# HG changeset patch
# User Matthew Wild <mwild1@gmail.com>
# Date 1556826185 -3600
# Node ID 8a93af85f3190c54417da5d595aafdb906443881
# Parent  cc4f7361dac76de7f25d888ab123efb2d98ed2ff
mod_muc_cloud_notify: Count codepoints instead of bytes

Still marked as a 'TODO' in XEP-0372, but Converse.js is
counting codepoints, and rough consensus is that this is
the easiest approach in the widest range of environments.

diff -r cc4f7361dac7 -r 8a93af85f319 mod_muc_cloud_notify/mod_muc_cloud_notify.lua
--- a/mod_muc_cloud_notify/mod_muc_cloud_notify.lua	Mon Apr 22 04:20:16 2019 +0200
+++ b/mod_muc_cloud_notify/mod_muc_cloud_notify.lua	Thu May 02 20:43:05 2019 +0100
@@ -440,6 +440,19 @@
 	return pushes;
 end
 
+local function extract_reference(text, i, j)
+        -- COMPAT w/ pre-Lua 5.3
+        local c, pos, p1 = 0, 0, nil;
+        for char in text:gmatch("([%z\1-\127\194-\244][\128-\191]*)") do
+                c, pos = c + 1, pos + #char;
+                if not p1 and i < c then
+                        p1 = pos;
+                end
+                if c == j then
+                        return text:sub(p1, pos);
+                end
+        end
+end
 
 -- archive message added
 local function archive_message_added(event)
@@ -451,7 +464,7 @@
 
 	for reference in stanza:childtags("reference", "urn:xmpp:reference:0") do
 		if reference.attr['type'] == 'mention' and reference.attr['begin'] and reference.attr['end'] then
-			local nick = body:sub(tonumber(reference.attr['begin'])+1, tonumber(reference.attr['end']));
+			local nick = extract_reference(body, reference.attr['begin'], reference.attr['end']);
 			local jid = room:get_registered_jid(nick);
 
 			if room._occupants[room.jid..'/'..nick] then