credit_card.rb

class CreditCard < ActiveRecord::Base

  belongs_to :order

  has_one :billing_address, :as => :addressable, :class_name => "Address", :dependent => :destroy

  accepts_nested_attributes_for :billing_address

  before_validation :clean_number

  validates_presence_of :first_name, :last_name, :number, :expiration_month, :expiration_year
  validates_inclusion_of :expiration_month, :in => (1..12), :message => "should be between 1 and 12"
  validates_inclusion_of :expiration_year, :in => (Date.today.year..(Date.today.year+10)),
                         :message => "should be between #{Date.today.year} and #{Date.today.year + 10}"
  validates_associated :billing_address

  def name
    "#{first_name} #{last_name}"
  end

  def details
    "#{censored_number} expires #{expiration_month}/#{expiration_year}"
  end

  def censored_number
    "X" * (number.length - 4) + number[(number.length - 4)..number.length]
  end

  def authorize!
    card = ActiveMerchant::Billing::CreditCard.new(:number => number, :month => expiration_month,
                                                   :year => expiration_year, :first_name => first_name,
                                                   :last_name => last_name)
    address = billing_address.for_active_merchant.merge(:name => "#{first_name} #{last_name}")
    response = Paypal.gateway.authorize(order.total * 100, card, :ip => ip_address, :billing_address => address)

    if (status = response.success?)
      update_attributes :authorization => response.authorization
      order.update_attributes :state => "authorized"
    else
      update_attributes :error => response.message
      order.update_attributes :state => "authorization_failed"
    end

    status
  end

  private

  def clean_number
    self.number.gsub! /[^0-9]/, ""
  end

end