Autocompletion of usernames in comment boxes

app/assets/javascripts/atWhoAutoComplete.js

@@ -1,8 +1,14 @@
 (function() {
 
   // settings at https://github.com/ichord/At.js/wiki/Base-Document#settings
+
+  const displayName = (item) => item.username ? item.username : item.name;
+
   var at_config = {
     at: "@",
+    displayTpl: (item) => `<li>${displayName(item)}</li>`,
+    insertTpl: (item) => `@${displayName(item)}`,
+    data: '/users/active',
     delay: 400,
     callbacks: {
       remoteFilter: debounce(function(query, callback) {

app/controllers/users_controller.rb

@@ -412,6 +412,11 @@ def verify_email
     redirect_to "/login", flash: { notice: action_msg }
   end
 
+  def recently_active_users
+    active_users = User.recently_active_users
+    render json: active_users, root: false
+  end
+
   private
 
   def subscribe_multiple_tag(tag_list)

app/models/user.rb

@@ -505,6 +505,17 @@ def latest_location
     recent_locations.last
   end
 
+  def self.recently_active_users(limit = 5, order = 'last_updated DESC')
+    Rails.cache.fetch('users/active', expires_in: 24.hours) do
+      User.select('rusers.username, rusers.id, MAX(node_revisions.timestamp) AS last_updated')
+        .joins("INNER JOIN `node_revisions` ON `node_revisions`.`uid` = `rusers`.`id` ")
+        .where("node_revisions.status = 1")
+        .group('rusers.id')
+        .order(order)
+        .limit(limit)
+    end
+  end
+
   private
 
   def decrease_likes_banned

config/routes.rb

@@ -53,6 +53,7 @@
   get 'signup' => 'users#new'
   get 'home' => 'home#front'
   get 'verify/:token' => 'users#verify_email'
+  get 'users/active' => 'users#recently_active_users'
   resources :relationships, only: [:create, :destroy]
 
   get '/wiki/:id/comments', to: 'wiki#comments'