feat: Add local system override and manual entry controls with offline systems caching

drb-edge-node/app/internal/system_cacher.py

@@ -0,0 +1,50 @@
+import json
+from pathlib import Path
+from typing import List, Dict, Any, Optional
+import httpx
+from app.config import settings
+from app.internal.logger import logger
+from app.internal import credentials
+
+_CACHE_FILE = Path(settings.config_path) / "systems_cache.json"
+
+async def fetch_and_cache_systems() -> bool:
+    """Fetch all systems from the C2 server and cache them locally."""
+    if not settings.c2_url:
+        logger.warning("C2_URL not configured. Skipping system caching.")
+        return False
+
+    url = f"{settings.c2_url}/systems"
+    api_key = credentials.get_api_key()
+    headers = {"Authorization": f"Bearer {api_key}"} if api_key else {}
+
+    try:
+        async with httpx.AsyncClient(timeout=10) as client:
+            r = await client.get(url, headers=headers)
+            r.raise_for_status()
+            systems = r.json()
+            
+            _CACHE_FILE.parent.mkdir(parents=True, exist_ok=True)
+            _CACHE_FILE.write_text(json.dumps(systems, indent=2))
+            logger.info(f"Cached {len(systems)} systems from C2.")
+            return True
+    except Exception as e:
+        logger.warning(f"Failed to fetch systems from C2: {e}. Offline cache will be used.")
+        return False
+
+def load_cached_systems() -> List[Dict[str, Any]]:
+    """Load cached systems from disk."""
+    if _CACHE_FILE.exists():
+        try:
+            return json.loads(_CACHE_FILE.read_text())
+        except Exception as e:
+            logger.error(f"Failed to read systems cache: {e}")
+    return []
+
+def get_cached_system(system_id: str) -> Optional[Dict[str, Any]]:
+    """Retrieve a single system config from the cache."""
+    systems = load_cached_systems()
+    for sys in systems:
+        if sys.get("system_id") == system_id:
+            return sys
+    return None