using Avalonia;
using Avalonia.Controls;
using Avalonia.Controls.Primitives;
using Avalonia.Controls.Templates;
using Avalonia.Data;
using Avalonia.Input;
using Avalonia.Interactivity;
using Avalonia.Media;
using LehrerApp.Core.Models;
using LehrerApp.Desktop.ViewModels.Groups;

namespace LehrerApp.Desktop.Views.Groups;

public partial class AttendanceHomeworkQuickInputDialog : Window
{
    private bool _leftAltDown;
    private bool _rightAltDown;

    public AttendanceHomeworkQuickInputDialog()
    {
        InitializeComponent();
        BuildColumns();
        // Im Tunnel lauschen, bevor DataGrid/Button einen Modifier-Event konsumieren können.
        AddHandler(KeyDownEvent, OnPreviewKeyDown, RoutingStrategies.Tunnel, handledEventsToo: true);
        AddHandler(KeyUpEvent, OnPreviewKeyUp, RoutingStrategies.Tunnel, handledEventsToo: true);
    }

    protected override void OnOpened(EventArgs e)
    {
        base.OnOpened(e);
        StatusGrid.Focus();
        if (ViewModel?.SelectedRow is { } row)
            StatusGrid.ScrollIntoView(row, null);
    }

    private void BuildColumns()
    {
        StatusGrid.Columns.Add(new DataGridTextColumn
        {
            Header = "Schüler",
            Binding = new Binding(nameof(ParticipationStudentRow.Name)),
            Width = new DataGridLength(1, DataGridLengthUnitType.Star),
        });
        StatusGrid.Columns.Add(new DataGridTemplateColumn
        {
            Header = "Anwesenheit",
            Width = new DataGridLength(210, DataGridLengthUnitType.Pixel),
            CellTemplate = BuildAttendanceTemplate(),
        });
        StatusGrid.Columns.Add(new DataGridTemplateColumn
        {
            Header = "Hausaufgaben",
            Width = new DataGridLength(270, DataGridLengthUnitType.Pixel),
            CellTemplate = BuildHomeworkTemplate(),
        });
    }

    private IDataTemplate BuildAttendanceTemplate() =>
        new FuncDataTemplate<ParticipationStudentRow>((row, _) =>
        {
            if (row is null) return new TextBlock();
            var button = StatusButton(185);
            var flyout = new MenuFlyout { Placement = PlacementMode.BottomEdgeAlignedLeft };
            AddAttendanceItem(flyout, row, "[1]  ✓  Anwesend", AttendanceStatus.Present);
            AddAttendanceItem(flyout, row, "[2]  ?  Entschuldigung offen", AttendanceStatus.ExcusePending);
            AddAttendanceItem(flyout, row, "[5]  ⊘  Krank, entschuldigt", AttendanceStatus.Excused);
            AddAttendanceItem(flyout, row, "[7]  ◇  Andere Schulveranstaltung", AttendanceStatus.OtherSchoolEvent);
            AddAttendanceItem(flyout, row, "[9]  ✕  Geschwänzt", AttendanceStatus.Truant);
            AddAttendanceItem(flyout, row, "[0]  !  Unentschuldigt", AttendanceStatus.Unexcused);
            flyout.Items.Add(new Separator());
            AddAttendanceItem(flyout, row, "V   Verspätet", AttendanceStatus.Late);
            AddAttendanceItem(flyout, row, "V!  Erheblich verspätet", AttendanceStatus.SignificantlyLate);
            AddAttendanceItem(flyout, row, "A   Während des Unterrichts abgängig", AttendanceStatus.LeftDuringClass);
            AddAttendanceItem(flyout, row, "L   Lerninsel", AttendanceStatus.LearningIsland);
            AddAttendanceItem(flyout, row, "S   Suspendiert", AttendanceStatus.Suspended);
            flyout.Items.Add(new Separator());
            AddAttendanceItem(flyout, row, "[X]  ·  Nicht kontrolliert", null);
            button.Flyout = flyout;

            void Refresh()
            {
                UpdateButton(button,
                    string.IsNullOrEmpty(row.AttendanceLabel) ? "·" : row.AttendanceLabel,
                    row.AttendanceTooltip, AttendanceDisplay.Color(row.Attendance));
            }
            Refresh();
            row.PropertyChanged += (_, args) =>
            {
                if (args.PropertyName == nameof(ParticipationStudentRow.AttendanceLabel)) Refresh();
            };
            return Center(button);
        });

    private IDataTemplate BuildHomeworkTemplate() =>
        new FuncDataTemplate<ParticipationStudentRow>((row, _) =>
        {
            if (row is null) return new TextBlock();
            var button = StatusButton(245);
            var flyout = new MenuFlyout { Placement = PlacementMode.BottomEdgeAlignedLeft };
            AddHomeworkItem(flyout, row, "[⌥1]  ✓  Gemacht", HomeworkStatus.Completed);
            AddHomeworkItem(flyout, row, "[⌥3]  ◐  Teilweise, Rest offen", HomeworkStatus.PartiallyCompleted);
            AddHomeworkItem(flyout, row, "[⌥4]  ◕  Rest nachgereicht", HomeworkStatus.PartialSubmittedLate);
            AddHomeworkItem(flyout, row, "[⌥5]  ◒  Rest nicht nachgereicht", HomeworkStatus.PartialMissingOverdue);
            AddHomeworkItem(flyout, row, "[⌥7]  !  Nicht gemacht, Nachreichen offen", HomeworkStatus.MissingOpen);
            AddHomeworkItem(flyout, row, "[⌥8]  ↺  Vollständig nachgereicht", HomeworkStatus.SubmittedLate);
            AddHomeworkItem(flyout, row, "[⌥0]  ✕  Nicht mehr nachgereicht", HomeworkStatus.MissingOverdue);
            AddHomeworkItem(flyout, row, "[⌥X]  ·  Keine Hausaufgabe aufgegeben", null);
            button.Flyout = flyout;

            void Refresh() => UpdateButton(button, row.HomeworkSymbol, row.HomeworkTooltip,
                HomeworkDisplay.Color(row.Homework));
            Refresh();
            row.PropertyChanged += (_, args) =>
            {
                if (args.PropertyName == nameof(ParticipationStudentRow.HomeworkSymbol)) Refresh();
            };
            return Center(button);
        });

    private void AddAttendanceItem(MenuFlyout flyout, ParticipationStudentRow row,
        string header, AttendanceStatus? status)
    {
        var item = new MenuItem { Header = header };
        item.Click += (_, _) => ViewModel?.ApplyAttendance(row, status);
        flyout.Items.Add(item);
    }

    private void AddHomeworkItem(MenuFlyout flyout, ParticipationStudentRow row,
        string header, HomeworkStatus? status)
    {
        var item = new MenuItem { Header = header };
        item.Click += (_, _) => ViewModel?.ApplyHomework(row, status);
        flyout.Items.Add(item);
    }

    private static Button StatusButton(double width) => new()
    {
        Width = width,
        Height = 29,
        Padding = new Thickness(8, 2),
        FontSize = 12,
        HorizontalContentAlignment = Avalonia.Layout.HorizontalAlignment.Center,
    };

    private static Control Center(Control child) => new Grid
    {
        Margin = new Thickness(0, 2),
        HorizontalAlignment = Avalonia.Layout.HorizontalAlignment.Center,
        Children = { child },
    };

    private static void UpdateButton(Button button, string symbol, string tooltip, string color)
    {
        button.Content = $"{symbol}   {tooltip}";
        ToolTip.SetTip(button, tooltip + " – klicken, um Status auszuwählen");
        if (Color.TryParse(color, out var parsed))
        {
            button.Background = new SolidColorBrush(parsed);
            button.Foreground = Brushes.White;
            button.Opacity = 1;
        }
        else
        {
            button.ClearValue(Button.BackgroundProperty);
            button.ClearValue(Button.ForegroundProperty);
            button.Opacity = 0.48;
        }
    }

    private void OnPreviewKeyDown(object? sender, KeyEventArgs e)
    {
        if (e.PhysicalKey == PhysicalKey.AltLeft)
        {
            _leftAltDown = true;
            return;
        }
        if (e.PhysicalKey == PhysicalKey.AltRight)
        {
            _rightAltDown = true;
            return;
        }

        var vm = ViewModel;
        var row = vm?.SelectedRow;
        if (vm is null || row is null) return;

        var digit = DigitFromEvent(e);
        var isX = e.Key == Key.X || e.PhysicalKey == PhysicalKey.X;
        var altDown = _leftAltDown || _rightAltDown ||
                      e.KeyModifiers.HasFlag(KeyModifiers.Alt);
        if (altDown)
        {
            HomeworkStatus? homework = isX ? null : digit switch
            {
                1 => HomeworkStatus.Completed,
                3 => HomeworkStatus.PartiallyCompleted,
                4 => HomeworkStatus.PartialSubmittedLate,
                5 => HomeworkStatus.PartialMissingOverdue,
                7 => HomeworkStatus.MissingOpen,
                8 => HomeworkStatus.SubmittedLate,
                0 => HomeworkStatus.MissingOverdue,
                _ => null,
            };
            var recognized = isX || digit is 0 or 1 or 3 or 4 or 5 or 7 or 8;
            if (recognized)
            {
                vm.ApplyHomework(row, homework);
                BringSelectionIntoView();
                e.Handled = true;
                return;
            }

            // Eine mit Alt/Option gedrückte Ziffer darf niemals in den
            // Anwesenheitszweig durchfallen, auch wenn sie nicht belegt ist.
            if (digit is not null)
            {
                e.Handled = true;
                return;
            }
        }

        AttendanceStatus? attendance = isX ? null : digit switch
        {
            1 => AttendanceStatus.Present,
            2 => AttendanceStatus.ExcusePending,
            5 => AttendanceStatus.Excused,
            7 => AttendanceStatus.OtherSchoolEvent,
            9 => AttendanceStatus.Truant,
            0 => AttendanceStatus.Unexcused,
            _ => null,
        };
        var attendanceRecognized = isX || digit is 0 or 1 or 2 or 5 or 7 or 9;
        if (attendanceRecognized)
        {
            vm.ApplyAttendance(row, attendance);
            BringSelectionIntoView();
            e.Handled = true;
            return;
        }

        switch (e.Key)
        {
            case Key.Up: vm.MoveSelection(-1); BringSelectionIntoView(); e.Handled = true; break;
            case Key.Down or Key.Enter: vm.MoveSelection(1); BringSelectionIntoView(); e.Handled = true; break;
            case Key.Escape: Close(); e.Handled = true; break;
            default: break;
        }
    }

    private void OnPreviewKeyUp(object? sender, KeyEventArgs e)
    {
        if (e.PhysicalKey == PhysicalKey.AltLeft) _leftAltDown = false;
        if (e.PhysicalKey == PhysicalKey.AltRight) _rightAltDown = false;
    }

    private AttendanceHomeworkQuickInputViewModel? ViewModel =>
        DataContext as AttendanceHomeworkQuickInputViewModel;

    private static int? DigitFromEvent(KeyEventArgs e) => e.PhysicalKey switch
    {
        PhysicalKey.Digit0 => 0,
        PhysicalKey.Digit1 => 1,
        PhysicalKey.Digit2 => 2,
        PhysicalKey.Digit3 => 3,
        PhysicalKey.Digit4 => 4,
        PhysicalKey.Digit5 => 5,
        PhysicalKey.Digit6 => 6,
        PhysicalKey.Digit7 => 7,
        PhysicalKey.Digit8 => 8,
        PhysicalKey.Digit9 => 9,
        _ => DigitFromKey(e.Key),
    };

    private static int? DigitFromKey(Key key) => key switch
    {
        Key.D0 or Key.NumPad0 => 0,
        Key.D1 or Key.NumPad1 => 1,
        Key.D2 or Key.NumPad2 => 2,
        Key.D3 or Key.NumPad3 => 3,
        Key.D4 or Key.NumPad4 => 4,
        Key.D5 or Key.NumPad5 => 5,
        Key.D6 or Key.NumPad6 => 6,
        Key.D7 or Key.NumPad7 => 7,
        Key.D8 or Key.NumPad8 => 8,
        Key.D9 or Key.NumPad9 => 9,
        _ => null,
    };

    private void BringSelectionIntoView()
    {
        if (ViewModel?.SelectedRow is { } row)
            StatusGrid.ScrollIntoView(row, null);
    }

    private void OnClose(object? sender, RoutedEventArgs e) => Close();
}