export declare enum Level {
    error = 0,
    warn = 1,
    info = 2,
    verbose = 3,
    debug = 4,
}
export declare type LevelSpec = string;
export declare function levelStr(spec: LevelSpec): string;
export declare function levelVal(spec: LevelSpec): Level;
export interface SimpleLogger {
    level: LevelSpec;
    log(level: LevelSpec, msg: string, ...args: any[]): SimpleLogger;
    error(msg: string | Error, ...args: any[]): SimpleLogger;
    warn(msg: string | Error, ...args: any[]): SimpleLogger;
    info(msg: string | Error, ...args: any[]): SimpleLogger;
    verbose(msg: string | Error, ...args: any[]): SimpleLogger;
    debug(msg: string | Error, ...args: any[]): SimpleLogger;
    visible(level: LevelSpec): boolean;
}
export declare abstract class BaseLogger implements SimpleLogger {
    abstract level: LevelSpec;
    abstract log(level: LevelSpec, msg: string, ...args: any[]): SimpleLogger;
    abstract visible(level: LevelSpec): boolean;
    errStackFlag: boolean;
    error(msg: string | Error, ...args: any[]): SimpleLogger;
    warn(msg: string | Error, ...args: any[]): SimpleLogger;
    info(msg: string | Error, ...args: any[]): SimpleLogger;
    verbose(msg: string | Error, ...args: any[]): SimpleLogger;
    debug(msg: string | Error, ...args: any[]): SimpleLogger;
}
export declare class ProxyLogger extends BaseLogger {
    private implVar;
    impl: SimpleLogger;
    level: LevelSpec;
    log(level: LevelSpec, msg: string | Error, ...args: any[]): SimpleLogger;
    visible(level: LevelSpec): boolean;
}
export declare abstract class ConfigurableLogger extends BaseLogger {
    private configVar;
    config: any;
    abstract configModified(): void;
}
export declare function proxyLogger(logger: SimpleLogger): ProxyLogger;
export declare function fileLogger(config?: any): BaseLogger;
export declare const defaultLogger: ProxyLogger;
export default defaultLogger;