import type { Invalidator, Subscriber, Unsubscriber } from 'svelte/store';
import { writable, derived } from 'svelte/store';

type Nullable<T> = T | null;

interface User {
    uuid: string;
    username: string;
}

interface TokenStore {
    subscribe: (run: Subscriber<Nullable<string>>, invalidate: Invalidator<Nullable<string>>) => Unsubscriber,
    authenticate: (newToken: string) => void,
    unauthenticate: () => void
}

function createTokenStore(): TokenStore {
    const storedToken = localStorage.getItem("token");
    const { subscribe, set } = writable<string | null>(storedToken); 

    function authenticate(newToken: string): void {
        try {
            localStorage.setItem("token", newToken);
            set(newToken);
        } catch (e) {
            console.error('error', e);
        }
    }

    function unauthenticate(): void {
        localStorage.removeItem("token");
        set(null);
    }

    return {
        subscribe, 
        authenticate,
        unauthenticate
    };
}

function onTokenChange ($token: Nullable<string>): boolean { 
    return $token ? true : false;
}

export const token = createTokenStore();
export const authenticated = derived(token, onTokenChange);
export const user = writable<User | null>(null);