"""Mapper from exceptions to HTTP responses is defined here"""

from typing import Callable, Type

from fastapi import HTTPException
from fastapi.responses import JSONResponse


class ExceptionMapper:
    def __init__(self):
        self._known_exceptions: dict[Type, Callable[[Exception], JSONResponse]] = {}

    def register_simple(self, exception_type: Type, status_code: int, detail: str) -> None:
        self._known_exceptions[exception_type] = lambda _: JSONResponse(
            {"code": status_code, "detail": detail}, status_code=status_code
        )

    def register_func(self, exception_type: Type, func: Callable[[Exception], JSONResponse]) -> None:
        self._known_exceptions[exception_type] = func

    def is_known(self, exc: Exception) -> bool:
        return type(exc) in self._known_exceptions or isinstance(exc, HTTPException)

    def apply(self, exc: Exception) -> JSONResponse:
        if (res := self.apply_if_known(exc)) is not None:
            return res
        return JSONResponse({"code": 500, "detail": "unhandled exception"}, status_code=500)

    def apply_if_known(self, exc: Exception) -> JSONResponse | None:
        if isinstance(exc, HTTPException):
            return JSONResponse({"code": exc.status_code, "detail": exc.detail}, status_code=exc.status_code)
        if (t := type(exc)) in self._known_exceptions:
            return self._known_exceptions[t](exc)
        return None