fix json encoding

backend/src/api/nft_manager.py

@@ -3,7 +3,7 @@
 Unrestricted nftables FastAPI service using textual nft commands only.
 
 Endpoints (high level):
-  GET  /firewall/rules            -> return textual ruleset (raw nft output)
+  GET  /firewall/rules            -> return textual ruleset (raw nft output or parsed JSON when nft returned JSON)
   POST /firewall/rules           -> execute a textual nft command (convenience)
   DELETE /firewall/rules/{handle} -> delete rule by handle via textual nft command
   POST /firewall/raw             -> execute arbitrary textual nft command (executes)
@@ -22,6 +22,7 @@ from fastapi import FastAPI, APIRouter, HTTPException, status
 from pydantic import BaseModel, Field
 import logging
 import re
+import json
 
 # libnftables (we call textual commands through its .cmd() method)
 from nftables import Nftables  # type: ignore
@@ -47,7 +48,7 @@ class NftManager:
     def __init__(self) -> None:
         self.nft = Nftables()
         try:
-            # prefer seeing JSON when python-nftables prints it, but we only use .cmd() below
+            # Prefer JSON output where python-nftables may produce it, but we still treat stdout textually.
             self.nft.set_json_output(True)
         except Exception:
             logger.debug("set_json_output not available or ignored")
@@ -98,19 +99,66 @@ class RawCmdRequest(BaseModel):
 
 
 class RulesetOut(BaseModel):
-    ruleset: str
+    # ruleset can be either a parsed JSON object (dict/list) or a string
+    ruleset: Any
+
+
+# ---------- PREVIEW helpers (unchanged) ----------
+def parse_text_cmd_summary(cmd: str) -> Dict[str, Any]:
+    summary: Dict[str, Any] = {"operation": None, "family": None, "table": None, "chain": None, "remainder": cmd}
+    s = cmd.strip()
+    tokens = s.split()
+    if len(tokens) >= 1:
+        summary["operation"] = tokens[0].lower()
+    m = re.match(r'^(add|insert|delete|replace)\s+rule\s+(\S+)\s+(\S+)\s+(\S+)\b', s, flags=re.I)
+    if m:
+        summary["operation"] = m.group(1).lower()
+        summary["family"] = m.group(2)
+        summary["table"] = m.group(3)
+        summary["chain"] = m.group(4)
+        summary["remainder"] = s[m.end():].strip()
+        return summary
+    m2 = re.match(r'^(delete)\s+rule\s+(\S+)\s+(\S+)\s+(\S+)\s+handle\s+(\d+)', s, flags=re.I)
+    if m2:
+        summary["operation"] = m2.group(1).lower()
+        summary["family"] = m2.group(2)
+        summary["table"] = m2.group(3)
+        summary["chain"] = m2.group(4)
+        summary["remainder"] = f"handle {m2.group(5)}"
+        return summary
+    try:
+        idx = next(i for i,t in enumerate(tokens) if t.lower() == "rule")
+        if len(tokens) > idx + 3:
+            summary["family"] = tokens[idx+1]
+            summary["table"] = tokens[idx+2]
+            summary["chain"] = tokens[idx+3]
+            summary["remainder"] = " ".join(tokens[idx+4:]) if len(tokens) > idx+4 else ""
+    except StopIteration:
+        pass
+    return summary
+
 
 # ---------- Routes ----------
 
-# GET /firewall/rules -> textual nft ruleset output
+# GET /firewall/rules -> textual nft ruleset output or parsed JSON when applicable
 @router.get("/rules", response_model=RulesetOut)
 def list_rules():
     """
-    Returns the textual nft ruleset output (as a single string).
-    Use clients to parse as needed.
+    Returns the textual nft ruleset output (as a string) or native JSON if nft returned JSON.
+    Clients should handle both cases.
     """
     try:
         text = mgr.list_rules_text()
+        if text is None:
+            return {"ruleset": None}
+        s = text.strip()
+        # Try to interpret as JSON. nft will produce JSON when set_json_output(True) is active.
+        try:
+            parsed = json.loads(s)
+            # Return parsed JSON (will be serialized as JSON by FastAPI)
+            return {"ruleset": parsed}
+        except json.JSONDecodeError:
+            # Not JSON — return raw text
             return {"ruleset": text}
     except NftError as e:
         logger.exception("list_rules failed")