HexaWetter v1.3.0: Add precipitation map feature, update README, and enhance UI elements

api/app/services/precipitation_map.py

@@ -0,0 +1,102 @@
+from __future__ import annotations
+
+from typing import Any
+
+from app.cache import cache_get, cache_set
+from app.config import CACHE_TTL_PRECIP_MAP, OPEN_METEO_BASE_URL
+from app.http_client import fetch_json
+
+BATCH_SIZE = 80
+DEFAULT_SPAN_DEG = 3.0
+DEFAULT_STEP_DEG = 0.25
+
+
+def _coord_key(lat: float, lon: float) -> tuple[float, float]:
+    return round(lat, 2), round(lon, 2)
+
+
+def _build_grid(center_lat: float, center_lon: float, span_deg: float, step_deg: float) -> list[tuple[float, float]]:
+    half = span_deg / 2
+    points: list[tuple[float, float]] = []
+    lat = center_lat - half
+    while lat <= center_lat + half + 1e-9:
+        lon = center_lon - half
+        while lon <= center_lon + half + 1e-9:
+            points.append((round(lat, 2), round(lon, 2)))
+            lon += step_deg
+        lat += step_deg
+    return points
+
+
+async def _fetch_batch(lats: list[float], lons: list[float], hours: int) -> list[dict[str, Any]]:
+    data = await fetch_json(
+        f"{OPEN_METEO_BASE_URL}/forecast",
+        params={
+            "latitude": ",".join(str(v) for v in lats),
+            "longitude": ",".join(str(v) for v in lons),
+            "hourly": "precipitation,precipitation_probability",
+            "forecast_hours": hours,
+            "timezone": "Europe/Berlin",
+        },
+        timeout=30.0,
+    )
+    if isinstance(data, list):
+        return data
+    return [data]
+
+
+async def get_precipitation_map(
+    lat: float,
+    lon: float,
+    hours: int = 24,
+    span_deg: float = DEFAULT_SPAN_DEG,
+    step_deg: float = DEFAULT_STEP_DEG,
+) -> dict[str, Any]:
+    hours = max(6, min(hours, 24))
+    span_deg = max(1.5, min(span_deg, 6.0))
+    step_deg = max(0.15, min(step_deg, 0.5))
+
+    lat_k, lon_k = _coord_key(lat, lon)
+    cache_key = f"precip_map:{lat_k}:{lon_k}:{hours}:{span_deg}:{step_deg}"
+    cached = await cache_get(cache_key)
+    if cached:
+        return {**cached, "cached": True}
+
+    grid = _build_grid(lat, lon, span_deg, step_deg)
+    cells: list[dict[str, Any]] = []
+    times: list[str] | None = None
+
+    for offset in range(0, len(grid), BATCH_SIZE):
+        batch = grid[offset : offset + BATCH_SIZE]
+        lats = [point[0] for point in batch]
+        lons = [point[1] for point in batch]
+        results = await _fetch_batch(lats, lons, hours)
+        for (point_lat, point_lon), item in zip(batch, results, strict=False):
+            hourly = item.get("hourly") or {}
+            cell_times = hourly.get("time") or []
+            if times is None:
+                times = cell_times
+            cells.append(
+                {
+                    "lat": point_lat,
+                    "lon": point_lon,
+                    "precipitation": hourly.get("precipitation") or [0.0] * len(cell_times),
+                    "probability": hourly.get("precipitation_probability") or [0] * len(cell_times),
+                }
+            )
+
+    payload = {
+        "source": OPEN_METEO_BASE_URL,
+        "model": "Open-Meteo ICON/DWD",
+        "center": {"lat": lat, "lon": lon},
+        "span_deg": span_deg,
+        "step_deg": step_deg,
+        "hours": hours,
+        "times": times or [],
+        "cells": cells,
+        "cell_count": len(cells),
+        "note": "Modellvorhersage, keine Radarmessung. Auflösung grob (~25 km).",
+        "cached": False,
+    }
+    await cache_set(cache_key, payload, CACHE_TTL_PRECIP_MAP)
+    return payload