geohash actor

lib/src/geo_actor.dart

@@ -0,0 +1,69 @@
+import 'package:actors/actors.dart';
+import 'package:dart_geohash/dart_geohash.dart';
+
+sealed class GeoMessage {
+  const GeoMessage();
+}
+
+final class EncodeLocation extends GeoMessage {
+  final double latitude;
+  final double longitude;
+  final int precision;
+  const EncodeLocation({
+    required this.latitude,
+    required this.longitude,
+    this.precision = 9,
+  });
+}
+
+final class DecodeGeohash extends GeoMessage {
+  final String geohash;
+  const DecodeGeohash(this.geohash);
+}
+
+final class NeighborsOf extends GeoMessage {
+  final String geohash;
+  const NeighborsOf(this.geohash);
+}
+
+sealed class GeoResult {
+  const GeoResult();
+}
+
+final class GeohashEncoded extends GeoResult {
+  final String geohash;
+  const GeohashEncoded(this.geohash);
+}
+
+final class LocationDecoded extends GeoResult {
+  final double latitude;
+  final double longitude;
+  const LocationDecoded({required this.latitude, required this.longitude});
+}
+
+// Keys: NORTH, NORTHEAST, EAST, SOUTHEAST, SOUTH, SOUTHWEST, WEST, NORTHWEST, CENTRAL
+final class NeighborsResult extends GeoResult {
+  final Map<String, String> neighbors;
+  const NeighborsResult(this.neighbors);
+}
+
+class GeoActor with Handler<GeoMessage, GeoResult> {
+  final _hasher = GeoHasher();
+
+  @override
+  Future<GeoResult> handle(GeoMessage message) => switch (message) {
+        EncodeLocation(:final latitude, :final longitude, :final precision) =>
+          Future.value(
+            GeohashEncoded(
+                _hasher.encode(longitude, latitude, precision: precision)),
+          ),
+        DecodeGeohash(:final geohash) => Future.value(_decode(geohash)),
+        NeighborsOf(:final geohash) =>
+          Future.value(NeighborsResult(_hasher.neighbors(geohash))),
+      };
+
+  LocationDecoded _decode(String geohash) {
+    final coords = _hasher.decode(geohash); // [longitude, latitude]
+    return LocationDecoded(latitude: coords[1], longitude: coords[0]);
+  }
+}