Add FastAPI wechat app: config, wechat handler, run scripts, requirements, env template

wechat.py

@@ -0,0 +1,111 @@
+"""
+微信公众号 FastAPI 应用
+
+GET  /wechat  - 微信服务器验证（签名校验 + 返回 echostr）
+POST /wechat  - 接收微信推送的消息和事件
+"""
+
+import hashlib
+import time
+import xml.etree.ElementTree as ET
+
+from fastapi import FastAPI, Request, Query, HTTPException
+from fastapi.responses import PlainTextResponse
+
+from config import WECHAT_TOKEN
+
+app = FastAPI(title="WeChat API", version="0.1.0")
+
+
+def verify_signature(signature: str, timestamp: str, nonce: str) -> bool:
+    """
+    微信签名验证:
+    1. 将 token、timestamp、nonce 三个参数字典序排序
+    2. 拼成一个字符串
+    3. sha1 加密
+    4. 和 signature 对比
+    """
+    if not WECHAT_TOKEN:
+        return False
+    items = sorted([WECHAT_TOKEN, timestamp, nonce])
+    sha1 = hashlib.sha1("".join(items).encode()).hexdigest()
+    return sha1 == signature
+
+
+@app.get("/wechat")
+async def wechat_verify(
+    signature: str = Query(...),
+    timestamp: str = Query(...),
+    nonce: str = Query(...),
+    echostr: str = Query(...),
+):
+    """GET: 微信服务器验证回调地址有效性"""
+    if not verify_signature(signature, timestamp, nonce):
+        raise HTTPException(status_code=403, detail="Invalid signature")
+    # 验证通过，原样返回 echostr
+    return PlainTextResponse(content=echostr)
+
+
+@app.post("/wechat")
+async def wechat_message(
+    request: Request,
+    signature: str = Query(...),
+    timestamp: str = Query(...),
+    nonce: str = Query(...),
+    openid: str = Query(...),
+):
+    """POST: 接收微信推送的消息和事件"""
+    # 验证签名
+    if not verify_signature(signature, timestamp, nonce):
+        raise HTTPException(status_code=403, detail="Invalid signature")
+
+    # 解析 XML 消息体
+    body = await request.body()
+    root = ET.fromstring(body)
+
+    msg_type = root.findtext("MsgType", "")
+    from_user = root.findtext("FromUserName", "")   # 发送方（用户 openid）
+    to_user = root.findtext("ToUserName", "")       # 接收方（公众号）
+    content = root.findtext("Content", "")
+    event = root.findtext("Event", "")
+    event_key = root.findtext("EventKey", "")
+
+    print(f"[WeChat] type={msg_type} from={from_user} event={event} content={content} key={event_key}")
+
+    # 处理事件推送
+    if msg_type == "event":
+        if event == "subscribe":
+            # 用户关注
+            return _reply_text(from_user, to_user, "欢迎关注！")
+        elif event == "unsubscribe":
+            # 用户取关
+            print(f"[WeChat] 用户取关: {from_user}")
+            return PlainTextResponse(content="success")
+        elif event == "SCAN":
+            # 已关注用户扫码
+            return _reply_text(from_user, to_user, f"扫码成功，场景值: {event_key}")
+        elif event == "CLICK":
+            # 菜单点击
+            return _reply_text(from_user, to_user, f"点击了: {event_key}")
+
+    # 处理文本消息
+    if msg_type == "text":
+        # 原样返回（echo 模式，方便测试）
+        return _reply_text(from_user, to_user, f"你说: {content}")
+
+    # 其他类型暂不处理
+    return _reply_text(from_user, to_user, "收到")
+
+
+def _reply_text(from_user: str, to_user: str, content: str) -> PlainTextResponse:
+    """构造文本回复 XML"""
+    xml = (
+        "<xml>"
+        f"<ToUserName><![CDATA[{from_user}]]></ToUserName>"
+        f"<FromUserName><![CDATA[{to_user}]]></FromUserName>"
+        f"<CreateTime>{int(time.time())}</CreateTime>"
+        "<MsgType><![CDATA[text]]></MsgType>"
+        f"<Content><![CDATA[{content}]]></Content>"
+        "</xml>"
+    )
+    return PlainTextResponse(content=xml, media_type="application/xml")