local filters = require "util.filters";
local st = require "util.stanza";

local dummy_stanza_mt = setmetatable({ __tostring = function () return ""; end }, { __index = st.stanza_mt });
local dummy_stanza = setmetatable(st.stanza(), dummy_stanza_mt);

module:depends("csi");

local function filter_chatstates(stanza)
	if stanza.name == "message" then
		stanza = st.clone(stanza);
		stanza:maptags(function (tag)
			if tag.attr.xmlns ~= "http://jabber.org/protocol/chatstates" then
				return tag;
			end
		end);
		if #stanza.tags == 0 then
			return dummy_stanza;
		end
	end
	return stanza;
end

module:hook("csi-client-inactive", function (event)
	local session = event.origin;
	filters.add_filter(session, "stanzas/out", filter_chatstates);
end);

module:hook("csi-client-active", function (event)
	local session = event.origin;
	filters.remove_filter(session, "stanzas/out", filter_chatstates);
end);