--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_muc_require_tos/mod_muc_require_tos.lua	Thu Sep 16 20:41:14 2021 +0200
@@ -0,0 +1,47 @@
+local jid = require "util.jid";
+local st = require "util.stanza";
+
+local quick_response_ns = "urn:xmpp:tmp:quick-response";
+local welcome_message = module:get_option_string("tos_welcome_message");
+local yes_message = module:get_option_string("tos_yes_message");
+local no_message = module:get_option_string("tos_no_message");
+
+module:hook("muc-occupant-joined", function(event)
+	local origin = event.origin;
+	local room = event.room;
+	local occupant = event.occupant;
+	local nick = occupant.nick;
+	module:log("debug", "%s joined %s (%s)", nick, room, origin);
+	if occupant.role == "visitor" then
+		local message = st.message({
+			type = "groupchat",
+			to = occupant.nick,
+			from = room.jid,
+			id = "foo",
+			["xml:lang"] = "en",
+		}, welcome_message)
+			:tag("response", { xmlns = quick_response_ns, value = "yes", label = "I accept." }):up()
+			:tag("response", { xmlns = quick_response_ns, value = "no", label = "I decline." }):up();
+		origin.send(message);
+	end
+end);
+
+module:hook("muc-occupant-groupchat", function(event)
+	local occupant = event.occupant;
+	if occupant.role ~= "visitor" then
+		return;
+	end
+	local origin = event.origin;
+	local room = event.room;
+	local stanza = event.stanza;
+	-- Namespace must be nil instead of "jabber:client" here.
+	local body = stanza:get_child_text("body", nil);
+	module:log("debug", "%s replied %s", occupant.nick, body);
+	if body == "yes" then
+		room:set_affiliation(true, occupant.bare_jid, "member", "Agreed to the TOS.");
+		origin.send(st.reply(stanza):body(yes_message, { ["xml:lang"] = "en" }));
+	elseif body == "no" then
+		origin.send(st.reply(stanza):body(no_message, { ["xml:lang"] = "en" }));
+		room:set_role(true, occupant.nick, "none", "Declined the TOS.");
+	end
+end, 51); -- Priority must be > 50, <forbidden/> is sent at this priority.