from django.db import models

from books.models import ContentBlock
from user.models import UserGroup


class Visibility(models.Model):
    class Meta:
        verbose_name = 'Visibility'
        verbose_name_plural = 'Visibilities'

    user_group = models.ForeignKey(UserGroup, blank=False, null=False, on_delete=models.CASCADE)
    content_block = models.ForeignKey(ContentBlock, blank=False, null=False, on_delete=models.CASCADE, related_name='visible_to')

    def __str__(self):
        return 'Visibility {}-{}'.format(self.user_group, self.content_block)