import { Request } from "express";
import { TokenExtractor } from "./types";
/**
 * Constructs a token extractor function with the given authentication scheme
 * and authentication header name.
 *
 * @param authScheme
 * @param authHeaderName
 * @returns
 */
export declare const fromAuthHeaderWithScheme: (authHeaderName: string, authScheme: string) => TokenExtractor;
export declare const fromHeader: (paramName: string) => TokenExtractor;
export declare const fromBodyField: (paramName: string) => TokenExtractor;
export declare const fromQueryParam: (paramName: string) => TokenExtractor;
/**
 * A ready made token extractor for 'Authorization' header
 * with 'Bearer' scheme. This is shorthand for
 *
 * @example
 * fromAuthHeaderWithScheme('authorization', 'bearer')
 *
 * @returns Token extractor for bearer authorization scheme
 */
export declare const fromAuthHeaderAsBearerToken: () => TokenExtractor;
/**
 * Takes in an array of valid extractors and returns an extractor that runs all the given extractors
 * against the request and tries to find a token. Returns the first token found. Extractors are
 * run in the order they are given in the array.
 * @param extractors An array of valid extractor functions
 * @returns token as string if some of the extractors finds a token, otherwise null
 *
 * @example
 * fromExtractors([
 *   fromAuthHeaderAsBearerToken(),
 *   fromAuthHeaderWithScheme('x-authorization', 'bearer'),
 *   fromBodyField('token')
 * ])
 */
export declare const fromExtractors: (extractors: TokenExtractor[]) => (request: Request) => string | null;