content: /*
   * Copyright (C) 2016-2023 ActionTech.
   * License: http://www.gnu.org/licenses/gpl.html GPL version 2 or higher.
   */
  
  package com.actiontech.dble.server.response;
  
  import com.actiontech.dble.backend.mysql.PacketUtil;
  import com.actiontech.dble.config.ErrorCode;
  import com.actiontech.dble.config.Fields;
  import com.actiontech.dble.meta.SchemaMeta;
  import com.actiontech.dble.meta.ViewMeta;
  import com.actiontech.dble.net.mysql.*;
  import com.actiontech.dble.route.parser.util.DruidUtil;
  import com.actiontech.dble.services.mysqlsharding.ShardingService;
  import com.actiontech.dble.singleton.ProxyMeta;
  import com.actiontech.dble.util.StringUtil;
  import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
  import com.alibaba.druid.sql.ast.expr.SQLPropertyExpr;
  import com.alibaba.druid.sql.ast.statement.SQLShowCreateViewStatement;
  
  import java.nio.ByteBuffer;
  import java.sql.SQLSyntaxErrorException;
  
  /**
   * Created by szf on 2017/12/15.
   */
  public final class ShowCreateView {
  
  
      private static final int FIELD_COUNT = 4;
      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("View", Fields.FIELD_TYPE_VAR_STRING);
          FIELDS[i++].setPacketId(++packetId);
  
          FIELDS[i] = PacketUtil.getField("Create View", Fields.FIELD_TYPE_VAR_STRING);
          FIELDS[i++].setPacketId(++packetId);
  
          FIELDS[i] = PacketUtil.getField("character_set_client", Fields.FIELD_TYPE_VAR_STRING);
          FIELDS[i++].setPacketId(++packetId);
  
          FIELDS[i] = PacketUtil.getField("collation_connection", Fields.FIELD_TYPE_VAR_STRING);
          FIELDS[i].setPacketId(++packetId);
  
          EOF.setPacketId(++packetId);
      }
  
      private ShowCreateView() {
      }
  
      public static void response(ShardingService service, String stmt) {
          try {
              SQLShowCreateViewStatement statement = (SQLShowCreateViewStatement) DruidUtil.parseMultiSQL(stmt);
              String schema = null;
              String view = null;
              if (statement.getName() instanceof SQLPropertyExpr) {
                  //show create view with sharding
                  SQLPropertyExpr sqlPropertyExpr = (SQLPropertyExpr) statement.getName();
                  //protocol not equals the nomul things
                  schema = sqlPropertyExpr.getOwner().toString();
                  view = sqlPropertyExpr.getName();
              } else if (statement.getName() instanceof SQLIdentifierExpr) {
                  schema = service.getSchema();
                  view = statement.getName().toString();
              }
              sendOutTheViewInfo(service, schema, view);
          } catch (SQLSyntaxErrorException syntaxExe) {
              service.writeErrMessage("42000", syntaxExe.getMessage(), ErrorCode.ER_PARSE_ERROR);
          }
      }
  
      public static void response(ShardingService service, String schema, String viewName) {
          sendOutTheViewInfo(service, schema, viewName);
      }
  
      public static void sendOutTheViewInfo(ShardingService service, String schema, String viewName) {
          //check if the view or sharding doesn't exist
          if (schema == null || "".equals(schema)) {
              service.writeErrMessage("3D000", "No database selected", ErrorCode.ER_NO_DB_ERROR);
              return;
          }
  
          schema = StringUtil.removeBackQuote(schema);
          SchemaMeta schemaMeta = ProxyMeta.getInstance().getTmManager().getCatalogs().get(schema);
          if (schemaMeta == null) {
              service.writeErrMessage("42S02", "Table '" + schema + "." + viewName + "' doesn't exist", ErrorCode.ER_NO_SUCH_TABLE);
              return;
          }
          viewName = StringUtil.removeBackQuote(viewName);
          ViewMeta view = schemaMeta.getViewMetas().get(viewName);
          if (view == null) {
              service.writeErrMessage("42S02", "Table '" + schema + "." + viewName + "' doesn't exist", ErrorCode.ER_NO_SUCH_TABLE);
              return;
          }
  
          ByteBuffer buffer = service.allocate();
          // writeDirectly header
          buffer = HEADER.write(buffer, service, true);
          // writeDirectly fields
          for (FieldPacket field : FIELDS) {
              buffer = field.write(buffer, service, true);
          }
          // writeDirectly eof
          buffer = EOF.write(buffer, service, true);
          // writeDirectly rows
          byte packetId = EOF.getPacketId();
          RowDataPacket row = getRow(view, service.getCharset().getResults(), service.getCharset().getCollation());
          row.setPacketId(++packetId);
          buffer = row.write(buffer, service, true);
          // writeDirectly last eof
          EOFRowPacket lastEof = new EOFRowPacket();
          lastEof.setPacketId(++packetId);
          lastEof.write(buffer, service);
      }
  
      public static RowDataPacket getRow(ViewMeta view, String charset, String collationConnection) {
          RowDataPacket row = new RowDataPacket(FIELD_COUNT);
          row.add(StringUtil.encode(view.getViewName(), charset));
          if (view.getViewColumnMeta() != null && view.getViewColumnMeta().size() > 0) {
              row.add(StringUtil.encode("create view " + view.getViewName() + view.getViewColumnMetaString() + " as" + view.getSelectSql(), charset));
          } else {
              row.add(StringUtil.encode("create view " + view.getViewName() + " as" + view.getSelectSql(), charset));
          }
          row.add(StringUtil.encode(charset, charset));
          row.add(StringUtil.encode(collationConnection, charset));
          return row;
      }
  
  }
  