diff --git a/app/controllers/spree/paypal_controller.rb b/app/controllers/spree/paypal_controller.rb
index 04cb987bc2..0b44ce3763 100644
--- a/app/controllers/spree/paypal_controller.rb
+++ b/app/controllers/spree/paypal_controller.rb
@@ -40,7 +40,10 @@ module Spree
       items.reject! do |item|
         item[:Amount][:value].zero?
       end
-      pp_request = provider.build_set_express_checkout(express_checkout_request_details(order, items))
+
+      pp_request = provider.build_set_express_checkout(
+        express_checkout_request_details(order, items)
+      )
 
       begin
         pp_response = provider.set_express_checkout(pp_request)
@@ -66,14 +69,14 @@ module Spree
       # last chance to interact with the payment process before the money moves...
       return reset_to_cart unless sufficient_stock?
 
-      @order.payments.create!({
-        source: Spree::PaypalExpressCheckout.create({
+      @order.payments.create!(
+        source: Spree::PaypalExpressCheckout.create(
           token: params[:token],
           payer_id: params[:PayerID]
-        }),
+        ),
         amount: @order.total,
         payment_method: payment_method
-      })
+      )
       @order.next
       if @order.complete?
         flash.notice = Spree.t(:order_processed_successfully)
@@ -106,8 +109,8 @@ module Spree
         Number: item.variant.sku,
         Quantity: item.quantity,
         Amount: {
-            currencyID: item.order.currency,
-            value: item.price
+          currencyID: item.order.currency,
+          value: item.price
         },
         ItemCategory: "Physical"
       }
@@ -140,12 +143,11 @@ module Spree
     end
 
     def reset_order_when_complete
-      if current_order.complete?
-        flash[:notice] = t(:order_processed_successfully)
+      return unless current_order.complete?
 
-        OrderCompletionReset.new(self, current_order).call
-        session[:access_token] = current_order.token
-      end
+      flash[:notice] = t(:order_processed_successfully)
+      OrderCompletionReset.new(self, current_order).call
+      session[:access_token] = current_order.token
     end
 
     def reset_to_cart
@@ -174,7 +176,7 @@ module Spree
       payment_method.provider
     end
 
-    def payment_details items
+    def payment_details(items)
       item_sum = items.sum { |i| i[:Quantity] * i[:Amount][:value] }
       # Would use tax_total here, but it can include "included" taxes as well.
       # For instance, tax_total would include the 10% GST in Australian stores.
diff --git a/app/models/spree/gateway/pay_pal_express.rb b/app/models/spree/gateway/pay_pal_express.rb
index 0cb4d38150..357d563264 100644
--- a/app/models/spree/gateway/pay_pal_express.rb
+++ b/app/models/spree/gateway/pay_pal_express.rb
@@ -1,106 +1,114 @@
+# frozen_string_literal: true
+
 require 'paypal-sdk-merchant'
+
 module Spree
-  class Gateway::PayPalExpress < Gateway
-    preference :login, :string
-    preference :password, :password
-    preference :signature, :string
-    preference :server, :string, default: 'sandbox'
-    preference :solution, :string, default: 'Mark'
-    preference :landing_page, :string, default: 'Billing'
-    preference :logourl, :string, default: ''
+  class Gateway
+    class PayPalExpress < Gateway
+      preference :login, :string
+      preference :password, :password
+      preference :signature, :string
+      preference :server, :string, default: 'sandbox'
+      preference :solution, :string, default: 'Mark'
+      preference :landing_page, :string, default: 'Billing'
+      preference :logourl, :string, default: ''
 
-    def supports?(source)
-      true
-    end
-
-    def provider_class
-      ::PayPal::SDK::Merchant::API
-    end
-
-    def provider
-      ::PayPal::SDK.configure(
-        :mode      => preferred_server.present? ? preferred_server : "sandbox",
-        :username  => preferred_login,
-        :password  => preferred_password,
-        :signature => preferred_signature)
-      provider_class.new
-    end
-
-    def auto_capture?
-      true
-    end
-
-    def method_type
-      'paypal'
-    end
-
-    def purchase(amount, express_checkout, gateway_options={})
-      pp_details_request = provider.build_get_express_checkout_details({
-        :Token => express_checkout.token
-      })
-      pp_details_response = provider.get_express_checkout_details(pp_details_request)
-
-      pp_request = provider.build_do_express_checkout_payment({
-        :DoExpressCheckoutPaymentRequestDetails => {
-          :PaymentAction => "Sale",
-          :Token => express_checkout.token,
-          :PayerID => express_checkout.payer_id,
-          :PaymentDetails => pp_details_response.get_express_checkout_details_response_details.PaymentDetails
-        }
-      })
-
-      pp_response = provider.do_express_checkout_payment(pp_request)
-      if pp_response.success?
-        # We need to store the transaction id for the future.
-        # This is mainly so we can use it later on to refund the payment if the user wishes.
-        transaction_id = pp_response.do_express_checkout_payment_response_details.payment_info.first.transaction_id
-        express_checkout.update_column(:transaction_id, transaction_id)
-        # This is rather hackish, required for payment/processing handle_response code.
-        Class.new do
-          def success?; true; end
-          def authorization; nil; end
-        end.new
-      else
-        class << pp_response
-          def to_s
-            errors.map(&:long_message).join(" ")
-          end
-        end
-        pp_response
+      def supports?(_source)
+        true
       end
-    end
 
-    def refund(payment, amount)
-      refund_type = payment.amount == amount.to_f ? "Full" : "Partial"
-      refund_transaction = provider.build_refund_transaction({
-        :TransactionID => payment.source.transaction_id,
-        :RefundType => refund_type,
-        :Amount => {
-          :currencyID => payment.currency,
-          :value => amount },
-        :RefundSource => "any" })
-      refund_transaction_response = provider.refund_transaction(refund_transaction)
-      if refund_transaction_response.success?
-        payment.source.update_attributes({
-          :refunded_at => Time.now,
-          :refund_transaction_id => refund_transaction_response.RefundTransactionID,
-          :state => "refunded",
-          :refund_type => refund_type
-        } )
+      def provider_class
+        ::PayPal::SDK::Merchant::API
+      end
 
-        payment.class.create!(
-          :order => payment.order,
-          :source => payment,
-          :payment_method => payment.payment_method,
-          :amount => amount.to_f.abs * -1,
-          :response_code => refund_transaction_response.RefundTransactionID,
-          :state => 'completed'
+      def provider
+        ::PayPal::SDK.configure(
+          mode: preferred_server.presence || "sandbox",
+          username: preferred_login,
+          password: preferred_password,
+          signature: preferred_signature
         )
+        provider_class.new
+      end
+
+      def auto_capture?
+        true
+      end
+
+      def method_type
+        'paypal'
+      end
+
+      def purchase(_amount, express_checkout, _gateway_options = {})
+        pp_details_request = provider.build_get_express_checkout_details(
+          Token: express_checkout.token
+        )
+        pp_details_response = provider.get_express_checkout_details(pp_details_request)
+
+        pp_request = provider.build_do_express_checkout_payment(
+          DoExpressCheckoutPaymentRequestDetails: {
+            PaymentAction: "Sale",
+            Token: express_checkout.token,
+            PayerID: express_checkout.payer_id,
+            PaymentDetails: pp_details_response.
+              get_express_checkout_details_response_details.PaymentDetails
+          }
+        )
+
+        pp_response = provider.do_express_checkout_payment(pp_request)
+        if pp_response.success?
+          # We need to store the transaction id for the future.
+          # This is mainly so we can use it later on to refund the payment if the user wishes.
+          transaction_id = pp_response.do_express_checkout_payment_response_details.
+            payment_info.first.transaction_id
+          express_checkout.update_column(:transaction_id, transaction_id)
+          # This is rather hackish, required for payment/processing handle_response code.
+          Class.new do
+            def success?; true; end
+
+            def authorization; nil; end
+          end.new
+        else
+          class << pp_response
+            def to_s
+              errors.map(&:long_message).join(" ")
+            end
+          end
+          pp_response
+        end
+      end
+
+      def refund(payment, amount)
+        refund_type = payment.amount == amount.to_f ? "Full" : "Partial"
+        refund_transaction = provider.build_refund_transaction(
+          TransactionID: payment.source.transaction_id,
+          RefundType: refund_type,
+          Amount: {
+            currencyID: payment.currency,
+            value: amount
+          },
+          RefundSource: "any"
+        )
+        refund_transaction_response = provider.refund_transaction(refund_transaction)
+        if refund_transaction_response.success?
+          payment.source.update_attributes(
+            refunded_at: Time.now,
+            refund_transaction_id: refund_transaction_response.RefundTransactionID,
+            state: "refunded",
+            refund_type: refund_type
+          )
+
+          payment.class.create!(
+            order: payment.order,
+            source: payment,
+            payment_method: payment.payment_method,
+            amount: amount.to_f.abs * -1,
+            response_code: refund_transaction_response.RefundTransactionID,
+            state: 'completed'
+          )
+        end
+        refund_transaction_response
       end
-      refund_transaction_response
     end
   end
 end
-
-#   payment.state = 'completed'
-#   current_order.state = 'complete'