TinfoilVibeServer/TinfoilVibeServer/Utilities/IdHelper.cs

using System.Globalization;
using System.Text.RegularExpressions;

namespace TinfoilVibeServer.Utilities;


public static class IdHelper
{
    public static string ToStrId(this int num)
    {
        return ToIdFromConvertedNumBytes(BitConverter.GetBytes(num));
    }

    public static string ToStrId(this uint num)
    {
        return ToIdFromConvertedNumBytes(BitConverter.GetBytes(num));
    }

    public static string ToStrId(this long num)
    {
        return ToIdFromConvertedNumBytes(BitConverter.GetBytes(num));
    }

    public static string ToStrId(this ulong num)
    {
        return ToIdFromConvertedNumBytes(BitConverter.GetBytes(num));
    }

    public static string ToStrId(this IEnumerable<byte> bytes)
    {
        return bytes.Aggregate("", (current, b) => current + b.ToString("X2"));
    }  
    
    public static string ToStrId(this Span<byte> bytes)
    {
        return bytes.ToArray().ToStrId();
    }

    private static string ToIdFromConvertedNumBytes(IEnumerable<byte> getBytes)
    {
        return ToStrId(getBytes.Reverse());
    }
    
    public static string GetTitleId(this FileInfo fileInfo)
    {
        var match = Regex.Match(fileInfo.Name, "^.*\\[(\\w{16})\\].*\\.nsp$");
        return match is { Length: > 0, Groups.Count: > 1 }?match.Groups[1].Value:string.Empty;
    } 
    #region 1️⃣ From hex string → byte[] (big‑endian)

    /// <summary>
    /// Turns an even‑length hex string into a byte array in **big‑endian** order
    /// (the same order that the original <c>ToStrId</c> creates).
    /// </summary>
    private static byte[] HexStringToBytes(string hex)
    {
        if (string.IsNullOrWhiteSpace(hex))
            throw new ArgumentException("ID string cannot be empty", nameof(hex));

        if (hex.Length % 2 != 0)
            throw new ArgumentException("ID string must contain an even number of hex digits", nameof(hex));

        var bytes = new byte[hex.Length / 2];
        for (var i = 0; i < bytes.Length; i++)
        {
            var chunk = hex.Substring(i * 2, 2);
            bytes[i] = byte.Parse(chunk, NumberStyles.HexNumber, CultureInfo.InvariantCulture);
        }

        return bytes;
    }

    #endregion

    public static long ToLongFromStrId(this string hex) =>
        BitConverter.ToInt64(HexStringToBytes(hex).Reverse().ToArray(), 0);

}