package com.lunhan.water.common.security;

import org.apache.commons.codec.binary.Base64;

import javax.crypto.Cipher;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

public class RSAUtil {
    private static String getKey(String filePath) {
        try {
            // Read key from file
            String strKeyPEM = "";
            BufferedReader br = new BufferedReader(new FileReader(filePath));
            String line;
            while ((line = br.readLine()) != null) {
                strKeyPEM += line + "\n";
            }
            br.close();
            return strKeyPEM;
        } catch (Exception e) {
            throw new RuntimeException("RSA读取文件(" + filePath + ")失败: " + e.getMessage());
        }
    }





    /**
     * 从pem文件获取私钥PrivateKey
     *
     * @param filePath pem文件路径
     */
    public static PrivateKey getPrivateKey(String filePath) {
        String privateKeyPEM = RSAUtil.getKey(filePath);
        return RSAUtil.getPrivateKeyFromString(privateKeyPEM);
    }
    /**
     * String转私钥PrivateKey
     *
     * @param key
     */
    public static PrivateKey getPrivateKeyFromString(String key) {
        try {
            String privateKeyPEM = key;
            privateKeyPEM = privateKeyPEM.replaceFirst("\\-+BEGIN PRIVATE KEY\\-+[^a-zA-Z0-9_\\-]+", "");
            privateKeyPEM = privateKeyPEM.replaceFirst("\\-+END PRIVATE KEY\\-+", "").replaceAll("\\s+", "");
            byte[] encoded = Base64.decodeBase64(privateKeyPEM);

            KeyFactory kf = KeyFactory.getInstance("RSA");
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(encoded);
            return kf.generatePrivate(keySpec);
        } catch (Exception e) {
            throw new RuntimeException("RSA从字符串获取私钥失败: " + e.getMessage());
        }
    }





    public static PublicKey getPublicKey(String filename) throws IOException, GeneralSecurityException {
        String publicKeyPEM = RSAUtil.getKey(filename);
        return RSAUtil.getPublicKeyFromString(publicKeyPEM);
    }

    public static PublicKey getPublicKeyFromString(String key) {
        try {
            String publicKeyPEM = key;
            publicKeyPEM = publicKeyPEM.replace("-----BEGIN PUBLIC KEY-----\n", "");
            publicKeyPEM = publicKeyPEM.replace("-----END PUBLIC KEY-----", "");
            byte[] encoded = Base64.decodeBase64(publicKeyPEM);
            KeyFactory kf = KeyFactory.getInstance("RSA");
            PublicKey pubKey = kf.generatePublic(new X509EncodedKeySpec(encoded));
            return pubKey;
        } catch (Exception e) {
            throw new RuntimeException("RSA从字符串获取公钥失败: " + e.getMessage());
        }
    }





    public static String sign(PrivateKey privateKey, String message) {
        try {
            Signature sign = Signature.getInstance("SHA1withRSA");
            sign.initSign(privateKey);
            sign.update(message.getBytes(StandardCharsets.UTF_8));
            return new String(Base64.encodeBase64(sign.sign()), StandardCharsets.UTF_8);
        } catch (Exception e) {
            throw new RuntimeException("RSA签名生成失败: " + e.getMessage());
        }
    }
    public static boolean verify(PublicKey publicKey, String message, String signature) {
        try {
            Signature sign = Signature.getInstance("SHA1withRSA");
            sign.initVerify(publicKey);
            sign.update(message.getBytes(StandardCharsets.UTF_8));
            return sign.verify(Base64.decodeBase64(signature.getBytes(StandardCharsets.UTF_8)));
        } catch (Exception e) {
            throw new RuntimeException("RSA签名验证失败: " + e.getMessage());
        }
    }





    public static String encryptRSA(String rawText, String publicKey) {
        return RSAUtil.encryptRSA(rawText, RSAUtil.getPublicKeyFromString(publicKey));
    }
    public static String encryptRSA(String rawText, PublicKey publicKey) {
        try {
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            return Base64.encodeBase64String(cipher.doFinal(rawText.getBytes(StandardCharsets.UTF_8)));
        } catch (Exception e) {
            throw new RuntimeException("RSA加密失败: " + e.getMessage());
        }
    }





    //公钥加密
//    public static String encrypt(String content, String publicKey) {
//        return RSAUtil.encrypt(content, RSAUtil.getPublicKeyFromString(publicKey));
//    }
//    public static String encrypt(String content, PublicKey publicKey) {
//        try {
//            byte[] output = RSAUtil.encrypt(content.getBytes(), publicKey);
//            BASE64Encoder encoder = new BASE64Encoder();
//            return encoder.encode(output);
//        } catch (Exception e) {
//            throw new RuntimeException("RSA加密失败: " + e.getMessage());
//        }
//    }
    //公钥加密
    public static byte[] encrypt(byte[] content, PublicKey publicKey) {
        try {
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");//java默认"RSA"="RSA/ECB/PKCS1Padding"
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            return cipher.doFinal(content);
        } catch (Exception e) {
            throw new RuntimeException("RSA加密失败: " + e.getMessage());
        }
    }





    public static String decryptRSA(String cipherText, String privateKey) {
        return RSAUtil.decryptRSA(cipherText, RSAUtil.getPrivateKey(privateKey));
    }

    public static String decryptRSA(String cipherText, PrivateKey privateKey) {
        try {
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            return new String(cipher.doFinal(Base64.decodeBase64(cipherText)), StandardCharsets.UTF_8);
        } catch (Exception e) {
            throw new RuntimeException("RSA解密失败: " + e.getMessage());
        }
    }





    //私钥解密
//    public static String decrypt(String content, String privateKey) {
//        return RSAUtil.decrypt(content, RSAUtil.getPrivateKey(privateKey));
//    }
//    public static String decrypt(String content, PrivateKey privateKey) {
//        try {
//            byte[] buffer = RSAUtil.decrypt(content.getBytes(), privateKey);
//            BASE64Encoder encoder = new BASE64Encoder();
//            return encoder.encode(buffer);
//        } catch (Exception e) {
//            throw new RuntimeException("RSA解密失败: " + e.getMessage());
//        }
//    }
    //私钥解密
    public static byte[] decrypt(byte[] content, PrivateKey privateKey) {
        try {
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            return cipher.doFinal(content);
        } catch (Exception e) {
            throw new RuntimeException("RSA解密失败: " + e.getMessage());
        }
    }
}