CanCan Abilities for Arbiters

arbiter_abilities.rb

#Abilities.rb:41 - Want some refactoring help
#
#Arbiters for a tournament can manage it
if user && !user.admin?
  can [:read, :update, :destroy], Tournament, ['? in (select user_id from tournaments_users where tournament_id = tournaments.id) or tournaments.group_id in (select group_id from group_users where user_id = ? and role = \'Administrator\')', user.id, user.id] do |tournament|
    tournament && (tournament.arbiters.include?(user) ||
    (tournament.group && tournament.group.administrators.include?(user)))
  end

  can [:manage], [Division, Round, Pairing, Entry] do |x|
    x && x.tournament && can?(:update, x.tournament)
  end
end