from django.core.management import BaseCommand
from django.db import transaction
from django.db.models import Count

from boards.models import Tag


__author__ = 'neko259'


class Command(BaseCommand):
    help = 'Removed tags that have no threads'

    @transaction.atomic
    def handle(self, *args, **options):
        empty = Tag.objects.annotate(num_threads=Count('thread_tags'))\
                .filter(num_threads=0).order_by('-required', 'name')
        print('Removing {} empty tags'.format(empty.count()))
        empty.delete()