refactor progress

fluxer_relay_directory/src/services/GeoSelectionService.tsx

@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2026 Fluxer Contributors
+ *
+ * This file is part of Fluxer.
+ *
+ * Fluxer is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Fluxer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Fluxer. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import type {RelayInfo} from '@app/repositories/RelayRepository';
+
+const EARTH_RADIUS_KM = 6371;
+
+export interface GeoLocation {
+	latitude: number;
+	longitude: number;
+}
+
+export interface RelayWithDistance extends RelayInfo {
+	distance_km: number;
+}
+
+export interface IGeoSelectionService {
+	calculateDistance(from: GeoLocation, to: GeoLocation): number;
+	sortByProximity(relays: Array<RelayInfo>, clientLocation: GeoLocation): Array<RelayWithDistance>;
+	selectNearestRelays(relays: Array<RelayInfo>, clientLocation: GeoLocation, limit: number): Array<RelayWithDistance>;
+}
+
+export class GeoSelectionService implements IGeoSelectionService {
+	calculateDistance(from: GeoLocation, to: GeoLocation): number {
+		const lat1Rad = this.toRadians(from.latitude);
+		const lat2Rad = this.toRadians(to.latitude);
+		const deltaLat = this.toRadians(to.latitude - from.latitude);
+		const deltaLon = this.toRadians(to.longitude - from.longitude);
+
+		const a =
+			Math.sin(deltaLat / 2) * Math.sin(deltaLat / 2) +
+			Math.cos(lat1Rad) * Math.cos(lat2Rad) * Math.sin(deltaLon / 2) * Math.sin(deltaLon / 2);
+
+		const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
+
+		return EARTH_RADIUS_KM * c;
+	}
+
+	sortByProximity(relays: Array<RelayInfo>, clientLocation: GeoLocation): Array<RelayWithDistance> {
+		const relaysWithDistance: Array<RelayWithDistance> = relays.map((relay) => ({
+			...relay,
+			distance_km: this.calculateDistance(clientLocation, {
+				latitude: relay.latitude,
+				longitude: relay.longitude,
+			}),
+		}));
+
+		relaysWithDistance.sort((a, b) => a.distance_km - b.distance_km);
+
+		return relaysWithDistance;
+	}
+
+	selectNearestRelays(relays: Array<RelayInfo>, clientLocation: GeoLocation, limit: number): Array<RelayWithDistance> {
+		const sorted = this.sortByProximity(relays, clientLocation);
+		return sorted.slice(0, limit);
+	}
+
+	private toRadians(degrees: number): number {
+		return degrees * (Math.PI / 180);
+	}
+}