Calculate the median of the server timestamps

[reliable-chat] / webclient / rc.html

diff --git a/webclient/rc.html b/webclient/rc.html
index bb998256ae8c809e379ae57abba904df9de70db6..988f1fb558be441382764d7c8e435241309bd397 100644 (file)
--- a/webclient/rc.html
+++ b/webclient/rc.html
@@ -82,6 +82,12 @@
        var session = Math.random();  // For outgoing message IDs
        var since = {};    // server -> time: For fetch?since=
        var seen = {};     // seen_key -> message
+       // Messages have these fields:
+       //   Time: The timestamp.  Median of ServerTimes
+       //   ID: Some unique string for deduping
+       //   Text: The text of the message
+       //   ServerTimes: server -> timestamp
+       //   UI: The DOM node for this message in the UI
 
        function rcnick() {
                var nick = localStorage.getItem("nick");
@@ -139,12 +145,32 @@
                return id.replace(/@/g, "@@") + "_@_" + text.replace(/@/g, "@@");
        }
 
+       function rcupdatemessagetime(message) {
+               // Set message.Time to be the median of message.ServerTimes
+               var times = [];
+               for (var i in message.ServerTimes) {
+                       times.push(message.ServerTimes[i]);
+               }
+               times.sort();
+               var middle = times.length/2;
+               if (times.length % 2) {
+                       message.Time = times[middle];
+               } else {
+                       var difference = times[middle].getTime() - times[middle-1].getTime();
+                       message.Time = new Date(times[middle-1].getTime() + difference/2);
+               }
+       }
+
        function rcreceivemessages(server, messages) {
                for (var i in messages) {
                        var m = messages[i];
                        m.Time = new Date(m.Time);
                        var seen_key = make_seen_key(m.ID, m.Text);
-                       if (!(seen_key in seen)) {
+                       if (seen_key in seen) {
+                               seen[seen_key].ServerTimes[server] = m.Time;
+                               rcupdatemessagetime(seen[seen_key]);
+                       } else {
+                               m.ServerTimes = {server: m.Time};
                                seen[seen_key] = m;
                                rcaddmessagetohistory(m);
                                for (var i in servers) {