/**
 * @file Web Vitals Collection and Reporting System
 * @description Enterprise-grade Core Web Vitals collection with analytics integration,
 * performance budgets, and real-time monitoring capabilities.
 *
 * Targets:
 * - LCP: < 2500ms (good), < 4000ms (needs improvement)
 * - INP: < 200ms (good), < 500ms (needs improvement)
 * - CLS: < 0.1 (good), < 0.25 (needs improvement)
 * - FCP: < 1800ms (good), < 3000ms (needs improvement)
 * - TTFB: < 800ms (good), < 1800ms (needs improvement)
 */
/**
 * Core Web Vitals metric names
 */
export type VitalMetricName = 'CLS' | 'FCP' | 'INP' | 'LCP' | 'TTFB';
/**
 * Performance rating based on Core Web Vitals thresholds
 */
export type PerformanceRating = 'good' | 'needs-improvement' | 'poor';
/**
 * Extended metric with rating and context
 */
export interface VitalMetricEntry {
    name: VitalMetricName;
    value: number;
    rating: PerformanceRating;
    delta: number;
    id: string;
    navigationType: string;
    timestamp: number;
    attribution?: unknown;
}
/**
 * Aggregated vitals snapshot
 */
export interface VitalsSnapshot {
    CLS?: VitalMetricEntry;
    FCP?: VitalMetricEntry;
    INP?: VitalMetricEntry;
    LCP?: VitalMetricEntry;
    TTFB?: VitalMetricEntry;
    timestamp: number;
    url: string;
    path: string;
    score: number;
    rating: PerformanceRating;
}
/**
 * Performance budget configuration
 */
export interface PerformanceBudget {
    CLS: {
        good: number;
        poor: number;
    };
    FCP: {
        good: number;
        poor: number;
    };
    INP: {
        good: number;
        poor: number;
    };
    LCP: {
        good: number;
        poor: number;
    };
    TTFB: {
        good: number;
        poor: number;
    };
}
/**
 * Budget violation event
 */
export interface BudgetViolation {
    metric: VitalMetricName;
    value: number;
    budget: number;
    severity: 'warning' | 'critical';
    timestamp: number;
    url: string;
}
/**
 * Vitals reporter callback
 */
export type VitalsReporter = (metric: VitalMetricEntry, snapshot: VitalsSnapshot) => void;
/**
 * Budget violation callback
 */
export type BudgetViolationHandler = (violation: BudgetViolation) => void;
/**
 * Configuration for vitals collection
 */
export interface VitalsCollectorConfig {
    /** Enable reporting to analytics endpoint */
    reportToAnalytics?: boolean;
    /** Analytics endpoint URL */
    analyticsEndpoint?: string;
    /** Custom performance budgets */
    budgets?: Partial<PerformanceBudget>;
    /** Callback for each metric update */
    onMetric?: VitalsReporter;
    /** Callback for budget violations */
    onBudgetViolation?: BudgetViolationHandler;
    /** Sample rate for reporting (0-1) */
    sampleRate?: number;
    /** Enable debug logging */
    debug?: boolean;
    /** Batch reports before sending */
    batchReports?: boolean;
    /** Batch flush interval in ms */
    batchInterval?: number;
}
/**
 * Default Core Web Vitals thresholds (Google recommended)
 */
export declare const DEFAULT_BUDGETS: PerformanceBudget;
/**
 * Calculate rating based on value and thresholds
 */
declare function calculateRating(value: number, thresholds: {
    good: number;
    poor: number;
}): PerformanceRating;
/**
 * Convert rating to numeric score (0-100)
 */
declare function ratingToScore(rating: PerformanceRating): number;
/**
 * Calculate overall performance score from vitals
 */
declare function calculateOverallScore(metrics: Partial<Record<VitalMetricName, VitalMetricEntry>>): number;
/**
 * Get overall rating from score
 */
declare function scoreToRating(score: number): PerformanceRating;
/**
 * Core Web Vitals collector with real-time monitoring
 */
export declare class VitalsCollector {
    private config;
    private metrics;
    private subscribers;
    private budgetHandlers;
    private reportBuffer;
    private flushTimer;
    private isInitialized;
    private cachedScore;
    private cachedScoreMetricsVersion;
    private metricsVersion;
    constructor(config?: VitalsCollectorConfig);
    /**
     * Initialize vitals collection
     */
    init(): () => void;
    /**
     * Flush buffered reports to analytics
     */
    flush(): void;
    /**
     * Get current vitals snapshot
     * Performance optimized: Uses cached score to avoid recalculation on every call
     */
    getSnapshot(): VitalsSnapshot;
    /**
     * Get specific metric
     */
    getMetric(name: VitalMetricName): VitalMetricEntry | undefined;
    /**
     * Subscribe to metric updates
     */
    subscribe(callback: VitalsReporter): () => void;
    /**
     * Subscribe to budget violations
     */
    onViolation(callback: BudgetViolationHandler): () => void;
    /**
     * Handle incoming metric
     */
    private handleMetric;
    /**
     * Extract attribution data from metric
     */
    private extractAttribution;
    /**
     * Check and report budget violations
     */
    private checkBudgetViolation;
    /**
     * Schedule batch flush
     */
    private scheduleBatchFlush;
    /**
     * Send metrics to analytics endpoint
     */
    private sendToAnalytics;
    /**
     * Get connection information
     */
    private getConnectionInfo;
    /**
     * Debug logging
     */
    private log;
}
/**
 * Get or create the global VitalsCollector instance
 */
export declare function getVitalsCollector(config?: VitalsCollectorConfig): VitalsCollector;
/**
 * Initialize vitals collection with config
 */
export declare function initVitals(config?: VitalsCollectorConfig): () => void;
/**
 * Format metric value for display
 */
export declare function formatMetricValue(name: VitalMetricName, value: number): string;
/**
 * Get color for rating
 */
export declare function getRatingColor(rating: PerformanceRating): string;
/**
 * Get metric description
 */
export declare function getMetricDescription(name: VitalMetricName): string;
/**
 * Get metric target value
 */
export declare function getMetricTarget(name: VitalMetricName): string;
export { calculateRating, calculateOverallScore, ratingToScore, scoreToRating, };