import { ExtensionKey } from "../http/index.js";
import type { HttpLayer } from "../layer/index.js";
import type { HttpService } from "../service/index.js";
/**
 * Extension key which holds the client IP.
 */
export declare const CLIENT_IP: ExtensionKey<string>;
/**
 * A layer that extracts the client IP address from the request.
 *
 * If `trustProxy` is set to true, the `x-forwarded-for` header is considered.
 *
 * The client IP can later be accessed through the {@link CLIENT_IP} extension
 * key.
 *
 * @example
 * ```ts
 * import { SetClientIpLayer } from "@taxum/core/middleware/client-ip";
 * import { m, Router } from "@taxum/core/routing";
 *
 * const router = new Router()
 *     .route("/", m.get(() => "Hello World))
 *     .layer(new SetClientIpLayer());
 * ```
 */
export declare class SetClientIpLayer implements HttpLayer {
    private readonly trustProxy;
    /**
     * Creates a new {@link SetClientIpLayer}.
     *
     * @param trustProxy - whether to trust proxy headers.
     */
    constructor(trustProxy?: boolean);
    layer(inner: HttpService): HttpService;
}