"""微信服务号消息接收回调 /wx/mp/callback(裸路径, 非 /api/v1)。

对应公众平台"设置与开发 → 基本配置 → 服务器配置"里填的 URL。
  GET  : URL 接入验证 → 校验 signature → 原样返回 echostr(明文)
  POST : 收用户消息(安全模式密文) → msg_signature 验签 → AES 解密 → 解析 XML
         图片消息(MsgType=image): 打日志(openid/PicUrl/MediaId) + 用 PicUrl 下载落盘
         其余消息/事件: 记一条日志忽略。一律返回 "success"(微信据此不再重试)。

MVP 只做"收到图片并落盘"证明链路通;后续接:识别平台+订单 → 打 pending_compare 标记
→ 心跳带回前端弹窗,以及 openid↔device 绑定。任何异常都返回 "success"、不让微信重试轰炸。
"""
from __future__ import annotations

import logging
import xml.etree.ElementTree as ET
from pathlib import Path

import httpx
from fastapi import APIRouter, Request
from fastapi.responses import PlainTextResponse

from app.core import wx_poc_signal
from app.core.config import settings
from app.integrations import wx_mp_crypto

logger = logging.getLogger("shagua.wx_mp")

router = APIRouter(prefix="/wx/mp", tags=["wx-mp"])

# 收到的截图暂存目录(MVP 验证用;接上识别后可改为不落盘或定期清理)
_INBOX = Path(settings.MEDIA_ROOT) / "wx_inbox"


@router.get("/callback", include_in_schema=False)
async def verify(
    signature: str = "", timestamp: str = "", nonce: str = "", echostr: str = ""
) -> PlainTextResponse:
    """微信 URL 接入验证:校验 signature 通过则原样返回 echostr。"""
    if not settings.WX_MP_TOKEN:
        logger.warning("wx_mp verify: WX_MP_TOKEN 未配置")
        return PlainTextResponse("", status_code=503)
    if wx_mp_crypto.verify_url_signature(
        settings.WX_MP_TOKEN, timestamp, nonce, signature
    ):
        return PlainTextResponse(echostr)
    logger.warning("wx_mp verify: signature 校验失败 ts=%s nonce=%s", timestamp, nonce)
    return PlainTextResponse("invalid signature", status_code=403)


@router.post("/callback", include_in_schema=False)
async def receive(request: Request) -> PlainTextResponse:
    """收用户消息(安全模式)。任何异常都吞掉返回 success,不让微信重试轰炸,靠日志排查。"""
    if not settings.wx_mp_callback_configured:
        logger.warning("wx_mp receive: 回调凭证未配齐(Token/AESKey/AppID)")
        return PlainTextResponse("success")
    try:
        body = (await request.body()).decode("utf-8")
        qp = request.query_params
        # 安全模式外层 XML 只有 ToUserName + Encrypt。来源=微信服务器(HTTPS)+ 下面验签,
        # 且 stdlib ET 不扩展外部实体, XXE 不适用。
        encrypt = ET.fromstring(body).findtext("Encrypt") or ""
        if not wx_mp_crypto.verify_msg_signature(
            settings.WX_MP_TOKEN,
            qp.get("timestamp", ""),
            qp.get("nonce", ""),
            encrypt,
            qp.get("msg_signature", ""),
        ):
            logger.warning("wx_mp receive: msg_signature 校验失败")
            return PlainTextResponse("success")
        xml = wx_mp_crypto.decrypt_message(
            settings.WX_MP_AES_KEY, settings.WX_MP_APPID, encrypt
        )
        await _handle_message(ET.fromstring(xml))
    except Exception:
        logger.exception("wx_mp receive: 处理异常")
    return PlainTextResponse("success")


async def _handle_message(root: ET.Element) -> None:
    openid = root.findtext("FromUserName") or ""
    msg_type = root.findtext("MsgType") or ""
    if msg_type == "image":
        pic_url = root.findtext("PicUrl") or ""
        media_id = root.findtext("MediaId") or ""
        logger.info(
            "wx_mp 收到图片: openid=%s media_id=%s pic_url=%s", openid, media_id, pic_url
        )
        # PoC: 写死"该测试设备要从美团比价", 下次心跳带回前端弹选平台窗
        poc_dev = settings.WX_POC_TEST_DEVICE_ID
        if poc_dev:
            wx_poc_signal.set_pending(poc_dev, "meituan")
            logger.info("wx_mp PoC: 已给测试设备 %s 打比价信号 source=meituan", poc_dev)
        await _download(pic_url, openid, media_id)
    else:
        logger.info("wx_mp 收到消息(暂忽略): openid=%s type=%s", openid, msg_type)


async def _download(pic_url: str, openid: str, media_id: str) -> None:
    """用 PicUrl 直接下载图片落盘。PicUrl 是临时公网链接,无需 access_token / IP 白名单。"""
    if not pic_url:
        return
    try:
        _INBOX.mkdir(parents=True, exist_ok=True)
        async with httpx.AsyncClient(timeout=15) as client:
            resp = await client.get(pic_url)
            resp.raise_for_status()
        dest = _INBOX / f"{openid[:12]}_{media_id[:16]}.jpg"
        dest.write_bytes(resp.content)
        logger.info("wx_mp 图片已落盘: %s (%d bytes)", dest, len(resp.content))
    except Exception:
        logger.exception("wx_mp 图片下载失败 pic_url=%s", pic_url)