package com.ynxbd.common.helper.rsa;

import com.ynxbd.common.helper.common.ErrorHelper;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.codec.binary.Base64;
import org.apache.commons.lang3.ObjectUtils;

import javax.crypto.Cipher;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

/**
 * RSA非对称加密
 *
 * @Author wsq
 * @Date 2021/07/28 11:01:28
 * @Copyright @ 2020 云南新八达科技有限公司 All rights reserved.
 */
@Slf4j
public class RSAHelper {
    private RSAHelper() {
    }

    private static final int KEY_LENGTH = 1024;
    private static final Map<Integer, String> KEY_MAP = new HashMap<>();  // 用于封装随机产生的公钥与私钥

    static {
        try {
            // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
            KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
            // 初始化密钥对生成器，密钥大小为96-1024位
            keyPairGen.initialize(KEY_LENGTH, new SecureRandom());
            // 生成一个密钥对，保存在keyPair中
            KeyPair keyPair = keyPairGen.generateKeyPair();
            RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();   // 得到私钥
            RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();  // 得到公钥
            String publicKeyStr = new String(Base64.encodeBase64(publicKey.getEncoded()));
            // 得到私钥字符串
            String privateKeyStr = new String(Base64.encodeBase64((privateKey.getEncoded())));
            // 将公钥和私钥保存到Map
            KEY_MAP.put(0, publicKeyStr);   // 0表示公钥
            KEY_MAP.put(1, privateKeyStr);  // 1表示私钥
        } catch (Exception e) {
            ErrorHelper.println(e);
        }
    }

    public static final String RSA_ECB_PKCS1Padding = "RSA/ECB/PKCS1Padding";

    /**
     * 获取公钥
     *
     * @return 公钥
     */
    public static String getPublicKey() {
        return KEY_MAP.get(0);
    }

    /**
     * 获取私钥
     *
     * @return 私钥
     */
    public static String getPrivateKey() {
        return KEY_MAP.get(1);
    }

    /**
     * RSA公钥加密
     *
     * @param encryptData 加密数据
     * @return 密文
     */
    public static String encrypt(String encryptData) {
        return encrypt(encryptData, getPublicKey());
    }


    /**
     * RSA公钥加密
     *
     * @param encryptData 加密数据
     * @return 密文
     */
    public static String encrypt(String encryptData, String publicKey) {
        if (ObjectUtils.isEmpty(encryptData)) {
            return null;
        }
        try {
            // Base64编码的公钥
            byte[] decoded = Base64.decodeBase64(publicKey);
            RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
            // RSA加密
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE, pubKey);
            return Base64.encodeBase64String(cipher.doFinal(encryptData.getBytes(StandardCharsets.UTF_8)));
        } catch (Exception e) {
            log.error("[RSA]加密失败:[{}]", e.getMessage());
        }
        return null;
    }


    /**
     * RSA私钥解密
     *
     * @param decryptData 加密数据
     * @return 明文
     */
    public static String decrypt(String decryptData) {
        return decrypt(decryptData, getPrivateKey());
    }

    /**
     * RSA私钥解密
     *
     * @param decryptData 加密数据
     * @return 明文
     */
    public static String decrypt(String decryptData, String privateKey) {
        if (ObjectUtils.isEmpty(decryptData)) {
            return null;
        }
        try {
            // 64位解码加密后的字符串
            byte[] inputByte = Base64.decodeBase64(decryptData.getBytes(StandardCharsets.UTF_8));
            // base64编码的私钥
            byte[] decoded = Base64.decodeBase64(privateKey);
            RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
            // RSA解密
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.DECRYPT_MODE, priKey);
            return new String(cipher.doFinal(inputByte));
        } catch (Exception e) {
            log.error("[RSA]解密失败:[{}]", e.getMessage());
        }
        return null;
    }


    public static String URLEncode(String data) {
        try {
            if (ObjectUtils.isEmpty(data)) return null;
            return URLEncoder.encode(data, String.valueOf(StandardCharsets.UTF_8));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static PublicKey getPublicKey(String base64PubKey) {
        try {
            byte[] keyBytes = java.util.Base64.getDecoder().decode(base64PubKey);
            X509EncodedKeySpec spec = new X509EncodedKeySpec(keyBytes);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            return keyFactory.generatePublic(spec);
        } catch (Exception e) {
            log.error("", e);
            return null;
        }
    }

    /**
     * PKCS8 格式私钥字符串转 PrivateKey
     *
     * @param privateKeyStr 带/不带头尾标记的base64私钥
     * @return PrivateKey
     */
    public static PrivateKey getPrivateKey(String privateKeyStr) {
        try {
            // 去除头尾标记、换行、空格
            String privateKeyPEM = privateKeyStr
                    .replace("-----BEGIN PRIVATE KEY-----", "")
                    .replace("-----END PRIVATE KEY-----", "")
                    .replaceAll("\\s+", "");
            byte[] keyBytes = java.util.Base64.getDecoder().decode(privateKeyPEM);
            PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            return keyFactory.generatePrivate(spec);
        } catch (Exception e) {
            log.error("", e);
            return null;
        }
    }

    // 加密方法（PKCS#1 v1.5填充）[对应前端JS加密]
    public static byte[] enPKCS1PaddingToByte(String content, String base64PublicKey) throws Exception {
        return enPKCS1PaddingToByte(content, getPublicKey(base64PublicKey));
    }

    public static byte[] enPKCS1PaddingToByte(String content, PublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] data = content.getBytes(StandardCharsets.UTF_8);
        return cipher.doFinal(data);
    }

    // 加密方法（PKCS#1 v1.5填充）[对应前端JS加密]
    public static String enPKCS1Padding(String content, PublicKey publicKey) throws Exception {
        byte[] data = enPKCS1PaddingToByte(content, publicKey);
        return java.util.Base64.getEncoder().encodeToString(data);
    }

    // 解密方法
    public static String dePKCS1Padding(String encryptedText, PrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        byte[] decryptedBytes = cipher.doFinal(java.util.Base64.getDecoder().decode(encryptedText));
        return new String(decryptedBytes, StandardCharsets.UTF_8);
    }

    // 去除空格、制表符、换行符等连续或多个空白符
    public static String replaceKey(String key) {
        if (key == null) return null;
        return key.replaceAll("\\s+", "");
    }


    public static void main(String[] args) throws Exception {
//        System.out.println("随机生成的公钥为:" + KEY_MAP.get(0));
//        System.out.println("随机生成的私钥为:" + KEY_MAP.get(1));
    }

//    public static void main(String[] args) throws Exception {
//        // Base64编码的公钥
//        byte[] decoded = Base64.decodeBase64(getPublicKey());
//        RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
//        // RSA加密
//        Cipher cipher = Cipher.getInstance("RSA");
//        cipher.init(Cipher.ENCRYPT_MODE, pubKey);
//
//        String a = Base64.encodeBase64String(cipher.doFinal("encryptData".getBytes(StandardCharsets.UTF_8)));
//        System.out.println(a);
//
//        String b = Base64.encodeBase64String(cipher.doFinal("encryptData".getBytes(StandardCharsets.UTF_8)));
//        System.out.println(a);
//
//        String c = Base64.encodeBase64String(cipher.doFinal("encryptData".getBytes(StandardCharsets.UTF_8)));
//        System.out.println(a);
//
//        String d = Base64.encodeBase64String(cipher.doFinal("encryptData".getBytes(StandardCharsets.UTF_8)));
//        System.out.println(a);
//    }
}