-- Track messages received by users of the MUC

-- We rewrite the 'id' attribute of outgoing stanzas to match the stanza (archive) id

-- This module is therefore incompatible with the muc#stable_id feature

-- We rewrite the id because XEP-0333 doesn't tell clients explicitly which id to use

-- in marker reports. However it implies the 'id' attribute through examples, and this

-- is what some clients implement.

-- Notably Conversations will ack the origin-id instead. We need to update the XEP to

-- clarify the correct behaviour.

local st = require "util.stanza";

local xmlns_markers = "urn:xmpp:chat-markers:0";

local marker_element_name = module:get_option_string("muc_marker_type", "displayed");

local muc_marker_map_store = module:open_store("muc_markers", "map");

local function get_stanza_id(stanza, by_jid)

	for tag in stanza:childtags("stanza-id", "urn:xmpp:sid:0") do

		if tag.attr.by == by_jid then

			return tag.attr.id;

		end

	end

	return nil;

end

module:hook("muc-broadcast-message", function (event)

	local stanza = event.stanza;

	local archive_id = get_stanza_id(stanza, event.room.jid);

	-- We are not interested in stanzas that didn't get archived

	if not archive_id then return; end

	-- Add stanza id as id attribute

	stanza.attr.id = archive_id;

	-- Add markable element to request markers from clients

	stanza:tag("markable", { xmlns = xmlns_markers }):up();

end, -1);

module:hook("muc-occupant-groupchat", function (event)

	local marker = event.stanza:get_child(marker_element_name, xmlns_markers);

	if not marker then return; end

	-- Store the id that the user has received to

	module:log("warn", "New marker for %s: %s", event.occupant.bare_jid, marker.attr.id);

	muc_marker_map_store:set(event.occupant.bare_jid, event.room.jid, marker.attr.id);

end);

module:hook("muc-message-is-historic", function (event)

	local marker = event.stanza:get_child("received", xmlns_markers);

	-- Prevent stanza from reaching the archive (it's just noise)

	if marker then

		return false

	end

end);

local function find_nickname(room, user_jid)

	-- Find their current nickname

	for nick, occupant in pairs(room._occupants) do

		if occupant.bare_jid == user_jid then

			return nick;

		end

	end

	-- Or if they're not here

	local nickname = room:get_affiliation_data(user_jid, "reserved_nickname");

	if nickname then return room.jid.."/"..nickname; end

end

-- Synthesize markers

if muc_marker_map_store.get_all then

module:hook("muc-occupant-session-new", function (event)

	local room, to = event.room, event.stanza.attr.from;

	local markers = muc_marker_map_store:get_all(room.jid);

	if not markers then return end

	for user_jid, id in pairs(markers) do

		local room_nick = find_nickname(room, user_jid);

		if room_nick then

			local recv_marker = st.message({ type = "groupchat", from = room_nick, to = to })

				:tag("received", { xmlns = xmlns_markers, id = id });

			room:route_stanza(recv_marker);

		end

	end

end);

end

-- Public API

function get_user_read_marker(user_jid, room_jid)

	return muc_marker_map_store:get(user_jid, room_jid);

end