#
# 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 hashlib
from importlib import import_module
from urllib.parse import (
    parse_qs, quote, urlencode, urljoin, urlparse, urlsplit, urlunparse,
)

from django.conf import settings
from django.contrib import messages
from django.core.exceptions import ValidationError
from django.core.signing import BadSignature, dumps, loads
from django.db import IntegrityError, transaction
from django.db.models import Count, IntegerField, OuterRef, Q, Subquery
from django.http import Http404, HttpResponseRedirect
from django.shortcuts import get_object_or_404, redirect, render
from django.utils.crypto import get_random_string
from django.utils.decorators import method_decorator
from django.utils.functional import cached_property
from django.utils.http import url_has_allowed_host_and_scheme
from django.utils.translation import gettext_lazy as _
from django.views.decorators.cache import never_cache
from django.views.decorators.csrf import csrf_protect
from django.views.decorators.debug import sensitive_post_parameters
from django.views.generic import DeleteView, FormView, ListView, View

from pretix.base.customersso.oidc import (
    oidc_authorize_url, oidc_validate_authorization,
)
from pretix.base.models import Customer, InvoiceAddress, Order, OrderPosition
from pretix.base.services.mail import mail
from pretix.base.settings import PERSON_NAME_SCHEMES
from pretix.multidomain.models import KnownDomain
from pretix.multidomain.urlreverse import build_absolute_uri, eventreverse
from pretix.presale.forms.customer import (
    AuthenticationForm, ChangeInfoForm, ChangePasswordForm, RegistrationForm,
    ResetPasswordForm, SetPasswordForm, TokenGenerator,
)
from pretix.presale.utils import (
    customer_login, customer_logout, update_customer_session_auth_hash,
)

SessionStore = import_module(settings.SESSION_ENGINE).SessionStore


class RedirectBackMixin:
    redirect_field_name = 'next'

    def get_redirect_url(self, redirect_to=None):
        """Return the user-originating redirect URL if it's safe."""
        redirect_to = redirect_to or self.request.POST.get(
            self.redirect_field_name,
            self.request.GET.get(self.redirect_field_name, '')
        )
        hosts = list(KnownDomain.objects.filter(event__organizer=self.request.organizer).values_list('domainname', flat=True))
        siteurlsplit = urlsplit(settings.SITE_URL)
        if siteurlsplit.port and siteurlsplit.port not in (80, 443):
            hosts = ['%s:%d' % (h, siteurlsplit.port) for h in hosts]

        url_is_safe = url_has_allowed_host_and_scheme(
            url=redirect_to,
            allowed_hosts=hosts,
            require_https=self.request.is_secure(),
        )
        return redirect_to if url_is_safe else ''


class LoginView(RedirectBackMixin, FormView):
    """
    Display the login form and handle the login action.
    """
    form_class = AuthenticationForm
    template_name = 'pretixpresale/organizers/customer_login.html'
    redirect_authenticated_user = True

    @method_decorator(sensitive_post_parameters())
    @method_decorator(csrf_protect)
    @method_decorator(never_cache)
    def dispatch(self, request, *args, **kwargs):
        if not request.organizer.settings.customer_accounts:
            raise Http404('Feature not enabled')
        if self.redirect_authenticated_user and self.request.customer:
            redirect_to = self.get_success_url()
            if redirect_to == self.request.path:
                raise ValueError(
                    "Redirection loop for authenticated user detected. Check that "
                    "your LOGIN_REDIRECT_URL doesn't point to a login page."
                )
            return HttpResponseRedirect(redirect_to)
        return super().dispatch(request, *args, **kwargs)

    def post(self, request, *args, **kwargs):
        if not request.organizer.settings.customer_accounts_native:
            raise Http404('Feature not enabled')
        return super().post(request, *args, **kwargs)

    def get_context_data(self, **kwargs):
        return super().get_context_data(
            **kwargs,
            providers=self.request.organizer.sso_providers.all()
        )

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        kwargs['request'] = self.request
        return kwargs

    def get_success_url(self):
        url = self.get_redirect_url()

        if not url:
            return eventreverse(self.request.organizer, 'presale:organizer.customer.profile', kwargs={})

        if self.request.GET.get("request_cross_domain_customer_auth") == "true":
            otpstore = SessionStore()
            otpstore[f'customer_cross_domain_auth_{self.request.organizer.pk}'] = self.request.session.session_key
            otpstore.set_expiry(60)
            otpstore.save(must_create=True)
            otp = otpstore.session_key

            u = urlparse(url)
            qsl = parse_qs(u.query)
            qsl['cross_domain_customer_auth'] = otp
            url = urlunparse((u.scheme, u.netloc, u.path, u.params, urlencode(qsl, doseq=True), u.fragment))

        return url

    def form_valid(self, form):
        """Security check complete. Log the user in."""
        customer_login(self.request, form.get_customer())
        return HttpResponseRedirect(self.get_success_url())


class LogoutView(View):
    redirect_field_name = 'next'

    @method_decorator(never_cache)
    def dispatch(self, request, *args, **kwargs):
        customer_logout(request)
        next_page = self.get_next_page()
        return HttpResponseRedirect(next_page)

    def get_next_page(self):
        if getattr(self.request, 'event_domain', False):
            # After we cleared the cookies on this domain, redirect to the parent domain to clear cookies as well
            next_page = eventreverse(self.request.organizer, 'presale:organizer.customer.logout', kwargs={})
            if self.redirect_field_name in self.request.POST or self.redirect_field_name in self.request.GET:
                after_next_page = self.request.POST.get(
                    self.redirect_field_name,
                    self.request.GET.get(self.redirect_field_name)
                )
                next_page += '?' + urlencode({
                    'next': urljoin(f'{self.request.scheme}://{self.request.get_host()}', after_next_page)
                })
        else:
            next_page = eventreverse(self.request.organizer, 'presale:organizer.index', kwargs={})

            if (self.redirect_field_name in self.request.POST or
                    self.redirect_field_name in self.request.GET):
                next_page = self.request.POST.get(
                    self.redirect_field_name,
                    self.request.GET.get(self.redirect_field_name)
                )
                hosts = list(KnownDomain.objects.filter(event__organizer=self.request.organizer).values_list('domainname', flat=True))
                siteurlsplit = urlsplit(settings.SITE_URL)
                if siteurlsplit.port and siteurlsplit.port not in (80, 443):
                    hosts = ['%s:%d' % (h, siteurlsplit.port) for h in hosts]
                url_is_safe = url_has_allowed_host_and_scheme(
                    url=next_page,
                    allowed_hosts=hosts,
                    require_https=self.request.is_secure(),
                )
                # Security check -- Ensure the user-originating redirection URL is
                # safe.
                if not url_is_safe:
                    next_page = self.request.path

        return next_page


class RegistrationView(RedirectBackMixin, FormView):
    form_class = RegistrationForm
    template_name = 'pretixpresale/organizers/customer_registration.html'
    redirect_authenticated_user = True

    @method_decorator(sensitive_post_parameters())
    @method_decorator(csrf_protect)
    @method_decorator(never_cache)
    def dispatch(self, request, *args, **kwargs):
        if not request.organizer.settings.customer_accounts:
            raise Http404('Feature not enabled')
        if not request.organizer.settings.customer_accounts_native:
            raise Http404('Feature not enabled')
        if self.redirect_authenticated_user and self.request.customer:
            redirect_to = self.get_success_url()
            if redirect_to == self.request.path:
                raise ValueError(
                    "Redirection loop for authenticated user detected. Check that "
                    "your LOGIN_REDIRECT_URL doesn't point to a login page."
                )
            return HttpResponseRedirect(redirect_to)
        return super().dispatch(request, *args, **kwargs)

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        kwargs['request'] = self.request
        kwargs['standalone'] = True
        return kwargs

    def get_success_url(self):
        url = self.get_redirect_url()
        return url or eventreverse(self.request.organizer, 'presale:organizer.customer.login', kwargs={})

    def form_valid(self, form):
        with transaction.atomic():
            form.create()
        messages.success(
            self.request,
            _('Your account has been created. Please follow the link in the email we sent you to activate your '
              'account and choose a password.')
        )
        return HttpResponseRedirect(self.get_success_url())


class SetPasswordView(FormView):
    form_class = SetPasswordForm
    template_name = 'pretixpresale/organizers/customer_setpassword.html'

    @method_decorator(sensitive_post_parameters())
    @method_decorator(csrf_protect)
    @method_decorator(never_cache)
    def dispatch(self, request, *args, **kwargs):
        if not request.organizer.settings.customer_accounts:
            raise Http404('Feature not enabled')
        if not request.organizer.settings.customer_accounts_native:
            raise Http404('Feature not enabled')
        try:
            self.customer = request.organizer.customers.get(identifier=self.request.GET.get('id'), provider__isnull=True)
        except Customer.DoesNotExist:
            messages.error(request, _('You clicked an invalid link.'))
            return HttpResponseRedirect(self.get_success_url())
        if not TokenGenerator().check_token(self.customer, self.request.GET.get('token', '')):
            messages.error(request, _('You clicked an invalid link.'))
            return HttpResponseRedirect(self.get_success_url())
        return super().dispatch(request, *args, **kwargs)

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        kwargs['customer'] = self.customer
        return kwargs

    def get_success_url(self):
        return eventreverse(self.request.organizer, 'presale:organizer.customer.login', kwargs={})

    def form_valid(self, form):
        with transaction.atomic():
            self.customer.set_password(form.cleaned_data['password'])
            self.customer.is_verified = True
            self.customer.save()
            self.customer.log_action('pretix.customer.password.set', {})
        messages.success(
            self.request,
            _('Your new password has been set! You can now use it to log in.'),
        )
        return HttpResponseRedirect(self.get_success_url())


class ResetPasswordView(FormView):
    form_class = ResetPasswordForm
    template_name = 'pretixpresale/organizers/customer_resetpw.html'

    @method_decorator(sensitive_post_parameters())
    @method_decorator(csrf_protect)
    @method_decorator(never_cache)
    def dispatch(self, request, *args, **kwargs):
        if not request.organizer.settings.customer_accounts:
            raise Http404('Feature not enabled')
        if not request.organizer.settings.customer_accounts_native:
            raise Http404('Feature not enabled')
        return super().dispatch(request, *args, **kwargs)

    def get_success_url(self):
        return eventreverse(self.request.organizer, 'presale:organizer.customer.login', kwargs={})

    def form_valid(self, form):
        customer = form.customer
        customer.log_action('pretix.customer.password.resetrequested', {})
        ctx = customer.get_email_context()
        token = TokenGenerator().make_token(customer)
        ctx['url'] = build_absolute_uri(self.request.organizer,
                                        'presale:organizer.customer.recoverpw') + '?id=' + customer.identifier + '&token=' + token
        mail(
            customer.email,
            _('Set a new password for your account at {organizer}').format(organizer=self.request.organizer.name),
            self.request.organizer.settings.mail_text_customer_reset,
            ctx,
            locale=customer.locale,
            customer=customer,
            organizer=self.request.organizer,
        )
        messages.success(
            self.request,
            _('We\'ve sent you an email with further instructions on resetting your password.')
        )
        return HttpResponseRedirect(self.get_success_url())

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        kwargs['request'] = self.request
        return kwargs


class CustomerRequiredMixin:
    def dispatch(self, request, *args, **kwargs):
        if not request.organizer.settings.customer_accounts:
            raise Http404('Feature not enabled')
        if not getattr(request, 'customer', None):
            return redirect(
                eventreverse(self.request.organizer, 'presale:organizer.customer.login', kwargs={}) +
                '?next=' + quote(self.request.path_info + '?' + self.request.GET.urlencode())
            )
        return super().dispatch(request, *args, **kwargs)


class ProfileView(CustomerRequiredMixin, ListView):
    template_name = 'pretixpresale/organizers/customer_profile.html'
    context_object_name = 'orders'
    paginate_by = 20

    def get_queryset(self):
        q = Q(customer=self.request.customer)
        if self.request.organizer.settings.customer_accounts_link_by_email:
            # This is safe because we only let customers with verified emails log in
            q |= Q(email__iexact=self.request.customer.email)
        qs = Order.objects.filter(
            q
        ).select_related('event').order_by('-datetime')
        return qs

    def get_context_data(self, **kwargs):
        ctx = super().get_context_data(**kwargs)
        ctx['customer'] = self.request.customer
        ctx['memberships'] = self.request.customer.memberships.with_usages().select_related(
            'membership_type', 'granted_in', 'granted_in__order', 'granted_in__order__event'
        )
        ctx['invoice_addresses'] = InvoiceAddress.profiles.filter(customer=self.request.customer)
        ctx['is_paginated'] = True

        for m in ctx['memberships']:
            if m.membership_type.max_usages:
                m.percent = int(m.usages / m.membership_type.max_usages * 100)
            else:
                m.percent = 0

        s = OrderPosition.objects.filter(
            order=OuterRef('pk')
        ).order_by().values('order').annotate(k=Count('id')).values('k')
        annotated = {
            o['pk']: o
            for o in
            Order.annotate_overpayments(Order.objects, sums=True).filter(
                pk__in=[o.pk for o in ctx['orders']]
            ).annotate(
                pcnt=Subquery(s, output_field=IntegerField()),
            ).values(
                'pk', 'pcnt',
            )
        }

        for o in ctx['orders']:
            if o.pk not in annotated:
                continue
            o.count_positions = annotated.get(o.pk)['pcnt']
        return ctx


class MembershipUsageView(CustomerRequiredMixin, ListView):
    template_name = 'pretixpresale/organizers/customer_membership.html'
    context_object_name = 'usages'
    paginate_by = 20

    @cached_property
    def membership(self):
        return get_object_or_404(
            self.request.customer.memberships,
            pk=self.kwargs.get('id')
        )

    def get_queryset(self):
        return self.membership.orderposition_set.select_related(
            'order', 'order__event', 'subevent', 'item', 'variation',
        )

    def get_context_data(self, **kwargs):
        ctx = super().get_context_data(**kwargs)
        ctx['membership'] = self.membership
        ctx['is_paginated'] = True
        return ctx


class AddressDeleteView(CustomerRequiredMixin, DeleteView):
    template_name = 'pretixpresale/organizers/customer_address_delete.html'
    context_object_name = 'address'

    def get_object(self, **kwargs):
        return get_object_or_404(InvoiceAddress.profiles, customer=self.request.customer, pk=self.kwargs.get('id'))

    def get_success_url(self):
        return eventreverse(self.request.organizer, 'presale:organizer.customer.profile', kwargs={})


class ProfileDeleteView(CustomerRequiredMixin, DeleteView):
    template_name = 'pretixpresale/organizers/customer_profile_delete.html'
    context_object_name = 'profile'

    def get_object(self, **kwargs):
        return get_object_or_404(self.request.customer.attendee_profiles, pk=self.kwargs.get('id'))

    def get_success_url(self):
        return eventreverse(self.request.organizer, 'presale:organizer.customer.profile', kwargs={})


class ChangePasswordView(CustomerRequiredMixin, FormView):
    template_name = 'pretixpresale/organizers/customer_password.html'
    form_class = ChangePasswordForm

    @method_decorator(sensitive_post_parameters())
    @method_decorator(csrf_protect)
    @method_decorator(never_cache)
    def dispatch(self, request, *args, **kwargs):
        if not request.organizer.settings.customer_accounts:
            raise Http404('Feature not enabled')
        if self.request.customer.provider_id:
            raise Http404('Feature not enabled')
        return super().dispatch(request, *args, **kwargs)

    def get_success_url(self):
        return eventreverse(self.request.organizer, 'presale:organizer.customer.profile', kwargs={})

    @transaction.atomic()
    def form_valid(self, form):
        customer = form.customer
        customer.log_action('pretix.customer.password.set', {})
        customer.set_password(form.cleaned_data['password'])
        customer.save()
        messages.success(self.request, _('Your changes have been saved.'))
        update_customer_session_auth_hash(self.request, customer)
        return HttpResponseRedirect(self.get_success_url())

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        kwargs['customer'] = self.request.customer
        return kwargs


class ChangeInformationView(CustomerRequiredMixin, FormView):
    template_name = 'pretixpresale/organizers/customer_info.html'
    form_class = ChangeInfoForm

    @method_decorator(sensitive_post_parameters())
    @method_decorator(csrf_protect)
    @method_decorator(never_cache)
    def dispatch(self, request, *args, **kwargs):
        if not request.organizer.settings.customer_accounts:
            raise Http404('Feature not enabled')
        if self.request.customer:
            self.initial_email = self.request.customer.email
        return super().dispatch(request, *args, **kwargs)

    def get_success_url(self):
        return eventreverse(self.request.organizer, 'presale:organizer.customer.profile', kwargs={})

    def form_valid(self, form):
        if form.cleaned_data['email'] != self.initial_email and not self.request.customer.provider:
            new_email = form.cleaned_data['email']
            form.cleaned_data['email'] = form.instance.email = self.initial_email
            ctx = form.instance.get_email_context()
            ctx['url'] = build_absolute_uri(
                self.request.organizer,
                'presale:organizer.customer.change.confirm'
            ) + '?token=' + dumps({
                'customer': form.instance.pk,
                'email': new_email
            }, salt='pretix.presale.views.customer.ChangeInformationView')
            mail(
                new_email,
                _('Confirm email address for your account at {organizer}').format(organizer=self.request.organizer.name),
                self.request.organizer.settings.mail_text_customer_email_change,
                ctx,
                locale=form.instance.locale,
                customer=form.instance,
                organizer=self.request.organizer,
            )
            messages.success(self.request, _('Your changes have been saved. We\'ve sent you an email with a link to update your '
                                             'email address. The email address of your account will be changed as soon as you '
                                             'click that link.'))
        else:
            messages.success(self.request, _('Your changes have been saved.'))

        with transaction.atomic():
            form.save()
            d = dict(form.cleaned_data)
            print(d)
            del d['email']
            self.request.customer.log_action('pretix.customer.changed', d)

        update_customer_session_auth_hash(self.request, form.instance)
        return HttpResponseRedirect(self.get_success_url())

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        kwargs['request'] = self.request
        kwargs['instance'] = self.request.customer
        return kwargs


class ConfirmChangeView(View):
    template_name = 'pretixpresale/organizers/customer_info.html'

    def get(self, request, *args, **kwargs):
        if not request.organizer.settings.customer_accounts:
            raise Http404('Feature not enabled')

        try:
            data = loads(request.GET.get('token', ''), salt='pretix.presale.views.customer.ChangeInformationView', max_age=3600 * 24)
        except BadSignature:
            messages.error(request, _('You clicked an invalid link.'))
            return HttpResponseRedirect(self.get_success_url())

        try:
            customer = request.organizer.customers.get(pk=data.get('customer'), provider__isnull=True)
        except Customer.DoesNotExist:
            messages.error(request, _('You clicked an invalid link.'))
            return HttpResponseRedirect(self.get_success_url())

        with transaction.atomic():
            customer.email = data['email']
            customer.save()
            customer.log_action('pretix.customer.changed', {
                'email': data['email']
            })

        messages.success(request, _('Your email address has been updated.'))

        if customer == request.customer:
            update_customer_session_auth_hash(self.request, customer)

        return HttpResponseRedirect(self.get_success_url())

    def get_success_url(self):
        return eventreverse(self.request.organizer, 'presale:organizer.customer.profile', kwargs={})


class SSOLoginView(RedirectBackMixin, View):
    """
    Start logging in with a SSO provider.
    """
    form_class = AuthenticationForm
    redirect_authenticated_user = True

    @method_decorator(sensitive_post_parameters())
    @method_decorator(csrf_protect)
    @method_decorator(never_cache)
    def dispatch(self, request, *args, **kwargs):
        if not request.organizer.settings.customer_accounts:
            raise Http404('Feature not enabled')
        if self.redirect_authenticated_user and self.request.customer:
            redirect_to = self.get_success_url()
            if redirect_to == self.request.path:
                raise ValueError(
                    "Redirection loop for authenticated user detected. Check that "
                    "your LOGIN_REDIRECT_URL doesn't point to a login page."
                )
            return HttpResponseRedirect(redirect_to)
        return super().dispatch(request, *args, **kwargs)

    @cached_property
    def provider(self):
        return get_object_or_404(self.request.organizer.sso_providers.filter(is_active=True), pk=self.kwargs['provider'])

    def get(self, request, *args, **kwargs):
        next_url = request.GET.get('next') or ''
        popup_origin = request.GET.get('popup_origin', '')
        if popup_origin:
            popup_origin_parsed = urlparse(popup_origin)
            untrusted = (
                popup_origin_parsed.hostname != urlparse(settings.SITE_URL).hostname and
                not KnownDomain.objects.filter(domainname=popup_origin_parsed.hostname, organizer=self.request.organizer.pk).exists()
            )
            if untrusted:
                # Do not accept faked origins
                popup_origin = None

        nonce = get_random_string(32)
        request.session[f'pretix_customerauth_{self.provider.pk}_nonce'] = nonce
        request.session[f'pretix_customerauth_{self.provider.pk}_popup_origin'] = popup_origin
        request.session[f'pretix_customerauth_{self.provider.pk}_cross_domain_requested'] = self.request.GET.get("request_cross_domain_customer_auth") == "true"
        redirect_uri = build_absolute_uri(self.request.organizer, 'presale:organizer.customer.login.return', kwargs={
            'provider': self.provider.pk
        })

        if self.provider.method == "oidc":
            return redirect(oidc_authorize_url(self.provider, f'{nonce}#{next_url}', redirect_uri))
        else:
            raise Http404("Unknown SSO method.")

    def get_success_url(self):
        url = self.get_redirect_url()

        if not url:
            return eventreverse(self.request.organizer, 'presale:organizer.customer.profile', kwargs={})
        return url


class SSOLoginReturnView(RedirectBackMixin, View):
    """
    Start logging in with a SSO provider.
    """
    form_class = AuthenticationForm
    redirect_authenticated_user = True

    @method_decorator(sensitive_post_parameters())
    @method_decorator(csrf_protect)
    @method_decorator(never_cache)
    def dispatch(self, request, *args, **kwargs):
        if not request.organizer.settings.customer_accounts:
            raise Http404('Feature not enabled')
        if self.redirect_authenticated_user and self.request.customer:
            redirect_to = self.get_success_url()
            if redirect_to == self.request.path:
                raise ValueError(
                    "Redirection loop for authenticated user detected. Check that "
                    "your LOGIN_REDIRECT_URL doesn't point to a login page."
                )
            return HttpResponseRedirect(redirect_to)
        r = super().dispatch(request, *args, **kwargs)
        request.session.pop(f'pretix_customerauth_{self.provider.pk}_nonce', None)
        request.session.pop(f'pretix_customerauth_{self.provider.pk}_popup_origin', None)
        request.session.pop(f'pretix_customerauth_{self.provider.pk}_cross_domain_requested', None)
        return r

    @cached_property
    def provider(self):
        return get_object_or_404(self.request.organizer.sso_providers.filter(is_active=True), pk=self.kwargs['provider'])

    def get(self, request, *args, **kwargs):
        redirect_to = None
        popup_origin = None

        if request.session.get(f'pretix_customerauth_{self.provider.pk}_popup_origin'):
            popup_origin = request.session[f'pretix_customerauth_{self.provider.pk}_popup_origin']

        if self.provider.method == "oidc":
            if not request.GET.get('state'):
                return self._fail(
                    _('Login was not successful. Error message: "{error}".').format(
                        error='state parameter missing',
                    ),
                    popup_origin,
                )

            nonce, redirect_to = request.GET['state'].split('#')

            if nonce != request.session.get(f'pretix_customerauth_{self.provider.pk}_nonce'):
                return self._fail(
                    _('Login was not successful. Error message: "{error}".').format(
                        error='invalid nonce',
                    ),
                    popup_origin,
                )
            redirect_uri = build_absolute_uri(
                self.request.organizer, 'presale:organizer.customer.login.return',
                kwargs={
                    'provider': self.provider.pk
                }
            )
            try:
                profile = oidc_validate_authorization(
                    self.provider,
                    request.GET.get('code'),
                    redirect_uri,
                )
            except ValidationError as e:
                for msg in e:
                    return self._fail(msg, popup_origin)
        else:
            raise Http404("Unknown SSO method.")

        identifier = hashlib.sha256(
            profile['uid'].encode() + b'@' + str(self.provider.pk).encode()
        ).hexdigest().upper()[:settings.ENTROPY['customer_identifier']]
        if "1" not in identifier and "0" not in identifier:
            # This is a hack to make sure the hash space does not overlap with the random identifiers generated by
            # Customer.assign_identifier()
            identifier = identifier[:4] + "1" + identifier[4:-1]

        try:
            customer = self.request.organizer.customers.get(
                provider=self.provider,
                identifier=identifier,
            )
        except Customer.MultipleObjectsReturned:
            return self._fail(
                _('Login was not successful. Error message: "{error}".').format(
                    error='identifier not unique',
                ),
                popup_origin,
            )
        except Customer.DoesNotExist:
            name_scheme = self.request.organizer.settings.name_scheme
            name_parts = {
                '_scheme': name_scheme,
            }
            scheme = PERSON_NAME_SCHEMES.get(name_scheme)
            for fname, label, size in scheme['fields']:
                if fname in profile:
                    name_parts[fname] = profile[fname] or ''
            if len(name_parts) == 1 and profile.get('name'):
                name_parts = {'_legacy': profile['name']}
            customer = Customer(
                organizer=self.request.organizer,
                identifier=identifier,
                external_identifier=profile['uid'],
                provider=self.provider,
                email=profile['email'],
                phone=profile.get('phone') or None,
                name_parts=name_parts,
                is_active=True,
                is_verified=True,  # todo: always?
                locale=request.LANGUAGE_CODE,
            )
            try:
                customer.save(force_insert=True)
            except IntegrityError:
                # This might either be a race condition or the email address is taken
                # by a different customer account
                try:
                    customer = self.request.organizer.customers.get(
                        provider=self.provider,
                        identifier=identifier,
                    )
                except Customer.DoesNotExist:
                    return self._fail(
                        _('We were unable to use your login since the email address {email} is already used for a '
                          'different account in this system.').format(email=profile['email']),
                        popup_origin,
                    )
        else:
            if customer.is_active and customer.email != profile['email']:
                customer.email = profile['email']
                try:
                    customer.save(update_fields=['email'])
                except IntegrityError:
                    return self._fail(
                        _('We were unable to use your login since the email address {email} is already used for a '
                          'different account in this system.').format(email=profile['email']),
                        popup_origin,
                    )
                customer.log_action('pretix.customer.changed', {
                    'email': profile['email'],
                    '_source': 'provider'
                })

        if customer.external_identifier != profile['uid']:
            return self._fail(
                _('Login was not successful. Error message: "{error}".').format(
                    error='identifier not unique',
                ),
                popup_origin,
            )

        if not customer.is_active:
            self._fail(
                AuthenticationForm.error_messages['inactive'],
                popup_origin,
            )

        if not customer.is_verified:
            return self._fail(
                AuthenticationForm.error_messages['unverified'],
                popup_origin
            )

        if popup_origin:
            return render(self.request, 'pretixpresale/postmessage.html', {
                'message': {
                    '__process': 'customer_sso_popup',
                    'status': 'ok',
                    'value': dumps({
                        'customer': customer.pk,
                    }, salt=f'customer_sso_popup_{self.request.organizer.pk}')
                },
                'origin': popup_origin,
            })
        else:
            customer_login(self.request, customer)
            return redirect(self.get_success_url(redirect_to))

    def _fail(self, message, popup_origin):
        if not popup_origin:
            messages.error(
                self.request,
                message,
            )
            return redirect(eventreverse(self.request.organizer, 'presale:organizer.customer.login', kwargs={}))
        else:
            return render(self.request, 'pretixpresale/postmessage.html', {
                'message': {
                    '__process': 'customer_sso_popup',
                    'status': 'error',
                    'value': str(message)
                },
                'origin': popup_origin,
            })

    def get_success_url(self, redirect_to=None):
        url = self.get_redirect_url(redirect_to)

        if not url:
            return eventreverse(self.request.organizer, 'presale:organizer.customer.profile', kwargs={})
        else:
            if self.request.session.get(f'pretix_customerauth_{self.provider.pk}_cross_domain_requested'):
                otpstore = SessionStore()
                otpstore[f'customer_cross_domain_auth_{self.request.organizer.pk}'] = self.request.session.session_key
                otpstore.set_expiry(60)
                otpstore.save(must_create=True)
                otp = otpstore.session_key

                u = urlparse(url)
                qsl = parse_qs(u.query)
                qsl['cross_domain_customer_auth'] = otp
                url = urlunparse((u.scheme, u.netloc, u.path, u.params, urlencode(qsl, doseq=True), u.fragment))

        return url