Created checkout using Pagseguro lightbox.

app/assets/javascripts/spree/frontend/pagseguro.js

@@ -0,0 +1,20 @@
+//Insira o código de checkout gerado no Passo 1
+var pagsegurCodeSelector = document.querySelector('div[data-pagseguro-code]')
+if (pagsegurCodeSelector) {
+  var code = pagsegurCodeSelector.dataset.pagseguroCode;
+  var callback = {
+    success : function(transactionCode) {
+      var checkoutPaymentForm = document.querySelector('form.checkout_form_payment');
+      var submit = checkout_form_payment.querySelector("input[type='submit']")
+      $(submit).trigger('click');
+    },
+    abort : function() {
+      console.log("abortado");
+    }
+  };
+  var isOpenLightbox = PagSeguroLightbox(code, callback);
+  if (!isOpenLightbox){
+    location.href="https://pagseguro.uol.com.br/v2/checkout/payment.html?code=" + code;
+    console.log("Redirecionamento")
+  }
+}

app/controllers/spree/checkout_controller_decorator.rb

@@ -0,0 +1,14 @@
+module Spree::CheckoutControllerDecorator
+  def self.prepended(base)
+    base.before_action :create_pag_seguro_transaction, only: :edit
+  end
+
+  def create_pag_seguro_transaction
+    return unless params[:state] == "payment"
+    payment = @order.payments.build(payment_method: Spree::PaymentMethod.where(type: 'Spree::PaymentMethod::Pagseguro').last)
+    SpreePagseguroSimple::Gateway.new(payment)
+    @pag_seguro_payment = Spree::PagSeguroTransaction.find_by_order_id @order.number
+  end
+end
+
+::Spree::CheckoutController.prepend Spree::CheckoutControllerDecorator

app/controllers/spree/pagseguro_controller.rb

@@ -27,20 +27,31 @@ def notify
                                       payment_method_id: payment_method.id,
                                       amount: notification.gross_amount).last
 
-      if payment
-        if notification.approved?
-          payment.complete!
-        end
+      pag_seguro_transaction = Spree::PagSeguroTransaction.find_by_order_id @order.number
 
-        if notification.cancelled? || notification.returned?
-          payment.void!
+      if payment
+        ActiveRecord::Base.transaction do
+          if notification.approved?
+            payment.complete!
+
+            if pag_seguro_transaction.present?
+              pag_seguro_transaction.update!(state: 'approved')
+            end
+          end
+
+          if notification.cancelled? || notification.returned?
+            payment.void!
+
+            if pag_seguro_transaction.present?
+              pag_seguro_transaction.update!(state: 'cancelled')
+            end
+          end
         end
       else
         raise StandardError
       end
 
-      render nothing: true, head: :ok
+      render body: :ok
     end
-
   end
 end

app/views/spree/checkout/payment/_pag_seguro.html.erb

@@ -1 +1,6 @@
 <p>Finalize seu pedido para efetuar o pagamento no PagSeguro</p>
+<%= content_for :head do %>
+  <script type="text/javascript" src="https://stc.sandbox.pagseguro.uol.com.br/pagseguro/api/v2/checkout/pagseguro.lightbox.js"></script>
+<% end %>
+
+<div data-pagseguro-code="<%= @pag_seguro_payment.code %>">

db/migrate/20200318233804_add_code_to_spree_payments.rb

@@ -0,0 +1,5 @@
+class AddCodeToSpreePayments < ActiveRecord::Migration[6.0]
+  def change
+    add_column :spree_payments, :code, :string
+  end
+end

db/migrate/20200410203710_remove_code_to_spree_payments.rb

@@ -0,0 +1,5 @@
+class RemoveCodeToSpreePayments < ActiveRecord::Migration[6.0]
+  def change
+    remove_column :spree_payments, :code
+  end
+end

lib/generators/spree_pagseguro_simple/install/install_generator.rb

@@ -1,9 +1,18 @@
 module SpreePagseguroSimple
   module Generators
     class InstallGenerator < Rails::Generators::Base
+      source_root File.expand_path("../../../templates", __FILE__)
 
       class_option :auto_run_migrations, :type => :boolean, :default => false
 
+      def add_javascripts
+        append_file 'vendor/assets/javascripts/spree/frontend/all.js', "//= require spree/frontend/pagseguro\n"
+      end
+
+      def copy_intializer
+        template "pagseguro.rb", "config/initializers/pagseguro.rb"
+      end
+
       def add_migrations
         run 'bundle exec rake railties:install:migrations FROM=spree_pagseguro_simple'
       end

lib/generators/templates/pagseguro.rb

@@ -0,0 +1 @@
+PagSeguro::Url.environment = ENV['PAGSEGURO_ENV'].to_sym

lib/spree_pagseguro_simple/gateway.rb

@@ -12,30 +12,31 @@ def initialize(payment)
       process
     end
 
+    def code
+      @pag_seguro_transaction.code
+    end
+
     def is_not_completed?
       !@payment.completed? && transaction_exists_and_is_loaded && @pag_seguro_transaction.state == 'pending'
     end
 
     def payment_url
-      subdomain = @env == :sandbox ? 'sandbox.pagseguro' : 'pagseguro'
       "https://#{subdomain}.uol.com.br/v2/checkout/payment.html?code=#{@pag_seguro_transaction.code}"
     end
 
     private
-    def process
-      set_environment
 
+    def subdomain
+      @subdomain ||= ENV['PAGSEGURO_ENV'].eql? 'sandbox' ? 'sandbox.pagseguro' : 'pagseguro'
+    end
+
+    def process
       unless transaction_exists_and_is_loaded
         build_pagseguro
         create_transaction
       end
     end
 
-    def set_environment
-      @env = ENV['PAGSEGURO_ENV'] ? :production : :sandbox
-      PagSeguro::Url.environment = @env
-    end
-
     def transaction_exists_and_is_loaded
       @pag_seguro_transaction ||= Spree::PagSeguroTransaction.find_by!(order_id: @order.number)
     rescue