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.plan.common.item.Item;
  import com.actiontech.dble.plan.common.item.function.ItemFunc;
  
  import java.util.ArrayList;
  import java.util.List;
  
  public class ItemFuncSubstrIndex extends ItemStrFunc {
  
      public ItemFuncSubstrIndex(List<Item> args, int charsetIndex) {
          super(args, charsetIndex);
      }
  
      @Override
      public final String funcName() {
          return "SUBSTRING_INDEX";
      }
  
      @Override
      public String valStr() {
          String str = args.get(0).valStr();
          String delim = args.get(1).valStr();
          int count = args.get(2).valInt().intValue();
          if (this.nullValue = (args.get(0).isNull() || args.get(1).isNull() || args.get(2).isNull()))
              return EMPTY;
          if (str.length() == 0 || delim.length() == 0 || count == 0)
              return EMPTY;
  
          int delimLen = delim.length();
  
          List<String> subs = new ArrayList<>();
          while (true) {
              int index = str.indexOf(delim);
              if (index < 0) {
                  subs.add(str);
                  break;
              }
              if (index == 0) {
                  str = str.substring(index + delimLen);
              } else {
                  subs.add(str.substring(0, index));
                  str = str.substring(index + delimLen);
              }
          }
          StringBuilder ret = new StringBuilder();
          if (count > 0) {
              int trueCount = Math.min(subs.size(), count);
              for (int i = 0; i < trueCount; i++) {
                  ret.append(subs.get(i) + delim);
              }
          } else {
              int trueCount = Math.min(subs.size(), -count);
              for (int i = subs.size() - trueCount; i < subs.size(); i++) {
                  ret.append(subs.get(i) + delim);
              }
          }
          // remove the last delim
          int lastDelim = ret.lastIndexOf(delim);
          return ret.substring(0, lastDelim);
      }
  
      @Override
      public ItemFunc nativeConstruct(List<Item> realArgs) {
          return new ItemFuncSubstrIndex(realArgs, charsetIndex);
      }
  }
  