using Org.BouncyCastle.Crypto;

namespace Admin.NET.Core;

public abstract class GeneralDigest : IDigest
{
    private const int BYTE_LENGTH = 64;

    private readonly byte[] xBuf;
    private int xBufOff;

    private long byteCount;

    internal GeneralDigest()
    {
        xBuf = new byte[4];
    }

    internal GeneralDigest(GeneralDigest t)
    {
        xBuf = new byte[t.xBuf.Length];
        Array.Copy(t.xBuf, 0, xBuf, 0, t.xBuf.Length);

        xBufOff = t.xBufOff;
        byteCount = t.byteCount;
    }

    public void Update(byte input)
    {
        xBuf[xBufOff++] = input;

        if (xBufOff == xBuf.Length)
        {
            ProcessWord(xBuf, 0);
            xBufOff = 0;
        }

        byteCount++;
    }

    public void BlockUpdate(byte[] input, int inOff, int length)
    {
        //
        // fill the current word
        //
        while ((xBufOff != 0) && (length > 0))
        {
            Update(input[inOff]);
            inOff++;
            length--;
        }

        //
        // process whole words.
        //
        while (length > xBuf.Length)
        {
            ProcessWord(input, inOff);

            inOff += xBuf.Length;
            length -= xBuf.Length;
            byteCount += xBuf.Length;
        }

        //
        // load in the remainder.
        //
        while (length > 0)
        {
            Update(input[inOff]);

            inOff++;
            length--;
        }
    }

    public void Finish()
    {
        long bitLength = (byteCount << 3);

        //
        // add the pad bytes.
        //
        Update(unchecked((byte)128));

        while (xBufOff != 0) Update(unchecked((byte)0));
        ProcessLength(bitLength);
        ProcessBlock();
    }

    public virtual void Reset()
    {
        byteCount = 0;
        xBufOff = 0;
        Array.Clear(xBuf, 0, xBuf.Length);
    }

    public int GetByteLength()
    {
        return BYTE_LENGTH;
    }

    internal abstract void ProcessWord(byte[] input, int inOff);

    internal abstract void ProcessLength(long bitLength);

    internal abstract void ProcessBlock();

    public abstract string AlgorithmName { get; }

    public abstract int GetDigestSize();

    public abstract void BlockUpdate(ReadOnlySpan<byte> input);

    public abstract int DoFinal(byte[] output, int outOff);

    public abstract int DoFinal(Span<byte> output);
}

public class SupportClass
{
    /// <summary>
    /// Performs an unsigned bitwise right shift with the specified number
    /// </summary>
    /// <param name="number">Number to operate on</param>
    /// <param name="bits">Ammount of bits to shift</param>
    /// <returns>The resulting number from the shift operation</returns>
    public static int URShift(int number, int bits)
    {
        if (number >= 0)
            return number >> bits;
        else
            return (number >> bits) + (2 << ~bits);
    }

    /// <summary>
    /// Performs an unsigned bitwise right shift with the specified number
    /// </summary>
    /// <param name="number">Number to operate on</param>
    /// <param name="bits">Ammount of bits to shift</param>
    /// <returns>The resulting number from the shift operation</returns>
    public static int URShift(int number, long bits)
    {
        return URShift(number, (int)bits);
    }

    /// <summary>
    /// Performs an unsigned bitwise right shift with the specified number
    /// </summary>
    /// <param name="number">Number to operate on</param>
    /// <param name="bits">Ammount of bits to shift</param>
    /// <returns>The resulting number from the shift operation</returns>
    public static long URShift(long number, int bits)
    {
        if (number >= 0)
            return number >> bits;
        else
            return (number >> bits) + (2L << ~bits);
    }

    /// <summary>
    /// Performs an unsigned bitwise right shift with the specified number
    /// </summary>
    /// <param name="number">Number to operate on</param>
    /// <param name="bits">Ammount of bits to shift</param>
    /// <returns>The resulting number from the shift operation</returns>
    public static long URShift(long number, long bits)
    {
        return URShift(number, (int)bits);
    }
}

public class SM3Digest : GeneralDigest
{
    public override string AlgorithmName
    {
        get
        {
            return "SM3";
        }
    }

    public override int GetDigestSize()
    {
        return DIGEST_LENGTH;
    }

    private const int DIGEST_LENGTH = 32;

    private static readonly int[] v0 = new int[] { 0x7380166f, 0x4914b2b9, 0x172442d7, unchecked((int)0xda8a0600), unchecked((int)0xa96f30bc), 0x163138aa, unchecked((int)0xe38dee4d), unchecked((int)0xb0fb0e4e) };

    private readonly int[] v = new int[8];
    private readonly int[] v_ = new int[8];

    private static readonly int[] X0 = new int[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

    private readonly int[] X = new int[68];
    private int xOff;

    private readonly int T_00_15 = 0x79cc4519;
    private readonly int T_16_63 = 0x7a879d8a;

    public SM3Digest()
    {
        Reset();
    }

    public SM3Digest(SM3Digest t) : base(t)
    {
        Array.Copy(t.X, 0, X, 0, t.X.Length);
        xOff = t.xOff;

        Array.Copy(t.v, 0, v, 0, t.v.Length);
    }

    public override void Reset()
    {
        base.Reset();

        Array.Copy(v0, 0, v, 0, v0.Length);

        xOff = 0;
        Array.Copy(X0, 0, X, 0, X0.Length);
    }

    internal override void ProcessBlock()
    {
        int i;

        int[] ww = X;
        int[] ww_ = new int[64];

        for (i = 16; i < 68; i++)
        {
            ww[i] = P1(ww[i - 16] ^ ww[i - 9] ^ (ROTATE(ww[i - 3], 15))) ^ (ROTATE(ww[i - 13], 7)) ^ ww[i - 6];
        }

        for (i = 0; i < 64; i++)
        {
            ww_[i] = ww[i] ^ ww[i + 4];
        }

        int[] vv = v;
        int[] vv_ = v_;

        Array.Copy(vv, 0, vv_, 0, v0.Length);

        int SS1, SS2, TT1, TT2, aaa;
        for (i = 0; i < 16; i++)
        {
            aaa = ROTATE(vv_[0], 12);
            SS1 = aaa + vv_[4] + ROTATE(T_00_15, i);
            SS1 = ROTATE(SS1, 7);
            SS2 = SS1 ^ aaa;

            TT1 = FF_00_15(vv_[0], vv_[1], vv_[2]) + vv_[3] + SS2 + ww_[i];
            TT2 = GG_00_15(vv_[4], vv_[5], vv_[6]) + vv_[7] + SS1 + ww[i];
            vv_[3] = vv_[2];
            vv_[2] = ROTATE(vv_[1], 9);
            vv_[1] = vv_[0];
            vv_[0] = TT1;
            vv_[7] = vv_[6];
            vv_[6] = ROTATE(vv_[5], 19);
            vv_[5] = vv_[4];
            vv_[4] = P0(TT2);
        }
        for (i = 16; i < 64; i++)
        {
            aaa = ROTATE(vv_[0], 12);
            SS1 = aaa + vv_[4] + ROTATE(T_16_63, i);
            SS1 = ROTATE(SS1, 7);
            SS2 = SS1 ^ aaa;

            TT1 = FF_16_63(vv_[0], vv_[1], vv_[2]) + vv_[3] + SS2 + ww_[i];
            TT2 = GG_16_63(vv_[4], vv_[5], vv_[6]) + vv_[7] + SS1 + ww[i];
            vv_[3] = vv_[2];
            vv_[2] = ROTATE(vv_[1], 9);
            vv_[1] = vv_[0];
            vv_[0] = TT1;
            vv_[7] = vv_[6];
            vv_[6] = ROTATE(vv_[5], 19);
            vv_[5] = vv_[4];
            vv_[4] = P0(TT2);
        }
        for (i = 0; i < 8; i++)
        {
            vv[i] ^= vv_[i];
        }

        // Reset
        xOff = 0;
        Array.Copy(X0, 0, X, 0, X0.Length);
    }

    internal override void ProcessWord(byte[] in_Renamed, int inOff)
    {
        int n = in_Renamed[inOff] << 24;
        n |= (in_Renamed[++inOff] & 0xff) << 16;
        n |= (in_Renamed[++inOff] & 0xff) << 8;
        n |= (in_Renamed[++inOff] & 0xff);
        X[xOff] = n;

        if (++xOff == 16)
        {
            ProcessBlock();
        }
    }

    internal override void ProcessLength(long bitLength)
    {
        if (xOff > 14)
        {
            ProcessBlock();
        }

        X[14] = (int)(SupportClass.URShift(bitLength, 32));
        X[15] = (int)(bitLength & unchecked((int)0xffffffff));
    }

    public static void IntToBigEndian(int n, byte[] bs, int off)
    {
        bs[off] = (byte)(SupportClass.URShift(n, 24));
        bs[++off] = (byte)(SupportClass.URShift(n, 16));
        bs[++off] = (byte)(SupportClass.URShift(n, 8));
        bs[++off] = (byte)(n);
    }

    public override int DoFinal(byte[] out_Renamed, int outOff)
    {
        Finish();

        for (int i = 0; i < 8; i++)
        {
            IntToBigEndian(v[i], out_Renamed, outOff + i * 4);
        }

        Reset();

        return DIGEST_LENGTH;
    }

    private static int ROTATE(int x, int n)
    {
        return (x << n) | (SupportClass.URShift(x, (32 - n)));
    }

    private static int P0(int X)
    {
        return ((X) ^ ROTATE((X), 9) ^ ROTATE((X), 17));
    }

    private static int P1(int X)
    {
        return ((X) ^ ROTATE((X), 15) ^ ROTATE((X), 23));
    }

    private static int FF_00_15(int X, int Y, int Z)
    {
        return (X ^ Y ^ Z);
    }

    private static int FF_16_63(int X, int Y, int Z)
    {
        return ((X & Y) | (X & Z) | (Y & Z));
    }

    private static int GG_00_15(int X, int Y, int Z)
    {
        return (X ^ Y ^ Z);
    }

    private static int GG_16_63(int X, int Y, int Z)
    {
        return ((X & Y) | (~X & Z));
    }

    public override void BlockUpdate(ReadOnlySpan<byte> input)
    {
    }

    public override int DoFinal(Span<byte> output)
    {
        return DIGEST_LENGTH;
    }

    //[STAThread]
    //public static void  Main()
    //{
    //    byte[] md = new byte[32];
    //    byte[] msg1 = Encoding.Default.GetBytes("ererfeiisgod");
    //    SM3Digest sm3 = new SM3Digest();
    //    sm3.BlockUpdate(msg1, 0, msg1.Length);
    //    sm3.DoFinal(md, 0);
    //    System.String s = new UTF8Encoding().GetString(Hex.Encode(md));
    //    System.Console.Out.WriteLine(s.ToUpper());

    //    Console.ReadLine();
    //}
}