from django.conf import settings
from django.db import models
from django.utils import timezone


class SoftDeleteQuerySet(models.QuerySet):
    def alive(self):
        return self.filter(deleted_at__isnull=True)

    def dead(self):
        return self.filter(deleted_at__isnull=False)


class SoftDeleteManager(models.Manager):
    def get_queryset(self):
        return SoftDeleteQuerySet(self.model, using=self._db).alive()


class AllObjectsManager(models.Manager):
    def get_queryset(self):
        return SoftDeleteQuerySet(self.model, using=self._db)


class SoftDeleteModelMixin(models.Model):
    deleted_at = models.DateTimeField(null=True, blank=True, db_index=True)
    deleted_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name='+',
    )

    objects = SoftDeleteManager()
    all_objects = AllObjectsManager()

    class Meta:
        abstract = True

    @property
    def is_deleted(self):
        return self.deleted_at is not None

    def soft_delete(self, user=None):
        self.deleted_at = timezone.now()
        self.deleted_by = user if getattr(user, 'is_authenticated', False) else None
        self.save(update_fields=['deleted_at', 'deleted_by', 'updated_at'])

    def restore(self):
        self.deleted_at = None
        self.deleted_by = None
        self.save(update_fields=['deleted_at', 'deleted_by', 'updated_at'])