#!/usr/bin/env python3
"""Check whether a date is a China statutory holiday using LLM with fallback."""

from __future__ import annotations

import argparse
import datetime as dt
import json
import os
import time
from typing import Any, Dict, Optional

import requests


def env(name: str, default: str = "") -> str:
    value = os.getenv(name, "").strip()
    return value if value else default


def parse_date(raw: str) -> dt.date:
    return dt.datetime.strptime(raw, "%Y-%m-%d").date()


def fallback(date_obj: dt.date, reason: str) -> Dict[str, Any]:
    is_weekend = date_obj.weekday() >= 5
    return {
        "is_holiday": is_weekend,
        "reason": reason if reason else ("周末自动判定为假期" if is_weekend else "工作日默认学习日"),
        "model_name": "fallback-rules",
    }


def call_llm(date_obj: dt.date) -> Dict[str, Any]:
    api_url = env("OI_LLM_API_URL") or env("CSP_LLM_API_URL")
    api_key = env("OI_LLM_API_KEY") or env("CSP_LLM_API_KEY")
    model = env("OI_LLM_MODEL", "qwen3-max")
    if not api_url:
        raise RuntimeError("missing OI_LLM_API_URL")

    weekday_labels = ["周一", "周二", "周三", "周四", "周五", "周六", "周日"]
    weekday_label = weekday_labels[date_obj.weekday()]

    system = (
        "你是中国节假日判定助手。给定日期后，只判断这一天是否属于中国法定节假日放假日。"
        "不需要解释历法推导，不需要输出多余文本。"
        "输出必须为纯 JSON，格式："
        '{"is_holiday":true/false,"reason":"简短中文原因","model_name":"模型名"}'
    )
    user = {
        "date": date_obj.isoformat(),
        "weekday": weekday_label,
        "task": "判断该日期是否是中国法定节假日放假日。仅判断当天，不跨天推断。",
    }

    headers = {"Content-Type": "application/json"}
    if api_key:
        headers["Authorization"] = f"Bearer {api_key}"

    body = {
        "model": model,
        "stream": False,
        "temperature": 0.0,
        "messages": [
            {"role": "system", "content": system},
            {"role": "user", "content": json.dumps(user, ensure_ascii=False)},
        ],
    }

    last_err: Optional[Exception] = None
    for attempt in range(3):
        try:
            resp = requests.post(api_url, headers=headers, json=body, timeout=25)
            if resp.status_code < 500:
                resp.raise_for_status()
            else:
                raise RuntimeError(f"HTTP {resp.status_code}")

            data = resp.json()
            content = data["choices"][0]["message"]["content"]
            txt = content.strip()
            if txt.startswith("```"):
                txt = txt.split("\n", 1)[-1]
                if txt.endswith("```"):
                    txt = txt[:-3]
                txt = txt.strip()
            parsed = json.loads(txt)
            if not isinstance(parsed, dict):
                raise RuntimeError("llm output is not object")
            return {
                "is_holiday": bool(parsed.get("is_holiday", False)),
                "reason": str(parsed.get("reason", "")).strip() or "LLM判定",
                "model_name": str(parsed.get("model_name", model)).strip() or model,
            }
        except Exception as exc:  # noqa: BLE001
            last_err = exc
            time.sleep(0.6 * (attempt + 1))

    raise RuntimeError(str(last_err) if last_err else "llm failed")


def main() -> int:
    ap = argparse.ArgumentParser()
    ap.add_argument("--date", required=True, help="Date in YYYY-MM-DD")
    args = ap.parse_args()

    try:
        date_obj = parse_date(args.date)
    except Exception:
        print(
            json.dumps(
                {"is_holiday": False, "reason": "invalid date format", "model_name": "fallback-rules"},
                ensure_ascii=False,
            )
        )
        return 0

    # Weekend is always holiday by rule.
    if date_obj.weekday() >= 5:
        print(
            json.dumps(
                {"is_holiday": True, "reason": "周末自动判定为假期", "model_name": "calendar-weekend"},
                ensure_ascii=False,
            )
        )
        return 0

    try:
        out = call_llm(date_obj)
    except Exception as exc:  # noqa: BLE001
        out = fallback(date_obj, f"工作日默认学习日（LLM失败: {exc}）")

    print(json.dumps(out, ensure_ascii=False))
    return 0


if __name__ == "__main__":
    raise SystemExit(main())