import { Paths } from 'env-paths';
import createYargs from 'yargs';
/** General configuration */
export interface Config {
    [key: Exclude<string, '_' | '$0'>]: unknown;
}
/** paths for local data, config, logs etc. */
type EnvPaths = Paths & {
    /**
     * provides the prefix into yargs.env, if `false`, no environment variables
     * will be read
     */
    env: string | false;
};
export declare class Env {
    readonly envPaths: EnvPaths;
    /**
     * The `appName` parameter drives the default paths determination, according
     * to the `env-paths` module; and also the default prefix for environment
     * variables.
     *
     * @see https://github.com/sindresorhus/env-paths#api
     * @see https://yargs.js.org/docs/#api-reference-envprefix
     */
    constructor(appName: string, envPaths?: Partial<EnvPaths>);
    /** @returns name uppercase snake-case */
    static toEnvVar(name: string): string;
    get envPrefix(): string;
    /**
     * @returns the config as an object containing environment variables, e.g. {
     *   TIMELD_GATEWAY_KEY1: 'key1',
     *   TIMELD_GATEWAY_NESTED__KEY2: 'key2',
     * }
     * @param config
     * @param filter if non-empty, the keys to include
     * @param env existing env to add to
     * @param prefix prefix for new entries
     */
    asEnv(config: Config, filter?: string[], env?: {
        [env: string]: string;
    }, prefix?: string): {
        [env: string]: string;
    };
    baseYargs(args?: string[]): createYargs.Argv<{}>;
    yargs(args?: string[]): Promise<createYargs.Argv<{
        logLevel: string | undefined;
    }>>;
    /**
     * Gets the path of a file or directory under an environment key.
     * Ensures that the parent directory exists.
     */
    readyPath(key: keyof Paths, ...path: string[]): Promise<string>;
    readConfig(): Promise<Config>;
    /** @returns config parameter, for chaining */
    writeConfig(config: Config): Promise<Config>;
    /** @returns final config written */
    updateConfig(...configs: Config[]): Promise<Config>;
    static isConfigKey(k: keyof Config): boolean;
    /**
     * @param {*} current
     * @param {*} override
     * @param {*} more
     * @returns {*}
     */
    static mergeConfig<T = Config>(current: any, override: any, ...more: any[]): T;
    /**
     * List the sub-paths, having no child directories, under the given key.
     * @returns leaf sub-paths
     */
    envDirs(key: keyof Paths): Promise<string[][]>;
    /** Deletes the given env directory */
    delEnvDir(key: keyof Paths, path: string[], { force }?: {
        force?: boolean;
    }): Promise<void>;
    delEnvFile(key: keyof Paths, path: string[]): Promise<void>;
    defaultIfNotExists<T>(err: any, defaultValue: T): T;
}
export {};