Add invitation stats

Show some stats about unused invitations and active inviters

app/assets/stylesheets/layout.scss

@@ -119,12 +119,7 @@ main {
   }
 
   section {
-    padding-bottom: 3rem;
     margin-bottom: 3rem;
-
-    &:not(:last-of-type) {
-      border-bottom: 1px dotted #ccc;
-    }
   }
 
   table {

app/controllers/admin/invitations_controller.rb

@@ -1,6 +1,8 @@
 class Admin::InvitationsController < Admin::BaseController
   def index
     @current_section = :invitations
+    @invitations_unused_count = Invitation.unused.count
+    @users_with_referrals_count = Invitation.used.distinct.count(:user_id)
     @invitations_used = Invitation.used.order('used_at desc')
   end
 end

app/views/admin/invitations/index.html.erb

@@ -1,7 +1,14 @@
 <section>
   <h2>Invitations</h2>
-
+  <p>
+    There are currently <strong><%= @invitations_unused_count %>
+    unused invitations</strong> available to existing users.
+    <strong><%= @users_with_referrals_count %> users</strong> have successfully
+    invited new users.
+  </p>
+</section>
 <% if @invitations_used.any? %>
+  <section>
     <h3>Accepted (<%= @invitations_used.length %>)</h3>
     <table>
       <thead>
@@ -21,5 +28,5 @@
         <% end %>
       </tbody>
     </table>
-  <% end %>
   </section>
+<% end %>