import type { Event } from "../event.js";
import { Level } from "../level.js";
import type { SpanAttributes } from "../span.js";
import { ManagedSubscriber } from "./ManagedSubscriber.js";
/**
 * Options for the FmtSubscriber.
 */
export type FmtSubscriberOptions = {
    /**
     * The minimum level of logs to display.
     *
     * @default Level.INFO
     */
    level?: Level;
    /**
     * Include a timestamp in the message.
     *
     * @default true
     */
    timestamp?: boolean;
    /**
     * Log messages in color.
     *
     * Defaults to true if supported by the terminal environment.
     *
     * @default true
     */
    color?: boolean;
    /**
     * Abbreviate long field values.
     *
     * @default false
     */
    abbreviateLongFieldValues?: boolean | number;
};
/**
 * The FmtSubscriber class is a subscriber which logs events to the console in a human-readable format.
 *
 * @example
 * ```ts
 * import { FmtSubscriber } from "@bcheidemann/tracing";
 *
 * // Initialize the subscriber and set it as the default global subscriber
 * // This should be called at the beginning of your program
 * FmtSubscriber.setGlobalDefault();
 * ```
 */
export declare class FmtSubscriber extends ManagedSubscriber {
    private readonly options;
    private color;
    constructor(options?: FmtSubscriberOptions);
    /**
     * Initialises the FmtSubscriber as the default global subscriber.
     *
     * @deprecated Use `FmtSubscriber.setGlobalDefault()` instead
     */
    static init(options?: FmtSubscriberOptions): FmtSubscriber;
    static setGlobalDefault(options?: FmtSubscriberOptions): FmtSubscriber;
    protected onEvent(event: Event, spans: SpanAttributes[]): void;
    private displayMessage;
    private displayLevel;
    private displayTimestamp;
    private get timestamp();
    private displaySpans;
    private displaySpan;
    private displayEventFields;
    private displaySpanFields;
    private flattenFields;
    private displayValue;
}
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