content: /*
   * Copyright 1999-2024 Alibaba Group Holding Ltd.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.alibaba.nacos.plugin.auth.impl.utils;
  
  import java.security.SecureRandom;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.stream.Collectors;
  
  /**
   * RandomPasswordGenerator .
   *
   * @author : huangtianhui
   */
  public class PasswordGeneratorUtil {
      
      private static final String LOWER_CASE = "abcdefghijklmnopqrstuvwxyz";
      
      private static final String UPPER_CASE = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
      
      private static final String DIGITS = "0123456789";
      
      private static final String SPECIAL_CHARS = "!@#$%&";
      
      private static final int PASSWORD_LENGTH = 8;
      
      /**
       * generateRandomPassword.
       * @return
       */
      public static String generateRandomPassword() {
          SecureRandom random = new SecureRandom();
          
          List<Character> pwdChars = new ArrayList<>();
          
          pwdChars.add(LOWER_CASE.charAt(random.nextInt(LOWER_CASE.length())));
          pwdChars.add(UPPER_CASE.charAt(random.nextInt(UPPER_CASE.length())));
          pwdChars.add(DIGITS.charAt(random.nextInt(DIGITS.length())));
          pwdChars.add(SPECIAL_CHARS.charAt(random.nextInt(SPECIAL_CHARS.length())));
          
          // Fill the rest of the password with random characters from all categories
          String allCharacters = LOWER_CASE + UPPER_CASE + DIGITS + SPECIAL_CHARS;
          while (pwdChars.size() < PASSWORD_LENGTH) {
              pwdChars.add(allCharacters.charAt(random.nextInt(allCharacters.length())));
          }
          
          // Shuffle to avoid predictable order
          Collections.shuffle(pwdChars, random);
          
          // Build the final password string
          return pwdChars.stream().map(String::valueOf).collect(Collectors.joining());
      }
  }
  