package wusthelper.web.util;

import cn.hutool.core.util.HexUtil;
import cn.hutool.crypto.Mode;
import cn.hutool.crypto.Padding;
import cn.hutool.crypto.symmetric.AES;
import cn.hutool.crypto.symmetric.SymmetricCrypto;

import java.nio.charset.StandardCharsets;
import java.util.StringJoiner;

/**
 * 密码编解码器，
 * 用aes加密而不是常规密码存储使用的hash摘要，是因为有获取明文密码的需求，毕竟登录进系统还是要明文密码的，
 * 日后如果将数据获取转到客户端上进行，可以改为bcrypt存储
 */
public class PasswordCodec {

    private final SymmetricCrypto aes;

    public PasswordCodec(String key) {
        byte[] keyBytes = normalization(key);
        this.aes = new AES(Mode.ECB, Padding.PKCS5Padding, keyBytes);
    }

    public PasswordCodec(byte[] key) {
        this.aes = new AES(Mode.ECB, Padding.PKCS5Padding, key);
    }

    private static byte[] normalization(String key) {
        if (key.length() < 16) {
            StringJoiner sj = new StringJoiner(key);
            for (int i = 0; i < 16 - key.length(); i++) {
                sj.add("a");
            }
            key = sj.toString();
        } else if (key.length() > 16) {
            key = key.substring(15);
        }

        return key.getBytes(StandardCharsets.UTF_8);
    }

    public String encode(String raw) {
        if (raw == null) {
            return null;
        }

        byte[] data = aes.encrypt(raw.getBytes(StandardCharsets.UTF_8));
        return HexUtil.encodeHexStr(data);
    }

    public String decode(String encodedHex) {
        if (encodedHex == null) {
            return null;
        }

        byte[] data = aes.decrypt(HexUtil.decodeHex(encodedHex));
        return new String(data);
    }
//
//    public static PasswordUtil getInstance(String key) {
//        if (instance == null) {
//            synchronized (PasswordUtil.class) {
//                if (instance == null) {
//                    instance = new PasswordUtil(key);
//                }
//            }
//        }
//
//        return instance;
//    }
}