export interface Credentials {
    privateKey: string;
    clientEmail?: string;
}
export interface TokenData {
    refresh_token?: string;
    expires_in?: number;
    access_token?: string;
    token_type?: string;
    id_token?: string;
}
export interface TokenOptions {
    keyFile?: string;
    key?: string;
    email?: string;
    iss?: string;
    sub?: string;
    scope?: string | string[];
    additionalClaims?: {};
}
export declare class GoogleToken {
    token?: string | null;
    expiresAt?: number | null;
    key?: string;
    keyFile?: string;
    iss?: string;
    sub?: string;
    scope?: string;
    rawToken: TokenData | null;
    tokenExpires: number | null;
    email?: string;
    additionalClaims?: {};
    /**
     * Create a GoogleToken.
     *
     * @param options  Configuration object.
     */
    constructor(options?: TokenOptions);
    /**
     * Returns whether the token has expired.
     *
     * @return true if the token has expired, false otherwise.
     */
    hasExpired(): boolean;
    /**
     * Returns a cached token or retrieves a new one from Google.
     *
     * @param callback The callback function.
     */
    getToken(): Promise<string | null | undefined>;
    getToken(callback: (err: Error | null, token?: string | null | undefined) => void): void;
    /**
     * Given a keyFile, extract the key and client email if available
     * @param keyFile Path to a json, pem, or p12 file that contains the key.
     * @returns an object with privateKey and clientEmail properties
     */
    getCredentials(keyFile: string): Promise<Credentials>;
    private getTokenAsync();
    private ensureEmail();
    /**
     * Revoke the token if one is set.
     *
     * @param callback The callback function.
     */
    revokeToken(): Promise<void>;
    revokeToken(callback: (err?: Error) => void): void;
    private revokeTokenAsync();
    /**
     * Configure the GoogleToken for re-use.
     * @param  {object} options Configuration object.
     */
    private configure(options?);
    /**
     * Request the token from Google.
     */
    private requestToken();
}