interface StorageAdapter {
    get(key: string): Promise<string | null>;
    set(key: string, value: string, ttlMs: number): Promise<void>;
    increment(key: string, ttlMs: number): Promise<number>;
    delete(key: string): Promise<void>;
}
type DurationString = `${number}${"s" | "m" | "h" | "d"}`;
type RateString = `${number}/${"s" | "m" | "h"}`;
type IdentifierFn = (request: Request) => string | Promise<string>;
interface AlgorithmState {
    allowed: boolean;
    remaining: number;
    reset: number;
}
interface RateLimitAlgorithm {
    kind: "sliding-window" | "fixed-window" | "token-bucket" | "leaky-bucket";
    limit: number;
    windowMs: number;
    evaluate(storage: StorageAdapter, key: string, nowMs: number): Promise<AlgorithmState>;
}
interface RateLimitTier {
    name: string;
    algorithm: RateLimitAlgorithm;
}
interface RateLimitResult {
    success: boolean;
    status: 200 | 429;
    reason: "ok" | "rate_limited" | "storage_error";
    headers: Headers;
    meta: {
        remaining: number;
        reset: number;
        limit: number;
        tier: string | null;
    };
}
interface RateLimitConfig {
    storage: StorageAdapter;
    algorithm?: RateLimitAlgorithm;
    tiers?: RateLimitTier[];
    identifier?: IdentifierFn;
    prefix?: string;
    failOpen?: boolean;
}
interface RateLimiter {
    check(request: Request): Promise<RateLimitResult>;
}

export type { DurationString as D, RateLimitAlgorithm as R, StorageAdapter as S, RateLimitConfig as a, RateLimitResult as b, RateLimiter as c, RateString as d };