Initial

LehrerApp.Data/LiteDbContext.cs

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+using LiteDB;
+using LehrerApp.Core.Models;
+
+namespace LehrerApp.Data;
+
+/// <summary>
+/// Zentrale Datenbankverbindung. Einmalig als Singleton registrieren.
+/// Eine Instanz = eine .db Datei = ein Nutzer.
+/// </summary>
+public class LiteDbContext : IDisposable
+{
+    private readonly LiteDatabase _db;
+
+    public LiteDbContext(string databasePath)
+    {
+        // WAL-Modus für bessere Performance bei Concurrent Reads
+        var connectionString = new ConnectionString(databasePath)
+        {
+            Connection = ConnectionType.Shared,
+        };
+
+        _db = new LiteDatabase(connectionString);
+        EnsureIndexes();
+    }
+
+    // ── Collections ──────────────────────────────────────────────────────────
+
+    public ILiteCollection<Student> Students =>
+        _db.GetCollection<Student>("students");
+
+    public ILiteCollection<LearningGroup> Groups =>
+        _db.GetCollection<LearningGroup>("groups");
+
+    public ILiteCollection<Enrollment> Enrollments =>
+        _db.GetCollection<Enrollment>("enrollments");
+
+    public ILiteCollection<Exam> Exams =>
+        _db.GetCollection<Exam>("exams");
+
+    public ILiteCollection<ExamResult> ExamResults =>
+        _db.GetCollection<ExamResult>("exam_results");
+
+    public ILiteCollection<Grade> Grades =>
+        _db.GetCollection<Grade>("grades");
+
+    public ILiteCollection<Unit> Units =>
+        _db.GetCollection<Unit>("units");
+
+    public ILiteCollection<Lesson> Lessons =>
+        _db.GetCollection<Lesson>("lessons");
+
+    public ILiteCollection<Documentation> Documentation =>
+        _db.GetCollection<Documentation>("documentation");
+
+    public ILiteCollection<WorkTask> Tasks =>
+        _db.GetCollection<WorkTask>("tasks");
+
+    public ILiteCollection<TimeEntry> TimeEntries =>
+        _db.GetCollection<TimeEntry>("time_entries");
+
+    // ── Transaktionen ─────────────────────────────────────────────────────────
+
+    public T Transaction<T>(Func<T> action) => _db.BeginTrans() ? action() : action();
+
+    public void Checkpoint() => _db.Checkpoint();
+
+    // ── Backup ───────────────────────────────────────────────────────────────
+
+    public void BackupTo(string targetPath)
+    {
+        _db.Checkpoint();
+        File.Copy(_db.UserVersion.ToString(), targetPath, overwrite: true);
+    }
+
+    // ── Indizes ──────────────────────────────────────────────────────────────
+
+    private void EnsureIndexes()
+    {
+        Students.EnsureIndex(x => x.LastName);
+        Students.EnsureIndex(x => x.IsActive);
+
+        Groups.EnsureIndex(x => x.SchoolYear);
+        Groups.EnsureIndex(x => x.Type);
+
+        Enrollments.EnsureIndex(x => x.StudentId);
+        Enrollments.EnsureIndex(x => x.GroupId);
+        Enrollments.EnsureIndex(x => x.SchoolYear);
+
+        Exams.EnsureIndex(x => x.GroupId);
+        Exams.EnsureIndex(x => x.Date);
+        Exams.EnsureIndex(x => x.Status);
+
+        ExamResults.EnsureIndex(x => x.ExamId);
+        ExamResults.EnsureIndex(x => x.StudentId);
+
+        Grades.EnsureIndex(x => x.StudentId);
+        Grades.EnsureIndex(x => x.GroupId);
+
+        Units.EnsureIndex(x => x.GroupId);
+        Units.EnsureIndex(x => x.Status);
+
+        Lessons.EnsureIndex(x => x.UnitId);
+        Lessons.EnsureIndex(x => x.GroupId);
+        Lessons.EnsureIndex(x => x.Date);
+
+        Documentation.EnsureIndex(x => x.StudentId);
+        Documentation.EnsureIndex(x => x.Type);
+
+        Tasks.EnsureIndex(x => x.Status);
+        Tasks.EnsureIndex(x => x.DueDate);
+
+        TimeEntries.EnsureIndex(x => x.Date);
+        TimeEntries.EnsureIndex(x => x.TaskId);
+    }
+
+    public void Dispose() => _db.Dispose();
+}