using System.Buffers.Binary;
using Yuanshen.Common.Security.Util;

namespace Yuanshen.Common.Security;

public static class MhySecurity
{
    public static byte[] InitialKey { get; } = new byte[0x1000];

    public static byte[] GenerateSecretKey(ulong seed)
    {
        byte[] key = GC.AllocateUninitializedArray<byte>(0x1000);
        Span<byte> keySpan = key.AsSpan();

        MT19937 mt = new(seed);

        for (int i = 0; i < 0x1000; i += 8)
        {
            BinaryPrimitives.WriteUInt64BigEndian(keySpan[i..], mt.Int63());
        }

        return key;
    }

    public static void Xor(Span<byte> data, ReadOnlySpan<byte> key)
    {
        for (int i = 0; i < data.Length; i++)
        {
            data[i] ^= key[i % key.Length];
        }
    }
}