import {useSyncExternalStore} from "react";

// The bearer token of the current dataset. It lives in sessionStorage - per tab, gone when the tab
// closes - because it is a per-dataset secret the next /start replaces, not a credential to keep.
const KEY = 'jfjoch_token';

export const getToken = (): string | undefined => {
    try {
        return sessionStorage.getItem(KEY) ?? undefined;
    } catch {
        return undefined;
    }
};

export const setToken = (token: string) => {
    try {
        if (token)
            sessionStorage.setItem(KEY, token);
        else
            sessionStorage.removeItem(KEY);
    } catch {
        // sessionStorage unavailable (private window, CSP): the token is simply not kept
    }
};

// For the few raw fetch() calls that bypass the generated client.
export const authHeaders = (): HeadersInit =>
    getToken() ? {Authorization: 'Bearer ' + getToken()} : {};

// Whether the broker last answered 401 - i.e. the dataset is protected and the token we hold (or
// its absence) does not open it. Set from the response interceptor, read by the UI.
let tokenRequired = false;
const listeners = new Set<() => void>();

export const noteResponse = (response: Response) => {
    const required = response.status === 401;
    if (required !== tokenRequired) {
        tokenRequired = required;
        listeners.forEach(l => l());
    }
};

export const useTokenRequired = () =>
    useSyncExternalStore(
        (l) => { listeners.add(l); return () => { listeners.delete(l); }; },
        () => tokenRequired);