import type { CustomOptions, CustomValidate } from "../custom/index.ts";
/**
 * @credits
 * [UUID](https://en.wikipedia.org/wiki/Universally_unique_identifier) regex.
 * [Valibot](https://github.com/fabian-hiller/valibot/blob/c3de9371c2cfa4e126734ddf0e2ab1de98e8a6ef/library/src/regex.ts#L166)
 */
export declare const GUID_REGEX: RegExp;
export declare const EMPTY_GUID: string;
/**
 * Determines whether the input is a GUID.
 *
 * @param input The value to check.
 * @param validate Additional validation to run against the input if it is a GUID. Default is `undefined`.
 * @returns `true` if the input is a GUID, `false` otherwise.
 */
export declare function isGuid(input: unknown, validate?: CustomValidate<string>): input is string;
export type GuidOptions = Omit<CustomOptions<string>, "typecheck">;
/**
 * Verifies that the input is a GUID, and returns it.
 * If the input is not a GUID, the fallback value is returned.
 *
 * @param input The value to check.
 * @param fallback The value to return if the input is not a GUID. Default is `null`.
 * @returns The GUID value of the input, or the fallback if the input is not a GUID.
 *
 * @remarks
 * This function will clean the input by removing any surrounding quotes or braces.
 *
 * @example
 * ```ts
 * guid("bf9ae065-a590-41e5-ac53-386c65f565db", null); // "bf9ae065-a590-41e5-ac53-386c65f565db"
 * guid("{bf9ae065-a590-41e5-ac53-386c65f565db}", null); // "bf9ae065-a590-41e5-ac53-386c65f565db"
 * guid("\"bf9ae065-a590-41e5-ac53-386c65f565db\"", null); // "bf9ae065-a590-41e5-ac53-386c65f565db"
 * ```
 */
export declare function guid(input: unknown, fallback: string, options?: GuidOptions): string;
export declare function guid(input: unknown, fallback?: string | null | undefined, options?: GuidOptions): string | null;