content: /*
   * Copyright (C) 2016-2023 ActionTech.
   * License: http://www.gnu.org/licenses/gpl.html GPL version 2 or higher.
   */
  
  package com.actiontech.dble.services.manager.response;
  
  import com.actiontech.dble.DbleServer;
  import com.actiontech.dble.backend.mysql.PacketUtil;
  import com.actiontech.dble.config.ErrorCode;
  import com.actiontech.dble.config.Fields;
  import com.actiontech.dble.config.model.sharding.SchemaConfig;
  import com.actiontech.dble.config.model.sharding.table.*;
  import com.actiontech.dble.net.mysql.*;
  import com.actiontech.dble.services.manager.ManagerService;
  import com.actiontech.dble.singleton.ProxyMeta;
  import com.actiontech.dble.util.StringUtil;
  
  import java.nio.ByteBuffer;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  import java.util.regex.Matcher;
  
  import static com.actiontech.dble.route.parser.ManagerParseShow.PATTERN_FOR_TABLE_INFO;
  
  public final class ShowTableAlgorithm {
      private ShowTableAlgorithm() {
      }
  
      private static final int FIELD_COUNT = 2;
      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.setPacketId(++packetId);
  
          FIELDS[i] = PacketUtil.getField("KEY", Fields.FIELD_TYPE_VAR_STRING);
          FIELDS[i++].setPacketId(++packetId);
  
          FIELDS[i] = PacketUtil.getField("VALUE", Fields.FIELD_TYPE_VAR_STRING);
          FIELDS[i].setPacketId(++packetId);
  
          EOF.setPacketId(++packetId);
      }
  
      private enum TableType {
          GLOBAL, SHARDING, CHILD, BASE, SINGLE
      }
  
      public static void execute(ManagerService service, String tableInfo) {
          Matcher ma = PATTERN_FOR_TABLE_INFO.matcher(tableInfo);
          if (!ma.matches()) {
              service.writeErrMessage(ErrorCode.ER_UNKNOWN_ERROR, "The Correct Query Format Is:show @@algorithm where schema='?' and table ='?'");
              return;
          }
          String schemaName = StringUtil.removeAllApostrophe(ma.group(1));
          String tableName = StringUtil.removeAllApostrophe(ma.group(5));
          if (DbleServer.getInstance().getSystemVariables().isLowerCaseTableNames()) {
              schemaName = schemaName.toLowerCase();
              tableName = tableName.toLowerCase();
          }
  
          SchemaConfig schemaConfig = DbleServer.getInstance().getConfig().getSchemas().get(schemaName);
          TableType tableType = null;
          BaseTableConfig tableConfig = null;
          if (schemaConfig == null) {
              service.writeErrMessage(ErrorCode.ER_UNKNOWN_ERROR, "the schema [" + schemaName + "] does not exists");
              return;
          } else if (schemaConfig.isNoSharding()) {
              if (ProxyMeta.getInstance().getTmManager().checkTableExists(schemaName, tableName)) {
                  tableType = TableType.BASE;
              }
          } else {
              tableConfig = schemaConfig.getTables().get(tableName);
              if (tableConfig == null) {
                  if (schemaConfig.getDefaultShardingNodes() == null) {
                      service.writeErrMessage(ErrorCode.ER_UNKNOWN_ERROR, "the table [" + tableName + "] in schema [" + schemaName + "] does not exists");
                      return;
                  } else if (ProxyMeta.getInstance().getTmManager().checkTableExists(schemaName, tableName)) {
                      tableType = TableType.BASE;
                  }
              } else if (tableConfig instanceof GlobalTableConfig) {
                  tableType = TableType.GLOBAL;
              } else if (tableConfig instanceof ChildTableConfig) {
                  tableType = TableType.CHILD;
              } else if (tableConfig instanceof SingleTableConfig) {
                  tableType = TableType.SINGLE;
              } else {
                  tableType = TableType.SHARDING;
              }
          }
          ByteBuffer buffer = service.allocate();
  
          // write header
          buffer = HEADER.write(buffer, service, true);
  
          // write fields
          for (FieldPacket field : FIELDS) {
              buffer = field.write(buffer, service, true);
          }
  
          // write eof
          buffer = EOF.write(buffer, service, true);
  
          // write rows
          byte packetId = EOF.getPacketId();
  
          if (tableType != null) {
              for (RowDataPacket row : getRows(tableConfig, tableType, service.getCharset().getResults())) {
                  row.setPacketId(++packetId);
                  buffer = row.write(buffer, service, true);
              }
          }
  
          // write last eof
          EOFRowPacket lastEof = new EOFRowPacket();
          lastEof.setPacketId(++packetId);
  
  
          lastEof.write(buffer, service);
      }
  
      private static List<RowDataPacket> getRows(BaseTableConfig tableConfig, TableType tableType, String charset) {
          List<RowDataPacket> list = new ArrayList<>();
          switch (tableType) {
              case GLOBAL: {
                  RowDataPacket row = new RowDataPacket(FIELD_COUNT);
                  row.add(StringUtil.encode("TYPE", charset));
                  row.add(StringUtil.encode("GLOBAL TABLE", charset));
                  list.add(row);
                  break;
              }
              case CHILD: {
                  RowDataPacket row = new RowDataPacket(FIELD_COUNT);
                  row.add(StringUtil.encode("TYPE", charset));
                  row.add(StringUtil.encode("CHILD TABLE", charset));
                  list.add(row);
                  break;
              }
              case BASE: {
                  RowDataPacket row = new RowDataPacket(FIELD_COUNT);
                  row.add(StringUtil.encode("TYPE", charset));
                  row.add(StringUtil.encode("BASE TABLE", charset));
                  list.add(row);
                  break;
              }
              case SINGLE: {
                  RowDataPacket row = new RowDataPacket(FIELD_COUNT);
                  row.add(StringUtil.encode("TYPE", charset));
                  row.add(StringUtil.encode("SINGLE TABLE", charset));
                  list.add(row);
                  break;
              }
              case SHARDING: {
                  RowDataPacket typeRow = new RowDataPacket(FIELD_COUNT);
                  typeRow.add(StringUtil.encode("TYPE", charset));
                  typeRow.add(StringUtil.encode("SHARDING TABLE", charset));
                  list.add(typeRow);
  
                  ShardingTableConfig shardingTableConfig = (ShardingTableConfig) tableConfig;
                  RowDataPacket columnRow = new RowDataPacket(FIELD_COUNT);
                  columnRow.add(StringUtil.encode("COLUMN", charset));
                  columnRow.add(StringUtil.encode(shardingTableConfig.getShardingColumn(), charset));
                  list.add(columnRow);
                  RowDataPacket classRow = new RowDataPacket(FIELD_COUNT);
                  classRow.add(StringUtil.encode("CLASS", charset));
                  classRow.add(StringUtil.encode(shardingTableConfig.getFunction().getClass().getName(), charset));
                  list.add(classRow);
                  for (Map.Entry<String, String> pairs : shardingTableConfig.getFunction().getAllProperties().entrySet()) {
                      RowDataPacket propertyRow = new RowDataPacket(FIELD_COUNT);
                      propertyRow.add(StringUtil.encode(pairs.getKey(), charset));
                      propertyRow.add(StringUtil.encode(pairs.getValue(), charset));
                      list.add(propertyRow);
                  }
                  break;
              }
              default:
                  break;
          }
          return list;
      }
  }
  