Add Feature: Monatsübersicht Fehlzeiten Widget

LehrerApp.Desktop/ViewModels/ClassTeacher/ClassTeacherOverviewViewModel.cs

@@ -392,6 +392,14 @@ public sealed record ClassTeacherOpenExcuseRow(string StudentName, DateOnly Date
             .ToList();
 }
 
+/// <summary>Eine einzelne, auf ein Minimum verdichtete Monatszelle im Übersichts-Widget.</summary>
+public sealed record ClassTeacherCompactCalendarDay(DateOnly Date, string SignalCode,
+    string SignalColorHex, string Tooltip, bool IsToday)
+{
+    public string DayNumber => Date.Day.ToString();
+    public bool HasSignal => !string.IsNullOrEmpty(SignalCode);
+}
+
 public partial class ClassTeacherOverviewViewModel : ObservableObject
 {
     private readonly WebUntisSettingsService _settings;
@@ -415,6 +423,7 @@ public partial class ClassTeacherOverviewViewModel : ObservableObject
     public ObservableCollection<ClassTeacherTrendDay> TrendDays { get; } = [];
     public ObservableCollection<ClassTeacherPatternNotice> PatternNotices { get; } = [];
     public ObservableCollection<ClassTeacherOpenExcuseRow> OpenExcuses { get; } = [];
+    public ObservableCollection<ClassTeacherCompactCalendarDay> CompactMonthDays { get; } = [];
 
     [ObservableProperty] private string? _homeroomClassName;
     [ObservableProperty] private int _activeTabIndex;
@@ -492,6 +501,8 @@ public partial class ClassTeacherOverviewViewModel : ObservableObject
     public double UnexcusedAbsenceFraction => StudentCount == 0 ? 0 : (double)UnexcusedAbsenceCount / StudentCount;
     public string DayOverviewTooltip => $"{PresentCount} anwesend · {LateCount} verspätet · " +
         $"{ExcusedAbsenceCount} entschuldigt · {UnexcusedAbsenceCount} unentschuldigt";
+    public string CompactMonthLabel => DateOnly.FromDateTime(DateTime.Today).ToString("MMMM yyyy",
+        System.Globalization.CultureInfo.GetCultureInfo("de-DE"));
 
     public Func<Task>? OnNavigateToSettings { get; set; }
     public Func<Task>? OnNavigateToWorkload { get; set; }
@@ -537,7 +548,7 @@ public partial class ClassTeacherOverviewViewModel : ObservableObject
     {
         ActiveTabIndex = 0;
         Roster.Clear(); PrimaryRoster.Clear(); SecondaryRoster.Clear(); TrendDays.Clear(); PatternNotices.Clear();
-        OpenExcuses.Clear(); OpenExcuseOverflowCount = 0;
+        OpenExcuses.Clear(); CompactMonthDays.Clear(); OpenExcuseOverflowCount = 0;
     }
 
     // Wird beim Navigieren auf diese Seite aufgerufen statt LoadCommand: baut nur den lokalen
@@ -676,6 +687,7 @@ public partial class ClassTeacherOverviewViewModel : ObservableObject
         UnexcusedAbsenceCount = Roster.Count(r => r.HasAbsenceToday && !r.IsLate && r.IsUnexcused);
         RecentClassRegisterCount = recentRegisterEntries.Count;
         BuildTrend(absenceDaysYear, trendDays);
+        BuildCompactMonth(absenceDaysYear, classRegisterEvents, today);
         BuildPatternNotices(absenceDaysYear, sevenDayStart);
         BuildWeekdayPatternNotices(absenceDaysYear);
         BuildAttendanceParticipationNotices();
@@ -708,6 +720,64 @@ public partial class ClassTeacherOverviewViewModel : ObservableObject
         DetailsTab.LoadCommand.Execute(null);
     }
 
+    [RelayCommand]
+    private void OpenMonthlyCalendar()
+    {
+        var today = DateOnly.FromDateTime(DateTime.Today);
+        DetailsTab.StudentFilter = "";
+        DetailsTab.CalendarMonth = new DateOnly(today.Year, today.Month, 1);
+        ActiveTabIndex = 2;
+        DetailsTab.ShowCalendarCommand.Execute(null);
+    }
+
+    private void BuildCompactMonth(IReadOnlyList<ClassAbsenceDaySummaryRow> absences,
+        IReadOnlyList<UntisForeignClassRegisterEventDto> registerEntries, DateOnly today)
+    {
+        CompactMonthDays.Clear();
+        foreach (var day in BuildCompactMonthDays(new DateOnly(today.Year, today.Month, 1),
+                     absences, registerEntries, today))
+            CompactMonthDays.Add(day);
+    }
+
+    public static IReadOnlyList<ClassTeacherCompactCalendarDay> BuildCompactMonthDays(DateOnly month,
+        IReadOnlyList<ClassAbsenceDaySummaryRow> absences,
+        IReadOnlyList<UntisForeignClassRegisterEventDto> registerEntries, DateOnly today)
+    {
+        var first = new DateOnly(month.Year, month.Month, 1);
+        var registerRows = registerEntries
+            .Select(e => (Entry: e, Valid: TryDate(e.Date, out var date), Date: date))
+            .Where(x => x.Valid && x.Date.Year == first.Year && x.Date.Month == first.Month)
+            .Select(x => new ClassTeacherClassRegisterRow(x.Date, x.Entry.Subject, x.Entry.StudentName,
+                x.Entry.TeacherUsername, x.Entry.CategoryName, x.Entry.CategoryGroup, x.Entry.Text))
+            .ToList();
+        var result = new List<ClassTeacherCompactCalendarDay>();
+        var days = DateTime.DaysInMonth(first.Year, first.Month);
+
+        for (var number = 1; number <= days; number++)
+        {
+            var date = new DateOnly(first.Year, first.Month, number);
+            var events = ClassTeacherDetailsViewModel.BuildDayEvents(date, absences, registerRows,
+                includeHomework: false);
+            var strongest = events.OrderBy(e => SignalPriority(e.Kind)).FirstOrDefault();
+            var tooltip = events.Count == 0
+                ? $"{date:dd.MM.yyyy}: unauffällig"
+                : $"{date:dd.MM.yyyy}\n" + string.Join("\n", events.Select(e => e.Tooltip));
+            result.Add(new ClassTeacherCompactCalendarDay(date, strongest?.Code ?? "",
+                strongest?.ColorHex ?? "#00000000", tooltip, date == today));
+        }
+        return result;
+    }
+
+    private static int SignalPriority(ClassTeacherCalendarEventKind kind) => kind switch
+    {
+        ClassTeacherCalendarEventKind.Unexcused => 0,
+        ClassTeacherCalendarEventKind.ClassRegister => 1,
+        ClassTeacherCalendarEventKind.Absent => 2,
+        ClassTeacherCalendarEventKind.Late => 3,
+        ClassTeacherCalendarEventKind.Excused => 4,
+        _ => 5,
+    };
+
     [RelayCommand]
     private void ShowDetailsForStudent(ClassTeacherRosterRow? row)
     {