From 06f9c28fd296808be4fae94a37046f3f9d7f447a Mon Sep 17 00:00:00 2001
From: Steve Howell <showell30@yahoo.com>
Date: Thu, 6 Apr 2017 16:30:13 -0700
Subject: [PATCH] settings: Lazy-load settings sections.

For the settings UI, we now wait until a user goes to a particular
settings section before calling the appropriate function to set
up the section (which usually involves setting up click handlers
and populating initial data).
---
 .eslintrc.json                 |  1 +
 static/js/click_handlers.js    |  1 +
 static/js/settings.js          | 11 +++-----
 static/js/settings_sections.js | 47 ++++++++++++++++++++++++++++++++++
 static/js/ui_init.js           |  1 +
 zproject/settings.py           |  1 +
 6 files changed, 54 insertions(+), 8 deletions(-)
 create mode 100644 static/js/settings_sections.js

diff --git a/.eslintrc.json b/.eslintrc.json
index 77f92b4a86..d70a755a9f 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -38,6 +38,7 @@
         "settings_muting": false,
         "settings_lab": false,
         "settings_bots": false,
+        "settings_sections": false,
         "settings": false,
         "resize": false,
         "loading": false,
diff --git a/static/js/click_handlers.js b/static/js/click_handlers.js
index 737b84dcf6..0c3093beb9 100644
--- a/static/js/click_handlers.js
+++ b/static/js/click_handlers.js
@@ -581,6 +581,7 @@ $(function () {
         }
 
         $(".settings-section, .settings-wrapper").removeClass("show");
+        settings_sections.load_settings_section(section);
         $(".settings-section" + sel + ", .settings-wrapper" + sel).addClass("show");
     });
 
diff --git a/static/js/settings.js b/static/js/settings.js
index d0f38717c9..e36bc8e4aa 100644
--- a/static/js/settings.js
+++ b/static/js/settings.js
@@ -66,14 +66,9 @@ function _setup_page() {
 
     $(".settings-box").html(settings_tab);
 
-    alert_words_ui.set_up_alert_words();
-    attachments_ui.set_up_attachments();
-    settings_account.set_up();
-    settings_display.set_up();
-    settings_notifications.set_up();
-    settings_bots.set_up();
-    settings_muting.set_up();
-    settings_lab.set_up();
+    // Since we just swapped in a whole new settings widget, we need to
+    // tell settings_sections nothing is loaded.
+    settings_sections.reset_sections();
 
     if (tab) {
         exports.launch_page(tab);
diff --git a/static/js/settings_sections.js b/static/js/settings_sections.js
new file mode 100644
index 0000000000..c71c7a615a
--- /dev/null
+++ b/static/js/settings_sections.js
@@ -0,0 +1,47 @@
+var settings_sections = (function () {
+
+var exports = {};
+
+var load_func_dict = new Dict(); // section -> function
+var is_loaded = new Dict(); // section -> bool
+
+exports.initialize = function () {
+    load_func_dict.set('your-account', settings_account.set_up);
+    load_func_dict.set('display-settings', settings_display.set_up);
+    load_func_dict.set('notifications', settings_notifications.set_up);
+    load_func_dict.set('your-bots', settings_bots.set_up);
+    load_func_dict.set('alert-words', alert_words_ui.set_up_alert_words);
+    load_func_dict.set('uploaded-files', attachments_ui.set_up_attachments);
+    load_func_dict.set('muted-topics', settings_muting.set_up);
+    load_func_dict.set('zulip-labs', settings_lab.set_up);
+};
+
+exports.load_settings_section = function (section) {
+    if (!load_func_dict.has(section)) {
+        // admin sections don't have loaders yet, and that's ok
+        return;
+    }
+
+    if (is_loaded.get(section)) {
+        // We only load sections once (unless somebody calls
+        // reset_sections).
+        return;
+    }
+
+    var load_func = load_func_dict.get(section);
+
+    // Do the real work here!
+    load_func();
+    is_loaded.set(section, true);
+};
+
+exports.reset_sections = function () {
+    is_loaded.clear();
+};
+
+return exports;
+}());
+
+if (typeof module !== 'undefined') {
+    module.exports = settings_sections;
+}
diff --git a/static/js/ui_init.js b/static/js/ui_init.js
index 090a7621d8..3042e2b812 100644
--- a/static/js/ui_init.js
+++ b/static/js/ui_init.js
@@ -257,6 +257,7 @@ $(function () {
     activity.initialize();
     emoji.initialize();
     hotspots.initialize();
+    settings_sections.initialize();
 });
 
 
diff --git a/zproject/settings.py b/zproject/settings.py
index e9345b5472..ea96a31207 100644
--- a/zproject/settings.py
+++ b/zproject/settings.py
@@ -911,6 +911,7 @@ JS_SPECS = {
             'js/settings_bots.js',
             'js/settings_muting.js',
             'js/settings_lab.js',
+            'js/settings_sections.js',
             'js/settings.js',
             'js/admin.js',
             'js/tab_bar.js',