Only load data if buffer is empty

Signed-off-by: Janne Koschinski <janne@kuschku.de>

app/src/main/java/de/kuschku/quasseldroid/ui/chat/messages/MessageListFragment.kt

@@ -324,9 +324,16 @@ class MessageListFragment : ServiceBoundFragment() {
       this, Observer {
       if (it?.orNull() == ConnectionState.CONNECTED) {
         runInBackgroundDelayed(16) {
+          viewModel.buffer { bufferId ->
+            // Try loading messages when switching to isEmpty buffer
+            if (database.message().bufferSize(bufferId) == 0) {
+              if (bufferId > 0 && bufferId != Int.MAX_VALUE) {
                 loadMore(initial = true)
               }
             }
+          }
+        }
+      }
     })
 
     viewModel.session.toLiveData().zip(lastMessageId).observe(