using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using LehrerApp.Core.Interfaces;
using LehrerApp.Core.Models;
using LehrerApp.Core.Services;
using LehrerApp.Data;
using LehrerApp.Desktop.Services;
using LehrerApp.Desktop.ViewModels.Planning;
using LehrerApp.Sync;
using LehrerApp.Sync.Crypto;
using System.Collections.ObjectModel;
using System.Globalization;
using System.Security.Cryptography;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace LehrerApp.Desktop.ViewModels.Settings;

public partial class SettingsViewModel
{
    // ── WebUntis-iCal-Abgleich (Nutzer-Feedback) ──────────────────────────────

    [ObservableProperty] private bool   _untisEnabled;
    [ObservableProperty] private bool   _untisIsConfigured;
    [ObservableProperty] private string _untisIcalUrlInput = "";
    [ObservableProperty] private string _untisUrlError = "";
    [ObservableProperty] private string _untisStatusDisplay = "";
    [ObservableProperty] private bool   _untisFetchBusy;
    [ObservableProperty] private bool   _untisApiIsConfigured;
    [ObservableProperty] private string _untisSchool = "";
    [ObservableProperty] private string _untisHost = "";
    [ObservableProperty] private string _untisUsername = "";
    [ObservableProperty] private string _untisPassword = "";
    [ObservableProperty] private string _untisApiStatus = "";
    [ObservableProperty] private bool   _untisApiBusy;
    [ObservableProperty] private string? _untisHomeroomClassName;
    public string UntisHomeroomClassDisplay => UntisHomeroomClassName is { Length: > 0 } name
        ? $"Ausgewählt: {name}"
        : "Keine Klasse ausgewählt.";
    partial void OnUntisHomeroomClassNameChanged(string? value) => OnPropertyChanged(nameof(UntisHomeroomClassDisplay));
    public Func<Task>? OnReviewUntisMapping { get; set; }
    /// Vom Code-Behind gesetzt: öffnet den WebUntis-Klassenauswahldialog, liefert null bei Abbruch.
    public Func<Task<(int UntisId, string Name)?>>? OnPickHomeroomClass { get; set; }

    // ── WebUntis-iCal-Abgleich: Laden / Speichern / Entfernen / Jetzt abrufen ────
    //
    // Wie bei Sync deckt ein Neustart das Registrieren von UntisSyncService ab
    // (AppBootstrapper registriert es nur einmalig beim Start, wenn URL+Enabled vorliegen).

    private void LoadUntisSettings()
    {
        UntisEnabled = _untisSettings.Enabled;
        UntisIsConfigured = _untisSettings.IsConfigured;
        UntisStatusDisplay = _untisSettings.LastSyncAt is { } at
            ? $"Letzter Abgleich: {at.ToLocalTime():dd.MM.yyyy HH:mm} — {_untisSettings.LastSyncStatus}"
            : "Noch kein Abgleich durchgeführt.";
        UntisApiIsConfigured = _untisSettings.ApiIsConfigured;
        if (_untisSettings.GetApiCredentials() is { } credentials)
        {
            UntisSchool = credentials.School;
            UntisHost = credentials.Host;
            UntisUsername = credentials.Username;
            UntisApiStatus = $"API-Zugang für {credentials.Username} ist lokal verschlüsselt gespeichert.";
        }
        UntisHomeroomClassName = _untisSettings.HomeroomClassName;
    }

    [RelayCommand]
    private async Task UntisSaveApi()
    {
        UntisApiStatus = "";
        if (_untisIntegration is null)
        {
            UntisApiStatus = "Die WebUntis-Integration ist nicht verfügbar.";
            return;
        }
        if (string.IsNullOrWhiteSpace(UntisSchool) || string.IsNullOrWhiteSpace(UntisUsername) ||
            string.IsNullOrWhiteSpace(UntisPassword))
        {
            UntisApiStatus = "Schule, Benutzername und Passwort sind erforderlich.";
            return;
        }
        UntisApiBusy = true;
        try
        {
            var credentials = new WebUntisCredentials(UntisSchool.Trim(), UntisHost.Trim(),
                UntisUsername.Trim(), UntisPassword);
            await _untisIntegration.ConnectAsync(credentials);
            _untisSettings.SetApiCredentials(credentials);
            UntisPassword = "";
            UntisApiIsConfigured = true;
            UntisApiStatus = "Anmeldung erfolgreich. Die WebUntis-Session bleibt bei Nutzung bis zu 10 Minuten offen.";
        }
        catch (WebUntisIntegrationException ex) { UntisApiStatus = ex.Message; }
        finally { UntisApiBusy = false; }
    }

    [RelayCommand]
    private async Task UntisRemoveApi()
    {
        UntisApiBusy = true;
        try { if (_untisIntegration is not null) await _untisIntegration.DisconnectAsync(); }
        catch (WebUntisIntegrationException) { /* lokale Zugangsdaten trotzdem sicher entfernen */ }
        finally
        {
            _untisSettings.ClearApiCredentials();
            UntisPassword = "";
            UntisApiIsConfigured = false;
            UntisApiStatus = "WebUntis-API-Zugang entfernt.";
            UntisApiBusy = false;
        }
    }

    [RelayCommand]
    private void UntisSaveUrl()
    {
        UntisUrlError = "";
        if (string.IsNullOrWhiteSpace(UntisIcalUrlInput)) { UntisUrlError = "iCal-URL erforderlich."; return; }
        if (!Uri.TryCreate(UntisIcalUrlInput, UriKind.Absolute, out _)) { UntisUrlError = "Ungültige URL."; return; }

        _untisSettings.SetIcalUrl(UntisIcalUrlInput.Trim());
        _untisSettings.SetEnabled(true);
        UntisIcalUrlInput = "";
        AppBootstrapper.RestartApplication();
    }

    [RelayCommand]
    private void UntisRemove()
    {
        _untisSettings.ClearIcalUrl();
        LoadUntisSettings();
        AppBootstrapper.RestartApplication();
    }

    [RelayCommand]
    private async Task UntisFetchNow()
    {
        if (_untisSync is null) { UntisStatusDisplay = "Abgleich nicht aktiv — App neu starten."; return; }
        UntisFetchBusy = true;
        try
        {
            await _untisSync.PollAsync();
            LoadUntisSettings();
        }
        finally { UntisFetchBusy = false; }
    }

    [RelayCommand]
    private async Task UntisReviewMapping()
    {
        if (OnReviewUntisMapping is not null) await OnReviewUntisMapping();
    }

    [RelayCommand]
    private async Task UntisPickHomeroomClass()
    {
        if (OnPickHomeroomClass is null) return;
        var result = await OnPickHomeroomClass();
        if (result is null) return;
        _untisSettings.SetHomeroomClass(result.Value.UntisId, result.Value.Name);
        LoadUntisSettings();
    }

    [RelayCommand]
    private void UntisClearHomeroomClass()
    {
        _untisSettings.SetHomeroomClass(null, null);
        LoadUntisSettings();
    }
}