from StringIO import StringIO

from util.config.validators import BaseValidator, ConfigValidationException
from util.security.signing import SIGNING_ENGINES

class SignerValidator(BaseValidator):
  name = "signer"

  @classmethod
  def validate(cls, validator_context):
    """ Validates the GPG public+private key pair used for signing converted ACIs. """
    config = validator_context.config
    config_provider = validator_context.config_provider

    if config.get('SIGNING_ENGINE') is None:
      return

    if config['SIGNING_ENGINE'] not in SIGNING_ENGINES:
      raise ConfigValidationException('Unknown signing engine: %s' % config['SIGNING_ENGINE'])

    engine = SIGNING_ENGINES[config['SIGNING_ENGINE']](config, config_provider)
    engine.detached_sign(StringIO('test string'))