api_error_response.py

import json
import logging
import uuid
from datetime import UTC, datetime
from enum import Enum
from http import HTTPStatus

from flask import make_response
from flask.typing import ResponseReturnValue

from eligibility_signposting_api.model.operation_outcome import OperationOutcome, OperationOutcomeIssue

logger = logging.getLogger(__name__)


class FHIRIssueSeverity(str, Enum):
    FATAL = "fatal"
    ERROR = "error"
    WARNING = "warning"
    INFORMATION = "information"


class FHIRIssueCode(str, Enum):
    FORBIDDEN = "forbidden"
    PROCESSING = "processing"
    VALUE = "value"


class FHIRSpineErrorCode(str, Enum):
    ACCESS_DENIED = "ACCESS_DENIED"
    INVALID_PARAMETER = "INVALID_PARAMETER"
    INTERNAL_SERVER_ERROR = "INTERNAL_SERVER_ERROR"
    REFERENCE_NOT_FOUND = "REFERENCE_NOT_FOUND"


class APIErrorResponse:
    def __init__(
        self,
        status_code: HTTPStatus,
        fhir_issue_code: FHIRIssueCode,
        fhir_issue_severity: FHIRIssueSeverity,
        fhir_error_code: str,
        fhir_display_message: str,
    ) -> None:
        self.status_code = status_code
        self.fhir_issue_code = fhir_issue_code
        self.fhir_issue_severity = fhir_issue_severity
        self.fhir_coding_system = "https://fhir.nhs.uk/STU3/ValueSet/Spine-ErrorOrWarningCode-1"
        self.fhir_error_code = fhir_error_code
        self.fhir_display_message = fhir_display_message

    def build_operation_outcome_issue(self, diagnostics: str, location: list[str] | None) -> OperationOutcomeIssue:
        details = {
            "coding": [
                {
                    "system": self.fhir_coding_system,
                    "code": self.fhir_error_code,
                    "display": self.fhir_display_message,
                }
            ]
        }
        return OperationOutcomeIssue(
            severity=self.fhir_issue_severity,
            code=self.fhir_issue_code,
            details=details,
            diagnostics=diagnostics,
            location=location,
        )

    def generate_response(self, diagnostics: str, location_param: str | None = None) -> ResponseReturnValue:
        issue_location = [f"parameters/{location_param}"] if location_param else None

        problem = OperationOutcome(
            id=str(uuid.uuid4()),
            meta={"lastUpdated": datetime.now(UTC)},
            issue=[self.build_operation_outcome_issue(diagnostics, issue_location)],
        )

        response_body = json.dumps(problem.model_dump(mode="json", exclude_none=True))
        return make_response(response_body, self.status_code, {"Content-Type": "application/fhir+json"})

    def log_and_generate_response(
        self, log_message: str, diagnostics: str, location_param: str | None = None
    ) -> ResponseReturnValue:
        logger.error(log_message)
        return self.generate_response(diagnostics, location_param)


INVALID_INCLUDE_ACTIONS_ERROR = APIErrorResponse(
    status_code=HTTPStatus.UNPROCESSABLE_ENTITY,
    fhir_issue_code=FHIRIssueCode.VALUE,
    fhir_issue_severity=FHIRIssueSeverity.ERROR,
    fhir_error_code=FHIRSpineErrorCode.INVALID_PARAMETER,
    fhir_display_message="The supplied value was not recognised by the API.",
)

INVALID_CATEGORY_ERROR = APIErrorResponse(
    status_code=HTTPStatus.UNPROCESSABLE_ENTITY,
    fhir_issue_code=FHIRIssueCode.VALUE,
    fhir_issue_severity=FHIRIssueSeverity.ERROR,
    fhir_error_code=FHIRSpineErrorCode.INVALID_PARAMETER,
    fhir_display_message="The supplied category was not recognised by the API.",
)

INVALID_CONDITION_FORMAT_ERROR = APIErrorResponse(
    status_code=HTTPStatus.BAD_REQUEST,
    fhir_issue_code=FHIRIssueCode.VALUE,
    fhir_issue_severity=FHIRIssueSeverity.ERROR,
    fhir_error_code=FHIRSpineErrorCode.INVALID_PARAMETER,
    fhir_display_message="The given conditions were not in the expected format.",
)

NHS_NUMBER_NOT_FOUND_ERROR = APIErrorResponse(
    status_code=HTTPStatus.NOT_FOUND,
    fhir_issue_code=FHIRIssueCode.PROCESSING,
    fhir_issue_severity=FHIRIssueSeverity.ERROR,
    fhir_error_code=FHIRSpineErrorCode.REFERENCE_NOT_FOUND,
    fhir_display_message="The given NHS number was not found in our datasets. "
    "This could be because the number is incorrect or "
    "some other reason we cannot process that number.",
)

INTERNAL_SERVER_ERROR = APIErrorResponse(
    status_code=HTTPStatus.INTERNAL_SERVER_ERROR,
    fhir_issue_code=FHIRIssueCode.PROCESSING,
    fhir_issue_severity=FHIRIssueSeverity.ERROR,
    fhir_error_code=FHIRSpineErrorCode.INTERNAL_SERVER_ERROR,
    fhir_display_message="An unexpected internal server error occurred.",
)

NHS_NUMBER_MISMATCH_ERROR = APIErrorResponse(
    status_code=HTTPStatus.FORBIDDEN,
    fhir_issue_code=FHIRIssueCode.FORBIDDEN,
    fhir_issue_severity=FHIRIssueSeverity.ERROR,
    fhir_error_code=FHIRSpineErrorCode.ACCESS_DENIED,
    fhir_display_message="Access has been denied to process this request.",
)

CONSUMER_ID_NOT_PROVIDED_ERROR = APIErrorResponse(
    status_code=HTTPStatus.FORBIDDEN,
    fhir_issue_code=FHIRIssueCode.FORBIDDEN,
    fhir_issue_severity=FHIRIssueSeverity.ERROR,
    fhir_error_code=FHIRSpineErrorCode.ACCESS_DENIED,
    fhir_display_message="Access has been denied to process this request.",
)