export interface ImpressionMetadata {
    elementID: string;
    elementType: "product" | "promotile";
    elementPosition: number;
    query?: string;
    categoryID?: string;
    pagenum?: number;
    sort_by?: string;
    narrow_by?: string;
}
export interface ImpressionRecord extends ImpressionMetadata {
    timestamp: number;
    isReported: boolean;
}
export interface ViewportImpressionTrackerConfig {
    threshold?: number;
    backupInterval?: number;
    onImpression?: (record: ImpressionRecord) => void;
    onReport?: (impressions: ImpressionRecord[]) => Promise<void>;
}
export declare class ViewportImpressionTracker {
    private impressions;
    private observers;
    private observerMetadata;
    private reportingTimer;
    private hasReportedOnPageLeave;
    private config;
    private pageLeaveCleanup;
    constructor(config?: ViewportImpressionTrackerConfig);
    track(element: Element, metadata: ImpressionMetadata): void;
    untrack(element: Element): void;
    reportNow(): Promise<void>;
    destroy(): void;
    private handleIntersection;
    private setupBackupTimer;
    private setupPageLeaveHandlers;
}