notifications-api/notifications_python_client/errors.py

from typing import List, Union  # noqa: UP035 – Python <3.10 compatibility

from requests import RequestException, Response

REQUEST_ERROR_STATUS_CODE = 503
REQUEST_ERROR_MESSAGE = "Request failed"

TOKEN_ERROR_GUIDANCE = "See our requirements for JSON Web Tokens \
    at https://docs.notifications.service.gov.uk/rest-api.html#authorisation-header"
TOKEN_ERROR_DEFAULT_ERROR_MESSAGE = "Invalid token: " + TOKEN_ERROR_GUIDANCE


class TokenError(Exception):
    def __init__(self, message=None, token=None):
        self.message = (
            message + ". " + TOKEN_ERROR_GUIDANCE
            if message
            else TOKEN_ERROR_DEFAULT_ERROR_MESSAGE
        )
        self.token = token
        super().__init__(self.message, token)


class TokenExpiredError(TokenError):
    pass


class TokenAlgorithmError(TokenError):
    def __init__(self):
        super().__init__("Invalid token: algorithm used is not HS256")


class TokenDecodeError(TokenError):
    def __init__(self, message=None):
        super().__init__(message or "Invalid token: signature")


class TokenIssuerError(TokenDecodeError):
    def __init__(self):
        super().__init__("Invalid token: iss field not provided")


class TokenIssuedAtError(TokenDecodeError):
    def __init__(self):
        super().__init__("Invalid token: iat field not provided")


class APIError(Exception):
    def __init__(self, response: Response = None, message: str = None):
        self.response = response
        self._message = message
        super().__init__(response, message)

    def __str__(self):
        return f"{self.status_code} - {self.message}"

    @property
    def message(
        self,
    ) -> Union[str, List[dict]]:  # noqa: UP006, UP007 – Python <3.10 compatibility
        try:
            json_resp = self.response.json()  # type: ignore
            return json_resp.get("message", json_resp.get("errors"))
        except (TypeError, ValueError, AttributeError, KeyError):
            return self._message or REQUEST_ERROR_MESSAGE

    @property
    def status_code(self) -> int:
        try:
            return self.response.status_code  # type: ignore
        except AttributeError:
            return REQUEST_ERROR_STATUS_CODE


class HTTPError(APIError):
    @staticmethod
    def create(e: RequestException) -> "HTTPError":
        error = HTTPError(e.response)
        if error.status_code == 503:
            error = HTTP503Error(e.response)
        return error


class HTTP503Error(HTTPError):
    """Specific instance of HTTPError for 503 errors

    Used for detecting whether failed requests should be retried.
    """


class InvalidResponse(APIError):
    pass