import { ILogEntry, ILogFilterOptions, LogFilter } from "@spinajs/log-common";
/**
 * Options for {@link RateLimitFilter}.
 */
export interface IRateLimitFilterOptions extends ILogFilterOptions {
    /** Max entries kept per window. Required. */
    limit: number;
    /** Fixed window length in SECONDS. Required. */
    intervalSeconds: number;
    /** Variable field used to bucket the limit ( eg. per-logger ). Global if unset. */
    key?: string;
}
interface IWindowRecord {
    count: number;
    windowStart: number;
}
/**
 * Fixed-window rate limiter. Keeps at most `limit` entries per `intervalSeconds`
 * window, bucketed by `entry.Variables[key]` when `key` is given ( else a single
 * global bucket ). Overflow entries within a window are DROPPED; the counter
 * resets when the window elapses. The bucket map is self-pruning ( stale windows
 * dropped on access ) so memory stays bounded. Clock is injectable for tests.
 */
export declare class RateLimitFilter extends LogFilter {
    protected now: () => number;
    protected limit: number;
    protected intervalMs: number;
    protected keyField?: string;
    protected windows: Map<string, IWindowRecord>;
    constructor(options?: IRateLimitFilterOptions, now?: () => number);
    protected keyOf(entry: ILogEntry): string;
    apply(entry: ILogEntry): ILogEntry | null;
    /** Drops windows whose interval has fully elapsed so the map stays bounded. */
    protected prune(now: number): void;
}
export {};
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