小程序后端接入微信登录与家长头像能力

mini-program/app/service/wechat_login.py

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+import logging
+from dataclasses import dataclass
+
+import httpx
+
+try:
+    from app.settings import settings
+except ModuleNotFoundError:
+    from settings import settings
+
+
+logger = logging.getLogger("app.wechat_login")
+
+INVALID_CODE_ERRCODES = {40029, 40163}
+MISCONFIGURED_APP_ERRCODES = {40013, 40125}
+
+
+@dataclass(frozen=True)
+class WechatCodeSession:
+    openid: str
+    session_key: str
+    unionid: str | None = None
+
+
+class WechatAuthError(Exception):
+    def __init__(self, detail: str, *, status_code: int, errcode: int | None = None):
+        super().__init__(detail)
+        self.status_code = status_code
+        self.errcode = errcode
+
+
+class WechatAuthService:
+    def __init__(self, client: httpx.Client | None = None):
+        self._client = client
+
+    def exchange_code(self, code: str) -> WechatCodeSession:
+        if not settings.wechat_app_id or not settings.wechat_app_secret:
+            raise WechatAuthError("wechat login is not configured", status_code=503)
+
+        response = self._request_code2session(code)
+        data = self._parse_response_json(response)
+
+        errcode = self._parse_errcode(data.get("errcode"))
+        if errcode not in (None, 0):
+            errmsg = data.get("errmsg")
+            logger.warning(
+                "wechat code2session rejected login code",
+                extra={
+                    "event": "wechat_code2session_rejected",
+                    "errcode": errcode,
+                    "errmsg": errmsg,
+                },
+            )
+            raise self._map_exchange_error(errcode)
+
+        openid = data.get("openid")
+        session_key = data.get("session_key")
+        unionid = data.get("unionid")
+
+        if not isinstance(openid, str) or not openid:
+            raise WechatAuthError("wechat login response missing openid", status_code=502)
+        if not isinstance(session_key, str) or not session_key:
+            raise WechatAuthError("wechat login response missing session_key", status_code=502)
+        if not isinstance(unionid, str) or not unionid:
+            unionid = None
+
+        return WechatCodeSession(openid=openid, session_key=session_key, unionid=unionid)
+
+    def _request_code2session(self, code: str) -> httpx.Response:
+        params = {
+            "appid": settings.wechat_app_id,
+            "secret": settings.wechat_app_secret,
+            "js_code": code,
+            "grant_type": "authorization_code",
+        }
+
+        client = self._client
+        owns_client = client is None
+        if client is None:
+            client = httpx.Client(
+                base_url=settings.wechat_api_base_url.rstrip("/"),
+                timeout=settings.wechat_http_timeout_seconds,
+            )
+
+        try:
+            response = client.get("/sns/jscode2session", params=params)
+            response.raise_for_status()
+            return response
+        except httpx.HTTPError as exc:
+            logger.warning(
+                "wechat code2session request failed",
+                extra={"event": "wechat_code2session_request_failed"},
+            )
+            raise WechatAuthError("wechat login service unavailable", status_code=502) from exc
+        finally:
+            if owns_client:
+                client.close()
+
+    def _parse_response_json(self, response: httpx.Response) -> dict:
+        try:
+            data = response.json()
+        except ValueError as exc:
+            raise WechatAuthError("invalid response from wechat login service", status_code=502) from exc
+        if not isinstance(data, dict):
+            raise WechatAuthError("invalid response from wechat login service", status_code=502)
+        return data
+
+    def _parse_errcode(self, value: object) -> int | None:
+        if value is None:
+            return None
+        try:
+            return int(value)
+        except (TypeError, ValueError):
+            return None
+
+    def _map_exchange_error(self, errcode: int) -> WechatAuthError:
+        if errcode in INVALID_CODE_ERRCODES:
+            return WechatAuthError("invalid or expired wechat login code", status_code=401, errcode=errcode)
+        if errcode in MISCONFIGURED_APP_ERRCODES:
+            return WechatAuthError("wechat login is not configured correctly", status_code=503, errcode=errcode)
+        return WechatAuthError("wechat login service unavailable", status_code=502, errcode=errcode)
+
+
+def get_wechat_auth_service() -> WechatAuthService:
+    return WechatAuthService()