src/backend/api/exceptions.py

from rest_framework.exceptions import APIException
from rest_framework.response import Response
from rest_framework.views import exception_handler


class ApiError(APIException):
    def __init__(self, code, message, status_code=400, details=None):
        self.code = code
        self.detail = message
        self.status_code = status_code
        self.details = details or {}


class NotFoundError(ApiError):
    def __init__(self, message, details=None):
        super().__init__("NOT_FOUND", message, status_code=404, details=details)


class InvalidRequestError(ApiError):
    def __init__(self, message, details=None):
        super().__init__("INVALID_REQUEST", message, status_code=400, details=details)


class InferenceError(ApiError):
    def __init__(self, message, details=None):
        super().__init__("INFERENCE_ERROR", message, status_code=422, details=details)


class InferenceBusy(ApiError):
    def __init__(self, message="Another inference is in progress.", details=None):
        super().__init__("INFERENCE_BUSY", message, status_code=429, details=details)


class ModelUnavailable(ApiError):
    def __init__(self, message, details=None):
        super().__init__("MODEL_UNAVAILABLE", message, status_code=503, details=details)


def api_exception_handler(exc, context):
    if isinstance(exc, ApiError):
        return Response(
            {"error": {"code": exc.code, "message": str(exc.detail), "details": exc.details}},
            status=exc.status_code,
        )
    response = exception_handler(exc, context)
    if response is not None:
        code = "UNKNOWN_ERROR"
        if response.status_code == 404:
            code = "NOT_FOUND"
        elif response.status_code == 400:
            code = "INVALID_REQUEST"
        response.data = {"error": {"code": code, "message": str(response.data), "details": {}}}
    return response