from django.utils.text import slugify


def generate_unique_slug(klass, text):
    """
    return unique slug if origin slug is exist.
    eg: `foo-bar` => `foo-bar-1`
    """
    origin_slug = slugify(text)
    unique_slug = origin_slug
    numb = 1
    while klass.objects.filter(slug=unique_slug).exists():
        unique_slug = f'{origin_slug}-{numb}'
        numb += 1
    return unique_slug