"""法定节假日获取、缓存与工作日判定。

数据来自 xiaoai.me 公共接口，一次性抓取全年并缓存到 .cache/，
后续判定只读本地缓存；缓存缺失或过期时才重新请求。
"""

from __future__ import annotations

import json
import logging
import ssl
import urllib.request
from datetime import date
from pathlib import Path

from daily.config import CACHE_DIR

logger = logging.getLogger(__name__)

_API_URL = "https://publicapi.xiaoai.me/holiday/year?date={year}"
_TIMEOUT = 15


def _cache_file(year: int) -> Path:
    return CACHE_DIR / f"holidays-{year}.json"


def _ssl_context() -> ssl.SSLContext:
    ctx = ssl.create_default_context()
    ctx.check_hostname = False
    ctx.verify_mode = ssl.CERT_NONE
    return ctx


def _fetch_year(year: int) -> dict[str, dict]:
    """请求全年节假日，返回 {date_str: {"rest": bool, "name": str}}。

    rest=1 表示休息（法定节假日/调休放假），rest=0 表示调休补班（需上班）。
    """
    url = _API_URL.format(year=year)
    req = urllib.request.Request(url, headers={"User-Agent": "Mozilla/5.0"})
    with urllib.request.urlopen(req, timeout=_TIMEOUT, context=_ssl_context()) as resp:
        payload = json.loads(resp.read().decode("utf-8"))
    items = payload.get("data") or []
    result: dict[str, dict] = {}
    for item in items:
        day = item.get("date")
        if not day:
            continue
        result[day] = {
            "rest": bool(item.get("rest", 0)),
            "name": item.get("holiday", ""),
        }
    if not result:
        raise RuntimeError(f"节假日接口返回为空 year={year}")
    return result


def load_holidays(year: int, *, refresh: bool = False) -> dict[str, dict]:
    """加载全年节假日缓存；缺失或 refresh 时联网抓取并写入缓存。

    联网失败时若已有缓存则回退用缓存，保证离线可用。
    """
    cache = _cache_file(year)
    if cache.exists() and not refresh:
        try:
            raw = json.loads(cache.read_text(encoding="utf-8"))
            if isinstance(raw, dict) and raw:
                return raw
        except (OSError, ValueError):
            logger.warning("节假日缓存损坏，重新获取 %s", cache)

    try:
        data = _fetch_year(year)
    except Exception as exc:
        if cache.exists():
            logger.warning("节假日获取失败，回退到本地缓存：%s", exc)
            return json.loads(cache.read_text(encoding="utf-8"))
        raise

    cache.parent.mkdir(parents=True, exist_ok=True)
    cache.write_text(json.dumps(data, ensure_ascii=False, indent=2), encoding="utf-8")
    logger.info("已缓存 %d 年节假日 %d 条 -> %s", year, len(data), cache)
    return data


def is_workday(day: date, holidays: dict[str, dict] | None = None) -> bool:
    """判断是否为工作日。

    规则：调休补班日（rest=0 且在表中）→ 上班；
    法定节假日/调休放假（rest=1）→ 休息；
    周六日 → 休息；其余 → 上班。
    """
    holidays = holidays if holidays is not None else load_holidays(day.year)
    key = day.isoformat()
    entry = holidays.get(key)
    if entry is not None:
        return not entry["rest"]
    return day.weekday() < 5  # 周一~周五


def workday_name(day: date, holidays: dict[str, dict] | None = None) -> str | None:
    """返回该天的节假日名（休息或调休补班），无则 None。用于日志。"""
    holidays = holidays if holidays is not None else load_holidays(day.year)
    entry = holidays.get(day.isoformat())
    return entry["name"] if entry else None