def payment_service_for(order, account, options = {}, &proc)
      raise ArgumentError, "Missing block" unless block_given?

      integration_module = OffsitePayments::integration(options.delete(:service).to_s)
      service_class = integration_module.const_get('Helper')

      form_options = options.delete(:html) || {}
      service = service_class.new(order, account, options)
      form_options[:method] = service.form_method
      result = []
      service_url = service.respond_to?(:credential_based_url) ? service.credential_based_url : integration_module.service_url
      result << form_tag(service_url, form_options)

      result << capture(service, &proc)

      service.form_fields.each do |field, value|
        result << hidden_field_tag(field, value)
      end

      service.raw_html_fields.each do |field, value|
        result << "<input id=\"#{field}\" name=\"#{field}\" type=\"hidden\" value=\"#{value}\" />\n"
      end

      result << '</form>'
      result= result.join("\n")

      concat(result.respond_to?(:html_safe) ? result.html_safe : result)
      nil
    end
def payment_service_for(order, account, options = {}, &proc)
      raise ArgumentError, "Missing block" unless block_given?

      integration_module = OffsitePayments::integration(options.delete(:service).to_s)
      service_class = integration_module.const_get('Helper')

      form_options = options.delete(:html) || {}
      service = service_class.new(order, account, options)
      form_options[:method] = service.form_method
      result = []
      service_url = service.respond_to?(:credential_based_url) ? service.credential_based_url : integration_module.service_url
      result << form_tag(service_url, form_options)

      result << capture(service, &proc)

      service.form_fields.each do |field, value|
        result << hidden_field_tag(field, value)
      end

      service.raw_html_fields.each do |field, value|
        result << "<input id=\"#{field}\" name=\"#{field}\" type=\"hidden\" value=\"#{value}\" />\n"
      end

      result << '</form>'
      result= result.join("\n")

      concat(result.respond_to?(:html_safe) ? result.html_safe : result)
      nil
    end
This helper allows the usage of different payment integrations
 through a single form helper.  Payment integrations are the
 type of service where the user is redirected to the secure
 site of the service, like Paypal or Chronopay.

 The helper creates a scope around a payment service helper
 which provides the specific mapping for that service.

  <% payment_service_for 1000, 'paypalemail@mystore.com',
                               :amount => 50.00,
                               :currency => 'CAD',
                               :service => :paypal,
                               :html => { :id => 'payment-form' } do |service| %>

    <% service.customer :first_name => 'Cody',
                       :last_name => 'Fauser',
                       :phone => '(555)555-5555',
                       :email => 'cody@example.com' %>

    <% service.billing_address :city => 'Ottawa',
                              :address1 => '21 Snowy Brook Lane',
                              :address2 => 'Apt. 36',
                              :state => 'ON',
                              :country => 'CA',
                              :zip => 'K1J1E5' %>

    <% service.invoice '#1000' %>
    <% service.shipping '0.00' %>
    <% service.tax '0.00' %>

    <% service.notify_url url_for(:only_path => false, :action => 'notify') %>
    <% service.return_url url_for(:only_path => false, :action => 'done') %>
    <% service.cancel_return_url 'http://mystore.com' %>
  <% end %>