import { TokenProviderAuthUser, TokenProviderExtras } from './types';
/**
 * Encodes the given extras object into a Base64 string.
 * This ensures that the encoded string is safe for use in URLs.
 *
 * @param extras - The extras object to encode.
 * @returns The Base64 encoded string representation of the extras object.
 */
export declare function encodeExtras(extras: TokenProviderExtras): string;
/**
 * Decodes the given Base64 string back into the original extras object,
 * which was encoded using `encodeExtras`.
 *
 * @param encodedExtras - The Base64 encoded string representation of the extras object.
 * @returns The decoded extras object.
 */
export declare function decodeExtras(encodedExtras?: string | null): TokenProviderExtras | undefined;
/**
 * Try to get the extras value from the URL params.
 */
export declare const getExtrasFromUrl: () => string | undefined;
/**
 * Validates if the user object received from `extras` is a valid one and can be added to the TokenProvider context.
 */
export declare function isValidUser(user?: TokenProviderAuthUser | null): user is TokenProviderAuthUser;