"""WeChat mini-program helpers (jscode2session)."""
from __future__ import annotations

import hashlib
import os
from typing import Any

import httpx

WECHAT_APPID = os.getenv("WECHAT_APPID", "").strip()
WECHAT_SECRET = os.getenv("WECHAT_SECRET", "").strip()
WECHAT_ALLOW_DEVTOOLS = os.getenv("WECHAT_ALLOW_DEVTOOLS", "true").lower() in {
  "1", "true", "yes", "on",
}


async def code2session(js_code: str) -> dict[str, Any]:
  code = (js_code or "").strip()
  if not code:
    raise RuntimeError("缺少微信登录 code")

  # Local / 开发者工具联调：无密钥或 mock code 时降级
  mock = code in {"dev", "the code is a mock one"} or code.startswith("mock")
  if mock or (not WECHAT_APPID or not WECHAT_SECRET):
    if WECHAT_ALLOW_DEVTOOLS or mock:
      digest = hashlib.sha256(code.encode("utf-8")).hexdigest()[:16]
      return {
        "openid": f"devtools_{digest}",
        "session_key": f"devtools_session_{digest}",
        "unionid": None,
      }
    raise RuntimeError("未配置 WECHAT_APPID / WECHAT_SECRET")

  url = "https://api.weixin.qq.com/sns/jscode2session"
  params = {
    "appid": WECHAT_APPID,
    "secret": WECHAT_SECRET,
    "js_code": code,
    "grant_type": "authorization_code",
  }
  async with httpx.AsyncClient(timeout=15) as client:
    r = await client.get(url, params=params)
    data = r.json()

  err = data.get("errcode")
  if err:
    if WECHAT_ALLOW_DEVTOOLS and int(err) in {40029, 40163, 40252}:
      digest = hashlib.sha256(code.encode("utf-8")).hexdigest()[:16]
      return {
        "openid": f"devtools_{digest}",
        "session_key": f"devtools_session_{digest}",
        "unionid": None,
      }
    raise RuntimeError(f"code2session failed: {data}")
  if not data.get("openid"):
    raise RuntimeError(f"code2session missing openid: {data}")
  return data