a

src/lib/stores/cache/users.ts

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+import { getUserById } from "$lib/api/user";
+import { isErrorResponse, type User } from "$lib/types";
+import { get, writable, type Writable } from "svelte/store";
+
+const usersCache: Writable<Map<number, User>> = writable(new Map<number, User>());
+
+const runningCaches = new Set();
+
+usersCache.subscribe((users) => {
+    console.log(`Cached users: ${JSON.stringify([...users.values()])}`);
+})
+
+export function addUserToCache(user: User) {
+    usersCache.update((users) => users.set(user.id, user));
+}
+
+export async function getCachedUser(userId: number): Promise<User | null> {
+    const cachedUser = get(usersCache).get(userId);
+
+    if (cachedUser)
+        return cachedUser;
+
+    if (runningCaches.has(userId)) {
+        return await new Promise((resolve) => {
+            usersCache.subscribe((users) => {
+                console.log(`subsribed called`);
+                const user = users.get(userId);
+                if (user) {
+                    runningCaches.delete(userId);
+                    resolve(user);
+                }
+            });
+        });
+    }
+
+    runningCaches.add(userId);
+
+    const response = await getUserById(userId);
+    if (isErrorResponse(response))
+        return null;
+
+    const user = response as User;
+
+    addUserToCache(user);
+
+    return user;
+}