/**
 * Metrics Collector Service
 *
 * Tracks and aggregates performance metrics for ABAC engine evaluations.
 * Provides insights into engine performance, decision distribution, and error rates.
 */
import { ABACDecision, EvaluationMetrics } from '../types';
/**
 * Service for collecting and managing performance metrics
 */
export declare class MetricsCollector {
    private metrics;
    private enabled;
    constructor(enabled?: boolean);
    /**
     * Record a policy evaluation
     *
     * @param decision - The decision result
     * @param evaluationTime - Time taken to evaluate (in milliseconds)
     * @param policyIds - IDs of policies that were evaluated
     */
    record(decision: ABACDecision, evaluationTime: number, policyIds?: string[]): void;
    /**
     * Get current metrics
     *
     * @returns Copy of current metrics
     */
    getMetrics(): EvaluationMetrics;
    /**
     * Reset all metrics to initial state
     */
    reset(): void;
    /**
     * Enable metrics collection
     */
    enable(): void;
    /**
     * Disable metrics collection
     */
    disable(): void;
    /**
     * Check if metrics collection is enabled
     *
     * @returns true if enabled, false otherwise
     */
    isEnabled(): boolean;
    /**
     * Get metrics summary as a formatted string
     *
     * @returns Formatted metrics summary
     */
    getSummary(): string;
    /**
     * Get percentage for a decision type
     */
    private getPercentage;
    /**
     * Get metrics for a specific policy
     *
     * @param policyId - Policy ID
     * @returns Hit count for the policy
     */
    getPolicyMetrics(policyId: string): number;
    /**
     * Get top N policies by hit count
     *
     * @param limit - Number of policies to return
     * @returns Array of [policyId, hitCount] tuples
     */
    getTopPolicies(limit?: number): Array<[string, number]>;
}
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