using Avalonia;
using Avalonia.Controls;
using LehrerApp.Desktop.Services;
using LehrerApp.WebUntis;
using Microsoft.Extensions.DependencyInjection;

namespace LehrerApp.Desktop.Views;

public sealed class OpenUntisPeriodsDialog : Window
{
    private readonly WebUntisIntegrationService _service = App.Services.GetRequiredService<WebUntisIntegrationService>();
    private readonly WebUntisSettingsService _settings = App.Services.GetRequiredService<WebUntisSettingsService>();
    private readonly CancellationTokenSource _closed = new();
    private readonly ComboBox _mode = new() { ItemsSource = new[] { "Mein Unterricht", "Meine Klasse" }, SelectedIndex = 0 };
    private readonly ComboBox _element = new() { MinWidth = 150 };
    private readonly DatePicker _start = new();
    private readonly DatePicker _end = new() { SelectedDate = DateTimeOffset.Now };
    private readonly Button _load = new() { Content = "Abrufen" };
    private readonly Button _schoolYear = new() { Content = "Seit Schuljahresbeginn" };
    private readonly TextBlock _status = new() { TextWrapping = Avalonia.Media.TextWrapping.Wrap };
    private readonly StackPanel _rows = new() { Spacing = 12 };
    private readonly StackPanel _filters = new() { Spacing = 10, IsEnabled = false };
    private UntisOpenPeriodsMeta? _meta;
    private int _yearId;

    public OpenUntisPeriodsDialog()
    {
        Title = "Offene WebUntis-Stunden";
        Width = 850; Height = 650; MinWidth = 600; MinHeight = 450;
        WindowStartupLocation = WindowStartupLocation.CenterOwner;
        var root = new DockPanel { Margin = new Thickness(20) };
        var header = new StackPanel { Spacing = 12 };
        header.Children.Add(new TextBlock { Text = Title, FontSize = 22 });
        var selection = new StackPanel { Orientation = Avalonia.Layout.Orientation.Horizontal, Spacing = 12 };
        selection.Children.Add(_mode); selection.Children.Add(_element);
        _filters.Children.Add(selection);
        var dates = new WrapPanel { Orientation = Avalonia.Layout.Orientation.Horizontal };
        dates.Children.Add(new TextBlock { Text = "Von ", VerticalAlignment = Avalonia.Layout.VerticalAlignment.Center });
        dates.Children.Add(_start);
        dates.Children.Add(new TextBlock { Text = "  bis ", VerticalAlignment = Avalonia.Layout.VerticalAlignment.Center });
        dates.Children.Add(_end);
        _filters.Children.Add(dates);
        var actions = new StackPanel { Orientation = Avalonia.Layout.Orientation.Horizontal, Spacing = 12 };
        actions.Children.Add(_schoolYear); actions.Children.Add(_load);
        _filters.Children.Add(actions);
        header.Children.Add(_filters); header.Children.Add(_status);
        DockPanel.SetDock(header, Dock.Top); root.Children.Add(header);
        root.Children.Add(new ScrollViewer { Content = _rows, Margin = new Thickness(0, 20, 0, 0) });
        Content = root;
        _mode.SelectionChanged += (_, _) => SelectMode();
        _element.SelectionChanged += (_, _) => ClearResults();
        _start.SelectedDateChanged += (_, _) => ClearResults();
        _end.SelectedDateChanged += (_, _) => ClearResults();
        _schoolYear.Click += (_, _) => { if (_meta is not null) _start.SelectedDate = new DateTimeOffset(_meta.SchoolYearStart.ToDateTime(TimeOnly.MinValue)); };
        _load.Click += async (_, _) => await LoadAsync();
        Opened += async (_, _) => await InitializeAsync();
        Closed += (_, _) => _closed.Cancel();
    }

    private void ClearResults() { _rows.Children.Clear(); _status.Text = "Auswahl festlegen und Abrufen wählen."; }

    private void SelectMode()
    {
        if (_meta is null) return;
        var own = _mode.SelectedIndex == 0;
        var elements = own ? _meta.Teachers : _meta.Classes;
        _element.ItemsSource = elements;
        var preferred = own ? _settings.TeacherUntisId ?? _meta.OwnTeacherId
            : _settings.HomeroomClassUntisId ?? _meta.MyClassIds.Cast<int?>().FirstOrDefault();
        _element.SelectedItem = elements.FirstOrDefault(x => x.Id == preferred)
            ?? (!own ? elements.FirstOrDefault(x => _meta.MyClassIds.Contains(x.Id)) : null);
        ClearResults();
    }

    private async Task InitializeAsync()
    {
        _status.Text = "WebUntis-Auswahl wird geladen …";
        try
        {
            var today = DateOnly.FromDateTime(DateTime.Today);
            var date = today.Year * 10000 + today.Month * 100 + today.Day;
            var years = await _service.GetSchoolYearsAsync(_closed.Token);
            var year = years.FirstOrDefault(x => x.StartDate <= date && date <= x.EndDate)
                ?? throw new InvalidDataException("Kein aktuelles WebUntis-Schuljahr gefunden.");
            _yearId = year.UntisId;
            _meta = await _service.GetOpenPeriodsMetaAsync(_yearId, _closed.Token);
            _start.SelectedDate = new DateTimeOffset(_meta.SchoolYearStart.ToDateTime(TimeOnly.MinValue));
            SelectMode();
            _filters.IsEnabled = true;
            if (_element.SelectedItem is not null) await LoadAsync();
        }
        catch (OperationCanceledException) when (_closed.IsCancellationRequested) { }
        catch (Exception ex) { _status.Text = $"Abruf fehlgeschlagen: {ex.Message}"; }
    }

    private async Task LoadAsync()
    {
        _rows.Children.Clear();
        if (_element.SelectedItem is not UntisOpenElement element || _start.SelectedDate is null || _end.SelectedDate is null)
        { _status.Text = "Bitte Lehrkraft oder Klasse und Zeitraum auswählen."; return; }
        var start = DateOnly.FromDateTime(_start.SelectedDate.Value.DateTime);
        var end = DateOnly.FromDateTime(_end.SelectedDate.Value.DateTime);
        if (start > end || start < _meta!.SchoolYearStart || end > _meta.SchoolYearEnd)
        { _status.Text = "Bitte einen gültigen Zeitraum innerhalb des Schuljahres auswählen."; return; }
        _filters.IsEnabled = false;
        _status.Text = "Offene Stunden werden geladen …";
        try
        {
            var own = _mode.SelectedIndex == 0;
            var periods = await _service.GetOpenPeriodsAsync(_yearId, own ? element.Id : null,
                own ? null : element.Id, start, end, _closed.Token);
            foreach (var period in periods)
                _rows.Children.Add(new TextBlock
                {
                    Text = $"{period.When}\n{period.Classes} · {period.Subject} · {period.Teachers}\n{period.Missing}",
                    TextWrapping = Avalonia.Media.TextWrapping.Wrap
                });
            _status.Text = periods.Count == 0 ? "Keine offenen Stunden im gewählten Zeitraum."
                : $"{periods.Count} offene Stunde(n) · Stand {DateTime.Now:HH:mm}";
        }
        catch (OperationCanceledException) when (_closed.IsCancellationRequested) { }
        catch (Exception ex) { _status.Text = $"Abruf fehlgeschlagen: {ex.Message}"; }
        finally { _filters.IsEnabled = true; }
    }
}