Initial code to report VAT on invoices.

pinaxcon/settings.py

@@ -1,6 +1,7 @@
 import os
 import dj_database_url
 
+from decimal import Decimal
 
 PROJECT_ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), os.pardir))
 PACKAGE_ROOT = os.path.abspath(os.path.dirname(__file__))
@@ -315,6 +316,13 @@ TICKET_PRODUCT_CATEGORY = 1
 
 INVOICE_CURRENCY = "USD"
 
+# VAT rate is 21%
+# When PINAX_VAT_RATE is set, this percentage of the invoice total is
+# displayed as a line item as the amount of VAT paid.
+INVOICE_VAT_RATE = Decimal(os.environ.get('PINAX_VAT_RATE') or 0)
+if INVOICE_VAT_RATE > 1:
+    INVOICE_VAT_RATE /= 100
+
 MARKDOWN_DEUX_STYLES = {
     "default": {
         "safe_mode": False,

pinaxcon/templates/registrasion/invoice/details.html

@@ -38,6 +38,13 @@
 {% endblock %}
 
 {% block extra_line_items_after_total %}
+  {% vat_amount(invoice) as vat %}
+  {% if vat %}
+    <tr>
+      <td colspan="3">Includes {{ vat_rate }} VAT:</td>
+      <td class="text-right">${{ vat }}</td>
+    </tr>
+  {% endif %}
   {% donation_income invoice as donation %}
   {% if donation %}
     <tr>

pinaxcon/templatetags/nbpy_tags.py

@@ -11,6 +11,16 @@ from urllib import urlencode  # TODO: s/urllib/six.moves.urllib/
 
 register = template.Library()
 
+CENTS_QUANT = Decimal('.01')
+VAT_RATE = str(settings.INVOICE_VAT_RATE * 100).rstrip('.0') + '%'
+
+@register.simple_tag
+def vat_amount(invoice):
+    return (invoice.value * settings.INVOICE_VAT_RATE).quantize(CENTS_QUANT)
+
+@register.simple_tag
+def vat_rate():
+    return VAT_RATE
 
 @register.simple_tag(takes_context=True)
 def donation_income(context, invoice):
@@ -42,7 +52,7 @@ def donation_income(context, invoice):
             rbi.append(line.total_price * fsa_rate)
 
     donation = max(Decimal('0'), (invoice.value - sum(rbi)))
-    return donation.quantize(Decimal('.01'))
+    return donation.quantize(CENTS_QUANT)
 
 
 # TODO: include van/de/van der/de la/etc etc etc