/**
 * A client for interacting with Google Cloud Secret Manager.
 *
 * This class provides a simplified interface for retrieving secrets from
 * Secret Manager, handling authentication using either a service account
 * JSON keyfile (passed as a string) or a pre-existing authorization token.
 */
export declare class SecretManagerClient {
    private credentials;
    /**
     * Initializes the SecretManagerClient.
     *
     * @param params Configuration parameters
     * @param params.serviceAccountJson The content of a service account JSON keyfile (as a string), not the file path. Must be valid JSON.
     * @param params.authToken An existing Google Cloud authorization token.
     * @throws Error if neither serviceAccountJson nor authToken is provided, or if both are provided. Also raised if the serviceAccountJson is not valid JSON.
     */
    constructor(params: {
        serviceAccountJson?: string;
        authToken?: string;
    });
    /**
     * Retrieves a secret from Google Cloud Secret Manager.
     *
     * @param resourceName The full resource name of the secret.
     *                    Usually you want the "latest" version, e.g., "projects/my-project/secrets/my-secret/versions/latest".
     * @returns The secret payload as a string.
     * @throws Error if the Secret Manager API returns an error
     */
    getSecret(resourceName: string): Promise<string>;
}