finally updated ChatRoomAdapter#prependData code: order of merging chat history updated.

app/src/main/java/chat/rocket/android/chatroom/adapter/ChatRoomAdapter.kt

@@ -158,15 +158,7 @@ class ChatRoomAdapter(
     }
 
     fun prependData(dataSet: List<BaseUiModel<*>>) {
-        val minAdditionDate = dataSet.minBy { it.message.timestamp } ?: return
-        //---1. In the most cases we will just add new elements to the top of messages heap
-        if (minAdditionDate.message.timestamp > this.dataSet[0].message.timestamp) {
-            this.dataSet.addAll(0, dataSet)
-            notifyItemRangeInserted(0, dataSet.size)
-            return
-        }
-        //---2. Else branch: merging messages---
-        //---2.1 At first we will update all already saved elements with received updated ones
+        //---At first we will update all already saved elements with received updated ones
         val filteredDataSet = dataSet.filter { newItem ->
             val matchedIndex = this.dataSet.indexOfFirst { it.messageId == newItem.messageId && it.viewType == newItem.viewType }
             if (matchedIndex > -1) {
@@ -175,7 +167,16 @@ class ChatRoomAdapter(
             }
             return@filter (matchedIndex < 0)
         }
-        //---2.2 At the second stage we are inserting new received elements into set.
+        val minAdditionDate = dataSet.minBy { it.message.timestamp } ?: return
+        //---In the most cases we will just add new elements to the top of messages heap
+        if (minAdditionDate.message.timestamp > this.dataSet[0].message.timestamp) {
+            this.dataSet.addAll(0, dataSet)
+            notifyItemRangeInserted(0, dataSet.size)
+            return
+        }
+
+        //---Else branch: merging messages---
+        //---We are inserting new received elements into set. Sort them by time+type and show
         if (filteredDataSet.isEmpty()) return
         this.dataSet.addAll(0, filteredDataSet)
         val tmp = this.dataSet.sortedWith(Comparator { t, t2 ->