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;
}