from fastapi import FastAPI, Request
from fastapi.responses import JSONResponse


class AppError(Exception):
    """Application-level error mapped to an HTTP response."""

    def __init__(self, message: str, status_code: int = 400) -> None:
        self.message = message
        self.status_code = status_code
        super().__init__(message)


def register_exception_handlers(app: FastAPI) -> None:
    @app.exception_handler(AppError)
    async def handle_app_error(_request: Request, exc: AppError) -> JSONResponse:
        return JSONResponse(status_code=exc.status_code, content={"detail": exc.message})

    @app.exception_handler(Exception)
    async def handle_unexpected_error(_request: Request, exc: Exception) -> JSONResponse:
        if app.debug:
            return JSONResponse(status_code=500, content={"detail": str(exc)})
        return JSONResponse(status_code=500, content={"detail": "Internal server error"})