package com.estate.expert.admin.utils;

import java.security.SecureRandom;
import java.util.Random;
import java.util.UUID;

/**
 * UUID生成器
 */
public class UUIDGenerator {

    private static final String CHARACTERS = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
    private static final SecureRandom RANDOM = new SecureRandom();

    public static String generate6Uuid() {
        StringBuilder sb = new StringBuilder(8);
        for (int i = 0; i < 8; i++) {
            int randomIndex = RANDOM.nextInt(CHARACTERS.length());
            char randomChar = CHARACTERS.charAt(randomIndex);
            sb.append(randomChar);
        }
        return sb.toString();
    }

    public static String generate32Uuid() {
        String uuid = UUID.randomUUID().toString().replace("-", "");
        char[] uuidArray = uuid.toCharArray();
        Random random = new Random();
        int count = 0;
        int[] lowerCaseIndexes = new int[32];
        int lowerCaseCount = 0;
        for (int i = 0; i < uuidArray.length; i++) {
            if (Character.isLowerCase(uuidArray[i])) {
                lowerCaseIndexes[lowerCaseCount] = i;
                lowerCaseCount++;
            }
        }
        if (lowerCaseCount <= 5) {
            for (int i = 0; i < lowerCaseCount; i++) {
                int index = lowerCaseIndexes[i];
                uuidArray[index] = Character.toUpperCase(uuidArray[index]);
            }
        } else {
            while (count < 5) {
                int index = random.nextInt(lowerCaseCount);
                int i = lowerCaseIndexes[index];
                uuidArray[i] = Character.toUpperCase(uuidArray[i]);
                count++;
            }
        }
        uuid = new String(uuidArray);
        return uuid;
    }

}