"""北京时间（Asia/Shanghai）格式化，用于推送与展示。"""

from __future__ import annotations

from datetime import datetime, timezone
from zoneinfo import ZoneInfo

_TZ_CN = ZoneInfo("Asia/Shanghai")


def utc_now() -> datetime:
    return datetime.now(timezone.utc)


def format_beijing_wall(dt: datetime | None = None) -> str:
    """与微信示例一致：YYYY-MM-DD HH:MM（北京时间，无时区后缀）。"""
    if dt is None:
        dt = utc_now()
    elif dt.tzinfo is None:
        dt = dt.replace(tzinfo=timezone.utc)
    return dt.astimezone(_TZ_CN).strftime("%Y-%m-%d %H:%M")