/**
 * The signed-in shopper's unread message count, shared between the shell badge
 * and the message center. Every read/mark-all/delete action refreshes the count
 * through `$api.getUnreadCount()` so the badge never drifts from the server.
 */
export function useUnreadMessages() {
  const { $api } = useNuxtApp();
  const session = useSessionStore();
  const unread = useState<number>("unread-messages", () => 0);

  /** Anonymous shoppers have no message center, so the count stays at zero. */
  async function refresh(): Promise<void> {
    if (!session.isLoggedIn) {
      unread.value = 0;
      return;
    }
    try {
      unread.value = (await $api.getUnreadCount()).unread;
    } catch {
      unread.value = 0;
    }
  }

  /** Let a mutating page push the authoritative number without a second call. */
  function setCount(count: number): void {
    unread.value = Math.max(0, count);
  }

  return { unread, refresh, setCount };
}