content: /*
   * Copyright 1999-2012 Alibaba Group.
   *  
   * Licensed 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 com.alibaba.cobar.server.response;
  
  import java.nio.ByteBuffer;
  import java.util.Map;
  import java.util.Set;
  import java.util.TreeSet;
  
  import com.alibaba.cobar.CobarConfig;
  import com.alibaba.cobar.CobarServer;
  import com.alibaba.cobar.config.Fields;
  import com.alibaba.cobar.config.model.UserConfig;
  import com.alibaba.cobar.mysql.PacketUtil;
  import com.alibaba.cobar.net.mysql.EOFPacket;
  import com.alibaba.cobar.net.mysql.FieldPacket;
  import com.alibaba.cobar.net.mysql.ResultSetHeaderPacket;
  import com.alibaba.cobar.net.mysql.RowDataPacket;
  import com.alibaba.cobar.server.ServerConnection;
  import com.alibaba.cobar.util.StringUtil;
  
  /**
   * @author xianmao.hexm
   */
  public class 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();
      static {
          int i = 0;
          byte packetId = 0;
          header.packetId = ++packetId;
          fields[i] = PacketUtil.getField("DATABASE", Fields.FIELD_TYPE_VAR_STRING);
          fields[i++].packetId = ++packetId;
          eof.packetId = ++packetId;
      }
  
      public static void response(ServerConnection c) {
          ByteBuffer buffer = c.allocate();
  
          // write header
          buffer = header.write(buffer, c);
  
          // write fields
          for (FieldPacket field : fields) {
              buffer = field.write(buffer, c);
          }
  
          // write eof
          buffer = eof.write(buffer, c);
  
          // write rows
          byte packetId = eof.packetId;
          CobarConfig conf = CobarServer.getInstance().getConfig();
          Map<String, UserConfig> users = conf.getUsers();
          UserConfig user = users == null ? null : users.get(c.getUser());
          if (user != null) {
              TreeSet<String> schemaSet = new TreeSet<String>();
              Set<String> schemaList = user.getSchemas();
              if (schemaList == null || schemaList.size() == 0) {
                  schemaSet.addAll(conf.getSchemas().keySet());
              } else {
                  for (String schema : schemaList) {
                      schemaSet.add(schema);
                  }
              }
              for (String name : schemaSet) {
                  RowDataPacket row = new RowDataPacket(FIELD_COUNT);
                  row.add(StringUtil.encode(name, c.getCharset()));
                  row.packetId = ++packetId;
                  buffer = row.write(buffer, c);
              }
          }
  
          // write last eof
          EOFPacket lastEof = new EOFPacket();
          lastEof.packetId = ++packetId;
          buffer = lastEof.write(buffer, c);
  
          // post write
          c.write(buffer);
      }
  
  }
  