initial commit

api/app/services/warncells.py

@@ -0,0 +1,93 @@
+from __future__ import annotations
+
+import asyncio
+import logging
+from typing import Any
+
+import httpx
+
+from app.cache import cache_get, cache_set
+from app.config import CACHE_TTL_GEOCODE, DWD_WMS_URL
+from app.http_client import get_client
+
+logger = logging.getLogger(__name__)
+
+WFS_URL = f"{DWD_WMS_URL.rsplit('/wms', 1)[0]}/ows"
+# Landkreise reicht fuer warnapp_landkreise/json/warnings.json
+WFS_LAYERS = ("dwd:Warngebiete_Kreise",)
+
+
+async def _wfs_intersects(layer: str, lat: float, lon: float) -> list[dict[str, Any]]:
+    params = {
+        "service": "WFS",
+        "version": "2.0.0",
+        "request": "GetFeature",
+        "typeName": layer,
+        "outputFormat": "application/json",
+        "count": 5,
+        "CQL_FILTER": f"INTERSECTS(SHAPE,POINT({lat} {lon}))",
+    }
+    client = get_client()
+    response = await client.get(WFS_URL, params=params, timeout=8.0)
+    response.raise_for_status()
+    payload = response.json()
+    results = []
+    for feature in payload.get("features", []):
+        props = feature.get("properties") or {}
+        cell_id = props.get("WARNCELLID")
+        if cell_id is None:
+            continue
+        results.append(
+            {
+                "warncell_id": str(cell_id),
+                "name": props.get("NAME"),
+                "short_name": props.get("KURZNAME"),
+                "layer": layer.split(":")[-1],
+                "state": props.get("BL"),
+            }
+        )
+    return results
+
+
+def _related_cell_ids(cell_id: str) -> set[str]:
+    ids = {cell_id}
+    if len(cell_id) >= 9:
+        core = cell_id[1:]
+        ids.add(f"1{core}")
+        ids.add(f"9{core}")
+        if cell_id.startswith("9"):
+            ids.add(f"1{cell_id[1:]}")
+        elif cell_id.startswith("1"):
+            ids.add(f"9{cell_id[1:]}")
+    return ids
+
+
+async def resolve_warncells(lat: float, lon: float) -> dict[str, Any]:
+    cache_key = f"warncell:{lat:.4f}:{lon:.4f}"
+    cached = await cache_get(cache_key)
+    if cached:
+        return cached
+
+    layer_results = await asyncio.gather(
+        *[_wfs_intersects(layer, lat, lon) for layer in WFS_LAYERS],
+        return_exceptions=True,
+    )
+    areas: list[dict[str, Any]] = []
+    for layer, result in zip(WFS_LAYERS, layer_results):
+        if isinstance(result, Exception):
+            logger.warning("WFS warncell lookup failed for %s: %s", layer, result)
+            continue
+        areas.extend(result)
+
+    cell_ids: set[str] = set()
+    for area in areas:
+        cell_ids.update(_related_cell_ids(area["warncell_id"]))
+
+    payload = {
+        "lat": lat,
+        "lon": lon,
+        "areas": areas,
+        "cell_ids": sorted(cell_ids),
+    }
+    await cache_set(cache_key, payload, CACHE_TTL_GEOCODE)
+    return payload