errors.py

import json
import traceback
from flask.wrappers import Response
from functools import wraps

from api.miscellaneous.util import *


class ApiError:
    
    def __init__(self, error_code: str, http_status_code: int, message: str):
        self.error_code = error_code
        self.http_status_code = http_status_code
        self.message = message


class ApiClientException(Exception):
    
    def __init__(self, error: ApiError):
        self.error = error


def api_handle_exceptions(func):
    @wraps(func)
    def decorator(*args, **kwargs):
        try:
            return func(*args, **kwargs)
        except ApiClientException as e:
            return api_on_error(e.error)
        except Exception as e:
            print("An exception occurred while handling api request:")
            traceback.print_exception(e)
            return api_on_error(ERROR_INTERNAL_SERVER_ERROR)
    
    return decorator


def api_on_error(error: ApiError) -> Response:
    error_json = {
        "error_code": error.error_code,
        "message": error.message
    }
    return Response(json.dumps(error_json), error.http_status_code, mimetype="application/json")


ERROR_BAD_REQUEST = ApiError("bad_request", HTTP_400_BAD_REQUEST,
                             "The request is invalid")
ERROR_METHOD_NOT_ALLOWED = ApiError("method_not_allowed", HTTP_405_METHOD_NOT_ALLOWED,
                                    "The specified request method is not allowed")
ERROR_MALFORMED_JSON = ApiError("malformed_json", HTTP_400_BAD_REQUEST,
                                "The request json is malformed or missing")
def ERROR_REQUEST_MISSING_PARAMETER(parameter_name: str) -> ApiError:
    return ApiError("request_missing_parameter", HTTP_400_BAD_REQUEST,
                    "Missing parameter " + parameter_name + " in request")
def ERROR_REQUEST_INVALID_PARAMETER(parameter_name: str, invalid_message: str) -> ApiError:
    return ApiError("request_invalid_parameter", HTTP_400_BAD_REQUEST,
                    "Parameter " + parameter_name + " in request is invalid: " + invalid_message)
ERROR_UNKNOWN_REQUEST_PATH = ApiError("unknown_request_path", HTTP_404_NOT_FOUND,
                                "The specified request path does not exist")
ERROR_UNKNOWN_COURSE = ApiError("unknown_course", HTTP_404_NOT_FOUND,
                                "The specified course cannot be found")
ERROR_UNKNOWN_LECTURE = ApiError("unknown_lecture", HTTP_404_NOT_FOUND,
                                 "The specified lecture cannot be found")
ERROR_INTERNAL_SERVER_ERROR = ApiError("internal_server_error", HTTP_500_INTERNAL_SERVER_ERROR,
                                       "An unknown internal server error occurred")
ERROR_LECTURE_HAS_NO_PASSWORD = ApiError("lecture_has_no_password", HTTP_400_BAD_REQUEST,
                                         "The specified lecture has no password authentication")
ERROR_AUTHENTICATION_FAILED = ApiError("authentication_failed", HTTP_403_FORBIDDEN,
                                       "Authentication failed")
ERROR_AUTHENTICATION_SERVERS_NOT_AVAILABLE = ApiError("authentication_servers_not_available", HTTP_503_SERVICE_UNAVAILABLE,
                                                      "Authentication servers are currently not available")
ERROR_UNAUTHORIZED = ApiError("unauthorized", HTTP_401_UNAUTHORIZED,
                              "You are not authorized")
ERROR_ACCESS_FORBIDDEN = ApiError("access_forbidden", HTTP_403_FORBIDDEN,
                                  "You do not not access to this resource")