import { DifficultyTier } from '../../enumerations/difficultyTier';
/**
 * Client identifier extraction strategy.
 */
export declare enum ClientIdentifierStrategy {
    IpAddress = "ip",
    AuthenticatedUser = "user",
    ApiKey = "apikey",
    /** Try user ID first, fall back to IP */
    UserOrIp = "user_or_ip"
}
/**
 * Fallback behavior when the rate limiter backing store is unavailable.
 */
export declare enum RateLimiterFallback {
    Allow = "allow",
    Deny = "deny",
    InMemory = "in_memory"
}
/**
 * Configuration for the PoUW rate limiting middleware.
 * All fields have sensible defaults except `hmacSecret`.
 */
export interface IPoUWConfig {
    /** HMAC secret for signing challenge tokens (REQUIRED) */
    hmacSecret: string;
    /** Maximum requests per window before rate limiting (default: 100) */
    rateLimit: number;
    /** Sliding window duration in milliseconds (default: 60_000) */
    windowMs: number;
    /** Client identifier strategy (default: UserOrIp) */
    identifierStrategy: ClientIdentifierStrategy;
    /** Challenge token TTL in seconds (default: 60) */
    tokenTtlSeconds: number;
    /** Initial difficulty tier (default: Low) */
    defaultDifficulty: DifficultyTier;
    /** Maximum difficulty tier (default: High) */
    maxDifficulty: DifficultyTier;
    /** Consecutive failures before circuit breaker opens (default: 10) */
    circuitBreakerThreshold: number;
    /** Circuit breaker recovery probe interval in ms (default: 30_000) */
    circuitBreakerProbeIntervalMs: number;
    /** Minimum work units to keep in the queue (default: 100) */
    minQueueDepth: number;
    /** Maximum age for unassigned work units in ms (default: 3_600_000) */
    workUnitMaxAgeMs: number;
    /** Fallback behavior when backing store is unavailable */
    fallbackBehavior: RateLimiterFallback;
    /** Difficulty escalation window in ms (default: 300_000) */
    escalationWindowMs: number;
    /** Cool-down period before difficulty decreases in ms (default: 600_000) */
    coolDownMs: number;
    /** Consecutive verification failures before security alert (default: 5) */
    securityAlertThreshold: number;
    /** Per-route rate limit overrides */
    routeOverrides?: Record<string, {
        rateLimit: number;
        windowMs: number;
    }>;
    /**
     * Optional callback to retrieve a client's reputation score (0.0 to 1.0).
     * 0.0 = unknown/no reputation, 1.0 = maximum reputation.
     * When provided, reputation influences the starting difficulty tier and escalation speed.
     * High-reputation clients start at a lower tier and escalate more slowly.
     */
    reputationProvider?: (clientId: string) => number | Promise<number>;
    /**
     * Reputation score threshold above which clients start at a reduced difficulty.
     * Clients with reputation >= this threshold start one tier lower than defaultDifficulty.
     * Default: 0.7
     */
    reputationDifficultyThreshold: number;
    /**
     * Reputation score threshold above which clients are exempt from PoUW challenges
     * and receive traditional rate limiting instead (429 + Retry-After).
     * Set to 1.1 (above max) to disable exemption. Default: 0.95
     */
    reputationExemptionThreshold: number;
    /**
     * Whether to award Joule credits for successfully completed work units.
     * Default: true
     */
    awardJouleCredits: boolean;
    /**
     * Micro-Joules (µJ) awarded per verified hash computation.
     * The total award for a work unit = this value × number of nodes computed.
     * Default: 100 (0.0001 Joules per hash)
     */
    microJoulesPerHash: number;
}
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