Add activity.process_loaded_messages() and get_huddles().

Activity.js now has the capability to track huddles that
come through in loaded messages and return them in reverse
chronological order by their most recent message.  Right
now this only connected to a unit test, not any production
code.

(imported from commit 59957086fa2e454e5711472df091f178217aed2b)

static/js/activity.js

@@ -39,6 +39,30 @@ $("html").on("mousemove", function () {
 
 var presence_info = {};
 
+var huddle_timestamps = new Dict();
+
+exports.process_loaded_messages = function (messages) {
+    _.each(messages, function (message) {
+        if (message.type === 'private') {
+            if (message.reply_to.indexOf(',') > 0) {
+                var old_timestamp = huddle_timestamps.get(message.reply_to);
+
+                if (!old_timestamp || (old_timestamp < message.timestamp)) {
+                    huddle_timestamps.set(message.reply_to, message.timestamp);
+                }
+            }
+        }
+    });
+};
+
+exports.get_huddles = function () {
+    var huddles = huddle_timestamps.keys();
+    huddles = _.sortBy(huddles, function (huddle) {
+        return huddle_timestamps.get(huddle);
+    });
+    return huddles.reverse();
+};
+
 function sort_users(users, presence_info) {
     // TODO sort by unread count first, once we support that
     users.sort(function (a, b) {

zerver/tests/frontend/node/activity.js

@@ -46,3 +46,45 @@ var activity = require('js/activity.js');
         'alice@zulip.com'
     ]);
 }());
+
+(function test_process_loaded_messages() {
+
+    var huddle1 = 'bar@zulip.com,foo@zulip.com';
+    var timestamp1 = 1382479029; // older
+
+    var huddle2 = 'alice@zulip.com,bob@zulip.com';
+    var timestamp2 = 1382479033; // newer
+
+    var old_timestamp = 1382479000;
+
+    var messages = [
+        {
+            type: 'private',
+            reply_to: huddle1,
+            timestamp: timestamp1
+        },
+        {
+            type: 'stream'
+        },
+        {
+            type: 'private',
+            reply_to: 'ignore@zulip.com'
+        },
+        {
+            type: 'private',
+            reply_to: huddle2,
+            timestamp: timestamp2
+        },
+        {
+            type: 'private',
+            reply_to: huddle2,
+            timestamp: old_timestamp
+        }
+    ];
+
+    activity.process_loaded_messages(messages);
+
+    assert.deepEqual(activity.get_huddles(), [huddle2, huddle1]);
+}());
+
+