using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using LehrerApp.Core.Services;
using LehrerApp.Desktop.ViewModels.Groups;
using LehrerApp.Desktop.ViewModels.Students;
using Microsoft.Extensions.DependencyInjection;

namespace LehrerApp.Desktop.ViewModels;

public partial class MainWindowViewModel : ObservableObject
{
    private readonly IServiceProvider _services;

    [ObservableProperty]
    private ObservableObject? _currentPage;

    [ObservableProperty]
    private NavItem _activeNavItem = NavItem.Dashboard;

    // ── Fehlende Property die im MainWindow.axaml referenziert wird ───────────
    [ObservableProperty]
    private string _currentSchoolYear = "";

    public MainWindowViewModel(
        IServiceProvider services,
        DashboardViewModel dashboard,
        SchoolYearService schoolYearService)
    {
        _services = services;
        CurrentPage = dashboard;
        CurrentSchoolYear = schoolYearService.CurrentSchoolYear();
    }

    // ── Navigation ────────────────────────────────────────────────────────────

    [RelayCommand]
    private void NavigateTo(NavItem item)
    {
        ActiveNavItem = item;
        CurrentPage = item switch
        {
            NavItem.Dashboard  => _services.GetRequiredService<DashboardViewModel>(),
            NavItem.Groups     => _services.GetRequiredService<GroupListViewModel>(),
            NavItem.Students   => _services.GetRequiredService<StudentListViewModel>(),
            NavItem.Exams      => CreatePlaceholder("Klausuren"),
            NavItem.Planner    => CreatePlaceholder("Unterrichtsplanung"),
            NavItem.Workload   => CreatePlaceholder("Arbeitszeit"),
            NavItem.Settings   => CreatePlaceholder("Einstellungen"),
            _ => CurrentPage,
        };
    }

    public void NavigateToGroup(Guid groupId)
    {
        ActiveNavItem = NavItem.Groups;
        var vm = _services.GetRequiredService<GroupDetailViewModel>();
        vm.LoadGroup(groupId);
        CurrentPage = vm;
    }

    public void NavigateToStudent(Guid studentId)
    {
        ActiveNavItem = NavItem.Students;
        var vm = _services.GetRequiredService<StudentDetailViewModel>();
        vm.LoadStudent(studentId);
        CurrentPage = vm;
    }

    private static PlaceholderViewModel CreatePlaceholder(string title) =>
        new() { Title = title };
}

public enum NavItem
{
    Dashboard,
    Groups,
    Students,
    Exams,
    Planner,
    Workload,
    Settings,
}

public partial class PlaceholderViewModel : ObservableObject
{
    [ObservableProperty] private string _title = "";
}