"""日历日分组键；可选周末跳过开仓（上海时区）。"""

from __future__ import annotations

from datetime import datetime
from zoneinfo import ZoneInfo

_SH = ZoneInfo("Asia/Shanghai")


def now_sh(now: datetime | None = None) -> datetime:
    return (now or datetime.now(tz=_SH)).astimezone(_SH)


def window_key(now: datetime | None = None) -> str:
    """组号日期键：日历日 YYYYMMDD。"""
    return now_sh(now).strftime("%Y%m%d")


def is_weekend(now: datetime | None = None) -> bool:
    """上海时区：周六=5、周日=6。"""
    return now_sh(now).weekday() >= 5


def can_open_new(
    now: datetime | None = None,
    *,
    skip_weekends: bool = True,
    open_hhmm: str = "16:00",
    stop_hhmm: str = "08:00",
) -> bool:
    """是否允许新开仓。开仓窗已取消；可选跳过周六日。持仓平仓不受此限制。"""
    _ = open_hhmm, stop_hhmm
    if skip_weekends and is_weekend(now):
        return False
    return True


def group_date_ymd(now: datetime | None = None) -> str:
    return window_key(now)