Implement setPaymentOptions call for PayPal

app/models/payments/paypal_payment.rb

@@ -9,13 +9,29 @@ def after_create_path
     PaypalAPI.checkout_url pay_key
   end
 
+  # totally untested function that really should be part of abacus
+  def total_tax
+    total = Money.new(0)
+
+    self.business_transactions.each do |bt|
+      price = bt.article_price - (bt.article_price / (1.0 + bt.article_vat / 100.0))
+      total += price * bt.quantity_bought
+    end
+
+    total
+  end
+
   private
 
   # send paypal request on init
   def initialize_payment
     response = PaypalAPI.new.request_for(self)
     if response.success?
       self.pay_key = response['payKey']
+
+      # here: second call to set_payment_options with pay_key and other data
+      # e.g. PaypalAPI.new.set_payment_options(self)
+
       true # continue
     else
       self.error = response.errors.to_json

app/objects/service/paypal_api.rb

@@ -17,7 +17,11 @@ def request_for payment
           'requestEnvelope' => { 'errorLanguage' => 'en_US' },
           'currencyCode' => 'EUR',
           'receiverList' => {
-            'receiver' => [{ 'email' => payment.line_item_group_seller_paypal_account, 'amount' => payment.total_price.to_f.to_s }] },
+            'receiver' => [{
+              'email' => payment.line_item_group_seller_paypal_account,
+              'amount' => payment.total_price.to_f.to_s
+            }]
+          },
           'cancelUrl' => line_item_group_url(payment.line_item_group, paid: false),
           'actionType' => 'PAY',
           'ipnNotificationUrl' => ipn_notification_url,
@@ -29,6 +33,26 @@ def request_for payment
     end
   end
 
+  def set_payment_options(payment)
+    begin
+      Timeout.timeout(15) do
+        paypal_client.set_payment_options(
+          'payKey' => payment.pay_key,
+          'requestEnvelope' => {
+            'errorLanguage' => 'en_US'
+          },
+          'receiverOptions' => {
+            'invoiceData' => {
+              'totalTax' => payment.total_tax
+            }
+          }
+        )
+      end
+    rescue Timeout::Error
+      Struct.new(:success?, :errors).new(false, 'Timeout') # Mock response object
+    end
+  end
+
   private
 
   def paypal_client