Ask and validate VAT IDs for Switzerland (#2259)

Co-authored-by: Richard Schreiber <schreiber@rami.io>

src/pretix/base/services/tax.py

@@ -0,0 +1,130 @@
+#
+# This file is part of pretix (Community Edition).
+#
+# Copyright (C) 2014-2020 Raphael Michel and contributors
+# Copyright (C) 2020-2021 rami.io GmbH and contributors
+#
+# This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General
+# Public License as published by the Free Software Foundation in version 3 of the License.
+#
+# ADDITIONAL TERMS APPLY: Pursuant to Section 7 of the GNU Affero General Public License, additional terms are
+# applicable granting you additional permissions and placing additional restrictions on your usage of this software.
+# Please refer to the pretix LICENSE file to obtain the full terms applicable to this work. If you did not receive
+# this file, see <https://pretix.eu/about/en/license>.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along with this program.  If not, see
+# <https://www.gnu.org/licenses/>.
+#
+import logging
+import re
+from urllib.error import HTTPError
+
+import vat_moss.errors
+import vat_moss.id
+from django.utils.translation import gettext_lazy as _
+from zeep import Client, Transport
+from zeep.cache import SqliteCache
+from zeep.exceptions import Fault
+
+from pretix.base.models.tax import cc_to_vat_prefix, is_eu_country
+
+logger = logging.getLogger(__name__)
+
+
+class VATIDError(Exception):
+    def __init__(self, message):
+        self.message = message
+
+
+class VATIDFinalError(VATIDError):
+    pass
+
+
+class VATIDTemporaryError(VATIDError):
+    pass
+
+
+def _validate_vat_id_EU(vat_id, country_code):
+    if vat_id[:2] != cc_to_vat_prefix(country_code):
+        raise VATIDFinalError(_('Your VAT ID does not match the selected country.'))
+
+    try:
+        result = vat_moss.id.validate(vat_id)
+        if result:
+            country_code, normalized_id, company_name = result
+            return normalized_id
+    except (vat_moss.errors.InvalidError, ValueError):
+        raise VATIDFinalError(_('This VAT ID is not valid. Please re-check your input.'))
+    except vat_moss.errors.WebServiceUnavailableError:
+        logger.exception('VAT ID checking failed for country {}'.format(country_code))
+        raise VATIDTemporaryError(_(
+            'Your VAT ID could not be checked, as the VAT checking service of '
+            'your country is currently not available. We will therefore '
+            'need to charge VAT on your invoice. You can get the tax amount '
+            'back via the VAT reimbursement process.'
+        ))
+    except (vat_moss.errors.WebServiceError, HTTPError):
+        logger.exception('VAT ID checking failed for country {}'.format(country_code))
+        raise VATIDTemporaryError(_(
+            'Your VAT ID could not be checked, as the VAT checking service of '
+            'your country returned an incorrect result. We will therefore '
+            'need to charge VAT on your invoice. Please contact support to '
+            'resolve this manually.'
+        ))
+
+
+def _validate_vat_id_CH(vat_id, country_code):
+    if vat_id[:3] != 'CHE':
+        raise VATIDFinalError(_('Your VAT ID does not match the selected country.'))
+
+    vat_id = re.sub('[^A-Z0-9]', '', vat_id.replace('HR', '').replace('MWST', ''))
+    try:
+        transport = Transport(cache=SqliteCache())
+        client = Client(
+            'https://www.uid-wse-a.admin.ch/V5.0/PublicServices.svc?wsdl',
+            transport=transport
+        )
+        if not client.service.ValidateUID(uid=vat_id):
+            raise VATIDFinalError(_('This VAT ID is not valid. Please re-check your input.'))
+        return vat_id
+    except Fault as e:
+        if e.message == 'Data_validation_failed':
+            raise VATIDFinalError(_('This VAT ID is not valid. Please re-check your input.'))
+        elif e.message == 'Request_limit_exceeded':
+            logger.exception('VAT ID checking failed for country {} due to request limit'.format(country_code))
+            raise VATIDTemporaryError(_(
+                'Your VAT ID could not be checked, as the VAT checking service of '
+                'your country returned an incorrect result. We will therefore '
+                'need to charge VAT on your invoice. Please contact support to '
+                'resolve this manually.'
+            ))
+        else:
+            logger.exception('VAT ID checking failed for country {}'.format(country_code))
+            raise VATIDTemporaryError(_(
+                'Your VAT ID could not be checked, as the VAT checking service of '
+                'your country returned an incorrect result. We will therefore '
+                'need to charge VAT on your invoice. Please contact support to '
+                'resolve this manually.'
+            ))
+    except:
+        logger.exception('VAT ID checking failed for country {}'.format(country_code))
+        raise VATIDTemporaryError(_(
+            'Your VAT ID could not be checked, as the VAT checking service of '
+            'your country is currently not available. We will therefore '
+            'need to charge VAT on your invoice. You can get the tax amount '
+            'back via the VAT reimbursement process.'
+        ))
+
+
+def validate_vat_id(vat_id, country_code):
+    country_code = str(country_code)
+    if is_eu_country(country_code):
+        return _validate_vat_id_EU(vat_id, country_code)
+    elif country_code == 'CH':
+        return _validate_vat_id_CH(vat_id, country_code)
+
+    raise VATIDTemporaryError(f'VAT ID should not be entered for country {country_code}')