package com.sckw.core.utils;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * 加密
 * @author zk
 * @date 2019-12-29
 */
public class EncryptionUtil {

	private final static String[] HEX_DIGITS = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d","e", "f" };
	private final static String MD5 = "MD5";
	private final static String SHA = "SHA";
	private final static String SHA256 = "SHA-256";

	private Object salt;
	private String algorithm;

	public EncryptionUtil() {

	}

	public EncryptionUtil(Object salt) {
		this(salt, MD5);
	}
	
	public EncryptionUtil(Object salt, String algorithm) {
		this.salt = salt;
		this.algorithm = algorithm;
	}

	/**
	 * 加密
	 * @param params
	 * @return
	 */
	public String encode(String params) {
		String result = null;
		try {
			MessageDigest md = MessageDigest.getInstance(algorithm);
			// 加密后的字符串
			result = byteArrayToHexString(md.digest(mergeEncryptionAndSalt(params).getBytes("utf-8")));
		} catch (Exception ex) {
		}
		return result;
	}

	/**
	 * 密码匹配验证
	 * @param encParams 密文
	 * @param rawParams 明文
	 * @return
	 */
	public boolean matches(String encParams, String rawParams) {
		String pass1 = "" + encParams;
		String pass2 = encode(rawParams);
		return pass1.equals(pass2);
	}

	private String mergeEncryptionAndSalt(String params) {
		if (params == null) {
			params = "";
		}

		if ((salt == null) || "".equals(salt)) {
			return params;
		} else {
			return params + "{" + salt.toString() + "}";
		}
	}

	/**
	 * 转换字节数组为16进制字串
	 * @param b 字节数组
	 * @return 16进制字串
	 */
	private String byteArrayToHexString(byte[] b) {
		StringBuffer resultSb = new StringBuffer();
		for (int i = 0; i < b.length; i++) {
			resultSb.append(byteToHexString(b[i]));
		}
		return resultSb.toString();
	}

	/**
	 * 将字节转换为16进制
	 * @param b
	 * @return
	 */
	private static String byteToHexString(byte b) {
		int n = b;
		if (n < 0) {
			n = 256 + n;
		}
		int d1 = n / 16;
		int d2 = n % 16;
		return HEX_DIGITS[d1] + HEX_DIGITS[d2];
	}

	/**
	 * SHA-256加密
	 * @param str
	 * @return
	 */
	public String getSHA256Str(String str){
		MessageDigest messageDigest;
		String encodeStr = "";
		try {
			messageDigest = MessageDigest.getInstance(SHA256);
			messageDigest.update(str.getBytes("UTF-8"));
			encodeStr = byteArrayToHexString(messageDigest.digest());
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}
		return encodeStr;
	}

}