app/APP/RegisterWin.cs

using APP.DTO;
using APP.Utility;

namespace APP;

public partial class RegisterWin : Form
{
    private readonly Auth? _prevAuth;
    private readonly List<User>? _users;
    private bool _exist;
    private bool _uChecked;
    private User? _user;

    public Auth Auth;
    public bool Cancelled;

    public RegisterWin(Auth? prevAuth, List<User>? existing)
    {
        _prevAuth = prevAuth;
        _user = new User();
        _users = existing;
        Cancelled = true;
        Auth = new Auth();
        InitializeComponent();
        Load += OnLoadEv;
    }

    private async Task<bool> PerformRegister(User user, Auth auth)
    {
        if (_exist)
        {
            // only try change login
            return await BackendComms.Auth(auth.Username, auth.Secret);
        }

        var register = new Register
        {
            Username = user.Username,
            MalId = user.Id,
            Secret = auth.Secret,
            Sauce = StringAssemble.CalcSauce(user.Id, user.Username)
        };
        var res = await BackendComms.Register(register);
        return res != null;
    }

    private void OnLoadEv(object? sender, EventArgs e)
    {
        // check if we exist
        if (_users == null || _users.All(u => u.Username != _prevAuth?.Username)) return;
        _exist = true;
        usernameBox.Name = _prevAuth?.Username;
    }

    private void cancelButton_Click(object sender, EventArgs e)
    {
        Cancelled = true;
        Close();
    }

    private async void okButton_Click(object sender, EventArgs e)
    {
        if (_uChecked && _user != null && !string.IsNullOrEmpty(_user.Username) && !string.IsNullOrEmpty(secretBox.Text))
        {
            // PERFORM ACTUAL REGISTER
            Auth = new Auth
            {
                Username = _user.Username,
                Secret = StringAssemble.CalcSha512(secretBox.Text)
            };
            if (await PerformRegister(_user, Auth))
            {
                await SaveBoy.SaveAuth(Auth);
                Cancelled = false;
            }
            else
            {
                MessageBox.Show(_exist ? @"Passwortänderung hat nicht geklappt -> Frag Admin" : @"Registrieren hat nicht geklappt", @"FEHLER", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        Close();
    }

    private async void checkUserButton_Click(object sender, EventArgs e)
    {
        _user = await BackendComms.GetUser(usernameBox.Text);
        if (_user == null || string.IsNullOrEmpty(_user.Username) || _user.Id == 0)
        {
            MessageBox.Show(@"Benutzer gibts nicht", @"FEHLER", MessageBoxButtons.OK, MessageBoxIcon.Error);
            return;
        }

        if (!string.IsNullOrWhiteSpace(_user.ImageUrl))
        {
            pictureBox.LoadAsync(_user.ImageUrl);
            pictureBox.Visible = true;
        }

        _exist = _users != null && _users.Any(u => u.Username == _user.Username);
        MessageBox.Show($@"Hi {_user.Username} mit ID {_user.Id}", @"OK", MessageBoxButtons.OK, MessageBoxIcon.Information);
        _uChecked = true;
    }

    private void usernameBox_TextChanged(object sender, EventArgs e)
    {
        _uChecked = false;
        pictureBox.Visible = false;
        checkUserButton.Enabled = !string.IsNullOrWhiteSpace(usernameBox.Text);
    }

    private void secretBox_TextChanged(object sender, EventArgs e)
    {
        var same = !string.IsNullOrWhiteSpace(secretBox.Text) && !string.IsNullOrWhiteSpace(secretBox2.Text) && secretBox.Text == secretBox2.Text;
        pwcheckLabel.Text = same ? @"✅" : @"❌";
        okButton.Enabled = _uChecked && same;
    }

    private void secretBox2_TextChanged(object sender, EventArgs e)
    {
        var same = !string.IsNullOrWhiteSpace(secretBox.Text) && !string.IsNullOrWhiteSpace(secretBox2.Text) && secretBox.Text == secretBox2.Text;
        pwcheckLabel.Text = same ? @"✅" : @"❌";
        okButton.Enabled = _uChecked && same;
    }
}