class ItemSerializer(serializers.ModelSerializer):
    class Meta:
        model = models.Item
        exclude = ('modified',)
        extra_kwargs = {'key': {'write_only': True}}

    robot_name = serializers.ReadOnlyField(source='run.robot.name')


class ItemsFilterset(FilterSet):
    class Meta:
        model = Item
        fields = {'run': ['exact']}

    item_id = CompoundRegexFilter(field_name='name', lookup_expr='regex')
    additional_info = CompoundRegexFilter(field_name='reference', lookup_expr='regex')
    start = DateTimeFromToRangeFilter(lookup_expr='exact')
    end = DateTimeFromToRangeFilter(lookup_expr='exact')
    status = MultipleChoiceFilter(choices=ITEM_STATUS_CHOICES, lookup_expr='exact')
    robot = NumberInFilter(field_name='run__robot__id', lookup_expr='in')


class PDItemViewSet(ReadOnlyModelViewSet):
    """List all latest items reported by PD robots."""
    permission_required = 'core.view_item'
    permission_classes = [IsAuthenticated & (HasUnitRole | HasPermission)]
    serializer_class = serializers.ItemSerializer
    filter_backends = [DjangoFilterBackend]
    filterset_class = ItemsFilterset

    def get_queryset(self):
        """Construct queryset of latest unique items."""
        items = models.Item.objects.order_by('key', '-modified').distinct('key')
        if not (self.request.user.is_superuser or self.request.user.is_staff):
            units = self.request.user.unit_roles.values('unit')
            items = items.filter(run__robot__unit__in=units)

        items = items.annotate(item_id=F('name'), additional_info=F('reference'), robot_name=F('run__robot__name'),
                               duration=Epoch(F('end') - F('start')))
        items = self.filter_queryset(items)

        return items