package com.winsun.utils;

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import org.apache.shiro.crypto.hash.Md5Hash;
import org.apache.shiro.crypto.hash.SimpleHash;
import org.apache.shiro.util.ByteSource;

import lombok.extern.slf4j.Slf4j;

@Slf4j
public class MD5Utils {
	
	/**
     * 加盐参数
     */
    public final static String hashAlgorithmName = "MD5";

    /**
     * 循环次数
     */
    public final static int hashIterations = 1024;
    
    /**
     * shiro密码加密工具类
     *
     * @param credentials 密码
     * @param saltSource 密码盐
     * @return
     */
    public static String md5(String credentials, String saltSource) {
        ByteSource salt = new Md5Hash(saltSource);
        return new SimpleHash(hashAlgorithmName, credentials, salt, hashIterations).toString();
    }
	
    /**
     * 使用md5的算法进行加密
     */
    public static String md5(String plainText) {
        byte[] secretBytes = null;
        try {
            secretBytes = MessageDigest.getInstance("md5").digest(
                    plainText.getBytes());
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException("没有md5这个算法！");
        }
        // 16进制数字
        String md5code = new BigInteger(1, secretBytes).toString(16);
        // 如果生成数字未满32位，需要前面补0
        for (int i = 0; i < 32 - md5code.length(); i++) {
            md5code = "0" + md5code;
        }
        return md5code;
    }

    public static String getDigestStr(String info) {
        try {
            byte[] res = info.getBytes();
            MessageDigest md = MessageDigest.getInstance("MD5");
            byte[] result = md.digest(res);
            for (int i = 0; i < result.length; i++) {
                md.update(result[i]);
            }
            byte[] hash = md.digest();
            StringBuffer d = new StringBuffer("");
            for (int i = 0; i < hash.length; i++) {
                int v = hash[i] & 0xFF;
                if (v < 16) {
                    d.append("0");
                }
                d.append(Integer.toString(v, 16).toUpperCase());
            }
            return d.toString();
        } catch (Exception e) {
            return null;
        }
    }
    
    /**
     * 获取随机位数的字符串
     */
    public static String getRandomString(int length) {
        String base = "abcdefghijklmnopqrstuvwxyz0123456789";
        SecureRandom random;
        StringBuffer sb = new StringBuffer();
        
		try {
			random = SecureRandom.getInstance("SHA1PRNG");
			for (int i = 0; i < length; i++) {
			    int number = random.nextInt(base.length());
			    sb.append(base.charAt(number));
			}
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
      
        return sb.toString();
    }
}
