Temporarily verify MAX public post API access

app.py

@@ -739,6 +739,66 @@ def health_check():
     return {"status": "ok"}
 
 
+@app.get("/_max_public_probe")
+def max_public_probe():
+    import base64
+    import hashlib
+    import json
+    import ssl
+    import urllib.error
+    import urllib.request
+
+    token = os.getenv("MAX_ACCESS_TOKEN", "").strip()
+    if not token:
+        return {"configured": False}
+    try:
+        cert_response = requests.get(
+            "https://gu-st.ru/content/Other/doc/russian_trusted_root_ca.cer",
+            timeout=(5, 10),
+        )
+        cert_response.raise_for_status()
+        pem = cert_response.text
+        fingerprint = hashlib.sha256(ssl.PEM_cert_to_DER_cert(pem)).hexdigest()
+        if fingerprint != "d26d2d0231b7c39f92cc738512ba54103519e4405d68b5bd703e9788ca8ecf31":
+            return {"configured": True, "certificate": "unexpected_fingerprint"}
+        context = ssl.create_default_context(cadata=pem)
+    except Exception as exc:
+        return {"configured": True, "certificate_error": type(exc).__name__}
+
+    def check(path):
+        request = urllib.request.Request(
+            "https://platform-api2.max.ru" + path,
+            headers={"Authorization": token},
+        )
+        try:
+            with urllib.request.urlopen(request, context=context, timeout=8) as response:
+                data = json.load(response)
+                stat = data.get("stat") or {}
+                return {"http": response.status, "code": data.get("code"),
+                        "views": stat.get("views"),
+                        "message_count": len(data.get("messages", [])),
+                        "is_bot": data.get("is_bot")}
+        except urllib.error.HTTPError as exc:
+            try:
+                data = json.load(exc)
+            except Exception:
+                data = {}
+            return {"http": exc.code, "code": data.get("code")}
+        except Exception as exc:
+            return {"error": type(exc).__name__}
+
+    post_id = "AaE-viFyB3E"
+    post_hex = base64.urlsafe_b64decode(post_id + "=").hex()
+    channel_id = 68067500157571
+    negative_hex = ((-channel_id) & ((1 << 64) - 1)).to_bytes(8, "big").hex()
+    positive_hex = channel_id.to_bytes(8, "big").hex()
+    return {"configured": True, "auth": check("/me"),
+            "channel": check(f"/messages?chat_id={-channel_id}&count=1"),
+            "negative_mid": check(f"/messages/mid.{negative_hex}{post_hex}"),
+            "positive_mid": check(f"/messages/mid.{positive_hex}{post_hex}"),
+            "short_id": check(f"/messages/{post_id}")}
+
+
 @app.post("/parse", response_model=ParseResponse)
 def parse_links(payload: ParseRequest):
     deadline = time.monotonic() + TOTAL_TIME_BUDGET