feat: add Deduplicator class for managing unique promises and implement icon library generator

src/lib/assets.ts

@@ -3,11 +3,13 @@ import { join } from "node:path";
 import { file, hash, write } from "bun";
 import { TTLCache } from "enka.ts";
 import { AvatarStore, EnkaLocs, RelicStore, WeaponStore } from "@/type/enka";
+import { Deduplicator } from "./dedupe";
 
 export const cache = new TTLCache();
 
 export class AssetManager {
   private cache = new Map<string, ArrayBuffer>();
+  private deduper = new Deduplicator<ArrayBuffer>();
 
   async getMissingAssets() {
     const avatars = await getEnkaAvatarStore();
@@ -51,8 +53,10 @@ export class AssetManager {
     const local = file(join("store", hash(path).toString(36)));
     if (await local.exists()) return local.arrayBuffer();
 
-    const data = await fetch(new URL(path, "https://enka.network")).then(
-      (res) => res.arrayBuffer(),
+    const data = await this.deduper.acquire(path, () =>
+      fetch(new URL(path, "https://enka.network")).then((res) =>
+        res.arrayBuffer(),
+      ),
     );
     this.cache.set(path, data);
     queueMicrotask(() => write(local, data));

src/lib/dedupe.ts

@@ -0,0 +1,24 @@
+export class Deduplicator<T> {
+  // biome-ignore lint/suspicious/noExplicitAny: This is a generic class, so we need to use any here.
+  private map: Map<string, Promise<any>> = new Map();
+
+  has(key: string): boolean {
+    return this.map.has(key);
+  }
+
+  get<C = T>(key: string): Promise<C> | undefined {
+    return this.map.get(key);
+  }
+
+  acquire<C = T>(key: string, factory: () => Promise<C>): Promise<C> {
+    if (this.map.has(key)) {
+      return this.map.get(key)!;
+    }
+    const value = factory();
+    this.map.set(key, value);
+    value.finally(() => {
+      this.map.delete(key);
+    });
+    return value;
+  }
+}