Add client code for handling submessages.

This commit lays the foundation to handle submessages for
plugin widgets.  Right now it just logs events, but subsequent
commits will add widget functionality.

.eslintrc.json

@@ -171,6 +171,7 @@
         "unread_ops": false,
         "upload": false,
         "user_events": false,
+        "submessage": false,
         "Plotly": false,
         "emoji_codes": false,
         "drafts": false,

frontend_tests/node_tests/submessage.js

@@ -0,0 +1,58 @@
+zrequire('submessage');
+
+set_global('channel', {});
+
+(function test_get_message_events() {
+    var msg = {};
+
+    assert.equal(submessage.get_message_events(msg), undefined);
+
+    msg = {
+        submessages: [],
+    };
+    assert.equal(submessage.get_message_events(msg), undefined);
+
+    var submessages = [
+        {id: 222, sender_id: 99, content: '84'},
+        {id: 9, sender_id: 33, content: '42'},
+    ];
+
+    msg = {
+        locally_echoed: true,
+        submessages: submessages,
+    };
+    assert.equal(submessage.get_message_events(msg), undefined);
+
+    msg = {
+        submessages: submessages,
+    };
+    assert.deepEqual(submessage.get_message_events(msg), [
+        {sender_id: 33, data: 42},
+        {sender_id: 99, data: 84},
+    ]);
+}());
+
+(function test_make_server_callback() {
+    var message_id = 444;
+    var callback = submessage.make_server_callback(message_id);
+    var was_posted;
+
+    channel.post = function (opts) {
+        was_posted = true;
+        assert.deepEqual(opts, {
+            url: '/json/submessage',
+            data: {
+                message_id: message_id,
+                msg_type: 'whatever',
+                content: '{"foo":32}',
+            },
+        });
+    };
+
+    callback({
+        msg_type: 'whatever',
+        data: {foo: 32},
+    });
+
+    assert(was_posted);
+}());

static/js/echo.js

@@ -204,6 +204,8 @@ exports.process_from_server = function process_from_server(messages) {
         // the backend.
         client_message.timestamp = message.timestamp;
 
+        client_message.submessages = message.submessages;
+
         msgs_to_rerender.push(client_message);
         delete waiting_for_ack[client_message.id];
     });

static/js/message_list_view.js

@@ -434,6 +434,10 @@ MessageListView.prototype = {
             var id = rows.id(row);
             message_edit.maybe_show_edit(row, id);
 
+            submessage.process_submessages({
+                row: row,
+                message_id: id,
+            });
         });
     },
 

static/js/server_events_dispatch.js

@@ -253,6 +253,15 @@ exports.dispatch_normal_event = function dispatch_normal_event(event) {
         }
         break;
 
+    case 'submessage':
+        submessage.handle_event({
+            sender_id: event.sender_id,
+            msg_type: event.msg_type,
+            message_id: event.message_id,
+            data: event.data,
+        });
+        break;
+
     case 'subscription':
         if (event.op === 'add') {
             _.each(event.subscriptions, function (rec) {

static/js/submessage.js

@@ -0,0 +1,75 @@
+var submessage = (function () {
+
+var exports = {};
+
+exports.get_message_events = function (message) {
+    if (message.locally_echoed) {
+        return;
+    }
+
+    if (!message.submessages) {
+        return;
+    }
+
+    if (message.submessages.length === 0) {
+        return;
+    }
+
+    // The server should sort messages for us, but this is defensive.
+    message.submessages.sort(function (m1, m2) {
+        return parseInt(m1.id, 10) - parseInt(m2.id, 10);
+    });
+
+    var events = _.map(message.submessages, function (obj) {
+        return {
+            sender_id: obj.sender_id,
+            data: JSON.parse(obj.content),
+        };
+    });
+
+    return events;
+};
+
+exports.process_submessages = function (in_opts) {
+    var message_id = in_opts.message_id;
+    var message = message_store.get(message_id);
+
+    if (!message) {
+        return;
+    }
+
+    var events = exports.get_message_events(message);
+
+    if (!events) {
+        return;
+    }
+
+    blueslip.info('submessages found for message id: ' + message_id);
+};
+
+
+exports.handle_event = function (event) {
+    blueslip.info('handle submessage: ' + JSON.stringify(event));
+};
+
+exports.make_server_callback = function (message_id) {
+    return function (opts) {
+        var url = '/json/submessage';
+
+        channel.post({
+            url: url,
+            data: {
+                message_id: message_id,
+                msg_type: opts.msg_type,
+                content: JSON.stringify(opts.data),
+            },
+        });
+    };
+};
+
+return exports;
+
+}());
+if (typeof module !== 'undefined') {
+    module.exports = submessage;
+}

zproject/settings.py

@@ -947,6 +947,7 @@ JS_SPECS = {
             'js/top_left_corner.js',
             'js/stream_list.js',
             'js/filter.js',
+            'js/submessage.js',
             'js/fetch_status.js',
             'js/message_list_data.js',
             'js/message_list_view.js',