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.strfunc;
  
  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.alibaba.druid.sql.ast.SQLExpr;
  import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
  
  import java.io.UnsupportedEncodingException;
  import java.util.ArrayList;
  import java.util.List;
  
  
  public class ItemFuncChar extends ItemStrFunc {
      private String mysqlCharset;
  
      public ItemFuncChar(List<Item> args, int charsetIndex) {
          super(args, charsetIndex);
          this.mysqlCharset = CharsetUtil.getCharset(charsetIndex);
          this.charsetIndex = charsetIndex;
      }
  
      public ItemFuncChar(List<Item> args, String charset, int charsetIndex) {
          super(args, charsetIndex);
          this.mysqlCharset = charset;
          this.charsetIndex = CharsetUtil.getCharsetDefaultIndex(charset);
      }
  
      @Override
      public final String funcName() {
          return "CHAR";
      }
  
      @Override
      public void fixLengthAndDec() {
          maxLength = args.size() * 4;
      }
  
      @Override
      public String valStr() {
          List<Byte> bytes = new ArrayList<>(args.size());
          for (Item arg : args) {
              if (!arg.isNull()) {
                  int value = arg.valInt().intValue();
                  String hex = Integer.toHexString(value);
                  if (hex.length() % 2 != 0) {
                      hex = "0" + hex;
                  }
                  for (int i = 0; i < hex.length(); i = i + 2) {
                      bytes.add((byte) (Integer.parseInt(hex.substring(i, i + 2), 16)));
                  }
              }
          }
          byte[] b = new byte[bytes.size()];
          for (int i = 0; i < bytes.size(); i++) {
              b[i] = bytes.get(i);
          }
          try {
              return new String(b, CharsetUtil.getJavaCharset(mysqlCharset));
          } catch (UnsupportedEncodingException e) {
              nullValue = true;
              Item.LOGGER.info("char() charset exception:", e);
              return null;
          }
      }
  
      @Override
      public SQLExpr toExpression() {
          SQLMethodInvokeExpr method = new SQLMethodInvokeExpr(funcName());
          for (Item arg : args) {
              method.addArgument(arg.toExpression());
          }
          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 ItemFuncChar(newArgs, mysqlCharset, charsetIndex);
      }
  
  }
  