fix(review): address audit findings before merge

src/utils/world/chunkInstances.ts

@@ -0,0 +1,55 @@
+import { CHUNK_CONFIG } from "@/data/world/chunkStreamingConfig";
+import type { Vector3Tuple } from "@/types/three/three";
+
+interface PositionedInstance {
+  position: Vector3Tuple;
+}
+
+export interface WorldInstanceChunk<TInstance extends PositionedInstance> {
+  centerX: number;
+  centerZ: number;
+  chunkKey: string;
+  instances: TInstance[];
+}
+
+function getWorldChunkKey(instance: PositionedInstance): string {
+  const [x, , z] = instance.position;
+  const chunkX = Math.floor(x / CHUNK_CONFIG.chunkSize);
+  const chunkZ = Math.floor(z / CHUNK_CONFIG.chunkSize);
+  return `${chunkX}:${chunkZ}`;
+}
+
+export function createWorldInstanceChunks<TInstance extends PositionedInstance>(
+  instances: TInstance[],
+): WorldInstanceChunk<TInstance>[] {
+  const chunks = new Map<string, TInstance[]>();
+
+  for (const instance of instances) {
+    const chunkKey = getWorldChunkKey(instance);
+    const chunk = chunks.get(chunkKey);
+
+    if (chunk) {
+      chunk.push(instance);
+    } else {
+      chunks.set(chunkKey, [instance]);
+    }
+  }
+
+  return [...chunks.entries()].map(([chunkKey, chunkInstances]) => {
+    const center = chunkInstances.reduce(
+      (sum, instance) => {
+        sum.x += instance.position[0];
+        sum.z += instance.position[2];
+        return sum;
+      },
+      { x: 0, z: 0 },
+    );
+
+    return {
+      centerX: center.x / chunkInstances.length,
+      centerZ: center.z / chunkInstances.length,
+      chunkKey,
+      instances: chunkInstances,
+    };
+  });
+}