from __future__ import unicode_literals

import yaml

from django.core.exceptions import ValidationError
from django.utils.translation import ugettext_lazy as _
from django.utils.deconstruct import deconstructible


@deconstructible
class YAMLValidator(object):
    """
    Validates that the input is YAML compliant.
    """

    def __call__(self, value):
        value = value.strip()
        try:
            yaml.safe_load(value)
        except yaml.error.YAMLError:
            raise ValidationError(_('Enter a valid YAML value.'), code='invalid')