Invoices: Allow to use currency rates from National Bank of Poland (#6100)

src/pretix/base/services/currencies.py

@@ -38,6 +38,7 @@ SOURCE_NAMES = {
     None: _('European Central Bank'),  # backwards-compatibility
     'eu:ecb:eurofxref-daily': _('European Central Bank'),
     'cz:cnb:rate-fixing-daily': _('Czech National Bank'),
+    'pl:nbp:table-a': _('National Bank of Poland'),
 }
 
 
@@ -49,6 +50,7 @@ def fetch_rates(sender, **kwargs):
     source_tasks = {
         'eu:ecb:eurofxref-daily': fetch_ecb_rates,
         'cz:cnb:rate-fixing-daily': fetch_cnb_cz_rates,
+        'pl:nbp:table-a': fetch_nbp_pl_rates,
     }
 
     for source_name, task in source_tasks.items():
@@ -144,3 +146,29 @@ def fetch_cnb_cz_rates():
                 rate=rate,
             )
         )
+
+
+@app.task()
+def fetch_nbp_pl_rates():
+    """
+    Fetches currency rates from the Polish National Bank.
+    """
+    r = requests.get("https://api.nbp.pl/api/exchangerates/tables/A/", headers={
+        "Accept": "application/json",
+    })
+    r.raise_for_status()
+    data = r.json()[0]
+
+    source_date = datetime.strptime(data["effectiveDate"], "%Y-%m-%d").date()
+
+    for r in data["rates"]:
+        rate = Decimal(r["mid"]).quantize(Decimal('0.000001'))
+        ExchangeRate.objects.update_or_create(
+            source='pl:nbp:table-a',
+            source_currency=r["code"],
+            other_currency='PLN',
+            defaults=dict(
+                source_date=source_date,
+                rate=rate,
+            )
+        )

src/pretix/base/services/invoices.py

@@ -205,6 +205,19 @@ def build_invoice(invoice: Invoice) -> Invoice:
                         invoice.foreign_currency_rate = rate.rate.quantize(Decimal('0.0001'), ROUND_HALF_UP)
                         invoice.foreign_currency_rate_date = rate.source_date
                         invoice.foreign_currency_source = 'cz:cnb:rate-fixing-daily'
+            elif invoice.event.settings.invoice_eu_currencies == 'PLN' and invoice.event.currency != 'PLN':
+                invoice.foreign_currency_display = 'PLN'
+                if settings.FETCH_ECB_RATES:
+                    rate = ExchangeRate.objects.filter(
+                        source='pl:nbp:table-a',
+                        source_currency=invoice.event.currency,
+                        other_currency=invoice.foreign_currency_display,
+                        source_date__gt=now().date() - timedelta(days=7)
+                    ).first()
+                    if rate:
+                        invoice.foreign_currency_rate = rate.rate.quantize(Decimal('0.0001'), ROUND_HALF_UP)
+                        invoice.foreign_currency_rate_date = rate.source_date
+                        invoice.foreign_currency_source = 'pl:nbp:table-a'
 
         except InvoiceAddress.DoesNotExist:
             ia = None

src/pretix/base/settings.py

@@ -574,6 +574,7 @@ DEFAULTS = {
                 ('True', _('Based on European Central Bank daily rates, whenever the invoice recipient is in an EU '
                            'country that uses a different currency.')),
                 ('CZK', _('Based on Czech National Bank daily rates, whenever the invoice amount is not in CZK.')),
+                ('PLN', _('Based on National Bank of Poland daily rates, whenever the invoice amount is not in PLN.')),
             ),
         ),
         'serializer_kwargs': dict(
@@ -582,6 +583,7 @@ DEFAULTS = {
                 ('True', _('Based on European Central Bank daily rates, whenever the invoice recipient is in an EU '
                            'country that uses a different currency.')),
                 ('CZK', _('Based on Czech National Bank daily rates, whenever the invoice amount is not in CZK.')),
+                ('PLN', _('Based on National Bank of Poland daily rates, whenever the invoice amount is not in PLN.')),
             ),
         ),
     },