shardingService.nextPacketId());
                  buffer = row.write(buffer, shardingService, true);
              }
          }
  
          // writeDirectly last eof
          EOFRowPacket lastEof = new EOFRowPacket();
          lastEof.setPacketId(shardingService.nextPacketId());
          lastEof.write(buffer, shardingService);
      }
  
  }
  