refactoring

def process
  !!if valid_card
    gateway :authorize, credit_card do |auth|
      gateway :capture, auth do |auth|
        update_columns(authorization_code: auth, success: true)
      end
    end
  end
end

def gateway(method, subject)
  response = GATEWAY.public_send(method, amount * 100, subject)

  if response.success?
    yield response.authorization
  else
    errors.add(:base, "The credit card you provided was declined.  Please double check your information and try again.") and return
  end
end