import jwt

from jwt.api import PyJWT

from . import get_permitted_algorithm_names
from .key import KeyIdentifier


class JWTAuthVerifier(object):

    """ This class can be used to verify a JWT. """

    def __init__(self, public_key_retriever, **kwargs):
        self.public_key_retriever = public_key_retriever
        self.algorithms = get_permitted_algorithm_names()
        self._seen_jti = set()

    def verify_claims(self, a_jwt, audience):
        """ returns verified claims if verification is successful. """
        options = {'verify_signature': True}
        payload, signing_input, header, signature = PyJWT()._load(a_jwt)
        key_identifier = KeyIdentifier(header['kid'])
        public_key = self.public_key_retriever.retrieve(key_identifier)
        claims = jwt.decode(
            a_jwt, key=public_key,
            algorithms=self.algorithms,
            options=options,
            audience=audience)
        if not key_identifier.key_id.startswith('%s/' % claims['iss']):
            raise ValueError('Issuer does not own the the supplied public key')
        if claims.get('sub') and claims['iss'] != claims['sub']:
            raise ValueError('Issuer does not match the subject.')
        _aud = claims['aud']
        _exp = int(claims['exp'])
        _iat = int(claims['iat'])
        if _exp - _iat > 3600:
            _msg = ("Claims validity, '%s', exceeds the maximum 1 hour." %
                    (_exp - _iat))
            raise ValueError(_msg)
        _jti = claims['jti']
        if _jti in self._seen_jti:
            raise ValueError("The jti. '%s' has already been used!" % _jti)
        else:
            if len(self._seen_jti) > 100:
                self._seen_jti = set()
            self._seen_jti.add(_jti)
        return claims

@@ -1048,20 +1048,16 @@
 own the 
-the 
 supplied

remove the superfluous 'the' in the issuer does not own the supplied public key message.