"""
微信公众平台开放接口封装

- get_access_token(): 获取并缓存 access_token（有效期 7200 秒）
- create_temp_qrcode(): 创建带字符串场景值的临时二维码，返回图片 URL

仅服务端调用，appid/secret 来自 .env。
"""

import logging
import time
from urllib.parse import quote

import httpx

from config import WECHAT_APPID, WECHAT_SECRET

logger = logging.getLogger(__name__)

API_BASE = "https://api.weixin.qq.com/cgi-bin"
QRCODE_URL = "https://mp.weixin.qq.com/cgi-bin/showqrcode"

# access_token 内存缓存（单 worker 部署足够；提前 5 分钟过期避免边界失效）
_token_cache = {"value": "", "expires_at": 0.0}


async def get_access_token() -> str:
    """获取 access_token，命中缓存则直接返回"""
    now = time.time()
    if _token_cache["value"] and now < _token_cache["expires_at"]:
        return _token_cache["value"]

    if not WECHAT_APPID or not WECHAT_SECRET:
        raise RuntimeError("WECHAT_APPID / WECHAT_SECRET 未配置")

    params = {
        "grant_type": "client_credential",
        "appid": WECHAT_APPID,
        "secret": WECHAT_SECRET,
    }
    async with httpx.AsyncClient(timeout=10) as client:
        resp = await client.get(f"{API_BASE}/token", params=params)
        data = resp.json()

    if "access_token" not in data:
        raise RuntimeError(f"获取 access_token 失败: {data}")

    _token_cache["value"] = data["access_token"]
    _token_cache["expires_at"] = now + int(data.get("expires_in", 7200)) - 300
    return _token_cache["value"]


async def create_temp_qrcode(scene_str: str, expire_seconds: int) -> str:
    """创建临时二维码（字符串场景值），返回扫码图片 URL"""
    token = await get_access_token()
    payload = {
        "expire_seconds": expire_seconds,
        "action_name": "QR_STR_SCENE",
        "action_info": {"scene": {"scene_str": scene_str}},
    }
    async with httpx.AsyncClient(timeout=10) as client:
        resp = await client.post(
            f"{API_BASE}/qrcode/create",
            params={"access_token": token},
            json=payload,
        )
        data = resp.json()

    ticket = data.get("ticket")
    if not ticket:
        # 40001 等 token 失效错误：清空缓存，下次重新获取
        if data.get("errcode") in (40001, 42001):
            _token_cache["value"] = ""
        raise RuntimeError(f"创建二维码失败: {data}")

    logger.info("已创建临时二维码 scene_str=%s", scene_str)
    return f"{QRCODE_URL}?ticket={quote(ticket)}"