class BaseOTPProvider:
    '''OTP providers must be subclasses of BaseOTPProvider and implement at least validate_token().'''

    @property
    def get_name(self):
        return "Base OTP Provider"

    @property
    def get_logo(self):
        return ""

    def __str__(self):
        return self.get_name

    @property
    def is_active(self):
        '''Returns True if the provider is properly configured and ready to use.'''
        raise NotImplementedError(f"{type(self)} does not implement is_active!")

    def active_for_user(self, user):
        '''Returns True if the provider is active and ready to be used by user.'''
        return self.is_active

    def start_authentication(self, user):
        return "Authentication started, please enter your 2FA token."

    def validate_token(self, user, token):
        raise NotImplementedError(f"{type(self)} does not implement validate_token()!")