content: /*
   * Copyright (C) 2016-2023 ActionTech.
   * License: http://www.gnu.org/licenses/gpl.html GPL version 2 or higher.
   */
  
  package com.actiontech.dble.plan.common.item.function.convertfunc;
  
  import com.actiontech.dble.backend.mysql.CharsetUtil;
  import com.actiontech.dble.plan.common.field.Field;
  import com.actiontech.dble.plan.common.item.Item;
  import com.actiontech.dble.plan.common.item.function.strfunc.ItemStrFunc;
  import com.alibaba.druid.sql.ast.SQLExpr;
  import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
  import com.alibaba.druid.sql.ast.expr.SQLIntegerExpr;
  import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
  
  import java.io.UnsupportedEncodingException;
  import java.util.ArrayList;
  import java.util.List;
  
  
  public class ItemCharTypeConvert extends ItemStrFunc {
      private int castLength;
      private String charSetName;
  
      public ItemCharTypeConvert(Item a, int lengthArg, String charSetName, int charsetIndex) {
          super(new ArrayList<Item>(), charsetIndex);
          args.add(a);
          this.castLength = lengthArg;
          this.charSetName = charSetName;
      }
  
      @Override
      public final String funcName() {
          return "convert_as_char";
      }
  
      @Override
      public void fixLengthAndDec() {
          fixCharLength(castLength >= 0 ? castLength : args.get(0).getMaxLength());
      }
  
      @Override
      public String valStr() {
          assert (fixed && castLength >= 0);
  
          String res = null;
          if ((res = args.get(0).valStr()) == null) {
              nullValue = true;
              return null;
          }
          nullValue = false;
          if (castLength < res.length()) {
              res = res.substring(0, castLength);
          }
          if (charSetName != null) {
              try {
                  res = new String(res.getBytes(), CharsetUtil.getJavaCharset(charSetName));
              } catch (UnsupportedEncodingException e) {
                  Item.LOGGER.info("convert using charset exception", e);
                  nullValue = true;
                  return null;
              }
          }
          return res;
      }
  
      @Override
      public SQLExpr toExpression() {
          SQLMethodInvokeExpr method = new SQLMethodInvokeExpr();
          method.setMethodName("CONVERT");
          method.addArgument(args.get(0).toExpression());
          if (castLength >= 0) {
              SQLMethodInvokeExpr dataType = new SQLMethodInvokeExpr();
              dataType.setMethodName("CHAR");
              dataType.addArgument(new SQLIntegerExpr(castLength));
              method.addArgument(dataType);
          } else {
              method.addArgument(new SQLIdentifierExpr("CHAR"));
          }
          return method;
      }
  
      @Override
      protected Item cloneStruct(boolean forCalculate, List<Item> calArgs, boolean isPushDown, List<Field> fields) {
          List<Item> newArgs = null;
          if (!forCalculate)
              newArgs = cloneStructList(args);
          else
              newArgs = calArgs;
          return new ItemCharTypeConvert(newArgs.get(0), castLength, charSetName, charsetIndex);
      }
  }
  