Refactor api/v1/apps controller (#3471)

app/controllers/api/v1/apps_controller.rb

@@ -4,11 +4,24 @@ class Api::V1::AppsController < ApiController
   respond_to :json
 
   def create
-    @app = Doorkeeper::Application.create!(name: app_params[:client_name], redirect_uri: app_params[:redirect_uris], scopes: (app_params[:scopes] || Doorkeeper.configuration.default_scopes), website: app_params[:website])
+    @app = Doorkeeper::Application.create!(application_options)
   end
 
   private
 
+  def application_options
+    {
+      name: app_params[:client_name],
+      redirect_uri: app_params[:redirect_uris],
+      scopes: app_scopes_or_default,
+      website: app_params[:website],
+    }
+  end
+
+  def app_scopes_or_default
+    app_params[:scopes] || Doorkeeper.configuration.default_scopes
+  end
+
   def app_params
     params.permit(:client_name, :redirect_uris, :scopes, :website)
   end