feat: fehlende Variablen ergänzen

LehrerApp.Desktop/ViewModels/Students/CreateLetterDialogViewModel.cs

@@ -35,7 +35,9 @@ public partial class CreateLetterDialogViewModel : ObservableObject
     public ObservableCollection<LetterContactChoice> Contacts { get; } = [];
     public ObservableCollection<LetterGroupChoice> Groups { get; } = [];
     public ObservableCollection<LetterGenerationIssue> Issues { get; } = [];
+    public ObservableCollection<LetterPlaceholderInput> CustomPlaceholders { get; } = [];
     public bool HasIssues => Issues.Count > 0;
+    public bool HasCustomPlaceholders => CustomPlaceholders.Count > 0;
     public bool HasNoTemplates => Templates.Count == 0;
     public bool HasNoContacts => Contacts.Count == 0;
     public bool UsesAttendanceAdvancedContent => UsesAttendanceCalendar || UsesAbsenceDayList;
@@ -68,6 +70,7 @@ public partial class CreateLetterDialogViewModel : ObservableObject
         OnPropertyChanged(nameof(UsesAttendanceAdvancedContent));
         AttendanceCalendarConfigured = false;
         ResetAttendanceCalendarOptions();
+        RebuildCustomPlaceholders(value);
         RefreshValidation();
     }
     partial void OnSelectedContactChanged(LetterContactChoice? value) => RefreshValidation();
@@ -117,11 +120,49 @@ public partial class CreateLetterDialogViewModel : ObservableObject
         OnPropertyChanged(nameof(HasIssues));
     }
 
-    private IReadOnlyDictionary<string, PlaceholderValue> BuildValues() => LetterPlaceholderBuilder.BuildStandardValues(
-        _student, SelectedContact?.Model, SelectedGroup?.Model,
-        DateOnly.FromDateTime((LetterDate ?? DateTimeOffset.Now).LocalDateTime), LetterText, TeacherName,
-        UsesAttendanceCalendar ? _attendanceCalendarFactory?.Invoke(_attendanceCalendarOptions) : null,
-        UsesAbsenceDayList ? _absenceDayListFactory?.Invoke(_attendanceCalendarOptions) : null);
+    private IReadOnlyDictionary<string, PlaceholderValue> BuildValues()
+    {
+        var values = LetterPlaceholderBuilder.BuildStandardValues(
+            _student, SelectedContact?.Model, SelectedGroup?.Model,
+            DateOnly.FromDateTime((LetterDate ?? DateTimeOffset.Now).LocalDateTime), LetterText, TeacherName,
+            UsesAttendanceCalendar ? _attendanceCalendarFactory?.Invoke(_attendanceCalendarOptions) : null,
+            UsesAbsenceDayList ? _absenceDayListFactory?.Invoke(_attendanceCalendarOptions) : null);
+        foreach (var custom in CustomPlaceholders) values[custom.Name] = custom.ToPlaceholderValue();
+        return values;
+    }
+
+    private void RebuildCustomPlaceholders(LetterTemplateChoice? choice)
+    {
+        foreach (var existing in CustomPlaceholders) existing.PropertyChanged -= OnCustomPlaceholderChanged;
+        CustomPlaceholders.Clear();
+        if (choice is not null)
+        {
+            try
+            {
+                var loaded = _templates.Load(choice.Model);
+                foreach (var placeholder in loaded.Manifest.Placeholders.Where(p => !p.IsConstant
+                             && !StandardPlaceholderNames.Contains(p.Name) && p.Type is PlaceholderType.Text
+                                 or PlaceholderType.Multiline or PlaceholderType.Date or PlaceholderType.Number))
+                {
+                    var input = new LetterPlaceholderInput(placeholder.Name, placeholder.Type);
+                    input.PropertyChanged += OnCustomPlaceholderChanged;
+                    CustomPlaceholders.Add(input);
+                }
+            }
+            catch (Exception ex) when (ex is IOException or InvalidDataException or TemplateValidationException) { }
+        }
+        OnPropertyChanged(nameof(HasCustomPlaceholders));
+    }
+
+    private void OnCustomPlaceholderChanged(object? sender, System.ComponentModel.PropertyChangedEventArgs e) => RefreshValidation();
+
+    private static readonly HashSet<string> StandardPlaceholderNames = new(StringComparer.Ordinal)
+    {
+        "Datum", "CurrentDate", "Empfaenger", "Anrede", "Brieftext", "LehrerName",
+        "Student.FirstName", "Student.LastName", "Contact.Name", "Contact.Address", "Contact.Street",
+        "Contact.PostalCode", "Contact.City", "Letter.Salutation", "Group.Name", "SchoolYear",
+        StudentAttendanceCalendarDrawingBuilder.PlaceholderName, StudentAbsenceDayListDrawingBuilder.PlaceholderName,
+    };
 
     public AttendanceCalendarOptions GetAttendanceCalendarOptions() => _attendanceCalendarOptions;
 
@@ -187,3 +228,33 @@ public sealed class LetterContactChoice(Contact model) { public Contact Model {
 public sealed class LetterGroupChoice(LearningGroup model) { public LearningGroup Model { get; } = model; public string Display => $"{Model.Name} · {Model.SchoolYear}"; }
 public sealed class LetterGenerationIssue(string message, bool isStrong)
 { public string Icon { get; } = isStrong ? "⚠" : "ⓘ"; public string Message { get; } = message; public string Color { get; } = isStrong ? "#D97706" : "#6B7280"; }
+
+public sealed partial class LetterPlaceholderInput : ObservableObject
+{
+    public string Name { get; }
+    public PlaceholderType Type { get; }
+    public string Label => Type switch
+    {
+        PlaceholderType.Date => $"{Name} (Datum)",
+        PlaceholderType.Number => $"{Name} (Zahl)",
+        _ => Name,
+    };
+    public bool IsTextType => Type == PlaceholderType.Text;
+    public bool IsMultilineType => Type == PlaceholderType.Multiline;
+    public bool IsDateType => Type == PlaceholderType.Date;
+    public bool IsNumberType => Type == PlaceholderType.Number;
+
+    [ObservableProperty] private string _textValue = "";
+    [ObservableProperty] private DateTimeOffset? _dateValue;
+    [ObservableProperty] private decimal? _numberValue;
+
+    public LetterPlaceholderInput(string name, PlaceholderType type) { Name = name; Type = type; }
+
+    public PlaceholderValue ToPlaceholderValue() => Type switch
+    {
+        PlaceholderType.Multiline => new MultilineValue(TextValue),
+        PlaceholderType.Date => new DateValue(DateValue.HasValue ? DateOnly.FromDateTime(DateValue.Value.LocalDateTime) : default),
+        PlaceholderType.Number => new NumberValue(NumberValue ?? 0),
+        _ => new TextValue(TextValue),
+    };
+}