Merge pull request 'Weather backend: NWS active alerts + nearest-METAR wind, cached (Refs #237)' (#263) from feat/237-weather-api into main

drb-c2-core/app/routers/weather.py

@@ -0,0 +1,51 @@
+"""Weather context for the map (server-26#237): NWS alerts + nearest-METAR wind.
+
+Public-domain US Government data, cached server-side in app/internal/weather.py;
+no licence gate (unlike 511NY / outage providers).
+"""
+from typing import Optional
+
+from fastapi import APIRouter, HTTPException, Query
+
+from app.internal import weather
+
+router = APIRouter(prefix="/weather", tags=["weather"])
+
+
+@router.get("/alerts")
+async def get_alerts(
+    south: Optional[float] = Query(None, ge=-90, le=90),
+    west: Optional[float] = Query(None, ge=-180, le=180),
+    north: Optional[float] = Query(None, ge=-90, le=90),
+    east: Optional[float] = Query(None, ge=-180, le=180),
+):
+    """Active NWS alerts with polygons, optionally filtered to those intersecting a bbox.
+
+    ``zone_only`` holds alerts whose zones could not be resolved to a polygon; it
+    is never bbox-filtered (there is no shape to test) and never dropped.
+    """
+    box = (south, west, north, east)
+    if any(v is not None for v in box) and any(v is None for v in box):
+        raise HTTPException(400, "give all of south, west, north, east or none")
+    if south is not None and (south > north or west > east):
+        raise HTTPException(400, "bbox must satisfy south<=north and west<=east")
+    feed = await weather.alerts.get()
+    items = feed.alerts
+    if south is not None:
+        items = [a for a in items if weather.intersects(a.get("bbox"), south, west, north, east)]
+    return {
+        "alerts": items,
+        "zone_only": feed.zone_only,
+        "fetched_at": feed.fetched_at,
+        "error": feed.error,
+        "credit": weather.CREDIT,
+    }
+
+
+@router.get("/wind")
+async def get_wind(
+    lat: float = Query(..., ge=-90, le=90),
+    lon: float = Query(..., ge=-180, le=180),
+):
+    """Wind from the nearest METAR station, or ``available: false`` with a reason."""
+    return await weather.nearest_wind(lat, lon)