using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Math.EC;
using Org.BouncyCastle.Utilities.Encoders;

namespace Admin.NET.Core;

/// <summary>
/// SM2工具类
/// </summary>
public class SM2Util
{
    /// <summary>
    /// 加密
    /// </summary>
    /// <param name="publicKey_string"></param>
    /// <param name="data_string"></param>
    /// <returns></returns>
    public static string Encrypt(string publicKey_string, string data_string)
    {
        var publicKey = Hex.Decode(publicKey_string);
        var data = Encoding.UTF8.GetBytes(data_string);
        return Encrypt(publicKey, data);
    }

    /// <summary>
    /// 解密
    /// </summary>
    /// <param name="privateKey_string"></param>
    /// <param name="encryptedData_string"></param>
    /// <returns></returns>
    public static string Decrypt(string privateKey_string, string encryptedData_string)
    {
        var privateKey = Hex.Decode(privateKey_string);
        var encryptedData = Hex.Decode(encryptedData_string);
        var de_str = SM2Util.Decrypt(privateKey, encryptedData);
        string plainText = Encoding.UTF8.GetString(de_str);
        return plainText;
    }

    public static void GenerateKeyPair()
    {
        SM2 sm2 = SM2.Instance;
        AsymmetricCipherKeyPair key = sm2.ecc_key_pair_generator.GenerateKeyPair();
        ECPrivateKeyParameters ecpriv = (ECPrivateKeyParameters)key.Private;
        ECPublicKeyParameters ecpub = (ECPublicKeyParameters)key.Public;
        BigInteger privateKey = ecpriv.D;
        ECPoint publicKey = ecpub.Q;

        Console.Out.WriteLine("公钥: " + Encoding.ASCII.GetString(Hex.Encode(publicKey.GetEncoded())).ToUpper());
        Console.Out.WriteLine("私钥: " + Encoding.ASCII.GetString(Hex.Encode(privateKey.ToByteArray())).ToUpper());
    }

    public static string Encrypt(byte[] publicKey, byte[] data)
    {
        if (null == publicKey || publicKey.Length == 0)
        {
            return null;
        }
        if (data == null || data.Length == 0)
        {
            return null;
        }

        byte[] source = new byte[data.Length];
        Array.Copy(data, 0, source, 0, data.Length);

        var cipher = new Cipher();
        SM2 sm2 = SM2.Instance;

        ECPoint userKey = sm2.ecc_curve.DecodePoint(publicKey);

        ECPoint c1 = cipher.Init_enc(sm2, userKey);
        cipher.Encrypt(source);

        byte[] c3 = new byte[32];
        cipher.Dofinal(c3);

        string sc1 = Encoding.ASCII.GetString(Hex.Encode(c1.GetEncoded()));
        string sc2 = Encoding.ASCII.GetString(Hex.Encode(source));
        string sc3 = Encoding.ASCII.GetString(Hex.Encode(c3));

        return (sc1 + sc2 + sc3).ToUpper();
    }

    public static byte[] Decrypt(byte[] privateKey, byte[] encryptedData)
    {
        if (null == privateKey || privateKey.Length == 0)
        {
            return null;
        }
        if (encryptedData == null || encryptedData.Length == 0)
        {
            return null;
        }

        string data = Encoding.ASCII.GetString(Hex.Encode(encryptedData));

        byte[] c1Bytes = Hex.Decode(Encoding.ASCII.GetBytes(data.Substring(0, 130)));
        int c2Len = encryptedData.Length - 97;
        byte[] c2 = Hex.Decode(Encoding.ASCII.GetBytes(data.Substring(130, 2 * c2Len)));
        byte[] c3 = Hex.Decode(Encoding.ASCII.GetBytes(data.Substring(130 + 2 * c2Len, 64)));

        SM2 sm2 = SM2.Instance;
        var userD = new BigInteger(1, privateKey);

        ECPoint c1 = sm2.ecc_curve.DecodePoint(c1Bytes);
        var cipher = new Cipher();
        cipher.Init_dec(userD, c1);
        cipher.Decrypt(c2);
        cipher.Dofinal(c3);

        return c2;
    }

    //[STAThread]
    //public static void Main()
    //{
    //    GenerateKeyPair();

    //    String plainText = "ererfeiisgod";
    //    byte[] sourceData = Encoding.Default.GetBytes(plainText);

    //    //下面的秘钥可以使用generateKeyPair()生成的秘钥内容
    //    // 国密规范正式私钥
    //    String prik = "3690655E33D5EA3D9A4AE1A1ADD766FDEA045CDEAA43A9206FB8C430CEFE0D94";
    //    // 国密规范正式公钥
    //    String pubk = "04F6E0C3345AE42B51E06BF50B98834988D54EBC7460FE135A48171BC0629EAE205EEDE253A530608178A98F1E19BB737302813BA39ED3FA3C51639D7A20C7391A";

    //    System.Console.Out.WriteLine("加密: ");
    //    String cipherText = SM2Utils.Encrypt(Hex.Decode(pubk), sourceData);
    //    System.Console.Out.WriteLine(cipherText);
    //    System.Console.Out.WriteLine("解密: ");
    //    plainText = Encoding.Default.GetString(SM2Utils.Decrypt(Hex.Decode(prik), Hex.Decode(cipherText)));
    //    System.Console.Out.WriteLine(plainText);

    //    Console.ReadLine();
    //}

    /// <summary>
    /// SM2加密
    /// </summary>
    /// <param name="plainText">明文</param>
    /// <returns>密文</returns>
    public static String 加密(String plainText)
    {
        // 国密规范正式公钥
        String pubk = "04F6E0C3345AE42B51E06BF50B98834988D54EBC7460FE135A48171BC0629EAE205EEDE253A530608178A98F1E19BB737302813BA39ED3FA3C51639D7A20C7391A";
        byte[] sourceData = Encoding.Default.GetBytes(plainText);
        String cipherText = SM2Util.Encrypt(Hex.Decode(pubk), sourceData);
        return cipherText;
    }

    /// <summary>
    /// SM2解密
    /// </summary>
    /// <param name="cipherText">密文</param>
    /// <returns>明文</returns>
    public static string 解密(String cipherText)
    {
        // 国密规范正式私钥
        String prik = "3690655E33D5EA3D9A4AE1A1ADD766FDEA045CDEAA43A9206FB8C430CEFE0D94";
        String plainText = Encoding.Default.GetString(SM2Util.Decrypt(Hex.Decode(prik), Hex.Decode(cipherText)));
        return plainText;
    }
}