fix: message insert mode when loading a room for 1st time on non-empt…

…y store

src/store/tables/inbox.ts

@@ -216,24 +216,35 @@ const detectInsertMode = function (
   container: InboxEntryMessages,
   messages: Array<CoreMessage>
 ): InboxInsertMode {
-  // Notice: this compares the first message entry date with the last core \
-  //   message date. If the first container message is more recent than \
-  //   the last core message to be inserted, then it means the whole block \
-  //   of messages to insert should be prepended BEFORE existing messages. \
-  //   This is required if there are already messages in the store, that \
-  //   could be more recent than those messages, eg. if a new message was \
-  //   received in-band and the room is opened later.
-  // Important: acquire insert mode AFTER loading messages and \
-  //   BEFORE inserting them to the store, since the loading could \
-  //   have taken quite some time, and some messages might have been \
-  //   inserted in the store mid-way.
-  if (
-    container.list.length > 0 &&
-    messages.length > 0 &&
-    container.list[0].timestamp >= messages[messages.length - 1].date.getTime()
-  ) {
-    // Use restore mode
-    return InboxInsertMode.Restore;
+  const storeMessages = container.list;
+
+  if (messages.length > 0 && storeMessages.length > 0) {
+    const lastStoreMessageTime =
+      storeMessages[storeMessages.length - 1].timestamp;
+
+    const firstInsertMessageTime = messages[0].date.getTime(),
+      lastInsertMessageTime = messages[messages.length - 1].date.getTime();
+
+    // Notice: this compares the last store message date with the first \
+    //   message date. If the last store message is more recent than \
+    //   the first message to be inserted, then it means the whole block \
+    //   of messages to insert should be prepended BEFORE existing messages. \
+    //   This is required if there are already messages in the store, that \
+    //   could be more recent than those messages, eg. if a new message was \
+    //   received in-band and the room is opened later.
+    // Important: acquire insert mode AFTER loading messages and \
+    //   BEFORE inserting them to the store, since the loading could \
+    //   have taken quite some time, and some messages might have been \
+    //   inserted in the store mid-way.
+    if (lastInsertMessageTime >= lastStoreMessageTime) {
+      // Use insert mode
+      return InboxInsertMode.Insert;
+    }
+
+    if (firstInsertMessageTime < lastStoreMessageTime) {
+      // Use restore mode
+      return InboxInsertMode.Restore;
+    }
   }
 
   // Use insert mode (default)