// Per-device "this is a shared computer" flag. localStorage is the source of
// truth (shared-ness is a property of THIS browser, not the family — a DB
// flag would force PIN mode on every device including a parent's phone).
// A plain cookie mirror lets server loads see it too (localStorage never
// reaches the server). Neither is a security boundary: the PIN + device
// session cookies remain the actual gate (see shared-device.md).
const LS_KEY = 'fam_shared_device';
const COOKIE = 'fam_shared_device';

export function isSharedDevice(): boolean {
	if (typeof localStorage === 'undefined') return false;
	try {
		return localStorage.getItem(LS_KEY) === '1';
	} catch {
		return false;
	}
}

export function setSharedDevice(on: boolean) {
	try {
		if (on) localStorage.setItem(LS_KEY, '1');
		else localStorage.removeItem(LS_KEY);
	} catch {
		/* private mode etc. — flag simply doesn't persist */
	}
	if (typeof document !== 'undefined') {
		document.cookie =
			on
				? `${COOKIE}=1; path=/; max-age=31536000; SameSite=Lax`
				: `${COOKIE}=; path=/; max-age=0; SameSite=Lax`;
	}
}