using Avalonia.Controls;
using Avalonia.Interactivity;
using Avalonia.Platform.Storage;
using LehrerApp.Core.Importing;
using LehrerApp.Core.Services;
using LehrerApp.Desktop.Services;
using LehrerApp.Desktop.ViewModels.Students;
using Microsoft.Extensions.DependencyInjection;

namespace LehrerApp.Desktop.Views.Students;

public partial class StudentListView : UserControl
{
    private const int MaximumImportFileSize = 20 * 1024 * 1024;

    public StudentListView() => InitializeComponent();

    private async void OnImportClick(object? sender, RoutedEventArgs e)
    {
        var owner = TopLevel.GetTopLevel(this) as Window;
        if (owner is null || DataContext is not StudentListViewModel list) return;

        var service = App.Services.GetRequiredService<StudentImportService>();
        var patterns = service.SupportedExtensions.Select(extension => $"*{extension}").ToArray();
        var files = await owner.StorageProvider.OpenFilePickerAsync(new FilePickerOpenOptions
        {
            Title = "Schüler-Stammdaten importieren",
            AllowMultiple = false,
            FileTypeFilter =
            [
                new FilePickerFileType("Unterstützte Schülerlisten")
                {
                    Patterns = patterns.Length > 0 ? patterns : ["*.csv"],
                },
            ],
        });
        if (files.Count == 0) return;

        list.IsImporting = true;
        try
        {
            await using var source = await files[0].OpenReadAsync();
            if (source.CanSeek && source.Length > MaximumImportFileSize)
                throw new InvalidDataException("Die Importdatei ist größer als 20 MB.");

            using var buffer = new MemoryStream();
            await source.CopyToAsync(buffer);
            if (buffer.Length > MaximumImportFileSize)
                throw new InvalidDataException("Die Importdatei ist größer als 20 MB.");

            var importFile = new ImportFile(files[0].Name, buffer.ToArray());
            var preview = await Task.Run(async () =>
                await service.AnalyzeAsync(importFile).ConfigureAwait(false));
            var dialogVm = new StudentImportDialogViewModel(service, preview, files[0].Name);
            var dialog = new StudentImportDialog { DataContext = dialogVm };
            if (!await dialog.ShowDialog<bool>(owner)) return;

            list.LoadStudents();
            var result = dialogVm.Result!;
            App.Services.GetRequiredService<NotificationService>().ShowSuccess(
                $"Import abgeschlossen: {result.CreatedStudents} neu, {result.UpdatedStudents} ergänzt, "
                + $"{result.CreatedMemberships} Gruppenzuordnungen.");
        }
        catch (Exception ex) when (ex is ImportFormatException
                                   or InvalidDataException
                                   or IOException
                                   or UnauthorizedAccessException)
        {
            App.Services.GetRequiredService<NotificationService>().ShowError(ex.Message);
        }
        finally
        {
            list.IsImporting = false;
        }
    }
}