Improve invoice view

app/models/invoice.rb

@@ -7,4 +7,24 @@ class Invoice < ActiveRecord::Base
   def seller_address
     [seller_street, seller_city, seller_state, seller_zip].reject(&:blank?).compact.join(', ')
   end
+
+  def buyer_address
+    [buyer_street, buyer_city, buyer_state, buyer_zip].reject(&:blank?).compact.join(', ')
+  end
+
+  def items
+    invoice_items
+  end
+
+  def total_without_vat
+    items.map(&:item_total_without_vat).sum
+  end
+
+  def total_vat
+    total_without_vat * vat_prc
+  end
+
+  def total
+    total_without_vat + total_vat
+  end
 end

app/models/invoice_item.rb

@@ -1,3 +1,7 @@
 class InvoiceItem < ActiveRecord::Base
   belongs_to :invoice
+
+  def item_total_without_vat
+    amount * price
+  end
 end

app/models/registrar.rb

@@ -67,9 +67,9 @@ class Registrar < ActiveRecord::Base
       invoice_items_attributes: [
         {
           description: 'prepayment',
-          item_unit: 'piece',
-          item_amount: 1,
-          item_price: amount
+          unit: 'piece',
+          amount: 1,
+          price: amount
         }
       ]
     )