import { VariantId, UserId, EvaluationReason, JsonValue } from '../advanced/types';
/**
 * Evaluation event for analytics.
 */
export interface EvaluationEvent {
    /** Flag key */
    readonly flagKey: string;
    /** Variant ID */
    readonly variantId: VariantId;
    /** User ID */
    readonly userId?: UserId;
    /** Session ID */
    readonly sessionId?: string;
    /** Evaluation reason */
    readonly reason?: EvaluationReason;
    /** Evaluation time in ms */
    readonly durationMs?: number;
    /** Timestamp */
    readonly timestamp: Date;
    /** Whether value was from cache */
    readonly cached?: boolean;
    /** Additional metadata */
    readonly metadata?: Record<string, JsonValue>;
}
/**
 * Aggregated metrics for a flag.
 */
export interface FlagMetrics {
    /** Flag key */
    readonly flagKey: string;
    /** Total evaluations */
    readonly evaluationCount: number;
    /** Evaluations per variant */
    readonly variantCounts: Record<VariantId, number>;
    /** Unique users */
    readonly uniqueUsers: number;
    /** Unique sessions */
    readonly uniqueSessions: number;
    /** Average evaluation time */
    readonly avgDurationMs: number;
    /** Cache hit rate */
    readonly cacheHitRate: number;
    /** Errors count */
    readonly errorCount: number;
    /** First evaluation */
    readonly firstSeen: Date;
    /** Last evaluation */
    readonly lastSeen: Date;
}
/**
 * Analytics configuration.
 */
export interface FlagAnalyticsConfig {
    /** Enable analytics collection */
    readonly enabled?: boolean;
    /** Batch size before flushing */
    readonly batchSize?: number;
    /** Flush interval in ms */
    readonly flushInterval?: number;
    /** Analytics endpoint URL */
    readonly endpoint?: string;
    /** API key for endpoint */
    readonly apiKey?: string;
    /** Custom flush handler */
    readonly onFlush?: (events: EvaluationEvent[]) => Promise<void>;
    /** Error handler */
    readonly onError?: (error: Error) => void;
    /** Enable debug logging */
    readonly debug?: boolean;
    /** Sample rate (0-1) */
    readonly sampleRate?: number;
    /** Max events to store */
    readonly maxEvents?: number;
}
/**
 * Analytics report.
 */
export interface AnalyticsReport {
    /** Report generation time */
    readonly generatedAt: Date;
    /** Time period start */
    readonly periodStart: Date;
    /** Time period end */
    readonly periodEnd: Date;
    /** Total evaluations */
    readonly totalEvaluations: number;
    /** Unique flags evaluated */
    readonly uniqueFlags: number;
    /** Unique users */
    readonly uniqueUsers: number;
    /** Metrics per flag */
    readonly flagMetrics: FlagMetrics[];
    /** Top flags by evaluation count */
    readonly topFlags: Array<{
        flagKey: string;
        count: number;
    }>;
    /** Error rate */
    readonly errorRate: number;
}
/**
 * Analytics collector for feature flags.
 */
export declare class FlagAnalytics {
    private events;
    private flushTimer;
    private config;
    private flagMetrics;
    private listeners;
    private periodStart;
    constructor(config?: FlagAnalyticsConfig);
    /**
     * Track a flag evaluation event.
     */
    trackEvaluation(event: Omit<EvaluationEvent, 'timestamp'>): void;
    /**
     * Track an error during evaluation.
     */
    trackError(flagKey: string, error: Error, metadata?: Record<string, JsonValue>): void;
    /**
     * Flush pending events.
     */
    flush(): Promise<void>;
    /**
     * Get metrics for a specific flag.
     */
    getMetrics(flagKey: string): FlagMetrics | null;
    /**
     * Get all flag metrics.
     */
    getAllMetrics(): FlagMetrics[];
    /**
     * Generate an analytics report.
     */
    getReport(): AnalyticsReport;
    /**
     * Subscribe to flush events.
     */
    subscribe(listener: (events: EvaluationEvent[]) => void): () => void;
    /**
     * Reset all metrics and events.
     */
    reset(): void;
    /**
     * Shutdown the analytics collector.
     */
    shutdown(): Promise<void>;
    /**
     * Enable or disable analytics.
     */
    setEnabled(enabled: boolean): void;
    private updateMetrics;
    private getOrCreateMetrics;
    /**
     * Default flush handler that sends events to the configured endpoint.
     *
     * Note: This method intentionally uses raw fetch() rather than apiClient because:
     * 1. Analytics should be independent of the main API client to avoid circular dependencies
     * 2. Analytics endpoints may be on a different domain/service
     * 3. This should work even if the main API client fails
     *
     * @see {@link @/lib/api/api-client} for the main API client
     */
    private defaultFlush;
    private startFlushTimer;
    private stopFlushTimer;
    private notifyListeners;
    private log;
}
/**
 * Get the singleton analytics instance.
 */
export declare function getFlagAnalytics(): FlagAnalytics;
/**
 * Initialize the singleton with configuration.
 */
export declare function initFlagAnalytics(config: FlagAnalyticsConfig): FlagAnalytics;
/**
 * Reset the singleton instance.
 */
export declare function resetFlagAnalytics(): void;