@aws-amplify/core/src/clients/middleware/userAgent/middleware.ts

Core category of aws-amplify

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0

import { HttpRequest, HttpResponse } from '../../types/http';
import { Middleware } from '../../types/core';

export interface UserAgentOptions {
	userAgentHeader?: string;
	userAgentValue?: string;
}

/**
 * Middleware injects user agent string to specified header(default to 'x-amz-user-agent'),
 * if the header is not set already.
 *
 * TODO: incorporate new user agent design
 */
export const userAgentMiddleware: Middleware<
	HttpRequest,
	HttpResponse,
	UserAgentOptions
> =
	({
		userAgentHeader = 'x-amz-user-agent',
		userAgentValue = '',
	}: UserAgentOptions) =>
	next => {
		return async function userAgentMiddleware(request) {
			if (userAgentValue.trim().length === 0) {
				const result = await next(request);
				return result;
			} else {
				const headerName = userAgentHeader.toLowerCase();
				request.headers[headerName] = request.headers[headerName]
					? `${request.headers[headerName]} ${userAgentValue}`
					: userAgentValue;
				const response = await next(request);
				return response;
			}
		};
	};