CVRManager/Services/BranchCodeService.cs

using SteamKit2;

namespace CVRManager.Services;

public static class BranchCodeService
{
    public static async Task<Dictionary<string, byte[]>> ResolveAsync(string code, string account, string refreshToken, CancellationToken ct)
    {
        await using var link = await SteamLink.OpenAsync(account, refreshToken, ct);
        return await ResolveAsync(link, code);
    }

    public static async Task<Dictionary<string, byte[]>> ResolveAsync(SteamLink link, string code)
    {
        var call = link.Apps.CheckAppBetaPassword((uint)Paths.AppId, code).ToTask();
        if (await Task.WhenAny(call, Task.Delay(TimeSpan.FromSeconds(25))) != call)
            throw new TimeoutException("Steam did not answer the code check. It limits how often codes can be checked; try again in a few minutes.");
        var reply = await call;
        if (reply.Result == EResult.OK) return new Dictionary<string, byte[]>(reply.BetaPasswords);
        throw new InvalidOperationException(reply.Result switch
        {
            EResult.InvalidPassword => "Steam did not accept that access code.",
            EResult.RateLimitExceeded => "Steam is rate limiting code checks. Wait a few minutes and try again.",
            _ => $"Steam could not check the code ({reply.Result}){(link.IsAnonymous ? "; sign in to Steam in Settings and try again" : "")}.",
        });
    }

    public static string ProtectKey(byte[] key) => TokenVault.Protect(Convert.ToBase64String(key));

    public static byte[]? UnprotectKey(string stored)
    {
        var text = TokenVault.Unprotect(stored);
        try { return text.Length == 0 ? null : Convert.FromBase64String(text); }
        catch (FormatException) { return null; }
    }
}