import { BacktraceApi } from '@src/backtraceApi';
import { IBacktraceClientOptions } from './backtraceClientOptions';
/**
 * Handles Backtrace Metrics.
 */
export declare class BacktraceMetrics {
    private readonly _backtraceApi;
    private readonly attributeProvider;
    private readonly universe;
    private readonly token;
    private readonly hostname;
    private readonly persistenceInterval;
    private readonly heartbeatInterval;
    private readonly timestamp;
    private summedEndpoint;
    private uniqueEndpoint;
    private sessionId;
    private lastActive;
    constructor(configuration: IBacktraceClientOptions, _backtraceApi: BacktraceApi, attributeProvider: () => object);
    /**
     * Handle persisting of session. When called, will create or manage current session.
     * when appropriate.
     */
    private persistSession;
    /**
     * Persist session if page is focused.
     */
    private persistIfFocused;
    /**
     * Send POST to unique-events API endpoint
     */
    sendUniqueEvent(): Promise<void>;
    /**
     * Send POST to summed-events API endpoint
     */
    sendSummedEvent(metricGroup: string): Promise<void>;
    private getEventAttributes;
    /**
     * Create new sessionId and set local sessionId.
     */
    private createNewSession;
    /**
     * Get stored sessionId
     */
    private getSessionId;
    /**
     * Get stored time since last page navigation or current time
     */
    private getLastActive;
    /**
     * Set time to localStorage "lastActive" and class variable `lastActive`.
     * @param time Integer seconds since epoch
     */
    private setLastActive;
}