Initial

2026-03-29 23:47:31 +02:00
commit 216d5d2280
75 changed files with 5702 additions and 0 deletions
--- a/LehrerApp.Api/EventStore.cs
+++ b/LehrerApp.Api/EventStore.cs
@@ -0,0 +1,144 @@
+using LiteDB;
+using LehrerApp.Sync.Models;
+
+namespace LehrerApp.Api;
+
+/// <summary>
+/// Server-seitiger Event-Speicher.
+/// Speichert verschlüsselte Events pro User – versteht den Payload nicht.
+/// Eine LiteDB-Datei pro User in dataPath/{userId}.db
+/// </summary>
+public class EventStore
+{
+    private readonly string _dataPath;
+    private readonly Dictionary<string, LiteDatabase> _dbs = new();
+    private readonly Lock _lock = new();
+
+    public EventStore(string dataPath)
+    {
+        _dataPath = dataPath;
+        Directory.CreateDirectory(dataPath);
+    }
+
+    // ── Push: Events vom Client entgegennehmen ────────────────────────────────
+
+    public PushResponse Push(string userId, List<SyncEvent> events)
+    {
+        var db = GetDb(userId);
+        var col = db.GetCollection<ServerEvent>("events");
+        col.EnsureIndex(x => x.ServerSequenceNr);
+
+        var conflictIds = new List<Guid>();
+        long serverSeq = GetLastSequenceNr(col);
+
+        foreach (var evt in events.OrderBy(e => e.Timestamp))
+        {
+            // Konflikt: anderes Gerät hat dieselbe Entity kürzlich geändert
+            var recent = col.FindOne(e =>
+                e.EntityType == evt.EntityType &&
+                e.EntityId == evt.EntityId &&
+                e.DeviceId != evt.DeviceId &&
+                e.Timestamp > evt.Timestamp.AddSeconds(-30));
+
+            if (recent is not null)
+            {
+                conflictIds.Add(evt.EventId);
+                continue;
+            }
+
+            col.Insert(new ServerEvent
+            {
+                EventId = evt.EventId,
+                DeviceId = evt.DeviceId,
+                DeviceType = evt.DeviceType,
+                Timestamp = evt.Timestamp,
+                ClientSequenceNr = evt.SequenceNr,
+                ServerSequenceNr = ++serverSeq,
+                EntityType = evt.EntityType,
+                EntityId = evt.EntityId,
+                Operation = evt.Operation,
+                Payload = evt.Payload,         // verschlüsselt – Server liest nicht
+            });
+        }
+
+        return new PushResponse
+        {
+            Success = true,
+            ServerSequenceNr = serverSeq,
+            ConflictingEventIds = conflictIds,
+        };
+    }
+
+    // ── Pull: neue Events für Client bereitstellen ────────────────────────────
+
+    public PullResponse Pull(string userId, long since, string requestingDeviceId)
+    {
+        var db = GetDb(userId);
+        var col = db.GetCollection<ServerEvent>("events");
+
+        // Nur Events anderer Geräte zurückgeben
+        var events = col
+            .Find(e => e.ServerSequenceNr > since && e.DeviceId != requestingDeviceId)
+            .OrderBy(e => e.ServerSequenceNr)
+            .Take(500)
+            .Select(e => new SyncEvent
+            {
+                EventId = e.EventId,
+                DeviceId = e.DeviceId,
+                DeviceType = e.DeviceType,
+                Timestamp = e.Timestamp,
+                SequenceNr = e.ServerSequenceNr,
+                EntityType = e.EntityType,
+                EntityId = e.EntityId,
+                Operation = e.Operation,
+                Payload = e.Payload,
+            })
+            .ToList();
+
+        return new PullResponse
+        {
+            Events = events,
+            ServerSequenceNr = GetLastSequenceNr(col),
+        };
+    }
+
+    // ── Hilfsmethoden ─────────────────────────────────────────────────────────
+
+    private LiteDatabase GetDb(string userId)
+    {
+        lock (_lock)
+        {
+            if (!_dbs.TryGetValue(userId, out var db))
+            {
+                // Sanitize userId für Dateinamen
+                var safeName = string.Concat(userId
+                    .Where(c => char.IsLetterOrDigit(c) || c == '-' || c == '_'));
+                var path = Path.Combine(_dataPath, $"{safeName}.db");
+                db = new LiteDatabase(path);
+                _dbs[userId] = db;
+            }
+            return db;
+        }
+    }
+
+    private static long GetLastSequenceNr(ILiteCollection<ServerEvent> col)
+    {
+        var last = col.FindOne(Query.All(nameof(ServerEvent.ServerSequenceNr), Query.Descending));
+        return last?.ServerSequenceNr ?? 0;
+    }
+}
+
+// Internes Dokument im Server-EventStore
+internal class ServerEvent
+{
+    public Guid EventId { get; set; }
+    public string DeviceId { get; set; } = "";
+    public DeviceType DeviceType { get; set; }
+    public DateTime Timestamp { get; set; }
+    public long ClientSequenceNr { get; set; }
+    public long ServerSequenceNr { get; set; }
+    public string EntityType { get; set; } = "";
+    public string EntityId { get; set; } = "";
+    public string Operation { get; set; } = "";
+    public string Payload { get; set; } = "";   // AES-256 – Server liest nicht
+}