Jugenddienst-Stunden/Jugenddienst Stunden/ViewModels/LoginViewModel.cs

using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using Jugenddienst_Stunden.Interfaces;

namespace Jugenddienst_Stunden.ViewModels;

/// <summary>
/// ViewModel für die Loginseite (MVVM)
/// </summary>
public partial class LoginViewModel : ObservableObject {
	private readonly IAuthService _auth;
	private readonly IAppSettings _settings;
	private readonly IAlertService? _alerts;
	private DateTime _lastDetectionTime = DateTime.MinValue;
	private readonly TimeSpan _detectionInterval = TimeSpan.FromSeconds(5);

	public event EventHandler<string>? AlertEvent;
	public event EventHandler<string>? InfoEvent;

	/// <summary>
	/// Name der Anwendung
	/// </summary>
	public string AppTitle => AppInfo.Name;

	/// <summary>
	/// Programmversion
	/// </summary>
	public string Version => AppInfo.VersionString;

	[ObservableProperty]
	private string message = "Scanne den QR-Code von deinem Benutzerprofil auf der Stundenseite.";

	[ObservableProperty]
	private string? server;

	[ObservableProperty]
	private string? serverLabel;

	[ObservableProperty]
	private string title = Preferences.Default.Get("name", "Nicht") + " " + Preferences.Default.Get("surname", "eingeloggt");

	[ObservableProperty]
	private string? username;

	[ObservableProperty]
	private string? password;

	[ObservableProperty]
	private bool isManualMode;

	[ObservableProperty]
	private bool isBusy;

	[ObservableProperty]
	private bool isDetecting;

	// Explizite Command-Property für den QR-Scanner-Event, damit das Binding in XAML zuverlässig greift
	public IAsyncRelayCommand<object?> QrDetectedCommand { get; }

	public LoginViewModel(IAuthService auth, IAppSettings settings) {
		_auth = auth;
		_settings = settings;

		// gespeicherte Präferenz für Logintyp laden
		var lt = Preferences.Default.Get("logintype", "qr");
		isManualMode = string.Equals(lt, "manual", StringComparison.OrdinalIgnoreCase);
		// Scanner standardmäßig nur im QR-Modus aktivieren
		IsDetecting = !isManualMode;

		// Serveranzeige vorbereiten
		var apiUrl = Preferences.Default.Get("apiUrl", string.Empty);
		if (!string.IsNullOrWhiteSpace(apiUrl)) {
			Server = apiUrl.Replace("/appapi", "").Replace("https://", "").Replace("http://", "");
			ServerLabel = "Server: " + Server;
		}

		// Command initialisieren
		QrDetectedCommand = new AsyncRelayCommand<object?>(QrDetectedAsync);
	}

	// DI-Konstruktor: AlertService anbinden und Alerts an VM-Event weiterreichen (analog StundeViewModel)
	internal LoginViewModel(IAuthService auth, IAppSettings settings, IAlertService alertService) : this(auth, settings) {
		_alerts = alertService;
		if (alertService is not null) {
			alertService.AlertRaised += (s, msg) => AlertEvent?.Invoke(this, msg);
		}
	}

	partial void OnIsManualModeChanged(bool value) {
		Preferences.Default.Set("logintype", value ? "manual" : "qr");
		// Scanner nur aktiv, wenn QR-Modus aktiv ist
		IsDetecting = !value;
	}

	[RelayCommand]
	private async Task LoginAsync() {
		if (IsBusy) return;
		try {
			IsBusy = true;
			var user = await _auth.LoginWithCredentials(Username?.Trim() ?? string.Empty,
				Password ?? string.Empty,
				(Server ?? string.Empty).Trim());

			Title = $"{user.Name} {user.Surname}";
			InfoEvent?.Invoke(this, "Login erfolgreich");

			await Shell.Current.GoToAsync("//StundenPage");
		} catch (Exception ex) {
			if (_alerts is not null) {
				_alerts.Raise(ex.Message);
			} else {
				AlertEvent?.Invoke(this, ex.Message);
			}
		} finally {
			IsBusy = false;
		}
	}

	private async Task QrDetectedAsync(object? args) {
		var now = DateTime.Now;
		if ((now - _lastDetectionTime) <= _detectionInterval) return;
		_lastDetectionTime = now;

		try {
			var token = ExtractFirstBarcodeValue(args);
			if (string.IsNullOrWhiteSpace(token)) return;

			var user = await _auth.LoginWithToken(token);
			Title = $"{user.Name} {user.Surname}";

			await Shell.Current.GoToAsync("//StundenPage");
		} catch (Exception ex) {
			if (_alerts is not null) {
				_alerts.Raise(ex.Message);
			} else {
				AlertEvent?.Invoke(this, ex.Message);
			}
		}
	}

	private static string? ExtractFirstBarcodeValue(object? args) {
		try {
			if (args is ZXing.Net.Maui.BarcodeDetectionEventArgs e && e.Results is not null) {
				return e.Results.FirstOrDefault()?.Value;
			}
		} catch { }
		return null;
	}
}