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config/custom_components/blitzortung/geohash_utils.py

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+import math
+from collections import namedtuple
+
+from . import geohash
+
+Box = namedtuple("Box", ["s", "w", "n", "e"])
+
+
+def geohash_bbox(gh):
+    ret = geohash.bbox(gh)
+    return Box(ret["s"], ret["w"], ret["n"], ret["e"])
+
+
+def bbox(lat, lon, radius):
+    lat_delta = radius * 360 / 40000
+    lon_delta = lat_delta / math.cos(lat * math.pi / 180.0)
+    return Box(lat - lat_delta, lon - lon_delta, lat + lat_delta, lon + lon_delta)
+
+
+def overlap(a1, a2, b1, b2):
+    return a1 < b2 and a2 > b1
+
+
+def box_overlap(box1: Box, box2: Box):
+    return overlap(box1.s, box1.n, box2.s, box2.n) and overlap(
+        box1.w, box1.e, box2.w, box2.e
+    )
+
+
+def compute_geohash_tiles(lat, lon, radius, precision):
+    bounds = bbox(lat, lon, radius)
+    center = geohash.encode(lat, lon, precision)
+
+    stack = set()
+    checked = set()
+
+    stack.add(center)
+    checked.add(center)
+
+    while stack:
+        current = stack.pop()
+        for neighbor in geohash.neighbors(current):
+            if neighbor not in checked and box_overlap(geohash_bbox(neighbor), bounds):
+                stack.add(neighbor)
+                checked.add(neighbor)
+    return checked
+
+
+def geohash_overlap(lat, lon, radius, max_tiles=9):
+    result = []
+    for precision in range(1, 13):
+        tiles = compute_geohash_tiles(lat, lon, radius, precision)
+        if len(tiles) <= 9:
+            result = tiles
+            precision += 1
+        else:
+            break
+    return result