import { type ShortenOptions, type StoreAdapter } from '../types/types';
/**
 * URLShortener provides methods to shorten URLs and resolve aliases.
 * All methods are asynchronous and include robust error handling.
 */
export declare class URLShortener {
    private readonly baseDomain;
    private readonly store;
    private static readonly DEFAULT_CODE_LENGTH;
    private static readonly CHAR_SET;
    /**
     * Create a new URLShortener instance.
     * @param baseDomain - Domain used for returned shortened URLs (e.g., "https://sho.rt")
     * @param store - Redis-backed implementation of the StoreAdapter interface
     */
    constructor(baseDomain: string, store: StoreAdapter);
    /**
     * Shortens a long URL into a shorter one with an alias.
     * - Generates alias if not provided
     * - Validates the URL
     * - Checks for collisions
     * - Supports optional expiration time and override flag
     *
     * @param longUrl - The full, original URL to shorten
     * @param options - Optional config (alias, override, expiresIn)
     * @returns A Promise that resolves to the full shortened URL string
     */
    shorten(longUrl: string, options?: ShortenOptions): Promise<string>;
    /**
     * Resolves a short alias back to its original long URL.
     * - If alias doesn’t exist, returns null
     * - If alias exists but expired, deletes it and returns null
     *
     * @param alias - The short code to resolve
     * @returns The original long URL or null if not found/expired
     */
    resolve(alias: string): Promise<string | null>;
    /**
     * Helper method to validate a URL string using the built-in URL constructor.
     */
    private isValidUrl;
    /**
     * Generates a random alphanumeric code of the specified length.
     * Used for alias generation.
     */
    private generateCode;
}