class CreditCard
  attr_accessor :number, :number2, :number3, :number4, :number5, :number6, :number7, :card_type
  include ActiveModel::Validations
  validates :number, credit_card_number: {brands: [:amex, :maestro]} , allow_blank: true
  validates :number2, credit_card_number: {only: [:amex, :maestro]},  allow_blank: true
  validates :number3, credit_card_number: {except: [:amex, :maestro]} , allow_blank: true
  validates :number4, credit_card_number: {brands: :any}  , allow_blank: true
  validates :number5, credit_card_number: true , allow_blank: true
  validates :number6, credit_card_number: { brands: ->(record){ record.supported_brand } } , allow_blank: true
  validates :number7, credit_card_number: { message: "Custom message" } , allow_blank: true

  def supported_brand
    {
      "Master Card" => :mastercard,
      "Visa" => :visa
    }[self.card_type]
  end

end