using NPOI.POIFS.Crypt.Dsig;
using Org.BouncyCastle.Asn1.GM;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Digests;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Crypto.Signers;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Utilities.Encoders;
using System;
using System.Buffers.Text;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reactive;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Text.Unicode;
using System.Threading.Tasks;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Asn1;

namespace Infrastructure.Helpers
{
    public class EncryptionHelper
    {
        //String privateKey = "ABA4354EFAFE944C2F226A3981C7DC70F43BD6053EDA83F4DC274242BBB23CAA";
        String privateKey = "32E324B2FBA5A6CF0D4645EE2D6B3295A6D9D3682C172B2D32E95EDD04340EF1";
        //String publicKey = "04F1BF1BEFD63F16E5DB3BCD32CA5D9A8E8DF7ADD67D6C4F293FB23F7BDA74F52D31B8DDAD03D955D566505A15D8B7DBE83B42378B8E8749C0EB6E2FBC8675838B";
        //string publickey = "04D6974E2384ECE39F5ADF1473E4B9B60E0D438A6F701F667C0C88D25BE2F8508A3AAFF9D9500ECFFD8E79B2DE58C024B689B5C207486646EA08A352FBB0016D46";
        //string publickey = "04CF7CAE31B5130D1D5D1AC1DC2778D94533868A8D57FC02BBD97B688E07145DAAA96462DC83D9F348261F738D51C049770C43BA53B584917C9E30C6221B737CDD";
        string publickey = "04D9D42CFD9633871B5540A4C891A6230A872EBB661FD2537C19817052728143AF53FEF4B38FCF8C2395C237308B7B8C21D93E94FE34E826220580D7BAFCD5F04B";
        //国土云分中心公钥
        string guotukey = "04CF7CAE31B5130D1D5D1AC1DC2778D94533868A8D57FC02BBD97B688E07145DAAA96462DC83D9F348261F738D51C049770C43BA53B584917C9E30C6221B737CDD";
        byte[] sm4Key = null;
        public EncryptionHelper()
        {
        }

        /// <summary>
        /// 获取x-lc-secret
        /// </summary>
        /// <returns></returns>
        public string getxseret()
        {
            if (sm4Key == null)
            {
                sm4Key = SM4CryptoHelper.GenerateSM4Key();
            }

            //十六进制字符串 → 字节数组  publickey
            byte[] publickeybyte = HexToBytes(guotukey);
            var encryptdatasm2 = SM2CryptoHelper.Encrypt(publickeybyte, sm4Key);
            return Convert.ToBase64String(encryptdatasm2);
        }

        /// <summary>
        /// 数据加密
        /// </summary>
        /// <param name="input"></param>
        /// <returns></returns>
        public string Encrypt(byte[] input)
        {
            if (sm4Key == null)
            {
                sm4Key = SM4CryptoHelper.GenerateSM4Key();
            }
            var encryptdatasm4 = SM4CryptoHelper.Encrypt(sm4Key, input);
            return Convert.ToBase64String(encryptdatasm4);
        }

        /// <summary>
        /// 数据解密
        /// </summary>
        /// <param name="x_lc_screte"></param>
        /// <param name="output"></param>
        /// <returns></returns>
        public string Decrypt(byte[] x_lc_screte, byte[] output)
        {
            byte[] privatekeybyte = HexToBytes(privateKey);
            byte[] sm4key = SM2CryptoHelper.Decrypt(privatekeybyte, x_lc_screte);
            var decryptdata = SM4CryptoHelper.Decrypt(sm4key, output);

            return Encoding.UTF8.GetString(decryptdata);
        }

        /// <summary>
        /// 获取x-lc-token
        /// </summary>
        /// <param name="certCode"></param>
        /// <returns></returns>
        /// <exception cref="InvalidOperationException"></exception>
        public string GetToken(string certCode)
        {
            // 获取毫秒级时间戳（.NET 中 Ticks 转换为毫秒）
            long timestamp = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
            //long timestamp = 1751274197662;

            // 拼接待签名数据
            string needSignData = certCode + timestamp;
            byte[] needSignDataByte = Encoding.UTF8.GetBytes(needSignData);

            // 4. SM2签名
            byte[] signData;
            byte[] privatekeybyte = HexToBytes(privateKey);
            try
            {
                signData = SM2CryptoHelper.Sign(privatekeybyte, needSignDataByte);
            }
            catch (Exception ex)
            {
                throw new InvalidOperationException("SM2签名失败", ex);
            }

            // Base64 编码签名（直接使用 Convert）
            string signDataBase64 = Convert.ToBase64String(signData);

            // 生成 token
            string token = $"{certCode}.{timestamp}.{signDataBase64}";

            return token;
        }

        public bool Verify(string str)
        {
            string signData = "";
            // 拼接待签名数据
            string needSignData = "";

            if (!string.IsNullOrEmpty(str))
            {
                string[] tokenstr = str.Split(".");
                signData = tokenstr[2];
                needSignData = tokenstr[0] + tokenstr[1];
            }
            byte[] signbyte = Convert.FromBase64String(signData);
            byte[] needSignDataByte = Encoding.UTF8.GetBytes(needSignData);
            // 4. SM2验签  publickey
            byte[] publickeybyte = HexToBytes(publickey);
            try
            {
                return SM2CryptoHelper.Verify(publickeybyte, needSignDataByte, signbyte);
            }
            catch (Exception ex)
            {
                throw new InvalidOperationException("SM2签名失败", ex);
            }
        }

        /// <summary>
        /// 内部转byte方法
        /// </summary>
        /// <param name="hex"></param>
        /// <returns></returns>
        /// <exception cref="ArgumentNullException"></exception>
        /// <exception cref="ArgumentException"></exception>
        public static byte[] HexToBytes(string hex)
        {
            if (hex == null)
                throw new ArgumentNullException(nameof(hex));
            if (hex.Length % 2 != 0)
                throw new ArgumentException("十六进制字符串长度必须是偶数");

            byte[] bytes = new byte[hex.Length / 2];
            for (int i = 0; i < bytes.Length; i++)
            {
                string byteStr = hex.Substring(i * 2, 2);
                bytes[i] = Convert.ToByte(byteStr, 16);
            }
            return bytes;
        }

        #region 图片上传校验码生成


        public string GetJYM(string str)
        {
            string sm3str = ComputeSm3Hash(str);

            //return GenerateSm2Signature(sm3str);
            byte[] needSignDataByte = Encoding.UTF8.GetBytes(sm3str);

            // 4. SM2签名
            byte[] signData;
            byte[] privatekeybyte = HexToBytes(privateKey);
            try
            {
                signData = SM2CryptoHelper.Sign(privatekeybyte, needSignDataByte);
                // 将签名结果转换为十六进制大写字符串
                string hexSignature = BytesToHexUpper(signData);

                return hexSignature;
            }
            catch (Exception ex)
            {
                throw new InvalidOperationException("SM2签名失败", ex);
            }

        }

        // 将字节数组转换为十六进制大写字符串
        private static string BytesToHexUpper(byte[] bytes)
        {
            StringBuilder hex = new StringBuilder(bytes.Length * 2);
            foreach (byte b in bytes)
            {
                hex.AppendFormat("{0:X2}", b);
            }
            return hex.ToString();
        }

        /// <summary>
        /// 计算SM3哈希值
        /// </summary>
        private string ComputeSm3Hash(string input)
        {
            byte[] msg = Encoding.UTF8.GetBytes(input);
            SM3Digest digest = new SM3Digest();
            digest.BlockUpdate(msg, 0, msg.Length);
            byte[] result = new byte[digest.GetDigestSize()];
            digest.DoFinal(result, 0);
            return Hex.ToHexString(result).ToUpper();
        }

        #endregion
    }
}