feat: Send state event to timeline on creating new megolm session

Author: krille-chan

lib/encryption/key_manager.dart

@@ -348,6 +348,10 @@ class KeyManager {
       sess.outboundGroupSession!.session_id(),
     );
     if (inboundSess == null) {
+      Logs().e(
+        'No inbound session found for outbound group session!',
+        sess.outboundGroupSession?.session_id(),
+      );
       wipe = true;
     }
 
@@ -601,6 +605,27 @@ class KeyManager {
       );
       await storeOutboundGroupSession(roomId, sess);
       _outboundGroupSessions[roomId] = sess;
+      final devices = deviceKeys.map((keys) => keys.deviceId).toList();
+      final users = deviceKeys.fold(
+        <String>{},
+        (users, keys) => users..add(keys.userId),
+      ).toList();
+      client.onTimelineEvent.add(
+        Event(
+          eventId: 'fake_event_${rawSession['session_id']}',
+          content: {
+            'body':
+                '🔒 Verschlüsselte Unterhaltung von ${users.length} Benutzern mit ${devices.length} Geräten',
+            'devices': devices,
+            'members': users,
+          },
+          type: 'sdk.dart.matrix.new_megolm_session',
+          senderId: client.userID!,
+          originServerTs: DateTime.now(),
+          room: room,
+          stateKey: '',
+        ),
+      );
     } catch (e, s) {
       Logs().e(
         '[LibOlm] Unable to send the session key to the participating devices',

lib/src/utils/event_localizations.dart

@@ -119,6 +119,7 @@ abstract class EventLocalizations {
     EventTypes.Sticker: (event, i18n, body) => i18n.sentASticker(
           event.senderFromMemoryOrFallback.calcDisplayname(i18n: i18n),
         ),
+    'sdk.dart.matrix.new_megolm_session': (event, i18n, body) => body,
     EventTypes.Redaction: (event, i18n, body) => i18n.redactedAnEvent(event),
     EventTypes.RoomAliases: (event, i18n, body) => i18n.changedTheRoomAliases(
           event.senderFromMemoryOrFallback.calcDisplayname(i18n: i18n),