discourse/app/models/trust_level_and_staff_setting.rb

require_dependency 'enum_site_setting'

class TrustLevelAndStaffSetting < TrustLevelSetting
  def self.valid_value?(val)
    special_group?(val) ||
    (val.to_i.to_s == val.to_s &&
     valid_values.any? { |v| v == val.to_i })
  end

  def self.valid_values
    TrustLevel.valid_range.to_a + special_groups
  end

  def self.special_group?(val)
    special_groups.include?(val.to_s)
  end

  def self.special_groups
    ['staff', 'admin']
  end
end