Doorkeeper/CanCan scope hack--restrict Oauth applications to user who created them

doorkeeper-cancan-hack.rb

  admin_authenticator do |routes|
    # Put your admin authentication logic here.
    # If you want to use named routes from your app you need
    # to call them on routes object eg.
    # routes.new_admin_session_path
    # Admin.find_by_id(session[:admin_id]) || redirect_to(routes.new_admin_session_path)
    if current_user
      if session[:customer_id]
        current_customer = Customer.find_by_id(session[:customer_id])
        redirect_to(routes.customers_path) if !current_customer 
        if params[:controller] == 'doorkeeper/applications'
          case params[:action]
            when 'create': params[:application][:customer_id] = session[:customer_id]
            when 'index', 'show': redirect_to routes.edit_customer_path(session[:customer_id])
            when 'update', 'destroy', 'edit'
              if !current_customer.oauth_applications.collect(&:id).include? params[:id].to_i
                flash[:warning] = "You don't have access to that application."
                redirect_to routes.edit_customer_path(session[:customer_id])
              end
          end
        end
      elsif !current_user.admin?
        flash[:warning] = "You don't have access to that application."
        redirect_to routes.root_path
      end
    else
      flash[:warning] = "You must be logged in to access to that application."
      redirect_to routes.login_path
    end
  end