Add admin panel and make it work for user resource

app/controllers/admin/application_controller.rb

@@ -0,0 +1,31 @@
+# All Administrate controllers inherit from this `Admin::ApplicationController`,
+# making it the ideal place to put authentication logic or other
+# before_actions.
+#
+# If you want to add pagination or other controller-level concerns,
+# you're free to overwrite the RESTful controller actions.
+module Admin
+  class ApplicationController < Administrate::ApplicationController
+    before_action :authenticate_admin
+
+    def authenticate_admin
+      unless user_signed_in?
+        flash[:alert] = "You must be logged in to access this page."
+        redirect_to new_user_session_path
+        return
+      end
+
+      unless current_user.moderator? || current_user.admin?
+        flash[:alert] = "You do not have the privilegies to access this page."
+        redirect_to root_path
+        return
+      end
+    end
+
+    # Override this value to specify the number of elements to display at a time
+    # on index pages. Defaults to 20.
+    # def records_per_page
+    #   params[:per_page] || 20
+    # end
+  end
+end