from abc import ABCMeta, abstractmethod, abstractproperty
from six import add_metaclass

class ConfigValidationException(Exception):
  """ Exception raised when the configuration fails to validate for a known reason. """
  pass


@add_metaclass(ABCMeta)
class BaseValidator(object):
  @abstractproperty
  def name(self):
    """ The key for the validation API. """
    pass

  @classmethod
  @abstractmethod
  def validate(cls, config, user, user_password, app):
    """ Raises Exception if failure to validate. """
    pass