using NCC.Dependency;
using System;
using System.Buffers.Text;
using System.IO;
using System.Runtime.CompilerServices;
using System.Security.Cryptography;
using System.Text;

namespace NCC.DataEncryption
{
    /// <summary>
    /// AES 加解密
    /// </summary>
    [SuppressSniffer]
    public class AESEncryption
    {
        /// <summary>
        /// 加密
        /// </summary>
        /// <param name="text">加密文本</param>
        /// <param name="skey">密钥</param>
        /// <returns></returns>
        public static string Encrypt(string text, string skey)
        {
            var encryptKey = Encoding.UTF8.GetBytes(skey);

            using var aesAlg = Aes.Create();
            using var encryptor = aesAlg.CreateEncryptor(encryptKey, aesAlg.IV);
            using var msEncrypt = new MemoryStream();
            using (var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write, true))

            using (var swEncrypt = new StreamWriter(csEncrypt, leaveOpen: true))
            {
                swEncrypt.Write(text);
            }

            var iv = aesAlg.IV;
            var dataLength = iv.Length + (int)msEncrypt.Length;
            var decryptedContent = msEncrypt.GetBuffer();
            var base64Length = Base64.GetMaxEncodedToUtf8Length(dataLength);
            var result = new byte[base64Length];

            Unsafe.CopyBlock(ref result[0], ref iv[0], (uint)iv.Length);
            Unsafe.CopyBlock(ref result[iv.Length], ref decryptedContent[0], (uint)msEncrypt.Length);

            Base64.EncodeToUtf8InPlace(result, dataLength, out base64Length);

            return Encoding.ASCII.GetString(result.AsSpan()[..base64Length]);
        }

        /// <summary>
        /// 解密
        /// </summary>
        /// <param name="hash">加密后字符串</param>
        /// <param name="skey">密钥</param>
        /// <returns></returns>
        public static string Decrypt(string hash, string skey)
        {
            var fullCipher = Convert.FromBase64String(hash);

            var iv = new byte[16];
            var cipher = new byte[fullCipher.Length - iv.Length];

            Unsafe.CopyBlock(ref iv[0], ref fullCipher[0], (uint)iv.Length);
            Unsafe.CopyBlock(ref cipher[0], ref fullCipher[iv.Length], (uint)(fullCipher.Length - iv.Length));
            var decryptKey = Encoding.UTF8.GetBytes(skey);

            using var aesAlg = Aes.Create();
            using var decryptor = aesAlg.CreateDecryptor(decryptKey, iv);
            using var msDecrypt = new MemoryStream(cipher);
            using var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read);
            using var srDecrypt = new StreamReader(csDecrypt);
            return srDecrypt.ReadToEnd();
        }
    }
}