/**
 * Represents a log level.
 */
export type LogLevel = 'debug' | 'info' | 'warn' | 'error';
/**
 * Represents a single log entry.
 */
export interface LogEntry {
    level: LogLevel;
    space: string;
    message: string;
    data?: object;
}
/**
 * A function that handles log entries.
 *
 * @param entry The log entry to handle.
 */
export type LogHandler = (entry: LogEntry) => void;
/**
 * Options for configuring the logger.
 */
export interface LogOptions {
    handler?: LogHandler;
    space: string;
}
/**
 * A logger that provides structured logging with namespaces.
 * Supports custom log handlers or if no handler is provided, logging to the console.
 */
export declare class Log {
    /**
     * The default log instance, logging to the console with the `global` namespace.
     */
    static readonly default: Log;
    _handler?: LogHandler;
    _space: string;
    _type: string;
    /**
     * Creates a new Log instance.
     *
     * @param options Options for the logger.
     */
    constructor(options?: LogOptions);
    /**
     * Logs a debug message.
     *
     * @param message The debug message.
     * @param data Optional additional data.
     */
    debug(message: string, data?: any): void;
    /**
     * Logs an informational message.
     *
     * @param message The informational message.
     * @param data Optional additional data.
     */
    info(message: string, data?: any): void;
    /**
     * Logs a warning message.
     *
     * @param message The warning message.
     * @param data Optional additional data.
     */
    warn(message: string, data?: any): void;
    /**
     * Logs an error message.
     *
     * @param message The error message or an Error object.
     * @param data Optional additional data.
     */
    error(message: string | Error, data?: any): void;
    /**
     * Writes a log entry.
     *
     * @param level The log level.
     * @param message The log message.
     * @param data Optional additional data.
     */
    write(level: LogLevel, message: string, data?: any): void;
    /**
     * Creates a new Log instance with a sub-namespace.
     * Namespaces are separated by dots (e.g., "global.api.getUser").
     *
     * @param subSpace The sub-namespace to add in camel-case (e.g. `api` and `api.getUser`)
     *
     * @returns A new Log instance with the updated namespace.
     */
    space(subSpace: string): Log;
    /**
     * Measures the execution time of an asynchronous function and logs a debug message.
     *
     * @param message A message to include in the log output.
     * @param func The asynchronous function to time.
     *
     * @returns A Promise that resolves with the result of the timed function.
     */
    time<T = any>(message: string, func: () => T): Promise<T>;
    /**
     * Attaches the log instance to a request object.
     * This is typically used in server middleware.
     *
     * @param req The request object.
     * @param log The Log instance to attach.
     *
     * @example
     * Log.attachToRequest(req, new Log({ space: 'myModule' }))
     *
     * @deprecated
     */
    static attachToRequest(req: any, log: Log): void;
}