feat(invoice): add tax document warning on proforma

Author: nijel

weblate_web/invoices/models.py

@@ -763,6 +763,10 @@ def can_be_paid(self, *state: InvoiceKind) -> bool:
     def is_final(self):
         return self.kind == InvoiceKind.INVOICE
 
+    @property
+    def is_proforma(self):
+        return self.kind == InvoiceKind.PROFORMA
+
     def get_payment_url(self) -> str | None:
         if self.can_be_paid():
             return get_site_url("invoice-pay", pk=self.pk)

weblate_web/invoices/templates/invoice-template.html

@@ -223,14 +223,20 @@ <h2>Issued by</h2>
 
           {% endif %}
         {% endif %}
-        {% if invoice.is_final %}This is a computer-generated invoice; signature not required.{% endif %}
+        {% if invoice.is_final %}
+          This is a computer-generated invoice; signature not required.
+        {% elif invoice.is_proforma %}
+          This is not a tax document.
+        {% endif %}
       </p>
       <table id="details">
         <tbody>
           <tr>
             <th>
               {% if invoice.is_draft %}
                 Quote date
+              {% elif invoice.is_proforma %}
+                Issue date
               {% else %}
                 Date of taxable supply
               {% endif %}