Notenverwaltung (Kapitel 2) und Mitarbeits-Assistent

Notenübersicht der Gruppe (Matrix, Gesamt-Spalte, Sortierung, Halbjahresfilter),
Einzelnoten-Pflege samt Sammelerfassung, Gewichtungsschema mit Voreinstellung je
Gruppentyp, Zeugnisnoten-Berechnung mit Übersteuern/Festschreiben/Export und
Notenentwicklung im Schülerdetail.

Dazu Anwesenheits-/Hausaufgaben-Tracking je Mitarbeit-Sitzung, ein neuer
Mitarbeits-Assistent (Zeitleiste mit Abschnitten, automatischer Notenvorschlag,
Zusammenzug zur Halbjahresnote) und eine Dashboard-Kachel für offene
Entschuldigungen. Außerdem: verbliebene englische Begriffe in Auswahlfeldern
und Buttons auf Deutsch umgestellt.

LehrerApp.Desktop/ViewModels/Students/StudentViewModels.cs

@@ -2,7 +2,9 @@ using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 using LehrerApp.Core.Interfaces;
 using LehrerApp.Core.Models;
+using LehrerApp.Desktop.ViewModels.Groups;
 using System.Collections.ObjectModel;
+using System.Globalization;
 
 namespace LehrerApp.Desktop.ViewModels.Students;
 
@@ -72,6 +74,9 @@ public partial class StudentDetailViewModel : ObservableObject
     private readonly IGroupRepository _groups;
     private readonly ISubjectRepository _subjects;
     private readonly IDocumentationRepository _docs;
+    private readonly IExamRepository _exams;
+    private readonly IExamResultRepository _examResults;
+    private readonly IGradeRepository _grades;
 
     [ObservableProperty] private Student? _student;
     [ObservableProperty] private string _studentTitle = "";
@@ -83,16 +88,19 @@ public partial class StudentDetailViewModel : ObservableObject
     public ObservableCollection<GroupMembershipEntry> GroupMemberships { get; } = [];
     public ObservableCollection<DocEntry>        Documentation { get; } = [];
     public ObservableCollection<ContactItem>     Contacts      { get; } = [];
+    public ObservableCollection<StudentGradeHistoryGroup> GradeHistory { get; } = [];
     public bool HasNoContacts => Contacts.Count == 0;
     public Func<Contact?, Task<Contact?>>? OnEditContact { get; set; }
     public Action<ContactItem>? OnViewAddress { get; set; }
 
     public StudentDetailViewModel(IStudentRepository students,
         IGroupMembershipRepository memberships, IGroupRepository groups, ISubjectRepository subjects,
-        IDocumentationRepository docs)
+        IDocumentationRepository docs, IExamRepository exams, IExamResultRepository examResults,
+        IGradeRepository grades)
     {
         _students = students; _memberships = memberships;
         _groups = groups; _subjects = subjects; _docs = docs;
+        _exams = exams; _examResults = examResults; _grades = grades;
     }
 
     public void LoadStudent(Guid id)
@@ -104,12 +112,16 @@ public partial class StudentDetailViewModel : ObservableObject
         EditLastName  = Student.LastName;
 
         GroupMemberships.Clear();
+        GradeHistory.Clear();
         foreach (var membership in _memberships.GetByStudent(Student.Id))
         {
             var g = _groups.GetById(membership.GroupId);
             if (g is null) continue;
             var subject = g.SubjectId is Guid subjectId ? _subjects.GetById(subjectId)?.Name ?? "" : "";
             GroupMemberships.Add(new() { SchoolYear = g.SchoolYear, GroupName = g.Name, Subject = subject });
+
+            var historyGroup = BuildGradeHistory(g, subject);
+            if (historyGroup is not null) GradeHistory.Add(historyGroup);
         }
 
         LoadContacts();
@@ -128,6 +140,49 @@ public partial class StudentDetailViewModel : ObservableObject
                 IsConfidential = d.IsConfidential });
     }
 
+    // ── Notenentwicklung (2.5) ────────────────────────────────────────────────
+
+    private StudentGradeHistoryGroup? BuildGradeHistory(LearningGroup g, string subject)
+    {
+        var label = string.IsNullOrEmpty(subject) ? g.Name : $"{g.Name} · {subject}";
+        var entries = new List<(DateOnly Date, string PointLabel, string Value)>();
+
+        foreach (var exam in _exams.GetByGroup(g.Id))
+        {
+            var result = _examResults.GetByExamAndStudent(exam.Id, Student!.Id);
+            if (result is null || result.Absent || result.Grade is null) continue;
+            entries.Add((exam.Date, exam.Title, result.Grade));
+        }
+        foreach (var grade in _grades.GetByStudentAndGroup(Student!.Id, g.Id))
+            entries.Add((grade.Date, GradeCategoryDisplay.Label(grade.Category), grade.Value));
+
+        var ordered = entries.OrderBy(e => e.Date).ToList();
+        if (ordered.Count == 0) return null;
+
+        var historyGroup = new StudentGradeHistoryGroup(label);
+        int? previousNoteEquivalent = null;
+        foreach (var e in ordered)
+        {
+            int? noteEquivalent = int.TryParse(e.Value, out var raw)
+                ? (g.GradingSystem == GradingSystem.Grades1To6 ? raw : int.Parse(PointsNoteMapping.PointsToNote(raw)))
+                : null;
+
+            var isFailing = noteEquivalent is >= 5;
+            var isDrop = noteEquivalent.HasValue && previousNoteEquivalent.HasValue
+                         && noteEquivalent.Value - previousNoteEquivalent.Value >= 1;
+
+            var warnings = new List<string>();
+            if (isDrop) warnings.Add("Abfall um ≥ 1 Note");
+            if (isFailing) warnings.Add("Versetzungsgefährdung");
+
+            historyGroup.Points.Add(new GradeHistoryPoint(e.Date, e.PointLabel, e.Value,
+                noteEquivalent, warnings.Count > 0, string.Join(" · ", warnings)));
+
+            if (noteEquivalent.HasValue) previousNoteEquivalent = noteEquivalent;
+        }
+        return historyGroup;
+    }
+
     [RelayCommand] private void StartEdit() => IsEditing = true;
     [RelayCommand] private void CancelEdit()
     {
@@ -200,6 +255,43 @@ public partial class StudentDetailViewModel : ObservableObject
 public class GroupMembershipEntry { public string SchoolYear { get; set; } = ""; public string GroupName { get; set; } = ""; public string Subject { get; set; } = ""; }
 public class DocEntry { public string Date { get; set; } = ""; public string Title { get; set; } = ""; public string TypeLabel { get; set; } = ""; public bool IsConfidential { get; set; } }
 
+// ── Notenentwicklung (2.5) ──────────────────────────────────────────────────
+
+public class StudentGradeHistoryGroup(string label)
+{
+    public string Label { get; } = label;
+    public ObservableCollection<GradeHistoryPoint> Points { get; } = [];
+    public bool HasWarnings => Points.Any(p => p.IsWarning);
+}
+
+public class GradeHistoryPoint
+{
+    public string DateDisplay { get; }
+    public string Label { get; }
+    public string Value { get; }
+    public double BarHeight { get; }
+    public bool IsWarning { get; }
+    public string WarningText { get; }
+    public string TooltipText { get; }
+
+    public GradeHistoryPoint(DateOnly date, string label, string value, int? noteEquivalent,
+        bool isWarning, string warningText)
+    {
+        DateDisplay = date.ToString("dd.MM.", CultureInfo.InvariantCulture);
+        Label = label;
+        Value = value;
+        IsWarning = isWarning;
+        WarningText = warningText;
+        // Balkenhöhe nach Notenqualität (1 = beste Note) auf 6..60px, sonst neutrale Mindesthöhe.
+        BarHeight = noteEquivalent.HasValue
+            ? 6 + Math.Clamp((6 - noteEquivalent.Value) / 5.0, 0, 1) * 54
+            : 6;
+        TooltipText = warningText.Length > 0
+            ? $"{date:dd.MM.yyyy} · {label}: {value}  ⚠ {warningText}"
+            : $"{date:dd.MM.yyyy} · {label}: {value}";
+    }
+}
+
 public class ContactItem
 {
     public Contact Model { get; }