--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_track_muc_joins/README.markdown	Mon Mar 14 13:36:12 2016 +0100
@@ -0,0 +1,7 @@
+---
+summary: Keep track of joined chat rooms
+...
+
+This module attempts to keep track of what MUC chat rooms users have
+joined. It's not very useful on its own, but can be used by other
+modules to influence decisions.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_track_muc_joins/mod_track_muc_joins.lua	Mon Mar 14 13:36:12 2016 +0100
@@ -0,0 +1,37 @@
+
+module:hook("presence/full", function (event)
+	local stanza = event.stanza;
+	local session = sessions[stanza.attr.to];
+	if not session then return end;
+	local log = session.log or module._log;
+	local muc_x = stanza:get_child("x", "http://jabber.org/protocol/muc#user");
+	if not muc_x then return end -- Not MUC related
+
+	local room = jid_bare(stanza.attr.from);
+	local joined = stanza.attr.type;
+	if joined == nil then
+		joined = true;
+	elseif joined == "unavailable" then
+		joined = nil;
+	else
+		-- Ignore errors and whatever
+		return;
+	end
+
+	-- Check for status code 100, meaning it's their own reflected presence
+	for status in muc_x:childtags("status") do
+		log("debug", "Status code %d", status.attr.code);
+		if status.attr.code == "110" then
+			log("debug", "%s room %s", joined and "Joined" or "Left", room);
+			local rooms = session.rooms_joined;
+			if not rooms then
+				session.rooms_joined = { [room] = joined };
+			else
+				rooms[room] = joined;
+			end
+			return;
+		end
+	end
+end);
+
+-- TODO Check session.directed for outgoing presence?