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.information.builder;
  
  import com.actiontech.dble.backend.mysql.nio.handler.query.DMLResponseHandler;
  import com.actiontech.dble.backend.mysql.nio.handler.query.impl.DistinctHandler;
  import com.actiontech.dble.backend.mysql.nio.handler.query.impl.UnionHandler;
  import com.actiontech.dble.plan.node.MergeNode;
  import com.actiontech.dble.plan.node.PlanNode;
  import com.actiontech.dble.services.manager.ManagerSession;
  
  import java.util.ArrayList;
  import java.util.List;
  
  class ManagerMergeNodeHandlerBuilder extends ManagerBaseHandlerBuilder {
      private MergeNode node;
  
      ManagerMergeNodeHandlerBuilder(ManagerSession session, MergeNode node, ManagerHandlerBuilder hBuilder) {
          super(session, node, hBuilder);
          this.node = node;
      }
  
      @Override
      protected void handleSubQueries() {
      }
  
      @Override
      protected List<DMLResponseHandler> buildPre() {
          List<DMLResponseHandler> pres = new ArrayList<>();
          for (PlanNode child : node.getChildren()) {
              ManagerBaseHandlerBuilder builder = hBuilder.getBuilder(session, child);
              if (builder.getSubQueryBuilderList().size() > 0) {
                  this.getSubQueryBuilderList().addAll(builder.getSubQueryBuilderList());
              }
              DMLResponseHandler ch = builder.getEndHandler();
              pres.add(ch);
          }
          return pres;
      }
  
      @Override
      public void buildOwn() {
          UnionHandler uh = new UnionHandler(getSequenceId(), session, node.getComeInFields(), node.getChildren().size());
          addHandler(uh);
          if (node.isUnion()) {
              DistinctHandler dh = new DistinctHandler(getSequenceId(), session, node.getColumnsSelected());
              addHandler(dh);
          }
      }
  
  }
  