auto update alert in footer

app/assets/javascripts/app/frontend/controllers/_base.js

@@ -1,10 +1,14 @@
 class BaseCtrl {
-  constructor(syncManager, dbManager, analyticsManager) {
+  constructor($rootScope, $scope, syncManager, dbManager, analyticsManager) {
     dbManager.openDatabase(null, function(){
       // new database, delete syncToken so that items can be refetched entirely from server
       syncManager.clearSyncToken();
       syncManager.sync();
     })
+
+    $scope.onUpdateAvailable = function(version) {
+      $rootScope.$broadcast('new-update-available', version);
+    }
   }
 }
 

app/assets/javascripts/app/frontend/controllers/footer.js

@@ -1,11 +1,11 @@
 angular.module('app.frontend')
-  .directive("header", function(authManager){
+  .directive("footer", function(authManager){
     return {
       restrict: 'E',
       scope: {},
-      templateUrl: 'frontend/header.html',
+      templateUrl: 'frontend/footer.html',
       replace: true,
-      controller: 'HeaderCtrl',
+      controller: 'FooterCtrl',
       controllerAs: 'ctrl',
       bindToController: true,
 
@@ -22,7 +22,7 @@ angular.module('app.frontend')
       }
     }
   })
-  .controller('HeaderCtrl', function (authManager, modelManager, $timeout, dbManager, syncManager) {
+  .controller('FooterCtrl', function ($rootScope, authManager, modelManager, $timeout, dbManager, syncManager) {
 
     this.user = authManager.user;
 
@@ -78,4 +78,20 @@ angular.module('app.frontend')
     this.syncUpdated = function() {
       this.lastSyncDate = new Date();
     }
+
+    $rootScope.$on("new-update-available", function(version){
+      $timeout(function(){
+        // timeout calls apply() which is needed
+        this.onNewUpdateAvailable();
+      }.bind(this))
+    }.bind(this))
+
+    this.onNewUpdateAvailable = function() {
+      this.newUpdateAvailable = true;
+    }
+
+    this.clickedNewUpdateAnnouncement = function() {
+      this.newUpdateAvailable = false;
+      alert("A new update is ready to install. Updates address performance and security issues, as well as bug fixes and feature enhancements. Simply quit Standard Notes and re-open it for the update to be applied.")
+    }
 });