Calculate the median of the server timestamps

[reliable-chat] / webclient / rc.html

diff --git a/webclient/rc.html b/webclient/rc.html
index a062a176b2dc8a92e0bb7f62fee1ebf9cefa2d5a..988f1fb558be441382764d7c8e435241309bd397 100644 (file)
--- a/webclient/rc.html
+++ b/webclient/rc.html
@@ -80,8 +80,14 @@
        var servers = ['chkno.net', 'rc2.chkno.net', 'echto.net', 'the-wes.com', 'vibrantlogic.com'];
 
        var session = Math.random();  // For outgoing message IDs
-       var since = {};  // server -> time: For fetch?since=
-       var seen = {};  // seen_key -> true
+       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");
@@ -127,26 +133,45 @@
        }
 
        function rcaddmessagetohistory(message) {
-               var d = document.createElement("div");
+               message.UI = document.createElement("div");
                var text = (message.Time ? rcformattime(message.Time) : "") + " " + message.Text;
-               d.appendChild(document.createTextNode(text));
+               message.UI.appendChild(document.createTextNode(text));
                var h = document.getElementById("history");
-               h.appendChild(d);
+               h.appendChild(message.UI);
                window.scrollTo(0, document.body.scrollHeight);
-               return d;
        }
 
        function make_seen_key(id, text) {
                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)) {
-                               seen[seen_key] = true;
+                       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) {
                                        rcchangeserverstatus(servers[i], "sad");
@@ -166,11 +191,11 @@
                                        if (rtxt != null) {
                                                var messages = JSON.parse(rtxt);
                                                if (messages != null) {
-                                                       rcreceivemessages(server, messages);
                                                        delay = 40;
                                                        if (messages.length >= 1 && "Time" in messages[messages.length-1]) {
                                                                since[server] = messages[messages.length-1].Time;
                                                        }
+                                                       rcreceivemessages(server, messages);
                                                }
                                        }
                                }
@@ -198,7 +223,7 @@
 
        function rcsend(d, message) {
                var id = new Date().getTime() + "-" + session + "-" + Math.random();
-               seen[make_seen_key(id, message)] = true;
+               seen[make_seen_key(id, message)] = message;
                var path = "/speak" +
                        "?id=" + encodeURIComponent(id) +
                        "&text=" + encodeURIComponent(message);
@@ -223,8 +248,9 @@
                        message = "<" + rcnick() + "> " + input;
                }
 
-               var d = rcaddmessagetohistory({'Text': message});
-               rcsend(d, message);
+               var m = {'Text': message};
+               rcaddmessagetohistory(m);
+               rcsend(m.UI, m);
        }
 
        function rckeydown(event) {