package com.pj.api.pushfee.tools;

import cn.hutool.core.codec.Base64;
import cn.hutool.core.util.CharsetUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.crypto.SecureUtil;
import cn.hutool.crypto.asymmetric.KeyType;
import cn.hutool.crypto.asymmetric.RSA;
import cn.hutool.crypto.digest.DigestUtil;
import cn.hutool.crypto.symmetric.AES;
import cn.hutool.crypto.symmetric.SymmetricAlgorithm;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.pj.api.pushfee.tools.message.CuMessage;
import com.pj.api.pushfee.tools.message.Header;
import com.pj.api.pushfee.tools.message.Inter;
import com.pj.api.pushfee.tools.message.MessageInter;

public class EncryptTools {

    private String sysId;

    private String remotePublicKey;

    private String localPrivateKey;

    private RSA rsaInstance;

    private static final Gson gson = new GsonBuilder().disableHtmlEscaping().create();

    /**
     * 构造加密工具
     * @param sysId 系统Id，由统一计费系统分配
     * @param remotePublicKey 对方的公钥
     */
    public EncryptTools(String sysId, String remotePublicKey) {
        this.sysId = sysId;
        this.remotePublicKey = remotePublicKey;
        rsaInstance = SecureUtil.rsa(null, this.remotePublicKey);
    }

    /**
     * 构造解密工具
     * @param localPrivateKey 己方的私钥
     */
    public EncryptTools(String localPrivateKey) {
        this.localPrivateKey = localPrivateKey;
        rsaInstance = SecureUtil.rsa(this.localPrivateKey, null);
    }

    /**
     * 生成RSA密钥对
     */
    public static void generateKeyPairs(){
        RSA rsa = new RSA();
        // 获取公钥
        String pubKey = rsa.getPublicKeyBase64();
        System.out.println("公钥：" + pubKey);
        // 获取私钥
        String priKey = rsa.getPrivateKeyBase64();
        System.out.println("私钥：" + priKey);
    }

    /**
     * md5签名
     * @param text
     * @return
     */
    private String md5(String text){
        return DigestUtil.md5Hex(text);
    }

    /**
     * RSA私钥解密
     * @return
     */
    private String decryptStrByPrivateKey(String encrypt){
        try {
            return this.rsaInstance.decryptStr(encrypt, KeyType.PrivateKey);
        } catch (Exception e) {
            throw new RuntimeException("RSA私钥解密失败");
        }
    }

    /**
     * RSA公钥加密
     * @param text
     * @return
     */
    private String encryptByPublicKey(String text){
        try {
            return this.rsaInstance.encryptBase64(StrUtil.bytes(text,CharsetUtil.CHARSET_UTF_8), KeyType.PublicKey);
        } catch (Exception e) {
            throw new RuntimeException("RSA公钥加密失败");
        }
    }

    /**
     * 生成随机秘钥
     */
    private String getRandomKey(){
        return Base64.encode(SecureUtil.generateKey(SymmetricAlgorithm.AES.getValue()).getEncoded());
    }

    private String encodeByAES(String content, String randomKey){
        try {
            AES aes = SecureUtil.aes(Base64.decode(randomKey));
            return aes.encryptBase64(content);
        } catch (Exception e) {
            throw new RuntimeException("AES加密报文失败");
        }
    }

    private String decodeByAES(String sourceText, String randomKey){
        try {
            AES aes = SecureUtil.aes(Base64.decode(randomKey));
            return aes.decryptStr(sourceText);
        } catch (Exception e) {
            throw new RuntimeException("AES解密报文失败");
        }
    }

    private boolean verifySignature(CuMessage message){
        String signature = message.getSignature();
        return md5(gson.toJson(message.getHeader())).equals(signature);

    }

    /**
     * 加密报文
     */
    public String encryptMessage(MessageInter payLoad){

        //生成随机秘钥
        String randomKey = getRandomKey();
        //加密报文payLoad
        String encrypted = encodeByAES(gson.toJson(payLoad), randomKey);
        //加密随机秘钥
        String keyEncrypted = encryptByPublicKey(randomKey);

        Inter interAnnotation = payLoad.getClass().getAnnotation(Inter.class);
        String interId = interAnnotation.name();

        Header header = new Header(this.sysId, encrypted, keyEncrypted, interId);

        //签名：md5提取摘要
        String signature = md5(gson.toJson(header));

        CuMessage cuMessage = new CuMessage(header, signature);

        String msg = gson.toJson(cuMessage);

        System.out.println("密文：" + msg);

        return msg;

    }

    /**
     * 解密报文
     * @return
     */
    public MessageInter decryptMessage(String text){
        CuMessage cuMessage = gson.fromJson(text, CuMessage.class);
        return decryptMessage(cuMessage);
    }

    public MessageInter decryptMessage(CuMessage message){
        //验签
        if (!verifySignature(message)) {
            throw new RuntimeException("验签失败");
        }
        //用公钥解密得到randomKey
        String key = decryptStrByPrivateKey(message.getHeader().getKeyEncrypted());
        //用randomKey解密报文
        String originText = decodeByAES(message.getHeader().getEncrypted(), key);

        MessageInter inter = gson.fromJson(originText, InterEnum.findClass(message.getHeader().getInterId()));

        System.out.println("解密：" + originText);

        return inter;
    }

}