import json
import logging
import mimetypes
import os
import re
from datetime import datetime, time, timedelta
from decimal import Decimal, DecimalException
from urllib.parse import urlencode

import vat_moss.id
from django.conf import settings
from django.contrib import messages
from django.core.files import File
from django.db import transaction
from django.db.models import (
    Count, Exists, IntegerField, OuterRef, Prefetch, ProtectedError, Q,
    Subquery, Sum,
)
from django.forms import formset_factory
from django.http import (
    FileResponse, Http404, HttpResponseNotAllowed, HttpResponseRedirect,
    JsonResponse,
)
from django.shortcuts import get_object_or_404, redirect, render
from django.urls import reverse
from django.utils import formats
from django.utils.functional import cached_property
from django.utils.http import is_safe_url
from django.utils.timezone import make_aware, now
from django.utils.translation import gettext, gettext_lazy as _
from django.views.generic import (
    DetailView, FormView, ListView, TemplateView, View,
)
from i18nfield.strings import LazyI18nString

from pretix.base.channels import get_all_sales_channels
from pretix.base.decimal import round_decimal
from pretix.base.email import get_email_context
from pretix.base.i18n import language
from pretix.base.models import (
    CachedCombinedTicket, CachedFile, CachedTicket, Checkin, Invoice,
    InvoiceAddress, Item, ItemVariation, LogEntry, Order, QuestionAnswer,
    Quota, generate_position_secret, generate_secret,
)
from pretix.base.models.orders import (
    CancellationRequest, OrderFee, OrderPayment, OrderPosition, OrderRefund,
)
from pretix.base.models.tax import EU_COUNTRIES, cc_to_vat_prefix
from pretix.base.payment import PaymentException
from pretix.base.services import tickets
from pretix.base.services.cancelevent import cancel_event
from pretix.base.services.export import export
from pretix.base.services.invoices import (
    generate_cancellation, generate_invoice, invoice_pdf, invoice_pdf_task,
    invoice_qualified, regenerate_invoice,
)
from pretix.base.services.locking import LockTimeoutException
from pretix.base.services.mail import (
    SendMailException, TolerantDict, render_mail,
)
from pretix.base.services.orders import (
    OrderChangeManager, OrderError, approve_order, cancel_order, deny_order,
    extend_order, mark_order_expired, mark_order_refunded,
    notify_user_changed_order, reactivate_order,
)
from pretix.base.services.stats import order_overview
from pretix.base.services.tickets import generate
from pretix.base.signals import (
    order_modified, register_data_exporters, register_ticket_outputs,
)
from pretix.base.templatetags.money import money_filter
from pretix.base.templatetags.rich_text import markdown_compile_email
from pretix.base.views.mixins import OrderQuestionsViewMixin
from pretix.base.views.tasks import AsyncAction
from pretix.control.forms.filter import (
    EventOrderFilterForm, OverviewFilterForm, RefundFilterForm,
)
from pretix.control.forms.orders import (
    CancelForm, CommentForm, ConfirmPaymentForm, EventCancelForm, ExporterForm,
    ExtendForm, MarkPaidForm, OrderContactForm, OrderFeeChangeForm,
    OrderLocaleForm, OrderMailForm, OrderPositionAddForm,
    OrderPositionAddFormset, OrderPositionChangeForm, OrderRefundForm,
    OtherOperationsForm,
)
from pretix.control.permissions import EventPermissionRequiredMixin
from pretix.control.views import PaginationMixin
from pretix.helpers.safedownload import check_token
from pretix.presale.signals import question_form_fields

logger = logging.getLogger(__name__)


class OrderList(EventPermissionRequiredMixin, PaginationMixin, ListView):
    model = Order
    context_object_name = 'orders'
    template_name = 'pretixcontrol/orders/index.html'
    permission = 'can_view_orders'

    def get_queryset(self):
        qs = Order.objects.filter(
            event=self.request.event
        ).select_related('invoice_address')

        if self.filter_form.is_valid():
            qs = self.filter_form.filter_qs(qs)

        return qs

    def get_context_data(self, **kwargs):
        ctx = super().get_context_data(**kwargs)
        ctx['filter_form'] = self.filter_form

        # Only compute this annotations for this page (query optimization)
        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).filter(
                pk__in=[o.pk for o in ctx['orders']]
            ).annotate(
                pcnt=Subquery(s, output_field=IntegerField()),
                has_cancellation_request=Exists(CancellationRequest.objects.filter(order=OuterRef('pk')))
            ).values(
                'pk', 'pcnt', 'is_overpaid', 'is_underpaid', 'is_pending_with_full_payment', 'has_external_refund',
                'has_pending_refund', 'has_cancellation_request'
            )
        }

        for o in ctx['orders']:
            if o.pk not in annotated:
                continue
            o.pcnt = annotated.get(o.pk)['pcnt']
            o.is_overpaid = annotated.get(o.pk)['is_overpaid']
            o.is_underpaid = annotated.get(o.pk)['is_underpaid']
            o.is_pending_with_full_payment = annotated.get(o.pk)['is_pending_with_full_payment']
            o.has_external_refund = annotated.get(o.pk)['has_external_refund']
            o.has_pending_refund = annotated.get(o.pk)['has_pending_refund']
            o.has_cancellation_request = annotated.get(o.pk)['has_cancellation_request']

        if ctx['page_obj'].paginator.count < 1000:
            # Performance safeguard: Only count positions if the data set is small
            ctx['sums'] = self.get_queryset().annotate(
                pcnt=Subquery(s, output_field=IntegerField())
            ).aggregate(
                s=Sum('total'), pc=Sum('pcnt'), c=Count('id')
            )
        else:
            ctx['sums'] = self.get_queryset().aggregate(s=Sum('total'), c=Count('id'))
        return ctx

    @cached_property
    def filter_form(self):
        return EventOrderFilterForm(data=self.request.GET, event=self.request.event)


class OrderView(EventPermissionRequiredMixin, DetailView):
    context_object_name = 'order'
    model = Order

    def get_object(self, queryset=None):
        try:
            return self.request.event.orders.get(
                code=self.kwargs['code'].upper()
            )
        except Order.DoesNotExist:
            raise Http404()

    def _redirect_back(self):
        return redirect('control:event.order',
                        event=self.request.event.slug,
                        organizer=self.request.event.organizer.slug,
                        code=self.order.code)

    @cached_property
    def order(self):
        if hasattr(self, 'object') and self.object:
            return self.object
        return self.get_object()

    def get_context_data(self, **kwargs):
        ctx = super().get_context_data(**kwargs)
        ctx['can_generate_invoice'] = invoice_qualified(self.order) and (
            self.request.event.settings.invoice_generate in ('admin', 'user', 'paid', 'True')
        ) and (
            not self.order.invoices.exists()
            or (
                self.order.status in (Order.STATUS_PAID, Order.STATUS_PENDING)
                and self.order.invoices.filter(is_cancellation=True).count() >= self.order.invoices.filter(is_cancellation=False).count()
            )
        )
        return ctx

    def get_order_url(self):
        return reverse('control:event.order', kwargs={
            'event': self.request.event.slug,
            'organizer': self.request.event.organizer.slug,
            'code': self.order.code
        })


class OrderDetail(OrderView):
    template_name = 'pretixcontrol/order/index.html'
    permission = 'can_view_orders'

    def get_context_data(self, **kwargs):
        ctx = super().get_context_data(**kwargs)
        ctx['items'] = self.get_items()
        ctx['event'] = self.request.event
        ctx['payments'] = self.order.payments.order_by('-created')
        ctx['refunds'] = self.order.refunds.select_related('payment').order_by('-created')
        for p in ctx['payments']:
            if p.payment_provider:
                p.html_info = (p.payment_provider.payment_control_render(self.request, p) or "").strip()
        for r in ctx['refunds']:
            if r.payment_provider:
                r.html_info = (r.payment_provider.refund_control_render(self.request, r) or "").strip()
        ctx['invoices'] = list(self.order.invoices.all().select_related('event'))
        ctx['comment_form'] = CommentForm(initial={
            'comment': self.order.comment,
            'checkin_attention': self.order.checkin_attention
        })
        ctx['display_locale'] = dict(settings.LANGUAGES)[self.object.locale or self.request.event.settings.locale]

        ctx['overpaid'] = self.order.pending_sum * -1
        ctx['sales_channel'] = get_all_sales_channels().get(self.order.sales_channel)
        ctx['download_buttons'] = self.download_buttons
        return ctx

    @cached_property
    def download_buttons(self):
        buttons = []

        responses = register_ticket_outputs.send(self.request.event)
        for receiver, response in responses:
            provider = response(self.request.event)
            buttons.append({
                'text': provider.download_button_text or 'Ticket',
                'icon': provider.download_button_icon or 'fa-download',
                'identifier': provider.identifier,
                'multi': provider.multi_download_enabled,
                'javascript_required': provider.javascript_required
            })
        return buttons

    def get_items(self):
        queryset = self.object.all_positions

        cartpos = queryset.order_by(
            'item', 'variation'
        ).select_related(
            'item', 'variation', 'addon_to', 'tax_rule'
        ).prefetch_related(
            'item__questions', 'issued_gift_cards',
            Prefetch('answers', queryset=QuestionAnswer.objects.prefetch_related('options').select_related('question')),
            Prefetch('checkins', queryset=Checkin.objects.select_related('list').order_by('datetime')),
        ).order_by('positionid')

        positions = []
        for p in cartpos:
            responses = question_form_fields.send(sender=self.request.event, position=p)
            p.additional_fields = []
            data = p.meta_info_data
            for r, response in sorted(responses, key=lambda r: str(r[0])):
                if response:
                    for key, value in response.items():
                        p.additional_fields.append({
                            'answer': data.get('question_form_data', {}).get(key),
                            'question': value.label
                        })

            p.has_questions = (
                p.additional_fields or
                (p.item.admission and self.request.event.settings.attendee_names_asked) or
                (p.item.admission and self.request.event.settings.attendee_emails_asked) or
                p.item.questions.all()
            )
            p.cache_answers()
            p.order = self.order

            positions.append(p)

        positions.sort(key=lambda p: p.sort_key)

        return {
            'positions': positions,
            'raw': cartpos,
            'total': self.object.total,
            'fees': self.object.all_fees.all(),
            'net_total': self.object.net_total,
            'tax_total': self.object.tax_total,
        }


class OrderDownload(AsyncAction, OrderView):
    task = generate
    permission = 'can_view_orders'

    def get_success_url(self, value):
        return self.get_self_url()

    def get_error_url(self):
        return self.get_order_url()

    def get_self_url(self):
        return reverse('control:event.order.download.ticket', kwargs=self.kwargs)

    @cached_property
    def output(self):
        responses = register_ticket_outputs.send(self.request.event)
        for receiver, response in responses:
            provider = response(self.request.event)
            if provider.identifier == self.kwargs.get('output'):
                return provider

    @cached_property
    def order_position(self):
        try:
            return self.order.positions.get(pk=self.kwargs.get('position'))
        except OrderPosition.DoesNotExist:
            return None

    def get(self, request, *args, **kwargs):
        if 'async_id' in request.GET and settings.HAS_CELERY:
            return self.get_result(request)
        ct = self.get_last_ct()
        if ct:
            return self.success(ct)
        return self.http_method_not_allowed(request)

    def post(self, request, *args, **kwargs):
        if not self.output:
            return self.error(_('You requested an invalid ticket output type.'))
        if not self.order_position:
            raise Http404(_('Unknown order code or not authorized to access this order.'))
        if 'position' in kwargs and not self.order_position.generate_ticket:
            return self.error(_('Ticket download is not enabled for this product.'))

        ct = self.get_last_ct()
        if ct:
            return self.success(ct)
        return self.do('orderposition' if 'position' in kwargs else 'order',
                       self.order_position.pk if 'position' in kwargs else self.order.pk,
                       self.output.identifier)

    def get_success_message(self, value):
        return ""

    def success(self, value):
        if "ajax" in self.request.POST or "ajax" in self.request.GET:
            return JsonResponse({
                'ready': True,
                'success': True,
                'redirect': self.get_success_url(value),
                'message': str(self.get_success_message(value))
            })
        if isinstance(value, CachedTicket):
            if value.type == 'text/uri-list':
                resp = HttpResponseRedirect(value.file.file.read())
                return resp
            else:
                resp = FileResponse(value.file.file, content_type=value.type)
                resp['Content-Disposition'] = 'attachment; filename="{}-{}-{}-{}{}"'.format(
                    self.request.event.slug.upper(), self.order.code, self.order_position.positionid,
                    self.output.identifier, value.extension
                )
                return resp
        elif isinstance(value, CachedCombinedTicket):
            resp = FileResponse(value.file.file, content_type=value.type)
            resp['Content-Disposition'] = 'attachment; filename="{}-{}-{}{}"'.format(
                self.request.event.slug.upper(), self.order.code, self.output.identifier, value.extension
            )
            return resp
        else:
            return redirect(self.get_self_url())

    def get_last_ct(self):
        if 'position' in self.kwargs:
            ct = CachedTicket.objects.filter(
                order_position=self.order_position, provider=self.output.identifier, file__isnull=False
            ).last()
        else:
            ct = CachedCombinedTicket.objects.filter(
                order=self.order, provider=self.output.identifier, file__isnull=False
            ).last()
        if not ct or not ct.file:
            return None
        return ct


class OrderComment(OrderView):
    permission = 'can_change_orders'

    def post(self, *args, **kwargs):
        form = CommentForm(self.request.POST)
        if form.is_valid():
            if form.cleaned_data.get('comment') != self.order.comment:
                self.order.comment = form.cleaned_data.get('comment')
                self.order.log_action('pretix.event.order.comment', user=self.request.user, data={
                    'new_comment': form.cleaned_data.get('comment')
                })

            if form.cleaned_data.get('checkin_attention') != self.order.checkin_attention:
                self.order.checkin_attention = form.cleaned_data.get('checkin_attention')
                self.order.log_action('pretix.event.order.checkin_attention', user=self.request.user, data={
                    'new_value': form.cleaned_data.get('checkin_attention')
                })
            self.order.save(update_fields=['checkin_attention', 'comment'])
            messages.success(self.request, _('The comment has been updated.'))
        else:
            messages.error(self.request, _('Could not update the comment.'))
        return redirect(self.get_order_url())

    def get(self, *args, **kwargs):
        return HttpResponseNotAllowed(['POST'])


class OrderApprove(OrderView):
    permission = 'can_change_orders'

    def post(self, *args, **kwargs):
        if self.order.require_approval:
            try:
                approve_order(self.order, user=self.request.user)
            except OrderError as e:
                messages.error(self.request, str(e))
            else:
                messages.success(self.request, _('The order has been approved.'))
        return redirect(self.get_order_url())

    def get(self, *args, **kwargs):
        return render(self.request, 'pretixcontrol/order/approve.html', {
            'order': self.order,
        })


class OrderDelete(OrderView):
    permission = 'can_change_orders'

    def post(self, *args, **kwargs):
        if self.order.testmode:
            try:
                with transaction.atomic():
                    self.order.gracefully_delete(user=self.request.user)
                messages.success(self.request, _('The order has been deleted.'))
                return redirect(reverse('control:event.orders', kwargs={
                    'event': self.request.event.slug,
                    'organizer': self.request.organizer.slug,
                }))
            except ProtectedError:
                messages.error(self.request, _('The order could not be deleted as some constraints (e.g. data created '
                                               'by plug-ins) do not allow it.'))
                return self.get(self.request, *self.args, **self.kwargs)

        return redirect(self.get_order_url())

    def get(self, *args, **kwargs):
        if not self.order.testmode:
            messages.error(self.request, _('Only orders created in test mode can be deleted.'))
            return redirect(self.get_order_url())
        return render(self.request, 'pretixcontrol/order/delete.html', {
            'order': self.order,
        })


class OrderDeny(OrderView):
    permission = 'can_change_orders'

    def post(self, *args, **kwargs):
        if self.order.require_approval:
            try:
                deny_order(self.order, user=self.request.user,
                           comment=self.request.POST.get('comment'),
                           send_mail=self.request.POST.get('send_email') == 'on')
            except OrderError as e:
                messages.error(self.request, str(e))
            else:
                messages.success(self.request, _('The order has been denied and is therefore now canceled.'))
        return redirect(self.get_order_url())

    def get(self, *args, **kwargs):
        return render(self.request, 'pretixcontrol/order/deny.html', {
            'order': self.order,
        })


class OrderPaymentCancel(OrderView):
    permission = 'can_change_orders'

    @cached_property
    def payment(self):
        return get_object_or_404(self.order.payments, pk=self.kwargs['payment'])

    def post(self, *args, **kwargs):
        if self.payment.state in (OrderPayment.PAYMENT_STATE_CREATED, OrderPayment.PAYMENT_STATE_PENDING):
            try:
                with transaction.atomic():
                    self.payment.payment_provider.cancel_payment(self.payment)
                    self.order.log_action('pretix.event.order.payment.canceled', {
                        'local_id': self.payment.local_id,
                        'provider': self.payment.provider,
                    }, user=self.request.user if self.request.user.is_authenticated else None)
            except PaymentException as e:
                self.order.log_action(
                    'pretix.event.order.payment.canceled.failed',
                    {
                        'local_id': self.payment.local_id,
                        'provider': self.payment.provider,
                        'error': str(e)
                    },
                    user=self.request.user if self.request.user.is_authenticated else None,
                )
                messages.error(self.request, str(e))
            else:
                messages.success(self.request, _('This payment has been canceled.'))
        else:
            messages.error(self.request, _('This payment can not be canceled at the moment.'))
        return redirect(self.get_order_url())

    def get(self, *args, **kwargs):
        return render(self.request, 'pretixcontrol/order/pay_cancel.html', {
            'order': self.order,
        })


class OrderRefundCancel(OrderView):
    permission = 'can_change_orders'

    @cached_property
    def refund(self):
        return get_object_or_404(self.order.refunds, pk=self.kwargs['refund'])

    def post(self, *args, **kwargs):
        if self.refund.state in (OrderRefund.REFUND_STATE_CREATED, OrderRefund.REFUND_STATE_TRANSIT,
                                 OrderRefund.REFUND_STATE_EXTERNAL):
            with transaction.atomic():
                self.refund.state = OrderRefund.REFUND_STATE_CANCELED
                self.refund.save()
                self.order.log_action('pretix.event.order.refund.canceled', {
                    'local_id': self.refund.local_id,
                    'provider': self.refund.provider,
                }, user=self.request.user)
            messages.success(self.request, _('The refund has been canceled.'))
        else:
            messages.error(self.request, _('This refund can not be canceled at the moment.'))
        if "next" in self.request.GET and is_safe_url(self.request.GET.get("next"), allowed_hosts=None):
            return redirect(self.request.GET.get("next"))
        return redirect(self.get_order_url())

    def get(self, *args, **kwargs):
        return render(self.request, 'pretixcontrol/order/refund_cancel.html', {
            'order': self.order,
        })


class OrderRefundProcess(OrderView):
    permission = 'can_change_orders'

    @cached_property
    def refund(self):
        return get_object_or_404(self.order.refunds, pk=self.kwargs['refund'])

    def post(self, *args, **kwargs):
        if self.refund.state == OrderRefund.REFUND_STATE_EXTERNAL:
            self.refund.done(user=self.request.user)

            if self.request.POST.get("action") == "r" and self.order.status != Order.STATUS_CANCELED:
                mark_order_refunded(self.order, user=self.request.user)
            elif not (self.order.status == Order.STATUS_PAID and self.order.pending_sum <= 0):
                self.order.status = Order.STATUS_PENDING
                self.order.set_expires(
                    now(),
                    self.order.event.subevents.filter(
                        id__in=self.order.positions.values_list('subevent_id', flat=True))
                )
                self.order.save(update_fields=['status', 'expires'])

            messages.success(self.request, _('The refund has been processed.'))
        else:
            messages.error(self.request, _('This refund can not be processed at the moment.'))
        if "next" in self.request.GET and is_safe_url(self.request.GET.get("next"), allowed_hosts=None):
            return redirect(self.request.GET.get("next"))
        return redirect(self.get_order_url())

    def get(self, *args, **kwargs):
        return render(self.request, 'pretixcontrol/order/refund_process.html', {
            'order': self.order,
            'refund': self.refund,
            'pending_sum': self.order.pending_sum + self.refund.amount,
            'propose_cancel': self.order.pending_sum + self.refund.amount >= self.order.total
        })


class OrderRefundDone(OrderView):
    permission = 'can_change_orders'

    @cached_property
    def refund(self):
        return get_object_or_404(self.order.refunds, pk=self.kwargs['refund'])

    def post(self, *args, **kwargs):
        if self.refund.state in (OrderRefund.REFUND_STATE_CREATED, OrderRefund.REFUND_STATE_TRANSIT):
            self.refund.done(user=self.request.user)
            messages.success(self.request, _('The refund has been marked as done.'))
        else:
            messages.error(self.request, _('This refund can not be processed at the moment.'))
        if "next" in self.request.GET and is_safe_url(self.request.GET.get("next"), allowed_hosts=None):
            return redirect(self.request.GET.get("next"))
        return redirect(self.get_order_url())

    def get(self, *args, **kwargs):
        return render(self.request, 'pretixcontrol/order/refund_done.html', {
            'order': self.order,
        })


class OrderCancellationRequestDelete(OrderView):
    permission = 'can_change_orders'

    @cached_property
    def req(self):
        return get_object_or_404(self.order.cancellation_requests, pk=self.kwargs['req'])

    def post(self, *args, **kwargs):
        with transaction.atomic():
            self.req.delete()
            self.order.log_action('pretix.event.order.cancellationrequest.deleted', {
            }, user=self.request.user)

        messages.success(self.request, _('The request has been removed. If you want, you can now inform the user.'))
        with language(self.order.locale):
            return redirect(reverse('control:event.order.sendmail', kwargs={
                'event': self.request.event.slug,
                'organizer': self.request.event.organizer.slug,
                'code': self.order.code
            }) + '?' + urlencode({
                'subject': _('Your cancellation request'),
                'message': _('Hello,\n\nunfortunately, we were unable to accommodate your request and cancel your '
                             'order.\n\n'
                             'Your {event} team').format(
                    event="{event}",
                )
            }))

    def get(self, *args, **kwargs):
        return render(self.request, 'pretixcontrol/order/cancellation_request_delete.html', {
            'order': self.order,
        })


class OrderPaymentConfirm(OrderView):
    permission = 'can_change_orders'

    @cached_property
    def payment(self):
        return get_object_or_404(self.order.payments, pk=self.kwargs['payment'])

    @cached_property
    def mark_paid_form(self):
        return ConfirmPaymentForm(
            instance=self.order,
            data=self.request.POST if self.request.method == "POST" else None,
        )

    def post(self, *args, **kwargs):
        if self.payment.state in (OrderPayment.PAYMENT_STATE_CREATED, OrderPayment.PAYMENT_STATE_PENDING):
            if not self.mark_paid_form.is_valid():
                return render(self.request, 'pretixcontrol/order/pay_complete.html', {
                    'form': self.mark_paid_form,
                    'order': self.order,
                })
            try:
                self.payment.confirm(user=self.request.user,
                                     count_waitinglist=False,
                                     force=self.mark_paid_form.cleaned_data.get('force', False))
            except Quota.QuotaExceededException as e:
                messages.error(self.request, str(e))
            except PaymentException as e:
                messages.error(self.request, str(e))
            except SendMailException:
                messages.warning(self.request,
                                 _('The payment has been marked as complete, but we were unable to send a '
                                   'confirmation mail.'))
            else:
                messages.success(self.request, _('The payment has been marked as complete.'))
        else:
            messages.error(self.request, _('This payment can not be confirmed at the moment.'))
        return redirect(self.get_order_url())

    def get(self, *args, **kwargs):
        return render(self.request, 'pretixcontrol/order/pay_complete.html', {
            'form': self.mark_paid_form,
            'order': self.order,
        })


class OrderRefundView(OrderView):
    permission = 'can_change_orders'

    @cached_property
    def start_form(self):
        return OrderRefundForm(
            order=self.order,
            data=self.request.POST if self.request.method == "POST" else (
                self.request.GET if "start-action" in self.request.GET else None
            ),
            prefix='start',
            initial={
                'partial_amount': self.order.payment_refund_sum,
                'action': (
                    'mark_pending' if self.order.status == Order.STATUS_PAID
                    else 'do_nothing'
                )
            }
        )

    def choose_form(self):
        payments = list(self.order.payments.filter(state=OrderPayment.PAYMENT_STATE_CONFIRMED))
        if self.start_form.cleaned_data.get('mode') == 'full':
            full_refund = self.order.payment_refund_sum
        else:
            full_refund = self.start_form.cleaned_data.get('partial_amount')
        if self.request.GET.get('giftcard', 'false') == 'true':
            proposals = {
                None: full_refund
            }
            giftcard_proposal = full_refund
        else:
            proposals = self.order.propose_auto_refunds(full_refund, payments=payments)
            giftcard_proposal = Decimal('0.00')
        to_refund = full_refund - sum(proposals.values())
        for p in payments:
            p.propose_refund = proposals.get(p, 0)

        if 'perform' in self.request.POST:
            refund_selected = Decimal('0.00')
            refunds = []

            is_valid = True
            manual_value = self.request.POST.get('refund-manual', '0') or '0'
            manual_value = formats.sanitize_separators(manual_value)
            try:
                manual_value = Decimal(manual_value)
            except (DecimalException, TypeError):
                messages.error(self.request, _('You entered an invalid number.'))
                is_valid = False
            else:
                refund_selected += manual_value
                if manual_value:
                    refunds.append(OrderRefund(
                        order=self.order,
                        payment=None,
                        source=OrderRefund.REFUND_SOURCE_ADMIN,
                        state=(
                            OrderRefund.REFUND_STATE_DONE
                            if self.request.POST.get('manual_state') == 'done'
                            else OrderRefund.REFUND_STATE_CREATED
                        ),
                        amount=manual_value,
                        provider='manual'
                    ))

            giftcard_value = self.request.POST.get('refund-new-giftcard', '0') or '0'
            giftcard_value = formats.sanitize_separators(giftcard_value)
            try:
                giftcard_value = Decimal(giftcard_value)
            except (DecimalException, TypeError):
                messages.error(self.request, _('You entered an invalid number.'))
                is_valid = False
            else:
                if giftcard_value:
                    refund_selected += giftcard_value
                    giftcard = self.request.organizer.issued_gift_cards.create(
                        expires=self.request.organizer.default_gift_card_expiry,
                        currency=self.request.event.currency,
                        testmode=self.order.testmode
                    )
                    giftcard.log_action('pretix.giftcards.created', user=self.request.user, data={})
                    refunds.append(OrderRefund(
                        order=self.order,
                        payment=None,
                        source=OrderRefund.REFUND_SOURCE_ADMIN,
                        state=OrderRefund.REFUND_STATE_CREATED,
                        execution_date=now(),
                        amount=giftcard_value,
                        provider='giftcard',
                        info=json.dumps({
                            'gift_card': giftcard.pk
                        })
                    ))

            offsetting_value = self.request.POST.get('refund-offsetting', '0') or '0'
            offsetting_value = formats.sanitize_separators(offsetting_value)
            try:
                offsetting_value = Decimal(offsetting_value)
            except (DecimalException, TypeError):
                messages.error(self.request, _('You entered an invalid number.'))
                is_valid = False
            else:
                if offsetting_value:
                    refund_selected += offsetting_value
                    try:
                        order = Order.objects.get(code=self.request.POST.get('order-offsetting'),
                                                  event__organizer=self.request.organizer)
                    except Order.DoesNotExist:
                        messages.error(self.request, _('You entered an order that could not be found.'))
                        is_valid = False
                    else:
                        refunds.append(OrderRefund(
                            order=self.order,
                            payment=None,
                            source=OrderRefund.REFUND_SOURCE_ADMIN,
                            state=OrderRefund.REFUND_STATE_DONE,
                            execution_date=now(),
                            amount=offsetting_value,
                            provider='offsetting',
                            info=json.dumps({
                                'orders': [order.code]
                            })
                        ))

            for p in payments:
                value = self.request.POST.get('refund-{}'.format(p.pk), '0') or '0'
                value = formats.sanitize_separators(value)
                try:
                    value = Decimal(value)
                except (DecimalException, TypeError):
                    messages.error(self.request, _('You entered an invalid number.'))
                    is_valid = False
                else:
                    if value == 0:
                        continue
                    elif value > p.available_amount:
                        messages.error(self.request, _('You can not refund more than the amount of a '
                                                       'payment that is not yet refunded.'))
                        is_valid = False
                        break
                    elif value != p.amount and not p.partial_refund_possible:
                        messages.error(self.request, _('You selected a partial refund for a payment method that '
                                                       'only supports full refunds.'))
                        is_valid = False
                        break
                    elif (p.partial_refund_possible or p.full_refund_possible) and value > 0:
                        refund_selected += value
                        refunds.append(OrderRefund(
                            order=self.order,
                            payment=p,
                            source=OrderRefund.REFUND_SOURCE_ADMIN,
                            state=OrderRefund.REFUND_STATE_CREATED,
                            amount=value,
                            provider=p.provider
                        ))

            any_success = False
            if refund_selected == full_refund and is_valid:
                for r in refunds:
                    r.save()
                    self.order.log_action('pretix.event.order.refund.created', {
                        'local_id': r.local_id,
                        'provider': r.provider,
                    }, user=self.request.user)
                    if r.payment or r.provider == "offsetting" or r.provider == "giftcard":
                        try:
                            r.payment_provider.execute_refund(r)
                        except PaymentException as e:
                            r.state = OrderRefund.REFUND_STATE_FAILED
                            r.save()
                            messages.error(self.request, _('One of the refunds failed to be processed. You should '
                                                           'retry to refund in a different way. The error message '
                                                           'was: {}').format(str(e)))
                        else:
                            any_success = True
                            if r.state == OrderRefund.REFUND_STATE_DONE:
                                messages.success(self.request, _('A refund of {} has been processed.').format(
                                    money_filter(r.amount, self.request.event.currency)
                                ))
                            elif r.state == OrderRefund.REFUND_STATE_CREATED:
                                messages.info(self.request, _('A refund of {} has been saved, but not yet '
                                                              'fully executed. You can mark it as complete '
                                                              'below.').format(
                                    money_filter(r.amount, self.request.event.currency)
                                ))
                    else:
                        any_success = True

                if any_success:
                    if self.start_form.cleaned_data.get('action') == 'mark_refunded':
                        mark_order_refunded(self.order, user=self.request.user)
                    elif self.start_form.cleaned_data.get('action') == 'mark_pending':
                        if not (self.order.status == Order.STATUS_PAID and self.order.pending_sum <= 0):
                            self.order.status = Order.STATUS_PENDING
                            self.order.set_expires(
                                now(),
                                self.order.event.subevents.filter(
                                    id__in=self.order.positions.values_list('subevent_id', flat=True))
                            )
                            self.order.save(update_fields=['status', 'expires'])

                    if giftcard_value and self.order.email:
                        messages.success(self.request, _('A new gift card was created. You can now send the user their '
                                                         'gift card code.'))
                        with language(self.order.locale):
                            return redirect(reverse('control:event.order.sendmail', kwargs={
                                'event': self.request.event.slug,
                                'organizer': self.request.event.organizer.slug,
                                'code': self.order.code
                            }) + '?' + urlencode({
                                'subject': gettext('Your gift card code'),
                                'message': gettext(
                                    'Hello,\n\nwe have refunded you {amount} for your order.\n\nYou can use the gift '
                                    'card code {giftcard} to pay for future ticket purchases in our shop.\n\n'
                                    'Your {event} team'
                                ).format(
                                    event="{event}",
                                    amount=money_filter(giftcard_value, self.request.event.currency),
                                    giftcard=giftcard.secret,
                                )
                            }))
                return redirect(self.get_order_url())
            else:
                messages.error(self.request, _('The refunds you selected do not match the selected total refund '
                                               'amount.'))

        return render(self.request, 'pretixcontrol/order/refund_choose.html', {
            'payments': payments,
            'remainder': to_refund,
            'order': self.order,
            'giftcard_proposal': giftcard_proposal,
            'partial_amount': (
                self.request.POST.get('start-partial_amount') if self.request.method == 'POST'
                else self.request.GET.get('start-partial_amount')
            ),
            'start_form': self.start_form
        })

    def post(self, *args, **kwargs):
        if self.start_form.is_valid():
            return self.choose_form()
        return self.get(*args, **kwargs)

    def get(self, *args, **kwargs):
        if self.start_form.is_valid():
            return self.choose_form()
        return render(self.request, 'pretixcontrol/order/refund_start.html', {
            'form': self.start_form,
            'order': self.order,
        })


class OrderTransition(OrderView):
    permission = 'can_change_orders'

    @cached_property
    def req(self):
        if 'req' not in self.request.GET:
            return None
        return get_object_or_404(self.order.cancellation_requests, pk=self.request.GET.get('req'))

    @cached_property
    def mark_paid_form(self):
        return MarkPaidForm(
            instance=self.order,
            data=self.request.POST if self.request.method == "POST" else None,
        )

    @cached_property
    def mark_canceled_form(self):
        return CancelForm(
            instance=self.order,
            data=self.request.POST if self.request.method == "POST" else None,
            initial={
                'cancellation_fee': self.req.cancellation_fee if self.req else None
            }
        )

    def post(self, *args, **kwargs):
        to = self.request.POST.get('status', '')
        if self.order.status in (Order.STATUS_PENDING, Order.STATUS_EXPIRED) and to == 'p' and self.mark_paid_form.is_valid():
            ps = self.mark_paid_form.cleaned_data['amount']
            try:
                p = self.order.payments.get(
                    state__in=(OrderPayment.PAYMENT_STATE_PENDING, OrderPayment.PAYMENT_STATE_CREATED),
                    provider='manual',
                    amount=ps
                )
            except OrderPayment.DoesNotExist:
                for p in self.order.payments.filter(state__in=(OrderPayment.PAYMENT_STATE_PENDING,
                                                               OrderPayment.PAYMENT_STATE_CREATED)):
                    try:
                        with transaction.atomic():
                            p.payment_provider.cancel_payment(p)
                            self.order.log_action('pretix.event.order.payment.canceled', {
                                'local_id': p.local_id,
                                'provider': p.provider,
                            }, user=self.request.user if self.request.user.is_authenticated else None)
                    except PaymentException as e:
                        self.order.log_action(
                            'pretix.event.order.payment.canceled.failed',
                            {
                                'local_id': p.local_id,
                                'provider': p.provider,
                                'error': str(e)
                            },
                            user=self.request.user if self.request.user.is_authenticated else None,
                        )
                p = self.order.payments.create(
                    state=OrderPayment.PAYMENT_STATE_CREATED,
                    provider='manual',
                    amount=ps,
                    fee=None
                )

            payment_date = None
            if self.mark_paid_form.cleaned_data['payment_date'] != now().date():
                payment_date = make_aware(datetime.combine(
                    self.mark_paid_form.cleaned_data['payment_date'],
                    time(hour=0, minute=0, second=0)
                ), self.order.event.timezone)

            try:
                p.confirm(user=self.request.user, count_waitinglist=False, payment_date=payment_date,
                          force=self.mark_paid_form.cleaned_data.get('force', False))
            except Quota.QuotaExceededException as e:
                p.state = OrderPayment.PAYMENT_STATE_FAILED
                p.save()
                self.order.log_action('pretix.event.order.payment.failed', {
                    'local_id': p.local_id,
                    'provider': p.provider,
                    'message': str(e)
                })
                messages.error(self.request, str(e))
            except PaymentException as e:
                p.state = OrderPayment.PAYMENT_STATE_FAILED
                p.save()
                self.order.log_action('pretix.event.order.payment.failed', {
                    'local_id': p.local_id,
                    'provider': p.provider,
                    'message': str(e)
                })
                messages.error(self.request, str(e))
            except SendMailException:
                messages.warning(self.request, _('The order has been marked as paid, but we were unable to send a '
                                                 'confirmation mail.'))
            else:
                messages.success(self.request, _('The payment has been created successfully.'))
        elif self.order.cancel_allowed() and to == 'c' and self.mark_canceled_form.is_valid():
            try:
                cancel_order(self.order.pk, user=self.request.user,
                             send_mail=self.mark_canceled_form.cleaned_data['send_email'],
                             cancellation_fee=self.mark_canceled_form.cleaned_data.get('cancellation_fee'))
            except OrderError as e:
                messages.error(self.request, str(e))
            else:
                self.order.refresh_from_db()
                if self.order.pending_sum < 0:
                    messages.success(self.request, _('The order has been canceled. You can now select how you want to '
                                                     'transfer the money back to the user.'))
                    return redirect(reverse('control:event.order.refunds.start', kwargs={
                        'event': self.request.event.slug,
                        'organizer': self.request.event.organizer.slug,
                        'code': self.order.code
                    }) + '?start-action=do_nothing&start-mode=partial&start-partial_amount={}&giftcard={}'.format(
                        round_decimal(self.order.pending_sum * -1),
                        'true' if self.req and self.req.refund_as_giftcard else 'false'
                    ))

                messages.success(self.request, _('The order has been canceled.'))
        elif self.order.status == Order.STATUS_PENDING and to == 'e':
            mark_order_expired(self.order, user=self.request.user)
            messages.success(self.request, _('The order has been marked as expired.'))
        return redirect(self.get_order_url())

    def get(self, *args, **kwargs):
        to = self.request.GET.get('status', '')
        if self.order.status in (Order.STATUS_PENDING, Order.STATUS_EXPIRED) and to == 'p':
            return render(self.request, 'pretixcontrol/order/pay.html', {
                'form': self.mark_paid_form,
                'order': self.order,
            })
        elif self.order.cancel_allowed() and to == 'c':
            return render(self.request, 'pretixcontrol/order/cancel.html', {
                'form': self.mark_canceled_form,
                'order': self.order,
            })
        else:
            return HttpResponseNotAllowed(['POST'])


class OrderInvoiceCreate(OrderView):
    permission = 'can_change_orders'

    def post(self, *args, **kwargs):
        has_inv = self.order.invoices.exists() and not (
            self.order.status in (Order.STATUS_PAID, Order.STATUS_PENDING)
            and self.order.invoices.filter(is_cancellation=True).count() >= self.order.invoices.filter(is_cancellation=False).count()
        )
        if self.request.event.settings.get('invoice_generate') not in ('admin', 'user', 'paid', 'True') or not invoice_qualified(self.order):
            messages.error(self.request, _('You cannot generate an invoice for this order.'))
        elif has_inv:
            messages.error(self.request, _('An invoice for this order already exists.'))
        else:
            inv = generate_invoice(self.order)
            self.order.log_action('pretix.event.order.invoice.generated', user=self.request.user, data={
                'invoice': inv.pk
            })
            messages.success(self.request, _('The invoice has been generated.'))
        return redirect(self.get_order_url())

    def get(self, *args, **kwargs):
        return HttpResponseNotAllowed(['POST'])


class OrderCheckVATID(OrderView):
    permission = 'can_change_orders'

    def post(self, *args, **kwargs):
        try:
            ia = self.order.invoice_address
        except InvoiceAddress.DoesNotExist:
            messages.error(self.request, _('No VAT ID specified.'))
            return redirect(self.get_order_url())
        else:
            if not ia.vat_id:
                messages.error(self.request, _('No VAT ID specified.'))
                return redirect(self.get_order_url())

            if not ia.country:
                messages.error(self.request, _('No country specified.'))
                return redirect(self.get_order_url())

            if str(ia.country) not in EU_COUNTRIES:
                messages.error(self.request, _('VAT ID could not be checked since a non-EU country has been '
                                               'specified.'))
                return redirect(self.get_order_url())

            if ia.vat_id[:2] != cc_to_vat_prefix(str(ia.country)):
                messages.error(self.request, _('Your VAT ID does not match the selected country.'))
                return redirect(self.get_order_url())

            try:
                result = vat_moss.id.validate(ia.vat_id)
                if result:
                    country_code, normalized_id, company_name = result
                    ia.vat_id_validated = True
                    ia.vat_id = normalized_id
                    ia.save()
            except vat_moss.errors.InvalidError:
                messages.error(self.request, _('This VAT ID is not valid.'))
            except vat_moss.errors.WebServiceUnavailableError:
                logger.exception('VAT ID checking failed for country {}'.format(ia.country))
                messages.error(self.request, _('The VAT ID could not be checked, as the VAT checking service of '
                                               'the country is currently not available.'))
            else:
                messages.success(self.request, _('This VAT ID is valid.'))
            return redirect(self.get_order_url())

    def get(self, *args, **kwargs):  # NOQA
        return HttpResponseNotAllowed(['POST'])


class OrderInvoiceRegenerate(OrderView):
    permission = 'can_change_orders'

    def post(self, *args, **kwargs):
        try:
            inv = self.order.invoices.get(pk=kwargs.get('id'))
        except Invoice.DoesNotExist:
            messages.error(self.request, _('Unknown invoice.'))
        else:
            if inv.canceled:
                messages.error(self.request, _('The invoice has already been canceled.'))
            elif inv.shredded:
                messages.error(self.request, _('The invoice has been cleaned of personal data.'))
            else:
                inv = regenerate_invoice(inv)
                self.order.log_action('pretix.event.order.invoice.regenerated', user=self.request.user, data={
                    'invoice': inv.pk
                })
                messages.success(self.request, _('The invoice has been regenerated.'))
        return redirect(self.get_order_url())

    def get(self, *args, **kwargs):  # NOQA
        return HttpResponseNotAllowed(['POST'])


class OrderInvoiceReissue(OrderView):
    permission = 'can_change_orders'

    def post(self, *args, **kwargs):
        try:
            inv = self.order.invoices.get(pk=kwargs.get('id'))
        except Invoice.DoesNotExist:
            messages.error(self.request, _('Unknown invoice.'))
        else:
            if inv.canceled:
                messages.error(self.request, _('The invoice has already been canceled.'))
            elif inv.shredded:
                messages.error(self.request, _('The invoice has been cleaned of personal data.'))
            else:
                c = generate_cancellation(inv)
                if self.order.status != Order.STATUS_CANCELED:
                    inv = generate_invoice(self.order)
                else:
                    inv = c
                self.order.log_action('pretix.event.order.invoice.reissued', user=self.request.user, data={
                    'invoice': inv.pk
                })
                messages.success(self.request, _('The invoice has been reissued.'))
        return redirect(self.get_order_url())

    def get(self, *args, **kwargs):  # NOQA
        return HttpResponseNotAllowed(['POST'])


class OrderResendLink(OrderView):
    permission = 'can_change_orders'

    def post(self, *args, **kwargs):
        try:
            if 'position' in kwargs:
                p = get_object_or_404(self.order.positions, pk=kwargs['position'])
                p.resend_link(user=self.request.user)
            else:
                self.order.resend_link(user=self.request.user)
        except SendMailException:
            messages.error(self.request, _('There was an error sending the mail. Please try again later.'))
            return redirect(self.get_order_url())

        messages.success(self.request, _('The email has been queued to be sent.'))
        return redirect(self.get_order_url())

    def get(self, *args, **kwargs):
        return HttpResponseNotAllowed(['POST'])


class InvoiceDownload(EventPermissionRequiredMixin, View):
    permission = 'can_view_orders'

    def get_order_url(self):
        return reverse('control:event.order', kwargs={
            'event': self.request.event.slug,
            'organizer': self.request.event.organizer.slug,
            'code': self.invoice.order.code
        })

    def get(self, request, *args, **kwargs):
        try:
            self.invoice = Invoice.objects.get(
                event=self.request.event,
                id=self.kwargs['invoice']
            )
        except Invoice.DoesNotExist:
            raise Http404(_('This invoice has not been found'))

        if not self.invoice.file:
            invoice_pdf(self.invoice.pk)
            self.invoice = Invoice.objects.get(pk=self.invoice.pk)

        if self.invoice.shredded:
            messages.error(request, _('The invoice file is no longer stored on the server.'))
            return redirect(self.get_order_url())

        if not self.invoice.file:
            # This happens if we have celery installed and the file will be generated in the background
            messages.warning(request, _('The invoice file has not yet been generated, we will generate it for you '
                                        'now. Please try again in a few seconds.'))
            return redirect(self.get_order_url())

        try:
            resp = FileResponse(self.invoice.file.file, content_type='application/pdf')
        except FileNotFoundError:
            invoice_pdf_task.apply(args=(self.invoice.pk,))
            return self.get(request, *args, **kwargs)

        resp['Content-Disposition'] = 'inline; filename="{}.pdf"'.format(self.invoice.number)
        resp._csp_ignore = True  # Some browser's PDF readers do not work with CSP
        return resp


class OrderExtend(OrderView):
    permission = 'can_change_orders'

    def post(self, *args, **kwargs):
        if self.form.is_valid():
            try:
                extend_order(
                    self.order,
                    new_date=self.form.cleaned_data.get('expires'),
                    force=self.form.cleaned_data.get('quota_ignore', False),
                    user=self.request.user
                )
                messages.success(self.request, _('The payment term has been changed.'))
            except OrderError as e:
                messages.error(self.request, str(e))
                return self._redirect_here()
            except LockTimeoutException:
                messages.error(self.request, _('We were not able to process the request completely as the '
                                               'server was too busy.'))
            return self._redirect_back()
        else:
            return self.get(*args, **kwargs)

    def dispatch(self, request, *args, **kwargs):
        if self.order.status not in (Order.STATUS_PENDING, Order.STATUS_EXPIRED):
            messages.error(self.request, _('This action is only allowed for pending orders.'))
            return self._redirect_back()
        return super().dispatch(request, *kwargs, **kwargs)

    def _redirect_here(self):
        return redirect('control:event.order.extend',
                        event=self.request.event.slug,
                        organizer=self.request.event.organizer.slug,
                        code=self.order.code)

    def get(self, *args, **kwargs):
        return render(self.request, 'pretixcontrol/order/extend.html', {
            'order': self.order,
            'form': self.form,
        })

    @cached_property
    def form(self):
        return ExtendForm(instance=self.order,
                          data=self.request.POST if self.request.method == "POST" else None)


class OrderReactivate(OrderView):
    permission = 'can_change_orders'

    def post(self, *args, **kwargs):
        try:
            reactivate_order(
                self.order,
                user=self.request.user
            )
            messages.success(self.request, _('The order has been reactivated.'))
        except OrderError as e:
            messages.error(self.request, str(e))
            return self._redirect_here()
        except LockTimeoutException:
            messages.error(self.request, _('We were not able to process the request completely as the '
                                           'server was too busy.'))
        return self._redirect_back()

    def dispatch(self, request, *args, **kwargs):
        if self.order.status != Order.STATUS_CANCELED:
            messages.error(self.request, _('This action is only allowed for canceled orders.'))
            return self._redirect_back()
        return super().dispatch(request, *kwargs, **kwargs)

    def _redirect_here(self):
        return redirect('control:event.order.reactivate',
                        event=self.request.event.slug,
                        organizer=self.request.event.organizer.slug,
                        code=self.order.code)

    def get(self, *args, **kwargs):
        return render(self.request, 'pretixcontrol/order/reactivate.html', {
            'order': self.order,
        })


class OrderChange(OrderView):
    permission = 'can_change_orders'
    template_name = 'pretixcontrol/order/change.html'

    def dispatch(self, request, *args, **kwargs):
        if self.order.status not in (Order.STATUS_PENDING, Order.STATUS_PAID):
            messages.error(self.request, _('This action is only allowed for pending or paid orders.'))
            return self._redirect_back()
        return super().dispatch(request, *args, **kwargs)

    @cached_property
    def other_form(self):
        return OtherOperationsForm(prefix='other', order=self.order,
                                   data=self.request.POST if self.request.method == "POST" else None)

    @cached_property
    def add_formset(self):
        ff = formset_factory(
            OrderPositionAddForm, formset=OrderPositionAddFormset,
            can_order=False, can_delete=True, extra=0
        )
        return ff(
            prefix='add',
            order=self.order,
            items=self.items,
            data=self.request.POST if self.request.method == "POST" else None
        )

    @cached_property
    def items(self):
        return self.request.event.items.prefetch_related('variations', 'tax_rule').all()

    @cached_property
    def fees(self):
        fees = list(self.order.fees.all())
        for f in fees:
            f.form = OrderFeeChangeForm(prefix='of-{}'.format(f.pk), instance=f,
                                        data=self.request.POST if self.request.method == "POST" else None)
        return fees

    @cached_property
    def positions(self):
        positions = list(self.order.positions.select_related('item', 'item__tax_rule'))
        for p in positions:
            p.form = OrderPositionChangeForm(prefix='op-{}'.format(p.pk), instance=p, items=self.items,
                                             initial={'seat': p.seat.seat_guid if p.seat else None},
                                             data=self.request.POST if self.request.method == "POST" else None)
        return positions

    def get_context_data(self, **kwargs):
        ctx = super().get_context_data(**kwargs)
        ctx['positions'] = self.positions
        ctx['fees'] = self.fees
        ctx['add_formset'] = self.add_formset
        ctx['other_form'] = self.other_form
        return ctx

    def _process_other(self, ocm):
        if not self.other_form.is_valid():
            return False
        else:
            if self.other_form.cleaned_data['recalculate_taxes']:
                ocm.recalculate_taxes(
                    keep=self.other_form.cleaned_data['recalculate_taxes']
                )
            return True

    def _process_add(self, ocm):
        if not self.add_formset.is_valid():
            return False
        else:
            for f in self.add_formset.forms:
                if f in self.add_formset.deleted_forms or not f.has_changed():
                    continue

                if '-' in f.cleaned_data['itemvar']:
                    itemid, varid = f.cleaned_data['itemvar'].split('-')
                else:
                    itemid, varid = f.cleaned_data['itemvar'], None

                item = Item.objects.get(pk=itemid, event=self.request.event)
                if varid:
                    variation = ItemVariation.objects.get(pk=varid, item=item)
                else:
                    variation = None
                try:
                    ocm.add_position(item, variation,
                                     f.cleaned_data['price'],
                                     f.cleaned_data.get('addon_to'),
                                     f.cleaned_data.get('subevent'),
                                     f.cleaned_data.get('seat'))
                except OrderError as e:
                    f.custom_error = str(e)
                    return False
        return True

    def _process_fees(self, ocm):
        for f in self.fees:
            if not f.form.is_valid():
                return False

            try:
                if f.form.cleaned_data['operation_cancel']:
                    ocm.cancel_fee(f)
                    continue

                if f.form.cleaned_data['value'] != f.value:
                    ocm.change_fee(f, f.form.cleaned_data['value'])

                if f.form.cleaned_data['tax_rule'] and f.form.cleaned_data['tax_rule'] != f.tax_rule:
                    ocm.change_tax_rule(f, f.form.cleaned_data['tax_rule'])

            except OrderError as e:
                f.custom_error = str(e)
                return False
        return True

    def _process_change(self, ocm):
        for p in self.positions:
            if not p.form.is_valid():
                return False

            try:
                if p.form.cleaned_data['operation_cancel']:
                    ocm.cancel(p)
                    continue

                change_item = None
                if p.form.cleaned_data['itemvar']:
                    if '-' in p.form.cleaned_data['itemvar']:
                        itemid, varid = p.form.cleaned_data['itemvar'].split('-')
                    else:
                        itemid, varid = p.form.cleaned_data['itemvar'], None

                    item = Item.objects.get(pk=itemid, event=self.request.event)
                    if varid:
                        variation = ItemVariation.objects.get(pk=varid, item=item)
                    else:
                        variation = None
                    if item != p.item or variation != p.variation:
                        change_item = (item, variation)

                change_subevent = None
                if self.request.event.has_subevents and p.form.cleaned_data['subevent'] and p.form.cleaned_data['subevent'] != p.subevent:
                    change_subevent = (p.form.cleaned_data['subevent'],)

                if change_item is not None and change_subevent is not None:
                    ocm.change_item_and_subevent(p, *change_item, *change_subevent)
                elif change_item is not None:
                    ocm.change_item(p, *change_item)
                elif change_subevent is not None:
                    ocm.change_subevent(p, *change_subevent)

                if p.seat and p.form.cleaned_data['seat'] and p.form.cleaned_data['seat'] != p.seat.seat_guid:
                    ocm.change_seat(p, p.form.cleaned_data['seat'])

                if p.form.cleaned_data['price'] is not None and p.form.cleaned_data['price'] != p.price:
                    ocm.change_price(p, p.form.cleaned_data['price'])

                if p.form.cleaned_data['tax_rule'] and p.form.cleaned_data['tax_rule'] != p.tax_rule:
                    ocm.change_tax_rule(p, p.form.cleaned_data['tax_rule'])

                if p.form.cleaned_data['operation_split']:
                    ocm.split(p)

                if p.form.cleaned_data['operation_secret']:
                    ocm.regenerate_secret(p)

            except OrderError as e:
                p.custom_error = str(e)
                return False
        return True

    def post(self, *args, **kwargs):
        notify = self.other_form.cleaned_data['notify'] if self.other_form.is_valid() else True
        ocm = OrderChangeManager(
            self.order,
            user=self.request.user,
            notify=notify,
            reissue_invoice=self.other_form.cleaned_data['reissue_invoice'] if self.other_form.is_valid() else True
        )
        form_valid = self._process_add(ocm) and self._process_fees(ocm) and self._process_change(ocm) and self._process_other(ocm)

        if not form_valid:
            messages.error(self.request, _('An error occurred. Please see the details below.'))
        else:
            try:
                ocm.commit(check_quotas=not self.other_form.cleaned_data['ignore_quotas'])
            except OrderError as e:
                messages.error(self.request, str(e))
            else:
                if notify:
                    messages.success(self.request, _('The order has been changed and the user has been notified.'))
                else:
                    messages.success(self.request, _('The order has been changed.'))
                return self._redirect_back()

        return self.get(*args, **kwargs)


class OrderModifyInformation(OrderQuestionsViewMixin, OrderView):
    permission = 'can_change_orders'
    template_name = 'pretixcontrol/order/change_questions.html'
    only_user_visible = False
    all_optional = True

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

    @cached_property
    def other_form(self):
        return OtherOperationsForm(prefix='other', order=self.order, initial={'notify': False},
                                   data=self.request.POST if self.request.method == "POST" else None)

    def post(self, request, *args, **kwargs):
        failed = not self.save() or not self.invoice_form.is_valid() or not self.other_form.is_valid()
        notify = self.other_form.cleaned_data['notify'] if self.other_form.is_valid() else True
        if failed:
            messages.error(self.request,
                           _("We had difficulties processing your input. Please review the errors below."))
            return self.get(request, *args, **kwargs)

        if notify:
            notify_user_changed_order(self.order)

        if hasattr(self.invoice_form, 'save'):
            self.invoice_form.save()
        self.order.log_action('pretix.event.order.modified', {
            'invoice_data': self.invoice_form.cleaned_data,
            'data': [{
                k: (f.cleaned_data.get(k).name if isinstance(f.cleaned_data.get(k), File) else f.cleaned_data.get(k))
                for k in f.changed_data
            } for f in self.forms]
        }, user=request.user)
        if self.invoice_form.has_changed():
            success_message = ('The invoice address has been updated. If you want to generate a new invoice, '
                               'you need to do this manually.')
            messages.success(self.request, _(success_message))

        tickets.invalidate_cache.apply_async(kwargs={'event': self.request.event.pk, 'order': self.order.pk})

        order_modified.send(sender=self.request.event, order=self.order)
        return redirect(self.get_order_url())


class OrderContactChange(OrderView):
    permission = 'can_change_orders'
    template_name = 'pretixcontrol/order/change_contact.html'

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

    @cached_property
    def form(self):
        return OrderContactForm(
            instance=self.order,
            data=self.request.POST if self.request.method == "POST" else None
        )

    def post(self, *args, **kwargs):
        old_email = self.order.email
        changed = False
        if self.form.is_valid():
            new_email = self.form.cleaned_data['email']
            if new_email != old_email:
                changed = True
                self.order.log_action(
                    'pretix.event.order.contact.changed',
                    data={
                        'old_email': old_email,
                        'new_email': self.form.cleaned_data['email'],
                    },
                    user=self.request.user,
                )

            if self.form.cleaned_data['regenerate_secrets']:
                changed = True
                self.order.secret = generate_secret()
                for op in self.order.all_positions.all():
                    op.secret = generate_position_secret()
                    op.save()
                tickets.invalidate_cache.apply_async(kwargs={'event': self.request.event.pk, 'order': self.order.pk})
                self.order.log_action('pretix.event.order.secret.changed', user=self.request.user)

            self.form.save()
            if changed:
                messages.success(self.request, _('The order has been changed.'))
            else:
                messages.success(self.request, _('Nothing about the order had to be changed.'))
            return redirect(self.get_order_url())
        return self.get(*args, **kwargs)


class OrderLocaleChange(OrderView):
    permission = 'can_change_orders'
    template_name = 'pretixcontrol/order/change_locale.html'

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

    @cached_property
    def form(self):
        return OrderLocaleForm(
            instance=self.order,
            data=self.request.POST if self.request.method == "POST" else None
        )

    def post(self, *args, **kwargs):
        old_locale = self.order.locale
        if self.form.is_valid():
            self.order.log_action(
                'pretix.event.order.locale.changed',
                data={
                    'old_locale': old_locale,
                    'new_locale': self.form.cleaned_data['locale'],
                },
                user=self.request.user,
            )

            self.form.save()
            tickets.invalidate_cache.apply_async(kwargs={'event': self.request.event.pk, 'order': self.order.pk})
            messages.success(self.request, _('The order has been changed.'))
            return redirect(self.get_order_url())
        return self.get(*args, **kwargs)


class OrderViewMixin:
    def get_object(self, queryset=None):
        try:
            return Order.objects.get(
                event=self.request.event,
                code=self.kwargs['code'].upper()
            )
        except Order.DoesNotExist:
            raise Http404()

    @cached_property
    def order(self):
        return self.get_object()

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


class OrderSendMail(EventPermissionRequiredMixin, OrderViewMixin, FormView):
    template_name = 'pretixcontrol/order/sendmail.html'
    permission = 'can_change_orders'
    form_class = OrderMailForm

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        kwargs['order'] = Order.objects.get(
            event=self.request.event,
            code=self.kwargs['code'].upper()
        )
        kwargs['initial'] = {}
        if self.request.GET.get('subject'):
            kwargs['initial']['subject'] = self.request.GET.get('subject')
        if self.request.GET.get('message'):
            kwargs['initial']['message'] = self.request.GET.get('message')
        return kwargs

    def form_invalid(self, form):
        messages.error(self.request, _('We could not send the email. See below for details.'))
        return super().form_invalid(form)

    def form_valid(self, form):
        order = Order.objects.get(
            event=self.request.event,
            code=self.kwargs['code'].upper()
        )
        self.preview_output = {}
        with language(order.locale):
            email_context = get_email_context(event=order.event, order=order)
        email_template = LazyI18nString(form.cleaned_data['message'])
        email_subject = str(form.cleaned_data['subject']).format_map(TolerantDict(email_context))
        email_content = render_mail(email_template, email_context)
        if self.request.POST.get('action') == 'preview':
            self.preview_output = {
                'subject': _('Subject: {subject}').format(subject=email_subject),
                'html': markdown_compile_email(email_content)
            }
            return self.get(self.request, *self.args, **self.kwargs)
        else:
            try:
                order.send_mail(
                    form.cleaned_data['subject'], email_template,
                    email_context, 'pretix.event.order.email.custom_sent',
                    self.request.user, auto_email=False
                )
                messages.success(self.request,
                                 _('Your message has been queued and will be sent to {}.'.format(order.email)))
            except SendMailException:
                messages.error(
                    self.request,
                    _('Failed to send mail to the following user: {}'.format(order.email))
                )
            return super(OrderSendMail, self).form_valid(form)

    def get_success_url(self):
        return reverse('control:event.order', kwargs={
            'event': self.request.event.slug,
            'organizer': self.request.event.organizer.slug,
            'code': self.kwargs['code']
        })

    def get_context_data(self, *args, **kwargs):
        ctx = super().get_context_data(*args, **kwargs)
        ctx['preview_output'] = getattr(self, 'preview_output', None)
        return ctx


class OrderEmailHistory(EventPermissionRequiredMixin, OrderViewMixin, ListView):
    template_name = 'pretixcontrol/order/mail_history.html'
    permission = 'can_view_orders'
    model = LogEntry
    context_object_name = 'logs'
    paginate_by = 10

    def get_queryset(self):
        order = get_object_or_404(
            Order,
            event=self.request.event,
            code=self.kwargs['code'].upper()
        )
        qs = order.all_logentries()
        qs = qs.filter(
            action_type__contains="order.email"
        )
        return qs


class AnswerDownload(EventPermissionRequiredMixin, OrderViewMixin, ListView):
    permission = 'can_view_orders'

    def get(self, request, *args, **kwargs):
        answid = kwargs.get('answer')
        token = request.GET.get('token', '')

        answer = get_object_or_404(QuestionAnswer, orderposition__order=self.order, id=answid)
        if not answer.file:
            raise Http404()
        if not check_token(request, answer, token):
            raise Http404(_("This link is no longer valid. Please go back, refresh the page, and try again."))

        ftype, ignored = mimetypes.guess_type(answer.file.name)
        resp = FileResponse(answer.file, content_type=ftype or 'application/binary')
        resp['Content-Disposition'] = 'attachment; filename="{}-{}-{}-{}"'.format(
            self.request.event.slug.upper(), self.order.code,
            answer.orderposition.positionid,
            os.path.basename(answer.file.name).split('.', 1)[1]
        )
        return resp


class OverView(EventPermissionRequiredMixin, TemplateView):
    template_name = 'pretixcontrol/orders/overview.html'
    permission = 'can_view_orders'

    @cached_property
    def filter_form(self):
        return OverviewFilterForm(data=self.request.GET, event=self.request.event)

    def get_context_data(self, **kwargs):
        ctx = super().get_context_data()

        if self.filter_form.is_valid():
            ctx['items_by_category'], ctx['total'] = order_overview(
                self.request.event,
                subevent=self.filter_form.cleaned_data.get('subevent'),
                date_filter=self.filter_form.cleaned_data['date_axis'],
                date_from=self.filter_form.cleaned_data['date_from'],
                date_until=self.filter_form.cleaned_data['date_until'],
                fees=True
            )
        else:
            ctx['items_by_category'], ctx['total'] = order_overview(
                self.request.event,
                fees=True
            )
        ctx['subevent_warning'] = (
            self.request.event.has_subevents and
            self.filter_form.is_valid() and
            self.filter_form.cleaned_data.get('subevent') and
            OrderFee.objects.filter(order__event=self.request.event).exclude(value=0).exists()
        )
        ctx['filter_form'] = self.filter_form
        return ctx


class OrderGo(EventPermissionRequiredMixin, View):
    permission = 'can_view_orders'

    def get_order(self, code):
        try:
            return Order.objects.get(code=code, event=self.request.event)
        except Order.DoesNotExist:
            return Order.objects.get(code=Order.normalize_code(code), event=self.request.event)

    def get(self, request, *args, **kwargs):
        code = request.GET.get("code", "").upper().strip()
        if '://' in code:
            m = re.match('.*/ORDER/([A-Z0-9]{' + str(settings.ENTROPY['order_code']) + '})/.*', code)
            if m:
                code = m.group(1)
        try:
            if code.startswith(request.event.slug.upper()):
                code = code[len(request.event.slug):]
            if code.startswith('-'):
                code = code[1:]
            order = self.get_order(code)
            return redirect('control:event.order', event=request.event.slug, organizer=request.event.organizer.slug,
                            code=order.code)
        except Order.DoesNotExist:
            try:
                i = self.request.event.invoices.get(Q(invoice_no=code) | Q(full_invoice_no=code))
                return redirect('control:event.order', event=request.event.slug, organizer=request.event.organizer.slug,
                                code=i.order.code)
            except Invoice.DoesNotExist:
                pass

            messages.error(request, _('There is no order with the given order code.'))
            return redirect('control:event.orders', event=request.event.slug, organizer=request.event.organizer.slug)


class ExportMixin:
    @cached_property
    def exporters(self):
        exporters = []
        responses = register_data_exporters.send(self.request.event)
        for ex in sorted([response(self.request.event) for r, response in responses], key=lambda ex: str(ex.verbose_name)):
            if self.request.GET.get("identifier") and ex.identifier != self.request.GET.get("identifier"):
                continue

            # Use form parse cycle to generate useful defaults
            test_form = ExporterForm(data=self.request.GET, prefix=ex.identifier)
            test_form.fields = ex.export_form_fields
            test_form.is_valid()
            initial = {
                k: v for k, v in test_form.cleaned_data.items() if ex.identifier + "-" + k in self.request.GET
            }

            ex.form = ExporterForm(
                data=(self.request.POST if self.request.method == 'POST' else None),
                prefix=ex.identifier,
                initial=initial
            )
            ex.form.fields = ex.export_form_fields
            exporters.append(ex)
        return exporters


class ExportDoView(EventPermissionRequiredMixin, ExportMixin, AsyncAction, View):
    permission = 'can_view_orders'
    known_errortypes = ['ExportError']
    task = export

    def get_success_message(self, value):
        return None

    def get_success_url(self, value):
        return reverse('cachedfile.download', kwargs={'id': str(value)})

    def get_error_url(self):
        return reverse('control:event.orders.export', kwargs={
            'event': self.request.event.slug,
            'organizer': self.request.event.organizer.slug
        })

    @cached_property
    def exporter(self):
        for ex in self.exporters:
            if ex.identifier == self.request.POST.get("exporter"):
                return ex

    def post(self, request, *args, **kwargs):
        if not self.exporter:
            messages.error(self.request, _('The selected exporter was not found.'))
            return redirect('control:event.orders.export', kwargs={
                'event': self.request.event.slug,
                'organizer': self.request.event.organizer.slug
            })

        if not self.exporter.form.is_valid():
            messages.error(self.request, _('There was a problem processing your input. See below for error details.'))
            return self.get(request, *args, **kwargs)

        cf = CachedFile()
        cf.date = now()
        cf.expires = now() + timedelta(days=3)
        cf.save()
        return self.do(self.request.event.id, str(cf.id), self.exporter.identifier, self.exporter.form.cleaned_data)


class ExportView(EventPermissionRequiredMixin, ExportMixin, TemplateView):
    permission = 'can_view_orders'
    template_name = 'pretixcontrol/orders/export.html'

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


class RefundList(EventPermissionRequiredMixin, PaginationMixin, ListView):
    model = OrderRefund
    context_object_name = 'refunds'
    template_name = 'pretixcontrol/orders/refunds.html'
    permission = 'can_view_orders'

    def get_queryset(self):
        qs = OrderRefund.objects.filter(
            order__event=self.request.event
        ).select_related('order')

        if self.filter_form.is_valid():
            qs = self.filter_form.filter_qs(qs)

        return qs.distinct()

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

    @cached_property
    def filter_form(self):
        return RefundFilterForm(data=self.request.GET, event=self.request.event,
                                initial={'status': 'open'})


class EventCancel(EventPermissionRequiredMixin, AsyncAction, FormView):
    template_name = 'pretixcontrol/orders/cancel.html'
    permission = 'can_change_orders'
    form_class = EventCancelForm
    task = cancel_event
    known_errortypes = ['OrderError']

    def get(self, request, *args, **kwargs):
        if 'async_id' in request.GET and settings.HAS_CELERY:
            return self.get_result(request)
        return FormView.get(self, request, *args, **kwargs)

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

    def form_valid(self, form):
        return self.do(
            self.request.event.pk,
            subevent=form.cleaned_data['subevent'].pk if form.cleaned_data.get('subevent') else None,
            auto_refund=form.cleaned_data.get('auto_refund'),
            manual_refund=form.cleaned_data.get('manual_refund'),
            refund_as_giftcard=form.cleaned_data.get('refund_as_giftcard'),
            giftcard_expires=form.cleaned_data.get('gift_card_expires'),
            giftcard_conditions=form.cleaned_data.get('gift_card_conditions'),
            keep_fee_fixed=form.cleaned_data.get('keep_fee_fixed'),
            keep_fee_percentage=form.cleaned_data.get('keep_fee_percentage'),
            keep_fees=form.cleaned_data.get('keep_fees'),
            send=form.cleaned_data.get('send'),
            send_subject=form.cleaned_data.get('send_subject').data,
            send_message=form.cleaned_data.get('send_message').data,
            send_waitinglist=form.cleaned_data.get('send_waitinglist'),
            send_waitinglist_subject=form.cleaned_data.get('send_waitinglist_subject').data,
            send_waitinglist_message=form.cleaned_data.get('send_waitinglist_message').data,
            user=self.request.user.pk,
        )

    def get_success_message(self, value):
        if value == 0:
            return _('All orders have been canceled.')
        else:
            return _('The orders have been canceled. An error occurred with {count} orders, please '
                     'check all uncanceled orders.').format(count=value)

    def get_success_url(self, value):
        return reverse('control:event.cancel', kwargs={
            'organizer': self.request.organizer.slug,
            'event': self.request.event.slug,
        })

    def get_error_url(self):
        return reverse('control:event.cancel', kwargs={
            'organizer': self.request.organizer.slug,
            'event': self.request.event.slug,
        })

    def get_error_message(self, exception):
        if isinstance(exception, str):
            return exception
        return super().get_error_message(exception)

    def form_invalid(self, form):
        messages.error(self.request, _('Your input was not valid.'))
        return super().form_invalid(form)