Small cleanup to zone async_active_zone (#108629)

homeassistant/components/zone/__init__.py

 """Support for the definition of zones."""
 from __future__ import annotations
 
-from collections.abc import Callable
+from collections.abc import Callable, Iterable
 import logging
 from operator import attrgetter
+import sys
 from typing import Any, Self, cast
 
 import voluptuous as vol
@@ -109,40 +110,49 @@ def async_active_zone(
     This method must be run in the event loop.
     """
     # Sort entity IDs so that we are deterministic if equal distance to 2 zones
-    min_dist = None
-    closest = None
+    min_dist: float = sys.maxsize
+    closest: State | None = None
+
     # This can be called before async_setup by device tracker
-    zone_entity_ids: list[str] = hass.data.get(ZONE_ENTITY_IDS, [])
+    zone_entity_ids: Iterable[str] = hass.data.get(ZONE_ENTITY_IDS, ())
+
     for entity_id in zone_entity_ids:
-        zone = hass.states.get(entity_id)
         if (
-            not zone
+            not (zone := hass.states.get(entity_id))
+            # Skip unavailable zones
             or zone.state == STATE_UNAVAILABLE
-            or zone.attributes.get(ATTR_PASSIVE)
+            # Skip passive zones
+            or (zone_attrs := zone.attributes).get(ATTR_PASSIVE)
+            # Skip zones where we cannot calculate distance
+            or (
+                zone_dist := distance(
+                    latitude,
+                    longitude,
+                    zone_attrs[ATTR_LATITUDE],
+                    zone_attrs[ATTR_LONGITUDE],
+                )
+            )
+            is None
+            # Skip zone that are outside the radius aka the
+            # lat/long is outside the zone
+            or not (zone_dist - (radius := zone_attrs[ATTR_RADIUS]) < radius)
         ):
             continue
 
-        zone_dist = distance(
-            latitude,
-            longitude,
-            zone.attributes[ATTR_LATITUDE],
-            zone.attributes[ATTR_LONGITUDE],
-        )
-
-        if zone_dist is None:
+        # If have a closest and its not closer than the closest skip it
+        if closest and not (
+            zone_dist < min_dist
+            or (
+                # If same distance, prefer smaller zone
+                zone_dist == min_dist and radius < closest.attributes[ATTR_RADIUS]
+            )
+        ):
             continue
 
-        within_zone = zone_dist - radius < zone.attributes[ATTR_RADIUS]
-        closer_zone = closest is None or zone_dist < min_dist  # type: ignore[unreachable]
-        smaller_zone = (
-            zone_dist == min_dist
-            and zone.attributes[ATTR_RADIUS]
-            < cast(State, closest).attributes[ATTR_RADIUS]
-        )
-
-        if within_zone and (closer_zone or smaller_zone):
-            min_dist = zone_dist
-            closest = zone
+        # We got here which means it closer than the previous known closest
+        # or equal distance but this one is smaller.
+        min_dist = zone_dist
+        closest = zone
 
     return closest