using Avalonia.Controls;
using Avalonia.Interactivity;
using LehrerApp.Core.Interfaces;
using LehrerApp.Core.Models;
using LehrerApp.Core.Services;
using LehrerApp.Desktop.ViewModels;
using LehrerApp.Desktop.ViewModels.Planning;
using LehrerApp.Desktop.ViewModels.Groups;
using LehrerApp.Desktop.Views.Groups;
using LehrerApp.Desktop.Services;
using Microsoft.Extensions.DependencyInjection;

namespace LehrerApp.Desktop.Views.Planning;

public partial class TimetableView : UserControl
{
    public TimetableView() => InitializeComponent();

    protected override void OnDataContextChanged(EventArgs e)
    {
        base.OnDataContextChanged(e);
        if (DataContext is TimetableViewModel vm)
        {
            vm.OnEditSlot = ShowSlotDialog;
            vm.OnAddSubstitution = ShowSubstitutionDialog;
            vm.OnImportWebUntisTimetable = ShowWebUntisTimetableDialog;
            vm.OnOpenLessonViewer = ShowLessonViewerDialog;
            vm.OnOpenTeachingMode = ShowTeachingMode;
            vm.OnCreateLesson = ShowCreateLessonDialog;
            vm.OnMoveLesson = ShowMoveLessonDialog;
        }
    }

    /// Nutzer-Feedback (zweite Runde — die erste Fassung hatte das Problem an der falschen
    /// Stelle gelöst, in der "Heute"-Tagesliste statt im Wochenraster): im Wochenraster oben
    /// führt ein Klick auf eine Stunden-Kachel bislang entweder in den Planungsviewer oder zur
    /// Einheitenplanung — je nachdem, ob schon eine Lesson existiert, ohne dass das von außen
    /// erkennbar wäre. Popup-Menü (MenuFlyout, kein ComboBox mehr) mit allen Zielen einschließlich
    /// Direktanlage und Verschieben als
    /// Alternative zum Direktklick, siehe <see cref="TimetableViewModel.OpenWeekCellCommand"/>
    /// für den "einheitlicheren" Standard-Klick (Unterrichtsansicht bei laufender Stunde, sonst
    /// Planungsviewer, sonst Direktanlage). MenuItem.Click statt Command-Binding: ein
    /// $parent[ItemsControl]-Vorfahrenpfad (wie beim Zeilen-Button) funktioniert innerhalb eines
    /// Flyouts nicht zuverlässig, weil dessen Popup nicht im normalen visuellen Baum hängt (siehe
    /// TODO.md-Nachtrag zum Klassenlehrer-Bereich) — DataContext-Vererbung (kein Pfad-Suchen,
    /// nur der normale Eltern-Wert) funktioniert dort aber sehr wohl, deshalb liest der Handler
    /// die Zelle über <c>((MenuItem)sender).DataContext</c> statt über eine Binding.
    private async void OnWeekCellMenuItemClick(object? sender, RoutedEventArgs e)
    {
        if (sender is not MenuItem { Tag: TimetableLessonDestination destination } menuItem) return;
        if (menuItem.DataContext is not WeekCellItem cell) return;
        if (DataContext is not TimetableViewModel vm) return;

        switch (destination)
        {
            case TimetableLessonDestination.TeachingMode:
                if (cell.Lesson is { } teachLesson && vm.OnOpenTeachingMode is not null)
                    await vm.OnOpenTeachingMode(teachLesson);
                break;
            case TimetableLessonDestination.Viewer:
                if (cell.Lesson is { } viewLesson && vm.OnOpenLessonViewer is not null)
                    await vm.OnOpenLessonViewer(viewLesson);
                break;
            case TimetableLessonDestination.Create:
                if (cell.Date is { } createDate && vm.OnCreateLesson is not null)
                    await vm.OnCreateLesson(new TimetableLessonRequest(cell.GroupId, createDate, cell.PeriodNumber));
                break;
            case TimetableLessonDestination.Move:
                if (cell.Lesson is { } moveLesson && vm.OnMoveLesson is not null)
                    await vm.OnMoveLesson(new TimetableLessonMoveRequest(moveLesson, cell.PeriodNumber));
                break;
            case TimetableLessonDestination.Planning:
                if (cell.GroupId != Guid.Empty)
                    App.Services.GetRequiredService<MainWindowViewModel>().NavigateToGroupDetail(cell.GroupId, 6);
                break;
            case TimetableLessonDestination.SeatingPlan:
                if (cell.GroupId != Guid.Empty)
                    App.Services.GetRequiredService<MainWindowViewModel>().NavigateToGroupDetail(cell.GroupId, 2);
                break;
        }
    }

    private async Task ShowCreateLessonDialog(TimetableLessonRequest request)
    {
        var owner = TopLevel.GetTopLevel(this) as Window;
        var groups = App.Services.GetRequiredService<IGroupRepository>();
        var group = groups.GetById(request.GroupId);
        if (owner is null || group is null || !group.IsActive) return;

        var lessons = App.Services.GetRequiredService<ILessonRepository>();
        if (lessons.GetByGroupAndDate(request.GroupId, request.Date)
            .Any(l => l.LessonNumber == request.PeriodNumber))
        {
            App.Services.GetRequiredService<NotificationService>()
                .ShowError("Für diesen Termin existiert bereits eine Stundenplanung.");
            return;
        }

        var units = App.Services.GetRequiredService<IUnitRepository>();
        var pickerVm = new TimetableUnitPickerViewModel(units, group.Id, group.Name,
            request.Date, request.PeriodNumber);
        var picker = new TimetableUnitPickerDialog { DataContext = pickerVm };
        if (!await picker.ShowDialog<bool>(owner) || pickerVm.Result is not { } unit) return;

        var groupLessons = units.GetByGroup(group.Id).SelectMany(u => lessons.GetByUnit(u.Id)).ToList();
        var materials = groupLessons.SelectMany(l => l.Phases).Select(p => p.Material)
            .Where(x => !string.IsNullOrWhiteSpace(x)).Distinct(StringComparer.OrdinalIgnoreCase)
            .OrderBy(x => x, StringComparer.CurrentCultureIgnoreCase).ToList();
        var shorthands = groupLessons.SelectMany(l => l.Phases).Select(p => p.Shorthand)
            .Where(x => !string.IsNullOrWhiteSpace(x)).Distinct(StringComparer.OrdinalIgnoreCase)
            .OrderBy(x => x, StringComparer.CurrentCultureIgnoreCase).ToList();
        var subject = group.SubjectId is { } subjectId
            ? App.Services.GetRequiredService<ISubjectRepository>().GetById(subjectId) : null;

        var lessonVm = new LessonDialogViewModel(
            lessons,
            App.Services.GetRequiredService<IShorthandCodeRepository>(),
            App.Services.GetRequiredService<IAlternativeLessonPathRepository>(),
            App.Services.GetRequiredService<ITimetableSlotRepository>(),
            App.Services.GetRequiredService<PeriodScheduleService>(),
            App.Services.GetRequiredService<IAttachmentStorage>(),
            unit.Id, group.Id, group.Name, subject?.Name ?? "", materials, shorthands,
            editingLesson: null, suggestedDate: request.Date, suggestedPeriod: request.PeriodNumber);
        var lessonDialog = new LessonDialog { DataContext = lessonVm };
        if (await lessonDialog.ShowDialog<bool>(owner) && lessonVm.Result is not null)
        {
            if (pickerVm.ResultIsNew) units.Save(unit);
            (DataContext as TimetableViewModel)?.Load();
            App.Services.GetRequiredService<NotificationService>().ShowSuccess("Stunde angelegt.");
        }
    }

    private async Task ShowMoveLessonDialog(TimetableLessonMoveRequest request)
    {
        var owner = TopLevel.GetTopLevel(this) as Window;
        if (owner is null) return;
        var lesson = request.Lesson;
        var slots = App.Services.GetRequiredService<ITimetableSlotRepository>();
        var schedule = App.Services.GetRequiredService<PeriodScheduleService>();
        var anchor = lesson.LessonNumber;
        var firstPartMinutes = anchor is int p ? schedule.GetDurationMinutes(p) : 0;
        var isDouble = anchor is int start && firstPartMinutes > 0 &&
            slots.GetByGroup(lesson.GroupId).Any(s => s.Weekday == lesson.Date.DayOfWeek &&
                s.PeriodNumber == start + 1) && lesson.Phases.Sum(x => x.DurationMinutes) > firstPartMinutes;

        var dialogVm = new MoveLessonDialogViewModel(lesson.Date, lesson.LessonNumber, isDouble,
            isDouble && anchor is int a && request.SelectedPeriod > a);
        var dialog = new MoveLessonDialog { DataContext = dialogVm };
        if (!await dialog.ShowDialog<bool>(owner) || dialogVm.Result is not { } target) return;

        try
        {
            var service = new LessonSchedulingService(App.Services.GetRequiredService<ILessonRepository>());
            if (target.SplitDoubleLesson)
            {
                if (target.NewPeriod is not int newPeriod)
                    throw new InvalidOperationException("Für den zweiten Teil ist eine Zielstunde erforderlich.");
                service.SplitAndMoveSecondPart(lesson, firstPartMinutes, target.NewDate, newPeriod,
                    schedule.GetTimes(newPeriod)?.Start);
            }
            else service.Move(lesson, target.NewDate, target.NewPeriod, target.ShiftFollowing);

            (DataContext as TimetableViewModel)?.Load();
            App.Services.GetRequiredService<NotificationService>().ShowSuccess(
                target.SplitDoubleLesson ? "Doppelstunde getrennt und Fortsetzung verschoben." : "Stunde verschoben.");
        }
        catch (InvalidOperationException ex)
        {
            App.Services.GetRequiredService<NotificationService>().ShowError(ex.Message);
        }
    }

    private async Task ShowWebUntisTimetableDialog()
    {
        var owner = TopLevel.GetTopLevel(this) as Window;
        if (owner is null) return;
        var vm = new WebUntisTimetableImportViewModel(
            App.Services.GetRequiredService<WebUntisIntegrationService>(),
            App.Services.GetRequiredService<WebUntisSettingsService>(),
            App.Services.GetRequiredService<ITimetableSlotRepository>(),
            App.Services.GetRequiredService<IGroupRepository>());
        var dialog = new WebUntisTimetableImportDialog { DataContext = vm };
        vm.OnCreateGroup = dialog.CreateGroupAsync;
        await vm.InitializeAsync();
        await dialog.ShowDialog<bool>(owner);
    }

    private Task ShowTeachingMode(Lesson lesson)
    {
        TeachingModeWindow.Open(lesson);
        return Task.CompletedTask;
    }

    private async Task ShowLessonViewerDialog(Lesson lesson)
    {
        var owner = TopLevel.GetTopLevel(this) as Window;
        if (owner is null) return;

        var viewerVm = new LessonViewerViewModel(lesson,
            App.Services.GetRequiredService<IAlternativeLessonPathRepository>());
        var dialog = new LessonViewerDialog { DataContext = viewerVm };
        await dialog.ShowDialog(owner);
    }

    private async Task ShowSlotDialog(TimetableCellItem cell)
    {
        var owner = TopLevel.GetTopLevel(this) as Window;
        if (owner is null || cell.Weekday is null) return;

        var vm = new TimetableSlotDialogViewModel(
            App.Services.GetRequiredService<ITimetableSlotRepository>(),
            App.Services.GetRequiredService<IGroupRepository>(),
            App.Services.GetRequiredService<ISubjectRepository>(),
            App.Services.GetRequiredService<SchoolYearService>(),
            cell.Weekday.Value, cell.PeriodNumber, cell.Slot);

        var dialog = new TimetableSlotDialog { DataContext = vm };
        await dialog.ShowDialog(owner);
    }

    private async Task ShowSubstitutionDialog()
    {
        var owner = TopLevel.GetTopLevel(this) as Window;
        if (owner is null) return;

        var vm = new SubstitutionEntryDialogViewModel(
            App.Services.GetRequiredService<ISubstitutionEntryRepository>(),
            App.Services.GetRequiredService<IGroupRepository>(),
            App.Services.GetRequiredService<IUnitRepository>(),
            App.Services.GetRequiredService<ILessonRepository>());

        var dialog = new SubstitutionEntryDialog { DataContext = vm };
        await dialog.ShowDialog(owner);
    }
}