class Cart < ActiveRecord::Base
  attr_reader :currency
  include ActionView::Helpers::NumberHelper

  has_many :cart_items
  # Because 'has_many :cart_items, :as => :items' does not appear to work
  def items ; self.cart_items ; end

  def purchased?
    self.purchased_at.present?
  end

  # Add n number of this product to our cart (addition)
  def add(product, quantity=1)
    self.alter_cart_item_quantity(:add, product, quantity.to_i)
  end

  # Remove a product no matter what the quantity
  def remove(product)
    self.alter_cart_item_quantity(:set, product, 0)
  end

  # Set the total number of this product in our cart to quantity. Setting to 0 will remove the item
  def set_item_quantity(product, quantity)
    self.alter_cart_item_quantity(:set, product, quantity)
  end

  def alter_cart_item_quantity(change_type, product, quantity)
    item = self.items.detect{|item| item.product_id == product.id}
    if item
      if quantity >= 1
        case change_type
          when :add then item.increment_quantity(quantity)
          when :set then item.quantity = quantity
        end
      else
        item.remove_from_cart!
      end
    else
      item = self.items.build(:product_id => product.id, :quantity => quantity)
    end
    item.save!
  end

  def totalf
    Cart.format_price(self.total())
  end

  def total
    self.items.inject(0) { |sum, cart_item| sum + cart_item.price }
  end

  def shipping_weight
    self.items.inject(0) { |sum, cart_item| sum + cart_item.shipping_weight }
  end

  def empty?
    self.items.empty?
  end

  def empty!
    self.items.each{ |cart_item| cart_item.remove_from_cart! }
  end

  def item_count
    count = 0
    self.items.each{|item| count += item.quantity}
    count
  end

  # https://cms.paypal.com/cms_content/en_US/files/developer/PP_OrderMgmt_IntegrationGuide.pdf
  # https://cms.paypal.com/us/cgi-bin/?cmd=_render-content&content_ID=developer/e_howto_html_Appx_websitestandard_htmlvariables
  def paypal_encrypted(return_url, notify_url)
    values = {
      :invoice    => self.id,
      :notify_url => notify_url,
      :business   => ECO['paypal']['email'],
      :cert_id    => ECO['paypal']['cert_id'],
      :cmd        => '_cart',
      :upload     => 1,
      :weight     => self.shipping_weight
    }
  
    self.items.each_with_index do |item, index|
      values.merge!({
        "amount_#{index+1}"      => item.unit_price,
        "item_name_#{index+1}"   => item.name,
        "item_number_#{index+1}" => item.id,
        "quantity_#{index+1}"    => item.quantity
      })
    end
    encrypt_for_paypal(values)
  end
  
  protected
  def encrypt_for_paypal(values)
    signed = OpenSSL::PKCS7::sign(OpenSSL::X509::Certificate.new(APP_CERT_PEM), OpenSSL::PKey::RSA.new(APP_KEY_PEM, ''), values.map { |k, v| "#{k}=#{v}" }.join("\n"), [], OpenSSL::PKCS7::BINARY)
    OpenSSL::PKCS7::encrypt([OpenSSL::X509::Certificate.new(PAYPAL_CERT_PEM)], signed.to_der, OpenSSL::Cipher::Cipher::new("DES3"), OpenSSL::PKCS7::BINARY).to_s.gsub("\n", "")
  end

  def self.format_price(price)
    # WTF?!
    # undefined method `number_to_currency' for #<Class:0x370a064
    # number_to_currency(sprintf("%.02f", price))
    sprintf("$%.02f", price)
  end

end