Render prepaid amount in UBL invoice

Closes #14766

modules/edocument_ubl/CHANGELOG

@@ -1,3 +1,4 @@
+* Render prepaid amount
 * Fill invoice source amounts instead of checking amounts
 * Filter the MIME type of the additional documents allowed by the specification
 * Use VATEX as tax exemption reason code

modules/edocument_ubl/edocument.py

@@ -271,6 +271,17 @@ class Invoice(Model):
                         return
                 return product.unece_allowance_charge_code
 
+    @cached_property
+    def prepaid_amount(self):
+        def balance(line):
+            if self.invoice.currency == line.second_currency:
+                return line.amount_second_currency
+            elif self.invoice.currency == self.invoice.company.currency:
+                return line.debit - line.credit
+            else:
+                return 0
+        return sum(map(balance, self.invoice.lines_to_pay))
+
     @classmethod
     def parse(cls, document):
         pool = Pool()

modules/edocument_ubl/template/2/CreditNote.xml

@@ -124,7 +124,8 @@ this repository contains the full copyright notices and license terms. -->
     <py:if test="this.invoice.total_amount != (this.invoice.untaxed_amount + this.invoice.tax_amount)">
         <cbc:PayableRoundingAmount py:attrs="{'currencyID': this.invoice.currency.code}">${-(this.invoice.total_amount - this.invoice.untaxed_amount - this.invoice.tax_amount)}</cbc:PayableRoundingAmount>
     </py:if>
-    <cbc:PayableAmount py:attrs="{'currencyID': this.invoice.currency.code}">${-this.invoice.total_amount}</cbc:PayableAmount>
+    <cbc:PrepaidAmount py:if="this.prepaid_amount" py:attrs="{'currencyID': this.invoice.currency.code}">${-this.prepaid_amount}</cbc:PrepaidAmount>
+    <cbc:PayableAmount py:attrs="{'currencyID': this.invoice.currency.code}">${-this.invoice.total_amount + this.prepaid_amount}</cbc:PayableAmount>
 </cac:LegalMonetaryTotal>
 <cac:CreditNoteLine py:for="line_id, line in enumerate(this.lines, 1)">
     <cbc:ID>${line_id}</cbc:ID>

modules/edocument_ubl/template/2/Invoice.xml

@@ -124,7 +124,8 @@ this repository contains the full copyright notices and license terms. -->
     <py:if test="this.invoice.total_amount != (this.invoice.untaxed_amount + this.invoice.tax_amount)">
         <cbc:PayableRoundingAmount py:attrs="{'currencyID': this.invoice.currency.code}">${this.invoice.total_amount - this.invoice.untaxed_amount - this.invoice.tax_amount}</cbc:PayableRoundingAmount>
     </py:if>
-    <cbc:PayableAmount py:attrs="{'currencyID': this.invoice.currency.code}">${this.invoice.total_amount}</cbc:PayableAmount>
+    <cbc:PrepaidAmount py:if="this.prepaid_amount" py:attrs="{'currencyID': this.invoice.currency.code}">${this.prepaid_amount}</cbc:PrepaidAmount>
+    <cbc:PayableAmount py:attrs="{'currencyID': this.invoice.currency.code}">${this.invoice.total_amount - this.prepaid_amount}</cbc:PayableAmount>
 </cac:LegalMonetaryTotal>
 <cac:InvoiceLine py:for="line_id, line in enumerate(this.lines, 1)">
     <cbc:ID>${line_id}</cbc:ID>