"""Safe, JSON:API-compatible exception handling."""

import logging
import uuid

from rest_framework.exceptions import APIException
from rest_framework_json_api.exceptions import exception_handler as jsonapi_exception_handler

logger = logging.getLogger(__name__)

ERROR_ID_HEADER = "X-Error-ID"


class APIConflictException(APIException):
    """A deliberately raised, non-sensitive resource conflict."""

    status_code = 409
    default_detail = "The request conflicts with the current resource state."
    default_code = "conflict"


class InternalServerError(APIException):
    """Sanitized representation of an unexpected server exception."""

    status_code = 500
    default_detail = "An unexpected server error occurred."
    default_code = "internal_error"


def hardened_exception_handler(exc, context):
    """Render expected errors normally and sanitize unexpected exceptions.

    Unexpected exception details and tracebacks are logged server-side under a
    generated error identifier. Only that opaque identifier is returned to the
    client, in a response header, so operators can correlate a report safely.
    """

    response = jsonapi_exception_handler(exc, context)
    if response is not None:
        return response

    error_id = uuid.uuid4().hex
    logger.error(
        "Unhandled API exception; error_id=%s",
        error_id,
        exc_info=exc,
    )

    response = jsonapi_exception_handler(InternalServerError(), context)
    response[ERROR_ID_HEADER] = error_id
    return response


class HardenedExceptionHandlingMixin:
    """Opt a DRF view into :func:`hardened_exception_handler`."""

    def get_exception_handler(self):
        return hardened_exception_handler