super rough around the edges api for better spree paypal express

app/controllers/spree/api/paypal_controller.rb

@@ -0,0 +1,202 @@
+module Spree
+  module Api
+    class PaypalController < Spree::Api::BaseController
+      ssl_allowed
+
+      def express
+
+        order = current_order || raise(ActiveRecord::RecordNotFound)
+        items = order.line_items.map(&method(:line_item))
+
+        tax_adjustments = order.all_adjustments.tax.additional
+        shipping_adjustments = order.all_adjustments.shipping
+
+        order.all_adjustments.eligible.each do |adjustment|
+          next if (tax_adjustments + shipping_adjustments).include?(adjustment)
+          items << {
+            :Name => adjustment.label,
+            :Quantity => 1,
+            :Amount => {
+              :currencyID => order.currency,
+              :value => adjustment.amount
+            }
+          }
+        end
+
+        # Because PayPal doesn't accept $0 items at all.
+        # See #10
+        # https://cms.paypal.com/uk/cgi-bin/?cmd=_render-content&content_ID=developer/e_howto_api_ECCustomizing
+        # "It can be a positive or negative value but not zero."
+        items.reject! do |item|
+          item[:Amount][:value].zero?
+        end
+        pp_request = provider.build_set_express_checkout(express_checkout_request_details(order, items))
+
+        # Trying to conform to https://guides.spreecommerce.com/api/summary.html
+        # as much as possible
+        begin
+          pp_response = provider.set_express_checkout(pp_request)
+          if pp_response.success?
+            url = provider.express_checkout_url(pp_response, :useraction => 'commit')
+
+            response = Spree::Paypal.new
+            response.redirect_url = url
+            respond_with response
+          else
+            # this one is easy we can just respond with pp_response errors
+            render json: {errors:pp_response.errors.collect(&:long_message).join(" ")}, status: 500
+          end
+        rescue SocketError
+          render json: {errors:[Spree.t('flash.connection_failed', :scope => 'paypal')]}, status: 500
+        end
+      end
+
+      def confirm
+        order = current_order || raise(ActiveRecord::RecordNotFound)
+        order.payments.create!({
+          :source => Spree::PaypalExpressCheckout.create({
+            :token => params[:token],
+            :payer_id => params[:PayerID]
+          }),
+          :amount => order.total,
+          :payment_method => payment_method
+        })
+
+        # using code from regular controller as psuedocode comment for what you are need to do on frontend now
+        #
+        # order.next # move order to next state
+        #
+        # if order.complete?
+        #   flash.notice = Spree.t(:order_processed_successfully)
+        #   redirect_to completion_route(order)
+        # else
+        #   redirect_to checkout_state_path(order.state)
+        # end
+        respond_with order
+      end
+
+      def cancel
+        # unneeded in api version where paypal calls back to client first
+        # you can just do this client side
+        #
+        # flash[:notice] = Spree.t('flash.cancel', :scope => 'paypal')
+        # order = current_order || raise(ActiveRecord::RecordNotFound)
+        # redirect_to checkout_state_path(order.state, paypal_cancel_token: params[:token])
+
+        render status: 200
+      end
+
+      private
+
+      def current_order
+        @order = Spree::Order.find_by(number: order_id)
+      end
+
+      def line_item(item)
+        {
+            :Name => item.product.name,
+            :Number => item.variant.sku,
+            :Quantity => item.quantity,
+            :Amount => {
+                :currencyID => item.order.currency,
+                :value => item.price
+            },
+            :ItemCategory => "Physical"
+        }
+      end
+
+      def express_checkout_request_details order, items
+        { :SetExpressCheckoutRequestDetails => {
+            :InvoiceID => order.number,
+            :BuyerEmail => order.email,
+            # Here we tell paypal redirect to client and have the client post back status to rails server
+            :ReturnURL => params[:confirm_url],
+            :CancelURL => params[:cancel_url],
+            :SolutionType => payment_method.preferred_solution.present? ? payment_method.preferred_solution : "Mark",
+            :LandingPage => payment_method.preferred_landing_page.present? ? payment_method.preferred_landing_page : "Billing",
+            :cppheaderimage => payment_method.preferred_logourl.present? ? payment_method.preferred_logourl : "",
+            :NoShipping => 1,
+            :PaymentDetails => [payment_details(items)]
+        }}
+      end
+
+
+      def payment_method
+        Spree::PaymentMethod.find(params[:payment_method_id])
+      end
+
+      def provider
+        payment_method.provider
+      end
+
+      def payment_details items
+        # This retrieves the cost of shipping after promotions are applied
+        # For example, if shippng costs $10, and is free with a promotion, shipment_sum is now $10
+        shipment_sum = current_order.shipments.map(&:discounted_cost).sum
+
+        # This calculates the item sum based upon what is in the order total, but not for shipping
+        # or tax.  This is the easiest way to determine what the items should cost, as that
+        # functionality doesn't currently exist in Spree core
+        item_sum = current_order.total - shipment_sum - current_order.additional_tax_total
+
+        if item_sum.zero?
+          # Paypal does not support no items or a zero dollar ItemTotal
+          # This results in the order summary being simply "Current purchase"
+          {
+            :OrderTotal => {
+              :currencyID => current_order.currency,
+              :value => current_order.total
+            }
+          }
+        else
+          {
+            :OrderTotal => {
+              :currencyID => current_order.currency,
+              :value => current_order.total
+            },
+            :ItemTotal => {
+              :currencyID => current_order.currency,
+              :value => item_sum
+            },
+            :ShippingTotal => {
+              :currencyID => current_order.currency,
+              :value => shipment_sum,
+            },
+            :TaxTotal => {
+              :currencyID => current_order.currency,
+              :value => current_order.additional_tax_total
+            },
+            :ShipToAddress => address_options,
+            :PaymentDetailsItem => items,
+            :ShippingMethod => "Shipping Method Name Goes Here",
+            :PaymentAction => "Sale"
+          }
+        end
+      end
+
+      def address_options
+        return {} unless address_required?
+
+        address_to_bill = current_order.bill_address || current_order.ship_address 
+        {
+            :Name => address_to_bill.try(:full_name),
+            :Street1 => address_to_bill.address1,
+            :Street2 => address_to_bill.address2,
+            :CityName => address_to_bill.city,
+            :Phone => address_to_bill.phone,
+            :StateOrProvince => address_to_bill.state_text,
+            :Country => address_to_bill.country.iso,
+            :PostalCode => address_to_bill.zipcode
+        }
+      end
+
+      def completion_route(order)
+        order_path(order, :token => order.guest_token)
+      end
+
+      def address_required?
+        payment_method.preferred_solution.eql?('Sole')
+      end
+    end
+  end
+end

app/models/spree/paypal.rb

@@ -0,0 +1,13 @@
+module Spree
+  class Paypal
+    include ActiveModel::SerializerSupport
+
+    ## simple poro to make serializing easy
+    # http://blog.honeybadger.io/poro-plain-old-ruby-object-tests-and-specs/
+    #
+    # maybe this functionality should be rolled into 
+    # the paypal express checkout object or be called paypal express idk
+    #
+    attr_accessor :redirect_url
+  end
+end

config/routes.rb

@@ -15,4 +15,12 @@
       end
     end
   end
-end
+
+  namespace :api do
+    post '/paypal', :to => "paypal#express", :as => :paypal_express_api
+    post '/paypal/confirm', :to => "paypal#confirm", :as => :confirm_paypal_api
+    post '/paypal/cancel', :to => "paypal#cancel", :as => :cancel_paypal_api
+    get '/paypal/notify', :to => "paypal#notify", :as => :notify_paypal_api
+  end
+
+end

spree_paypal_express.gemspec

@@ -23,7 +23,9 @@ Gem::Specification.new do |s|
   s.requirements << 'none'
 
   s.add_dependency 'spree_core', '~> 2.4.0'
+  s.add_dependency 'spree_api', '~> 2.4.0'
   s.add_dependency 'paypal-sdk-merchant', '1.106.1'
+  s.add_dependency 'active_model_serializers', '~> 0.8.2'
 
   s.add_development_dependency 'capybara', '~> 2.1'
   s.add_development_dependency 'coffee-rails'