You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: sessions_controller.rb
    path of file: ./repos/zammad/app/controllers
    
    the code of the file until where you have to start completion: # Copyright (C) 2012-2024 Zammad Foundation, https://zammad-foundation.org/

class SessionsController < ApplicationController
  prepend_before_action :authenticate_and_authorize!, only: %i[switch_to_user list delete]
  skip_before_action :verify_csrf_token, only: %i[show destroy create_omniauth failure_omniauth
    
  def config_frontend

    # config
    config = {}
    Setting.select('name, preferences').where(frontend: true).each do |setting|
      next if setting.preferences[:authentication] == true && !current_user

      value = Setting.get(setting.name)
      next if !current_user && (value == false || value.nil?)

      config[setting.name] = value
    end

    Setting::Processed.process_frontend_settings! config

    # NB: Explicitly include SAML display name config
    #   This is needed because the setting is not frontend related,
    #   but we still to display one of the options
    # https://github.com/zammad/zammad/issues/4263
    config['auth_saml_display_name'] = Setting.get('auth_saml_credentials')[:display_name]

    # Include the flag for JSON column type support (currently only on PostgreSQL backend).
    config['column_type_json_supported'] =
      ActiveRecord::Base.connection_db_config.configuration_hash[:adapter] == 'postgresql'

    # Announce searchable models to the front end.
    config['models_searchable'] = Models.searchable.map(&:to_s)

    # remember if we can switch back to user
    if session[:switched_from_user_id]
      config['switch_back_to_possible'] = true
    end