import graphene
from graphene import relay
from graphene_django import DjangoObjectType
from graphene_django.filter import DjangoFilterConnectionField

from books.models import Topic, Module
from books.schema.nodes import ModuleNode

class NotFoundFailure:
    reason = 'Not Found'



class NotFound(graphene.ObjectType):
    reason = graphene.String()


class TopicNode(DjangoObjectType):
    pk = graphene.Int()
    modules = DjangoFilterConnectionField(ModuleNode)

    class Meta:
        model = Topic
        only_fields = [
            'slug', 'title', 'teaser', 'description', 'vimeo_id', 'order', 'instructions'
        ]
        filter_fields = {
            'slug': ['exact', 'icontains', 'in'],
            'title': ['exact', 'icontains', 'in'],
        }
        interfaces = (relay.Node,)

    def resolve_pk(self, *args, **kwargs):
        return self.id

    def resolve_modules(self, *args, **kwargs):
        return Module.get_by_parent(self)


class TopicOr404Node(graphene.Union):
    class Meta:
        types = (TopicNode, NotFound)

    @classmethod
    def resolve_type(cls, instance, info):
        if type(instance).__name__ == "Topic":
            return TopicNode
        return NotFound