Add more infos to the invoice page

When a foodcoop does not use the balancing feature the invoice page is
the main page for informations. Add all related information to it, so
people do not need to open the balancing page.

app/views/finance/invoices/show.html.haml

@@ -1,5 +1,7 @@
 - title t('.title', number: @invoice.number)
 
+- total = 0
+
 %p
   %b= heading_helper(Invoice, :created_at) + ':'
   = format_time(@invoice.created_at)
@@ -15,15 +17,21 @@
     %b= heading_helper(Invoice, :deliveries) + ':'
     %span><
       - @invoice.deliveries.order(:delivered_on).each_with_index do |delivery, index|
+        - sum = delivery.sum
+        - total += sum
         = ', ' if index > 0
         = link_to format_date(delivery.delivered_on), [delivery.supplier,delivery]
+        = ' (' + number_to_currency(sum) + ')'
 - if @invoice.orders.any?
   %p
     %b= heading_helper(Invoice, :orders) + ':'
     %span><
       - @invoice.orders.order(:ends).each_with_index do |order, index|
+        - sum = order.sum
+        - total += sum
         = ', ' if index > 0
         = link_to format_date(order.ends), new_finance_order_path(order_id: order)
+        = ' (' + number_to_currency(sum) + ')'
 
 %p
   %b= heading_helper(Invoice, :number) + ':'
@@ -43,6 +51,13 @@
 %p
   %b= heading_helper(Invoice, :deposit_credit) + ':'
   = number_to_currency @invoice.deposit_credit
+%p
+  %b= heading_helper(Invoice, :net_amount) + ':'
+  = number_to_currency @invoice.net_amount
+- if @invoice.deliveries.any? || @invoice.orders.any?
+  %p
+    %b= heading_helper(Invoice, :total) + ':'
+    = number_to_currency total
 %p
   %b= heading_helper(Invoice, :note) + ':'
   =h @invoice.note