Change logic for archiving mucsub messages

This change should apply usual logic for message wrapped in mucsub except
check for groupchat message, so messages without bodies for example
should be rejected

src/mod_mam.erl

@@ -648,9 +648,20 @@ should_archive(#message{body = Body, subject = Subject,
 		none when Type == headline ->
 		    false;
 		none ->
-		    xmpp:get_text(Body) /= <<>> orelse
-		    xmpp:get_text(Subject) /= <<>> orelse
-		    xmpp:has_subtag(Pkt, #ps_event{})
+		    case xmpp:get_text(Body) /= <<>> orelse
+			 xmpp:get_text(Subject) /= <<>> of
+			true ->
+			    true;
+			_ ->
+			    case mod_muc_room:unwrap_mucsub_message(Pkt) of
+				#message{type = groupchat} = Msg ->
+				    should_archive(Msg#message{type = chat}, LServer);
+				#message{} = Msg ->
+				    should_archive(Msg, LServer);
+				_ ->
+				    false
+			    end
+		    end
 	    end
     end;
 should_archive(_, _LServer) ->

src/mod_muc_room.erl

@@ -39,7 +39,8 @@
 	 is_occupant_or_admin/2,
 	 route/2,
 	 expand_opts/1,
-	 config_fields/0]).
+	 config_fields/0,
+	 unwrap_mucsub_message/1]).
 
 %% gen_fsm callbacks
 -export([init/1,
@@ -4459,6 +4460,24 @@ wrap(From, To, Packet, Node) ->
 					    id = p1_rand:get_string(),
 					    sub_els = [El]}]}}]}.
 
+-spec unwrap_mucsub_message(xmpp_element()) -> message() | false.
+unwrap_mucsub_message(#message{} = Packet) ->
+    case xmpp:get_subtag(Packet, #ps_event{}) of
+	#ps_event{
+	    items = #ps_items{
+		node = Node,
+		items = [
+		    #ps_item{
+			sub_els = [#message{} = Message]} | _]}}
+	    when Node == ?NS_MUCSUB_NODES_MESSAGES;
+		 Node == ?NS_MUCSUB_NODES_SUBJECT ->
+	    Message;
+	_ ->
+	    false
+    end;
+unwrap_mucsub_message(_Packet) ->
+    false.
+
 %% -spec send_multiple(jid(), binary(), [#user{}], stanza()) -> ok.
 %% send_multiple(From, Server, Users, Packet) ->
 %%     JIDs = [ User#user.jid || {_, User} <- ?DICT:to_list(Users)],