local id = require "util.id";

local jid = require "util.jid";

local set = require "util.set";

local st = require "util.stanza";

module:depends "track_muc_joins";

module:add_feature("https://modules.prosody.im/mod_" .. module.name);

local local_sessions = prosody.hosts[module.host].sessions;

module:hook_global("s2s-destroyed", function(event)

	local s2s_session = event.session;

	if s2s_session.direction == "outgoing" and s2s_session.from_host ~= module.host then

		return

	elseif s2s_session.direction == "incoming" and s2s_session.to_host ~= module.host then

		return

	end

	local related_hosts = set.new({ s2s_session.direction == "outgoing" and s2s_session.to_host or s2s_session.from_host });

	if s2s_session.hosts then

		-- While rarely used, multiplexing is still supported

		for host, state in pairs(s2s_session.hosts) do if state.authed then related_hosts:add(host); end end

	end

	for _, user_session in pairs(local_sessions) do

		for _, session in pairs(user_session.sessions) do

			if session.rooms_joined then

				for room, info in pairs(session.rooms_joined) do

					local nick = info.nick or info;

					local room_nick = room .. "/" .. nick;

					if related_hosts:contains(jid.host(room)) then

						-- User is in a MUC room for which the s2s connection was lost. Now what?

						-- Self-ping

						-- =========

						--

						-- Response of <iq type=result> means the user is still in the room

						-- (and self-ping is supported), so we do nothing.

						--

						-- An error reply either means the user has fallen out of the room,

						-- or that self-ping is unsupported. In the later case, whether the

						-- user is still joined is indeterminate and we might as well

						-- pretend they fell out.

						module:send_iq(st.iq({ type = "get"; id = id.medium(); from = session.full_jid; to = room_nick })

								:tag("ping", { xmlns = "urn:xmpp:ping"; }))

						:catch(function(err)

							module:send(

								st.presence({ type = "unavailable"; id = id.medium(); to = session.full_jid; from = room_nick })

									:tag("x", { xmlns = "http://jabber.org/protocol/muc#user" })

										:tag("item", { affiliation = "none"; role = "none" })

											:text_tag("reason", err.text or "Connection to remote server lost")

										:up()

										:tag("status", { code = "110" }):up()

										:tag("status", { code = "333" }):up()

									:reset());

						end);

						-- TODO do this with some delay?

					end

				end

			end

		end

	end

end);