text: import datetime
  from functools import lru_cache
  
  import python_jwt as jwt
  import jwcrypto.jwk as jwk
  from django.conf import settings
  
  from os import urandom
  from jwcrypto.jws import JWS
  from jwcrypto.common import base64url_encode, json_encode, json_decode
  from calendar import timegm
  
  
  # need to add "kid" header which the original python_jwt can not do
  from openid_connect_op.models import OpenIDClient
  
  
  def generate_jwt_patched(claims, priv_key=None,
                           algorithm='PS512', lifetime=None, expires=None,
                           not_before=None,
                           jti_size=16, extra_headers={}):
      """
      Generate a JSON Web Token.
  
      :param claims: The claims you want included in the signature.
      :type claims: dict
  
      :param priv_key: The private key to be used to sign the token. Note: if you pass ``None`` then the token will be returned with an empty cryptographic signature and :obj:`algorithm` will be forced to the value ``none``.
      :type priv_key: `jwcrypto.jwk.JWK <https://jwcrypto.readthedocs.io/en/latest/jwk.html>`_
  
      :param algorithm: The algorithm to use for generating the signature. ``RS256``, ``RS384``, ``RS512``, ``PS256``, ``PS384``, ``PS512``, ``ES256``, ``ES384``, ``ES512``, ``HS256``, ``HS384``, ``HS512`` and ``none`` are supported.
      :type algorithm: str
  
      :param lifetime: How long the token is valid for.
      :type lifetime: datetime.timedelta
  
      :param expires: When the token expires (if :obj:`lifetime` isn't specified)
      :type expires: datetime.datetime
  
      :param not_before: When the token is valid from. Defaults to current time (if ``None`` is passed).
      :type not_before: datetime.datetime
  
      :param jti_size: Size in bytes of the unique token ID to put into the token (can be used to detect replay attacks). Defaults to 16 (128 bits). Specify 0 or ``None`` to omit the JTI from the token.
      :type jti_size: int
  
      :rtype: unicode
      :returns: The JSON Web Token. Note this includes a header, the claims and a cryptographic signature. The following extra claims are added, per the `JWT spec <http://self-issued.info/docs/draft-ietf-oauth-json-web-token.html>`_:
  
      - **exp** (*IntDate*) -- The UTC expiry date and time of the token, in number of seconds from 1970-01-01T0:0:0Z UTC.
      - **iat** (*IntDate*) -- The UTC date and time at which the token was generated.
      - **nbf** (*IntDate*) -- The UTC valid-from date and time of the token.
      - **jti** (*str*) -- A unique identifier for the token.
      """
      header = {
          'typ': 'JWT',
          'alg': algorithm if priv_key else 'none'
      }
      header.update(extra_headers)
  
      claims = dict(claims)
  
      now = datetime.datetime.utcnow()
  
      if jti_size:
          claims['jti'] = base64url_encode(urandom(jti_size))
  
      claims['nbf'] = timegm((not_before or now).utctimetuple())
      claims['iat'] = timegm(now.utctimetuple())
  
      if lifetime:
          claims['exp'] = timegm((now + lifetime).utctimetuple())
      elif expires:
          claims['exp'] = timegm(expires.utctimetuple())
  
      if header['alg'] == 'none':
          signature = ''
      else:
          token = JWS(json_encode(claims))
          token.add_signature(priv_key, protected=header)
          signature = json_decode(token.serialize())['signature']
  
      return u'%s.%s.%s' % (
          base64url_encode(json_encode(header)),
          base64url_encode(json_encode(claims)),
          signature
      )
  
  
  class JWTTools:
  
      @staticmethod
      def generate_jwt(payload, for_client=None, ttl=None, from_client=None):
          if for_client is None:
              sign_alg = 'RS256'
          elif for_client.client_auth_type == OpenIDClient.CLIENT_AUTH_TYPE_SECRET_JWT:
              sign_alg = 'HS256'
          else:
              sign_alg = for_client.client_registration_data.get('id_token_signed_response_alg', 'RS256')
  
          return JWTTools.generate_jwt_with_sign_alg(payload, sign_alg, ttl=ttl, client=from_client)
  
      @staticmethod
      def generate_jwt_with_sign_alg(payload, sign_alg, ttl=None, client=None):
          from openid_connect_op.models import OpenIDClient
          if not client:
              client = OpenIDClient.self_instance()
          if client.client_auth_type == client.CLIENT_AUTH_TYPE_SECRET_JWT:
              sign_key = jwk.JWK(kty="oct", use="sig", alg="HS256", k=base64url_encode(client.client_hashed_secret))
              extra_headers = {}
              alg = 'HS256'
          else:
              sign_key = client.get_key(sign_alg)
              extra_headers = {
                  'kid': sign_key.key_id
              }
              alg = sign_key.alg
  
          return generate_jwt_patched(payload,
                                      sign_key,
                                      alg,
                                      extra_headers=extra_headers,
                                      lifetime=ttl)
  
      @staticmethod
      def validate_jwt(token, client=None):
          from openid_connect_op.models import OpenIDClient
          if client is None:
              client = OpenIDClient.self_instance()
  
          if client.client_auth_type == OpenIDClient.CLIENT_AUTH_TYPE_SECRET_JWT:
              key = jwk.JWK(kty="oct", use="sig", alg="HS256", k=base64url_encode(client.client_hashed_secret))
              return jwt.verify_jwt(token, key, ['HS256'], checks_optional=True)
  
          header, __ = jwt.process_jwt(token)
          key = client.get_key(alg=header.get('alg', 'RS256'), kid=header.get('kid', None))
          return jwt.verify_jwt(token, key, [key._params.get('alg', 'RS256')], checks_optional=True)
  
      @staticmethod
      def unverified_jwt_payload(token):
          return jwt.process_jwt(token)[1]