Tracking facebook friends with me app permission

gistfile1.rb

def suggested_rivals_facebook
    friend_user_ids = []
    if authentications.size > 0 && authentications.map(&:provider).include?("facebook")
      auth = authentications.where(:provider => 'facebook').map.first
      friends_application = FbGraph::Query.new("SELECT uid FROM user WHERE is_app_user=1 and uid IN (SELECT uid2 FROM friend WHERE uid1 = #{auth.uid})").fetch("#{auth.access_token}")
      friends_application.collect! {|par| par["uid"].to_s}
      friend_user_ids = User.where("authentications.provider" => "facebook").any_in("authentications.uid" => friends_application).not_in("_id" => rivals.map(&:competitor)).map
    end
    friend_user_ids
  end