package com.ruoyi.common.utils;

import org.apache.commons.codec.binary.Base64;
import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

/**
 * RSA加密工具类
 * @author Wzp
 * @date 2023-08-29
 */
public class RSAUtils {

    private static final Logger logger = LoggerFactory.getLogger(RSAUtils.class);

    public static final String CHARSET = "UTF-8";
    public static final String RSA_ALGORITHM = "RSA";

    /** 公钥 */
    public static final String PUBLIC_KEY = "MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBAOw0B3YgO68r2sZSzA8/ab9rAJHYRtux0NxofUNB4GrdMa8XcdHcrEL4ybIhjhl/2h5voNUJFd2pnkIwujZDKt0CAwEAAQ==";

    /** 私钥 */
    public static final String PRIVATE_KEY = "MIIBUwIBADANBgkqhkiG9w0BAQEFAASCAT0wggE5AgEAAkEA7DQHdiA7ryvaxlLMDz9pv2sAkdhG27HQ3Gh9Q0Hgat0xrxdx0dysQvjJsiGOGX/aHm+g1QkV3ameQjC6NkMq3QIDAQABAkBh2SfiInY3Gda2Y6RPCLj46A3DXTH1XtMkC1Eg5JBgE9f3HunYuQ1m5WiAuJAj3KnSldIiRCQI2n5Yy6C9ngCNAiEA+eSRkXbk8qzrmVAmtIWzSsSmG16IP22QpCdtuTrblKMCIQDx+dARTC7qEDsKZlOEK7zQ1fxbriJoiapNO1c4YLK6fwIgSlx37N+Cdax7V14AhouatM8b1t0kkitadV6+SfZ3zR0CIFDIHG1Z6KOdjYhYRvNuApgZiCk3RiduJhuofuLEbYaTAiALgjOFYwzlAT0U7DXdWgDBDUB9CKT+YmN6E8MCzzGoCQ==";


    public static Map<String, String> createKeys(int keySize){
        //为RSA算法创建一个KeyPairGenerator对象
        KeyPairGenerator kpg;
        try{
            kpg = KeyPairGenerator.getInstance(RSA_ALGORITHM);
        }catch(NoSuchAlgorithmException e){
            throw new IllegalArgumentException("No such algorithm-->[" + RSA_ALGORITHM + "]");
        }

        //初始化KeyPairGenerator对象,密钥长度
        kpg.initialize(keySize);
        //生成密匙对
        KeyPair keyPair = kpg.generateKeyPair();
        //得到公钥
        Key publicKey = keyPair.getPublic();
        String publicKeyStr = Base64.encodeBase64URLSafeString(publicKey.getEncoded());
        //得到私钥
        Key privateKey = keyPair.getPrivate();
        System.out.println("私钥格式:"+privateKey.getFormat());
        String privateKeyStr = Base64.encodeBase64URLSafeString(privateKey.getEncoded());
        Map<String, String> keyPairMap = new HashMap<String, String>();
        keyPairMap.put("publicKey", publicKeyStr);
        keyPairMap.put("privateKey", privateKeyStr);

        return keyPairMap;
    }

    /**
     * 获取公钥
     *
     * @param publicKey 公钥字符串
     * @return 公钥
     * @throws NoSuchAlgorithmException 异常
     * @throws InvalidKeySpecException 异常
     */
    public static RSAPublicKey getPublicKey(String publicKey) throws NoSuchAlgorithmException, InvalidKeySpecException {
        //通过X509编码的Key指令获得公钥对象
        KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(Base64.decodeBase64(publicKey));
        return (RSAPublicKey) keyFactory.generatePublic(x509KeySpec);
    }

    /**
     * 得到私钥
     *
     * @param privateKey 私钥字符串
     * @return 私钥
     * @throws NoSuchAlgorithmException 异常
     * @throws InvalidKeySpecException 异常
     */
    public static RSAPrivateKey getPrivateKey(String privateKey) throws NoSuchAlgorithmException, InvalidKeySpecException {
        //通过PKCS#8编码的Key指令获得私钥对象
        KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKey));
        return (RSAPrivateKey) keyFactory.generatePrivate(pkcs8KeySpec);
    }

    /**
     * 公钥加密
     *
     * @param data 原数据
     * @return 结果
     */
    public static String publicEncrypt(String data){
        try{
            // 获取公钥
            RSAPublicKey publicKey = getPublicKey(PUBLIC_KEY);
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            return Base64.encodeBase64URLSafeString(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes(CHARSET), publicKey.getModulus().bitLength()));
        }catch(Exception e){
            throw new RuntimeException("加密字符串[" + data + "]时遇到异常", e);
        }
    }

    /**
     * 私钥解密
     *
     * @param data 加密数据
     * @return 结果
     */
    public static String privateDecrypt(String data){
        try{
            // 获取私钥
            RSAPrivateKey privateKey = getPrivateKey(PRIVATE_KEY);
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            return new String(rsaSplitCodec(cipher, Cipher.DECRYPT_MODE, Base64.decodeBase64(data), privateKey.getModulus().bitLength()), CHARSET);
        }catch(Exception e){
            throw new RuntimeException("解密字符串[" + data + "]时遇到异常", e);
        }
    }

    /**
     * 私钥加密
     *
     * @param data 原数据
     * @return 结果
     */
    public static String privateEncrypt(String data){
        try{
            // 获取私钥
            RSAPrivateKey privateKey = getPrivateKey(PRIVATE_KEY);
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, privateKey);
            return Base64.encodeBase64URLSafeString(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes(CHARSET), privateKey.getModulus().bitLength()));
        }catch(Exception e){
            throw new RuntimeException("加密字符串[" + data + "]时遇到异常", e);
        }
    }

    /**
     * 公钥解密
     *
     * @param data 原数据
     * @return 结果
     */
    public static String publicDecrypt(String data){
        try{
            // 获取公钥
            RSAPublicKey publicKey = getPublicKey(PUBLIC_KEY);
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.DECRYPT_MODE, publicKey);
            return new String(rsaSplitCodec(cipher, Cipher.DECRYPT_MODE, Base64.decodeBase64(data), publicKey.getModulus().bitLength()), CHARSET);
        }catch(Exception e){
            throw new RuntimeException("解密字符串[" + data + "]时遇到异常", e);
        }
    }

    private static byte[] rsaSplitCodec(Cipher cipher, int opmode, byte[] datas, int keySize){
        int maxBlock = 0;
        if(opmode == Cipher.DECRYPT_MODE){
            maxBlock = keySize / 8;
        }else{
            maxBlock = keySize / 8 - 11;
        }
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] buff;
        int i = 0;
        try{
            while(datas.length > offSet){
                if(datas.length-offSet > maxBlock){
                    buff = cipher.doFinal(datas, offSet, maxBlock);
                }else{
                    buff = cipher.doFinal(datas, offSet, datas.length-offSet);
                }
                out.write(buff, 0, buff.length);
                i++;
                offSet = i * maxBlock;
            }
        }catch(Exception e){
            e.printStackTrace();
            throw new RuntimeException("加解密阀值为["+maxBlock+"]的数据时发生异常", e);
        }
        byte[] resultDatas = out.toByteArray();
        IOUtils.closeQuietly(out);
        return resultDatas;
    }

    public static byte[] decode(String base64) throws Exception {
        return Base64.decodeBase64(base64);
    }

    public static String encode(byte[] bytes) throws Exception {
        return new String(Base64.encodeBase64(bytes));
    }

}
