HOLI-5486: add util function to calculate radius

app/utils.ts

+import { GeolocationGeometry } from "./types.ts";
+import { turf } from "./deps.ts";
+import { ApiDefaults } from "./api_types.ts";
+
+/**
+ * Calculates the radius of a given polygon or multi-polygon geometry.
+ *
+ * @param {GeolocationGeometry} geometry - The input geometry to calculate the radius for.
+ * @returns {number} The calculated radius in kilometers.
+ */
+export function calculateRadius(geometry: GeolocationGeometry) {
+  if (geometry.type !== "Polygon" && geometry.type !== "MultiPolygon") {
+    return ApiDefaults.MIN_RADIUS;
+  }
+
+  const center = turf.center(geometry);
+  const vertices = turf.explode(geometry);
+
+  let maxDistance: number = ApiDefaults.MIN_RADIUS;
+
+  turf.coordEach(vertices, (vertice) => {
+    const distance = turf.distance(center, turf.point(vertice), {
+      units: "kilometers",
+    });
+
+    if (distance > maxDistance) {
+      maxDistance = distance;
+    }
+  });
+
+  const radius = Math.ceil(maxDistance);
+
+  if (radius >= ApiDefaults.MAX_RADIUS) {
+    return ApiDefaults.MAX_RADIUS;
+  }
+
+  return radius;
+}