Add balance auto reload

Closes #329

lib/tasks/registrars/reload_balance.rake

@@ -0,0 +1,35 @@
+namespace :registrars do
+  desc 'Reloads balance of registrars'
+
+  task reload_balance: :environment do
+    include ActionView::Helpers::NumberHelper
+    invoiced_registrar_count = 0
+
+    Registrar.transaction do
+      Registrar.all.each do |registrar|
+        balance_auto_reload_setting = registrar.settings['balance_auto_reload']
+        next unless balance_auto_reload_setting
+
+        reload_pending = balance_auto_reload_setting['pending']
+        threshold_reached = registrar.balance <= balance_auto_reload_setting['type']['threshold']
+        reload_amount = balance_auto_reload_setting['type']['amount']
+
+        next if reload_pending || !threshold_reached
+
+        Registrar.transaction do
+          invoice = registrar.issue_prepayment_invoice(reload_amount)
+          e_invoice = invoice.to_e_invoice
+          e_invoice.deliver
+
+          registrar.settings['balance_auto_reload']['pending'] = true
+          registrar.save!
+        end
+
+        puts %(Registrar "#{registrar}" got #{number_to_currency(reload_amount, unit: 'EUR')})
+        invoiced_registrar_count += 1
+      end
+    end
+
+    puts "Invoiced total: #{invoiced_registrar_count}"
+  end
+end