/**
 * API Metrics
 *
 * Collects and reports API performance metrics including
 * latency, error rates, and throughput.
 *
 * @module api/advanced/api-metrics
 */
/**
 * Single request metric.
 */
export interface RequestMetric {
    /** Request URL/endpoint */
    endpoint: string;
    /** HTTP method */
    method: string;
    /** Response status code */
    status: number;
    /** Request duration in milliseconds */
    duration: number;
    /** Request timestamp */
    timestamp: number;
    /** Whether request succeeded */
    success: boolean;
    /** Error message if failed */
    error?: string;
    /** Request size in bytes */
    requestSize?: number;
    /** Response size in bytes */
    responseSize?: number;
    /** Correlation ID */
    correlationId?: string;
    /** Custom tags */
    tags?: Record<string, string>;
}
/**
 * Aggregated metrics for an endpoint.
 */
export interface EndpointMetrics {
    /** Endpoint path */
    endpoint: string;
    /** Total request count */
    totalRequests: number;
    /** Successful requests */
    successCount: number;
    /** Failed requests */
    errorCount: number;
    /** Success rate (0-1) */
    successRate: number;
    /** Average duration in ms */
    avgDuration: number;
    /** Minimum duration in ms */
    minDuration: number;
    /** Maximum duration in ms */
    maxDuration: number;
    /** P50 latency in ms */
    p50Latency: number;
    /** P90 latency in ms */
    p90Latency: number;
    /** P95 latency in ms */
    p95Latency: number;
    /** P99 latency in ms */
    p99Latency: number;
    /** Status code distribution */
    statusCodes: Record<number, number>;
    /** Error distribution */
    errors: Record<string, number>;
    /** Last request timestamp */
    lastRequestAt: number;
    /** Requests per second (recent) */
    requestsPerSecond: number;
}
/**
 * Overall API metrics.
 */
export interface OverallMetrics {
    /** Total requests across all endpoints */
    totalRequests: number;
    /** Total successful requests */
    totalSuccess: number;
    /** Total failed requests */
    totalErrors: number;
    /** Overall success rate */
    successRate: number;
    /** Overall average duration */
    avgDuration: number;
    /** Overall P95 latency */
    p95Latency: number;
    /** Total requests per second */
    requestsPerSecond: number;
    /** Unique endpoints count */
    endpointCount: number;
    /** Metrics collection start time */
    collectionStartedAt: number;
    /** Time window in milliseconds */
    windowMs: number;
}
/**
 * Metrics collector configuration.
 */
export interface MetricsConfig {
    /** Maximum number of metrics to store */
    maxMetrics?: number;
    /** Time window for aggregation (ms) */
    windowMs?: number;
    /** Flush interval for reporters (ms) */
    flushInterval?: number;
    /** Enable detailed per-request storage */
    enableDetailedMetrics?: boolean;
    /** Endpoints to exclude from collection */
    excludeEndpoints?: string[];
    /** Custom metric reporter */
    reporter?: MetricsReporter;
}
/**
 * Metrics reporter interface.
 */
export interface MetricsReporter {
    /** Report a single metric */
    report: (metric: RequestMetric) => void;
    /** Flush all metrics */
    flush: (metrics: RequestMetric[]) => void;
    /** Report aggregated metrics */
    reportAggregated?: (metrics: OverallMetrics) => void;
}
/**
 * API Metrics Collector for performance monitoring.
 *
 * @example
 * ```typescript
 * const metrics = new APIMetricsCollector({
 *   maxMetrics: 10000,
 *   windowMs: 60000,
 *   reporter: {
 *     report: (metric) => console.log(metric),
 *     flush: (metrics) => sendToAnalytics(metrics),
 *   },
 * });
 *
 * // Record a metric
 * metrics.record({
 *   endpoint: '/users',
 *   method: 'GET',
 *   status: 200,
 *   duration: 150,
 *   timestamp: Date.now(),
 *   success: true,
 * });
 *
 * // Get endpoint metrics
 * const userMetrics = metrics.getEndpointMetrics('/users');
 * console.log(`P95 latency: ${userMetrics.p95Latency}ms`);
 * ```
 */
export declare class APIMetricsCollector {
    private config;
    private metrics;
    private endpointCache;
    private collectionStartedAt;
    private readonly flushTimer?;
    /**
     * Create a new metrics collector.
     *
     * @param config - Collector configuration
     */
    constructor(config?: MetricsConfig);
    /**
     * Record a request metric.
     *
     * @param metric - Metric to record
     */
    record(metric: RequestMetric): void;
    /**
     * Create a timing wrapper for requests.
     *
     * @param endpoint - Request endpoint
     * @param method - HTTP method
     * @param tags - Custom tags
     * @returns Timing functions
     */
    startTiming(endpoint: string, method: string, tags?: Record<string, string>): {
        success: (status: number, responseSize?: number) => void;
        error: (error: Error, status?: number) => void;
    };
    /**
     * Get metrics for a specific endpoint.
     *
     * @param endpoint - Endpoint path
     * @param method - Optional HTTP method filter
     * @returns Aggregated endpoint metrics
     */
    getEndpointMetrics(endpoint: string, method?: string): EndpointMetrics;
    /**
     * Get overall API metrics.
     */
    getOverallMetrics(): OverallMetrics;
    /**
     * Get metrics for all endpoints.
     */
    getAllEndpointMetrics(): EndpointMetrics[];
    /**
     * Get slow requests.
     *
     * @param threshold - Duration threshold in ms
     * @param limit - Maximum results
     */
    getSlowRequests(threshold: number, limit?: number): RequestMetric[];
    /**
     * Get recent errors.
     *
     * @param limit - Maximum results
     */
    getRecentErrors(limit?: number): RequestMetric[];
    /**
     * Get error distribution.
     */
    getErrorDistribution(): Record<string, number>;
    /**
     * Flush metrics to reporter.
     */
    flush(): void;
    /**
     * Export metrics as JSON.
     */
    exportJSON(): string;
    /**
     * Export metrics as CSV.
     */
    exportCSV(): string;
    /**
     * Clear all metrics.
     */
    clear(): void;
    /**
     * Dispose of the collector.
     */
    dispose(): void;
    /**
     * Check if endpoint should be excluded.
     */
    private shouldExclude;
    /**
     * Get cache key for endpoint.
     */
    private getEndpointKey;
    /**
     * Aggregate metrics for an endpoint.
     */
    private aggregateMetrics;
    /**
     * Create empty endpoint metrics.
     */
    private emptyEndpointMetrics;
    /**
     * Calculate percentile.
     */
    private percentile;
}
/**
 * Create a new metrics collector.
 *
 * @param config - Collector configuration
 * @returns APIMetricsCollector instance
 */
export declare function createMetricsCollector(config?: MetricsConfig): APIMetricsCollector;
/**
 * Console reporter for debugging.
 */
export declare const consoleReporter: MetricsReporter;
/**
 * Create a batched reporter that accumulates metrics.
 */
export declare function createBatchedReporter(onBatch: (metrics: RequestMetric[]) => void, options?: {
    batchSize?: number;
    maxWait?: number;
}): MetricsReporter;