import django_filters
from django_filters.rest_framework import DjangoFilterBackend, FilterSet
from django_scopes import scopes_disabled
from rest_framework import viewsets
from rest_framework.decorators import action
from rest_framework.exceptions import PermissionDenied, ValidationError
from rest_framework.filters import OrderingFilter
from rest_framework.response import Response

from pretix.api.serializers.waitinglist import WaitingListSerializer
from pretix.base.models import WaitingListEntry
from pretix.base.models.waitinglist import WaitingListException

with scopes_disabled():
    class WaitingListFilter(FilterSet):
        has_voucher = django_filters.rest_framework.BooleanFilter(method='has_voucher_qs')

        def has_voucher_qs(self, queryset, name, value):
            return queryset.filter(voucher__isnull=not value)

        class Meta:
            model = WaitingListEntry
            fields = ['item', 'variation', 'email', 'locale', 'has_voucher', 'subevent']


class WaitingListViewSet(viewsets.ModelViewSet):
    serializer_class = WaitingListSerializer
    queryset = WaitingListEntry.objects.none()
    filter_backends = (DjangoFilterBackend, OrderingFilter)
    ordering = ('created',)
    ordering_fields = ('id', 'created', 'email', 'item')
    filterset_class = WaitingListFilter
    permission = 'can_view_orders'
    write_permission = 'can_change_orders'

    def get_queryset(self):
        return self.request.event.waitinglistentries.all()

    def get_serializer_context(self):
        ctx = super().get_serializer_context()
        ctx['event'] = self.request.event
        return ctx

    def perform_create(self, serializer):
        serializer.save(event=self.request.event)
        serializer.instance.log_action(
            'pretix.event.orders.waitinglist.added',
            user=self.request.user,
            auth=self.request.auth,
        )

    def perform_update(self, serializer):
        if serializer.instance.voucher:
            raise PermissionDenied('This entry can not be changed as it has already been assigned a voucher.')
        serializer.save(event=self.request.event)
        serializer.instance.log_action(
            'pretix.event.orders.waitinglist.changed',
            user=self.request.user,
            auth=self.request.auth,
        )

    def perform_destroy(self, instance):
        if instance.voucher:
            raise PermissionDenied('This entry can not be deleted as it has already been assigned a voucher.')

        instance.log_action(
            'pretix.event.orders.waitinglist.deleted',
            user=self.request.user,
            auth=self.request.auth,
        )
        super().perform_destroy(instance)

    @action(detail=True, methods=['POST'])
    def send_voucher(self, *args, **kwargs):
        try:
            self.get_object().send_voucher(
                user=self.request.user,
                auth=self.request.auth,
            )
        except WaitingListException as e:
            raise ValidationError(str(e))
        else:
            return Response(status=204)