# Copyright (c) 2026 LightSeek Foundation
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from __future__ import annotations

from dataclasses import dataclass
from typing import Callable

__all__ = [
    "Tolerance",
    "ToleranceFn",
    "ToleranceOverride",
    "ToleranceOverrides",
    "get_family_tolerance",
    "list_family_tolerances",
    "set_family_tolerance",
]


@dataclass(frozen=True)
class Tolerance:
    atol: float
    rtol: float


ToleranceFn = Callable[..., Tolerance]
ToleranceOverride = Tolerance | ToleranceFn
ToleranceOverrides = dict[str, ToleranceOverride]


_FAMILY_TOLERANCES: dict[str, ToleranceFn] = {}


def set_family_tolerance(family: str, tolerance_fn: ToleranceFn) -> None:
    _FAMILY_TOLERANCES[family] = tolerance_fn


def get_family_tolerance(family: str) -> ToleranceFn:
    tolerance_fn = _FAMILY_TOLERANCES.get(family)
    if tolerance_fn is None:
        known = ", ".join(sorted(_FAMILY_TOLERANCES)) or "none"
        raise KeyError(
            f"No tolerance function registered for family={family!r}. Known: {known}"
        )
    return tolerance_fn


def list_family_tolerances() -> dict[str, ToleranceFn]:
    return dict(_FAMILY_TOLERANCES)