"""AWS 区域验证"""
from __future__ import annotations

import re


_AWS_REGION_RE = re.compile(r"^[a-z]{2}(-gov)?-[a-z]+-\d+$")
_AWS_AZ_RE = re.compile(r"^([a-z]{2}(-gov)?-[a-z]+-\d+)[a-z]$")


def normalize_aws_region(value: str | None) -> str:
    raw = (value or "").strip().lower()
    if not raw:
        return ""
    m = _AWS_AZ_RE.match(raw)
    if m:
        return m.group(1)
    return raw


def is_valid_aws_region(value: str | None) -> bool:
    if not value:
        return False
    return bool(_AWS_REGION_RE.match(value.strip().lower()))