import type { IncomingHttpHeaders } from 'node:http';
import { Route } from './router/route.js';
import { BriskRoute } from './router/brisk.js';
import { RouteGroup } from './router/group.js';
import type { RouteJSON } from './types/route.js';
import { RouteResource } from './router/resource.js';
/**
 * Validates that a URL is safe to use as a redirect destination.
 *
 * - Relative URLs must start with `/` and not be protocol-relative (`//`)
 * - Absolute URLs must parse successfully and their host must match
 *   `currentHost` or be listed in `allowedHosts`
 *
 * When `currentHost` and `allowedHosts` are omitted, absolute URLs
 * are accepted as long as they parse successfully.
 *
 * @param url - The URL to validate
 * @param currentHost - The current request's Host header value
 * @param allowedHosts - Array of additionally allowed hosts
 */
export declare function isValidRedirectUrl(url: string, currentHost?: string, allowedHosts?: string[]): boolean;
/**
 * Returns the previous URL from the request's `Referer` header,
 * validated against the request's `Host` header and an optional
 * list of allowed hosts using `isValidRedirectUrl`.
 *
 * @param headers - The incoming request headers
 * @param allowedHosts - Array of allowed referrer hosts
 * @param fallback - URL to return when referrer is missing or invalid
 */
export declare function getPreviousUrl(headers: IncomingHttpHeaders, allowedHosts: string[], fallback: string): string;
/**
 * Makes input string consistent by having only the starting
 * slash
 */
export declare function dropSlash(input: string): string;
/**
 * Returns a flat list of routes from the route groups and resources
 */
export declare function toRoutesJSON(routes: (RouteGroup | Route | RouteResource | BriskRoute)[]): RouteJSON[];
/**
 * Helper to know if the remote address should
 * be trusted.
 */
export declare function trustProxy(remoteAddress: string, proxyFn: (addr: string, distance: number) => boolean): boolean;
/**
 * Parses a range expression to an object filled with the range
 */
export declare function parseRange<T>(range: string, value: T): Record<number, T>;