LehrerApp/LehrerApp.Desktop/ViewModels/Settings/SettingsViewModel.WorksheetTemplates.cs

using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using LehrerApp.Desktop.Services;
using LehrerApp.Templating;
using System.Collections.ObjectModel;

namespace LehrerApp.Desktop.ViewModels.Settings;

public partial class SettingsViewModel
{
    private readonly TeacherSettingsService? _teacherSettings;

    /// <summary>Eigenes Kürzel für Formulare (Platzhalter <c>Teacher.Abbreviation</c> auf dem
    /// Klausur-Deckblatt). Wird sofort gespeichert; im Deckblatt-Dialog je Druck überschreibbar.</summary>
    [ObservableProperty] private string _teacherAbbreviation = "";
    partial void OnTeacherAbbreviationChanged(string value) => _teacherSettings?.SaveAbbreviation(value);

    [ObservableProperty] private string _worksheetTemplateStatus = "";
    public ObservableCollection<LetterTemplateListItem> WorksheetTemplateList { get; } = [];

    private void LoadWorksheetTemplates()
    {
        WorksheetTemplateList.Clear();
        foreach (var template in _worksheetTemplates.Store.GetTemplates()) WorksheetTemplateList.Add(CreateWorksheetItem(template));
    }

    public void ImportWorksheetTemplate(string path)
    {
        WorksheetTemplateStatus = "";
        try
        {
            var template = _worksheetTemplates.Store.Import(path);
            LoadWorksheetTemplates();
            WorksheetTemplateStatus = $"„{template.Name}“ wurde geprüft und lokal importiert.";
        }
        catch (Exception ex) when (ex is IOException or InvalidDataException or UnauthorizedAccessException or TemplateValidationException)
        { WorksheetTemplateStatus = $"Import fehlgeschlagen: {ex.Message}"; }
    }

    [RelayCommand]
    private void ValidateWorksheetTemplate(LetterTemplateListItem? item)
    {
        if (item is null) return;
        try
        {
            var refreshed = CreateWorksheetItem(item.Model);
            var index = WorksheetTemplateList.IndexOf(item);
            if (index >= 0) WorksheetTemplateList[index] = refreshed;
            WorksheetTemplateStatus = $"„{item.Name}“ ist gültig (Schema {refreshed.SchemaVersion}).";
        }
        catch (Exception ex) when (ex is IOException or InvalidDataException or TemplateValidationException)
        { WorksheetTemplateStatus = $"„{item.Name}“ ist ungültig: {ex.Message}"; }
    }

    [RelayCommand]
    private void DeleteWorksheetTemplate(LetterTemplateListItem? item)
    {
        if (item is null) return;
        _worksheetTemplates.Store.Delete(item.Id); WorksheetTemplateList.Remove(item); WorksheetTemplateStatus = "Vorlage gelöscht.";
    }

    private LetterTemplateListItem CreateWorksheetItem(InstalledTemplate template)
    {
        var loaded = _worksheetTemplates.Store.Load(template);
        return new(template, loaded.Manifest.SchemaVersion, loaded.Manifest.Placeholders.Count(x => !x.IsConstant),
            loaded.Manifest.Placeholders.Count(x => !x.IsConstant && x.Required));
    }
}