from typing import TypeVar
from django.db.models import Avg
from django.db import models

T = TypeVar('T')

class PublicationQuerySet(models.QuerySet[T]):
    def with_score(self):
        qs = self
        qs = qs.annotate(average_score=Avg("ratings__score"))
        return qs
    
    def only_publish(self):
        from .models import Publication
        qs = self
        return qs.filter(status=Publication.StatusVarioations.PUBLIC.value)

class PublicationManager(models.Manager[T]):
    def get_queryset(self):
        return PublicationQuerySet[T](self.model, using=self._db).with_score()
    
    def with_related(self):
        return self.get_queryset().select_related('user', 'category')
    
    def only_publish(self):
        return self.get_queryset().only_publish()