# -*- coding: utf-8 -*-
"""上海时区与每日任务时间计算。

B 站数据口径使用 ``Asia/Shanghai``。中国自 1991 年起不再使用夏令时，因此这里
用固定 UTC+8，避免 Windows 上依赖未安装的 ``tzdata`` 包。
"""

from __future__ import annotations

import re
import time
from datetime import datetime, timedelta, timezone

SHANGHAI_TZ = timezone(timedelta(hours=8))
_HHMM_RE = re.compile(r"^([01]\d|2[0-3]):([0-5]\d)$")
_DATE_RE = re.compile(r"^\d{4}-\d{2}-\d{2}$")


def shanghai_datetime(ts: float | None = None) -> datetime:
    return datetime.fromtimestamp(time.time() if ts is None else ts, SHANGHAI_TZ)


def shanghai_date(ts: float | None = None) -> str:
    return shanghai_datetime(ts).strftime("%Y-%m-%d")


def parse_hhmm(value: str) -> tuple[int, int]:
    match = _HHMM_RE.match(value or "")
    if not match:
        raise ValueError(f"时间必须是 HH:MM（24 小时制）: {value!r}")
    return int(match.group(1)), int(match.group(2))


def next_daily_run(now: float, hhmm: str) -> float:
    """返回 ``now`` 之后（严格大于）最近的 ``hh:mm`` 上海时间时间戳。"""
    hour, minute = parse_hhmm(hhmm)
    current = shanghai_datetime(now)
    target = current.replace(hour=hour, minute=minute, second=0, microsecond=0)
    if target.timestamp() <= now:
        target += timedelta(days=1)
    return target.timestamp()


def is_date(value: str) -> bool:
    if not _DATE_RE.match(value or ""):
        return False
    try:
        datetime.strptime(value, "%Y-%m-%d")
    except ValueError:
        return False
    return True


def day_bounds(date: str) -> tuple[float, float]:
    """返回上海时区某一天的 [start, end) 时间戳。"""
    if not is_date(date):
        raise ValueError(f"日期格式必须是 YYYY-MM-DD: {date!r}")
    start = datetime.strptime(date, "%Y-%m-%d").replace(tzinfo=SHANGHAI_TZ)
    return start.timestamp(), (start + timedelta(days=1)).timestamp()


# 全站快照静默窗：上海时区 [23:00, 01:00)。此间 discovery / recent / cleanup 不执行。
SNAPSHOT_QUIET_START_HOUR = 23
SNAPSHOT_QUIET_END_HOUR = 1


def in_snapshot_quiet_window(ts: float | None = None) -> bool:
    """是否处于全站快照静默窗 [23:00, 01:00)（上海时区，跨日）。"""
    dt = shanghai_datetime(ts)
    return dt.hour >= SNAPSHOT_QUIET_START_HOUR or dt.hour < SNAPSHOT_QUIET_END_HOUR


def next_after_snapshot_quiet_window(ts: float) -> float:
    """若 ``ts`` 落在静默窗内，推到窗结束后的 01:00；否则原样返回。"""
    if not in_snapshot_quiet_window(ts):
        return ts
    dt = shanghai_datetime(ts)
    if dt.hour >= SNAPSHOT_QUIET_START_HOUR:
        target = (dt + timedelta(days=1)).replace(
            hour=SNAPSHOT_QUIET_END_HOUR, minute=0, second=0, microsecond=0,
        )
    else:
        target = dt.replace(
            hour=SNAPSHOT_QUIET_END_HOUR, minute=0, second=0, microsecond=0,
        )
    if target.timestamp() <= ts:
        target += timedelta(days=1)
    return target.timestamp()


def interval_next_run(now: float, interval: float) -> float:
    """``now + interval``，若落入静默窗则推到 01:00 之后。"""
    if interval <= 0:
        raise ValueError("interval 必须大于 0")
    return next_after_snapshot_quiet_window(now + interval)