Provide credit card brand to Pin Payments

Spree replaced the Ruby code providing the credit card brand with a
jquery plugin providing it on the checkout screen.

I re-added Ruby code because it's easier and more robust than updating
the user interface with new Javascript.

app/services/checkout/form_data_adapter.rb

@@ -12,6 +12,8 @@ module Checkout
 
       move_payment_source_to_payment_attributes!
 
+      fill_in_card_type
+
       set_amount_in_payments_attributes
 
       construct_saved_card_attributes if @params[:order][:existing_card_id]
@@ -31,6 +33,18 @@ module Checkout
       @params[:order][:payments_attributes].first[:source_attributes] = payment_source_params
     end
 
+    def fill_in_card_type
+      payment = params[:order][:payments_attributes]&.first&.dig(:source_attributes)
+
+      return if payment&.dig(:number).blank?
+
+      payment[:cc_type] ||= card_brand(payment[:number])
+    end
+
+    def card_brand(number)
+      ActiveMerchant::Billing::CreditCard.brand?(number)
+    end
+
     def delete_payment_source_params!
       @params.delete(:payment_source)[
         @params[:order][:payments_attributes].first[:payment_method_id].underscore

spec/services/checkout/form_data_adapter_spec.rb

@@ -36,6 +36,26 @@ describe Checkout::FormDataAdapter do
         end
       end
 
+      describe "and a credit card is provided" do
+        before do
+          params[:order][:payments_attributes].first[:source_attributes] = {number: "4444333322221111"}
+        end
+
+        it "fills in missing credit card brand" do
+          expect(adapter.params[:order][:payments_attributes].first[:source_attributes][:cc_type]).to eq "visa"
+        end
+
+        it "leaves an existing credit card brand" do
+          params[:order][:payments_attributes].first[:source_attributes][:cc_type] = "test"
+          expect(adapter.params[:order][:payments_attributes].first[:source_attributes][:cc_type]).to eq "test"
+        end
+
+        it "doesn't touch the credit card brand without a number" do
+          params[:order][:payments_attributes].first[:source_attributes][:number] = ""
+          expect(adapter.params[:order][:payments_attributes].first[:source_attributes].key?(:cc_type)).to eq false
+        end
+      end
+
       describe "and existing credit card is provided" do
         before { params[:order][:existing_card_id] = credit_card.id }