using Avalonia.Controls;
using Avalonia.Input.Platform;
using Avalonia.Interactivity;
using Avalonia.Platform.Storage;
using LehrerApp.Core.Interfaces;
using LehrerApp.Core.Models;
using LehrerApp.Desktop.Services;
using LehrerApp.Desktop.ViewModels.Groups;
using LehrerApp.Desktop.ViewModels.Students;
using LehrerApp.Desktop.Views.Shared;
using Microsoft.Extensions.DependencyInjection;
using System.Globalization;

namespace LehrerApp.Desktop.Views.Groups;

public partial class LessonDialog : Window
{
    public LessonDialog() => InitializeComponent();

    protected override void OnDataContextChanged(EventArgs e)
    {
        base.OnDataContextChanged(e);
        if (DataContext is LessonDialogViewModel vm)
            vm.OnPickAlternativePath = ShowAlternativePathDialog;
    }

    private async Task<AlternativeLessonPath?> ShowAlternativePathDialog(Guid? currentId)
    {
        var dialogVm = new AlternativePathDialogViewModel(
            App.Services.GetRequiredService<IAlternativeLessonPathRepository>(), currentId);
        var dialog = new AlternativePathDialog { DataContext = dialogVm };

        var ok = await dialog.ShowDialog<bool>(this);
        return ok ? dialogVm.Result : null;
    }

    private void OnSave(object? s, RoutedEventArgs e)
    {
        if (DataContext is LessonDialogViewModel vm && vm.SaveCommand.CanExecute(null))
        {
            vm.SaveCommand.Execute(null);
            if (vm.Result is not null) Close(true);
        }
    }

    private void OnCancel(object? s, RoutedEventArgs e)
    {
        if (DataContext is LessonDialogViewModel vm) vm.DiscardUnsavedAttachments();
        Close(false);
    }

    /// Kopiert den beim letzten KI-"Übernehmen" gespeicherten Materialerstellungs-Prompt (4.5.36,
    /// Nachtrag zu 4.5.20) erneut in die Zwischenablage — derselbe Mechanismus wie im AiAssistDialog,
    /// hier aber für einen bereits gespeicherten, nicht mehr nur transienten Vorschlag.
    private async void OnCopyMaterialPrompt(object? sender, RoutedEventArgs e)
    {
        if (sender is not Button { DataContext: PhaseStepEditItem item } || string.IsNullOrWhiteSpace(item.MaterialPrompt))
            return;

        var clipboard = TopLevel.GetTopLevel(this)?.Clipboard;
        if (clipboard is null) return;
        await clipboard.SetTextAsync(item.MaterialPrompt);
        App.Services.GetRequiredService<NotificationService>().ShowSuccess("Prompt in die Zwischenablage kopiert.");
    }

    private async void OnAddAttachment(object? sender, RoutedEventArgs e)
    {
        if (DataContext is not LessonDialogViewModel vm) return;

        var files = await StorageProvider.OpenFilePickerAsync(new FilePickerOpenOptions
        {
            Title = "Anhang auswählen", AllowMultiple = false,
        });
        if (files.Count == 0) return;

        await using var stream = await files[0].OpenReadAsync();
        vm.AddAttachment(files[0].Name, stream);
    }

    private async void OnOpenAttachment(object? sender, RoutedEventArgs e)
    {
        if (DataContext is not LessonDialogViewModel vm) return;
        if (sender is not Button { Tag: AttachmentItem item }) return;

        using var source = vm.OpenAttachment(item);
        if (source is null) return;

        var file = await StorageProvider.SaveFilePickerAsync(new FilePickerSaveOptions
        {
            Title = "Anhang speichern unter", SuggestedFileName = item.FileName,
        });
        if (file is null) return;

        await using var target = await file.OpenWriteAsync();
        await source.CopyToAsync(target);
    }

    private async void OnCreateHazardAssessment(object? sender, RoutedEventArgs e)
    {
        if (DataContext is not LessonDialogViewModel vm) return;

        var (unit, contextLesson, groupName) = BuildHazardAssessmentContext(vm);
        var dialogVm = new HazardAssessmentWizardViewModel(null, groupName,
            App.Services.GetRequiredService<AiPlanningService>(), App.Services.GetRequiredService<AiSettingsService>(),
            unit, contextLesson);
        var dialog = new HazardAssessmentWizardDialog { DataContext = dialogVm };
        var ok = await dialog.ShowDialog<bool>(this);
        if (!ok || dialogVm.Result is null) return;

        UploadHazardAssessment(vm, dialogVm.Result);
    }

    private async void OnOpenHazardAssessment(object? sender, RoutedEventArgs e)
    {
        if (DataContext is not LessonDialogViewModel vm) return;
        if (sender is not Button { Tag: AttachmentItem item }) return;

        var editing = await ReadHazardAssessmentAsync(vm, item);
        if (editing is null) return;

        var (unit, contextLesson, _) = BuildHazardAssessmentContext(vm);
        var dialogVm = new HazardAssessmentWizardViewModel(editing, editing.GroupLabel,
            App.Services.GetRequiredService<AiPlanningService>(), App.Services.GetRequiredService<AiSettingsService>(),
            unit, contextLesson);
        var dialog = new HazardAssessmentWizardDialog { DataContext = dialogVm };
        var ok = await dialog.ShowDialog<bool>(this);
        if (!ok || dialogVm.Result is null) return;

        vm.RemoveAttachmentCommand.Execute(item);
        UploadHazardAssessment(vm, dialogVm.Result);
    }

    private async void OnPrintHazardAssessment(object? sender, RoutedEventArgs e)
    {
        var topLevel = TopLevel.GetTopLevel(this);
        if (topLevel is null || DataContext is not LessonDialogViewModel vm) return;
        if (sender is not Button { Tag: AttachmentItem item }) return;

        var assessment = await ReadHazardAssessmentAsync(vm, item);
        if (assessment is null) return;

        var data = new HazardAssessmentPrintData(
            assessment.Title, assessment.GroupLabel, assessment.Date?.ToString("dd.MM.yyyy") ?? "",
            ExperimentKindDisplay.Label(assessment.Kind), assessment.Procedure,
            assessment.Substances.Select(s => new HazardSubstancePrintRow(
                s.Name, s.Cas, s.Amount, string.Join(", ", s.GhsPictograms.Select(GhsPictogramDisplay.Code)),
                s.SignalWord, s.HStatements, s.PStatements, s.ActivityRestriction)).ToList(),
            assessment.Hazards, assessment.ProtectiveMeasures, assessment.FirstAid, assessment.Disposal,
            assessment.Notes, assessment.IsAiAssisted);
        var pdf = App.Services.GetRequiredService<PdfExportService>().BuildHazardAssessmentPdf(data);

        await App.Services.GetRequiredService<ExportService>().SaveAsync(topLevel.StorageProvider,
            ExportFile.Pdf("Gefährdungsbeurteilung als PDF speichern", $"GBU_{assessment.Title}", pdf));
    }

    /// Baut den Kontext für den Gefährdungsbeurteilungs-Assistenten (KI-Anfrage + Vorbelegung) aus
    /// dem gerade im Dialog bearbeiteten, ggf. noch nicht gespeicherten Stand — funktioniert damit
    /// auch beim Neuanlegen einer Stunde, bevor überhaupt gespeichert wurde.
    private (Unit? Unit, Lesson ContextLesson, string GroupName) BuildHazardAssessmentContext(LessonDialogViewModel vm)
    {
        var unit = App.Services.GetRequiredService<IUnitRepository>().GetById(vm.UnitId);
        var groupName = unit is null ? "" : App.Services.GetRequiredService<IGroupRepository>().GetById(unit.GroupId)?.Name ?? "";
        var contextLesson = new Lesson { Topic = vm.Topic, Phases = vm.Phases.Select(p => p.ToModel()).ToList() };
        return (unit, contextLesson, groupName);
    }

    private static async Task<HazardAssessment?> ReadHazardAssessmentAsync(LessonDialogViewModel vm, AttachmentItem item)
    {
        using var source = vm.OpenAttachment(item);
        if (source is null) return null;
        using var reader = new StreamReader(source);
        var json = await reader.ReadToEndAsync();
        return System.Text.Json.JsonSerializer.Deserialize<HazardAssessment>(json);
    }

    private static void UploadHazardAssessment(LessonDialogViewModel vm, HazardAssessment result)
    {
        var json = System.Text.Json.JsonSerializer.Serialize(result);
        using var stream = new MemoryStream(System.Text.Encoding.UTF8.GetBytes(json));
        vm.AddAttachment(HazardAssessmentFileName(result.Title), stream);
    }

    private static string HazardAssessmentFileName(string title)
    {
        var invalid = Path.GetInvalidFileNameChars();
        var safe = new string(title.Select(c => invalid.Contains(c) ? '_' : c).ToArray()).Trim();
        if (safe.Length == 0) safe = "Gefaehrdungsbeurteilung";
        return safe + AttachmentItem.HazardAssessmentSuffix;
    }

    /// KI-Unterstützung mit Fokus auf genau diese (bereits gespeicherte) Stunde, statt den Umweg
    /// über die Einheiten-Übersicht nehmen zu müssen (4.5.22, Nutzer-Feedback). Die Übernahme im
    /// AiAssistDialog speichert direkt ins Repository — dieser Dialog schließt sich danach mit dem
    /// frisch geladenen Stand, statt seine eigenen (jetzt veralteten) Feldwerte zu speichern.
    private async void OnAiAssist(object? s, RoutedEventArgs e)
    {
        if (DataContext is not LessonDialogViewModel vm || vm.EditingLesson is null) return;

        var unitRepo = App.Services.GetRequiredService<IUnitRepository>();
        var unit = unitRepo.GetById(vm.UnitId);
        if (unit is null) return;

        var lessonRepo = App.Services.GetRequiredService<ILessonRepository>();
        var currentLesson = lessonRepo.GetByUnit(vm.UnitId).FirstOrDefault(l => l.Id == vm.EditingLesson.Id);
        if (currentLesson is null) return;

        var dialogVm = new AiAssistDialogViewModel(
            App.Services.GetRequiredService<AiPlanningService>(),
            App.Services.GetRequiredService<AiSettingsService>(),
            lessonRepo, unit, focusLesson: currentLesson);

        var dialog = new AiAssistDialog { DataContext = dialogVm };
        var ok = await dialog.ShowDialog<bool>(this);
        if (!ok) return;

        var updated = lessonRepo.GetByUnit(vm.UnitId).FirstOrDefault(l => l.Id == vm.EditingLesson.Id);
        if (updated is not null) vm.MarkAppliedExternally(updated);
        Close(true);
    }

    /// Deckt die Lücke ab, dass der Stundenplan eine Stunde nur über Datum+Stundennummer findet
    /// (kein gespeichertes Verknüpfungsfeld) — eine per JSON-Import oder KI ohne Stundennummer
    /// angelegte Stunde taucht dort nie auf und würde sonst beim Klick auf den Termin dupliziert.
    /// Statt neu anzulegen, wird die gefundene vorhandene Stunde auf diesen Termin umgehängt.
    private async void OnFixIt(object? s, RoutedEventArgs e)
    {
        if (DataContext is not LessonDialogViewModel vm) return;
        if (!DateOnly.TryParseExact(vm.DateText, "dd.MM.yyyy", null, DateTimeStyles.None, out var date))
        {
            App.Services.GetRequiredService<NotificationService>()
                .ShowError("Bitte zuerst ein gültiges Datum eintragen.");
            return;
        }

        var lessonRepo = App.Services.GetRequiredService<ILessonRepository>();
        var candidates = LessonFixItSearch.FindCandidates(lessonRepo, vm.GroupId, date);

        if (candidates.Count == 0)
        {
            App.Services.GetRequiredService<NotificationService>()
                .ShowError("Keine passende bestehende Stunde gefunden.");
            return;
        }

        Lesson chosen;
        if (candidates.Count == 1)
        {
            var info = new ConfirmDialogInfo
            {
                Title = "Vorhandene Stunde verknüpfen?",
                Message = $"Vorhandene Stunde „{candidates[0].Topic}“ vom {candidates[0].Date:dd.MM.yyyy} gefunden. " +
                          "Mit diesem Termin verknüpfen, statt eine neue Stunde anzulegen?",
                ConfirmText = "Verknüpfen",
            };
            var confirm = new ConfirmDialog { DataContext = info };
            if (!await confirm.ShowDialog<bool>(this)) return;
            chosen = candidates[0];
        }
        else
        {
            var pickerVm = new LinkExistingLessonDialogViewModel(candidates,
                App.Services.GetRequiredService<IUnitRepository>());
            var picker = new LinkExistingLessonDialog { DataContext = pickerVm };
            if (!await picker.ShowDialog<bool>(this) || pickerVm.Result is not { } picked) return;
            chosen = picked;
        }

        chosen.UnitId = vm.UnitId;
        chosen.Date = date;
        chosen.LessonNumber = vm.LessonNumber;
        lessonRepo.Save(chosen);
        vm.MarkAppliedExternally(chosen);
        Close(true);
    }
}