#
# 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 os
import re
from xml.etree import ElementTree

import requests
import vat_moss.id
from django.conf import settings
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__)
error_messages = {
    'unavailable': _(
        '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.'
    ),
    'invalid': _('This VAT ID is not valid. Please re-check your input.'),
    'country_mismatch': _('Your VAT ID does not match the selected country.'),
}


class VATIDError(Exception):
    def __init__(self, message):
        self.message = message


class VATIDFinalError(VATIDError):
    pass


class VATIDTemporaryError(VATIDError):
    pass


def _validate_vat_id_NO(vat_id, country_code):
    # Inspired by vat_moss library
    if not vat_id.startswith("NO"):
        # prefix is not usually used in Norway, but expected by vat_moss library
        vat_id = "NO" + vat_id
    try:
        vat_id = vat_moss.id.normalize(vat_id)
    except ValueError:
        raise VATIDFinalError(error_messages['invalid'])

    if not vat_id or len(vat_id) < 3 or not re.match('^\\d{9}MVA$', vat_id[2:]):
        raise VATIDFinalError(error_messages['invalid'])

    organization_number = vat_id[2:].replace('MVA', '')
    validation_url = 'https://data.brreg.no/enhetsregisteret/api/enheter/%s' % organization_number

    try:
        response = requests.get(validation_url, timeout=10)
        if response.status_code in (404, 400):
            raise VATIDFinalError(error_messages['invalid'])

        response.raise_for_status()

        info = response.json()
        # This should never happen, but keeping it incase the API is changed
        if 'organisasjonsnummer' not in info or info['organisasjonsnummer'] != organization_number:
            logger.warning(
                'VAT ID checking failed for Norway due to missing or mismatching organisasjonsnummer in repsonse'
            )
            raise VATIDFinalError(error_messages['invalid'])
    except requests.RequestException:
        logger.exception('VAT ID checking failed for country {}'.format(country_code))
        raise VATIDTemporaryError(error_messages['unavailable'])
    else:
        return vat_id


def _validate_vat_id_EU(vat_id, country_code):
    # Inspired by vat_moss library
    try:
        vat_id = vat_moss.id.normalize(vat_id)
    except ValueError:
        raise VATIDFinalError(error_messages['invalid'])

    if not vat_id or len(vat_id) < 3:
        raise VATIDFinalError(error_messages['invalid'])

    number = vat_id[2:]

    if vat_id[:2] != cc_to_vat_prefix(country_code):
        raise VATIDFinalError(error_messages['country_mismatch'])

    if not re.match(vat_moss.id.ID_PATTERNS[cc_to_vat_prefix(country_code)]['regex'], number):
        raise VATIDFinalError(error_messages['invalid'])

    # We are relying on the country code of the normalized VAT-ID and not the user/InvoiceAddress-provided
    # VAT-ID, since Django and the EU have different ideas of which country is using which country code.
    # For example: For django and most people, Greece is GR. However, the VAT-service expects EL.
    payload = """
            <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:urn="urn:ec.europa.eu:taxud:vies:services:checkVat:types">
               <soapenv:Header/>
               <soapenv:Body>
                  <urn:checkVat>
                     <urn:countryCode>%s</urn:countryCode>
                     <urn:vatNumber>%s</urn:vatNumber>
                  </urn:checkVat>
               </soapenv:Body>
            </soapenv:Envelope>
    """.strip() % (vat_id[:2], number)

    try:
        response = requests.post(
            'https://ec.europa.eu/taxation_customs/vies/services/checkVatService',
            data=payload,
            timeout=10,
        )
        response.raise_for_status()

        return_xml = response.text

        try:
            envelope = ElementTree.fromstring(return_xml)
        except ElementTree.ParseError:
            logger.error(
                f'VAT ID checking failed for {country_code} due to XML parse error'
            )
            raise VATIDTemporaryError(error_messages['unavailable'])

        namespaces = {
            'soap': 'http://schemas.xmlsoap.org/soap/envelope/',
            'vat': 'urn:ec.europa.eu:taxud:vies:services:checkVat:types'
        }
        valid_elements = envelope.findall('./soap:Body/vat:checkVatResponse/vat:valid', namespaces)
        if not valid_elements:
            logger.error(
                f'VAT ID checking failed for {country_code} due to missing <valid> tag, response was: {return_xml}'
            )
            raise VATIDTemporaryError(error_messages['unavailable'])

        if valid_elements[0].text.lower() != 'true':
            raise VATIDFinalError(error_messages['invalid'])

    except requests.RequestException:
        logger.exception('VAT ID checking failed for country {}'.format(country_code))
        raise VATIDTemporaryError(error_messages['unavailable'])
    else:
        return vat_id


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(os.path.join(settings.CACHE_DIR, "validate_vat_id_ch_zeep_cache.db")),
            timeout=10
        )
        client = Client(
            'https://www.uid-wse.admin.ch/V5.0/PublicServices.svc?wsdl',
            transport=transport,
        )
        result = client.service.ValidateUID(uid=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.'
        ))
    else:
        if not result:
            raise VATIDFinalError(_('This VAT ID is not valid. Please re-check your input.'))
        return vat_id


def validate_vat_id(vat_id, country_code):
    if not vat_id:
        return vat_id
    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)
    elif country_code == 'NO':
        return _validate_vat_id_NO(vat_id, country_code)

    raise VATIDTemporaryError(f'VAT ID should not be entered for country {country_code}')