from rest_framework import serializers
from rest_framework.reverse import reverse


class EventHyperlinkedFieldMixin:

    def get_url(self, obj, view_name, request, format):
        url_kwargs = {'pk': obj.pk}
        if getattr(obj, 'event', None):
            url_kwargs['event_pk'] = obj.event.pk
        return reverse(
            view_name, kwargs=url_kwargs, request=request, format=format)

    def get_object(self, view_name, view_args, view_kwargs):
        lookup_kwargs = {
            'pk': view_kwargs['pk'],
            'event_id': view_kwargs.get('event_pk'),
        }
        return self.get_queryset().get(**lookup_kwargs)


class EventHyperlinkedRelatedField(
            EventHyperlinkedFieldMixin,
            serializers.HyperlinkedRelatedField,
        ):
    pass


class EventHyperlinkedIdentityField(
            EventHyperlinkedFieldMixin,
            serializers.HyperlinkedIdentityField
        ):
    pass