from requests import Session
from authlib.oauth2.rfc7521 import AssertionClient
from authlib.oauth2.rfc7523 import JWTBearerGrant
from .oauth2_session import OAuth2Auth


class AssertionAuth(OAuth2Auth):
    def ensure_active_token(self):
        if not self.token or self.token.is_expired() and self.client:
            return self.client.refresh_token()


class AssertionSession(AssertionClient, Session):
    """Constructs a new Assertion Framework for OAuth 2.0 Authorization Grants
    per RFC7521_.

    .. _RFC7521: https://tools.ietf.org/html/rfc7521
    """
    token_auth_class = AssertionAuth
    JWT_BEARER_GRANT_TYPE = JWTBearerGrant.GRANT_TYPE
    ASSERTION_METHODS = {
        JWT_BEARER_GRANT_TYPE: JWTBearerGrant.sign,
    }
    DEFAULT_GRANT_TYPE = JWT_BEARER_GRANT_TYPE

    def __init__(self, token_endpoint, issuer, subject, audience=None, grant_type=None,
                 claims=None, token_placement='header', scope=None, **kwargs):
        Session.__init__(self)

        token_url = kwargs.pop('token_url', None)
        if token_url:
            # TODO: deprecate
            token_endpoint = token_url

        AssertionClient.__init__(
            self, session=self,
            token_endpoint=token_endpoint, issuer=issuer, subject=subject,
            audience=audience, grant_type=grant_type, claims=claims,
            token_placement=token_placement, scope=scope, **kwargs
        )

    def request(self, method, url, withhold_token=False, auth=None, **kwargs):
        """Send request with auto refresh token feature."""
        if not withhold_token and auth is None:
            auth = self.token_auth
        return super(AssertionSession, self).request(
            method, url, auth=auth, **kwargs)