Nativefier/src/infer/inferUserAgent.js

import axios from 'axios';
import _ from 'lodash';

const ELECTRON_VERSIONS_URL = 'https://atom.io/download/atom-shell/index.json';
const DEFAULT_CHROME_VERSION = '47.0.2526.73';

function getChromeVersionForElectronVersion(electronVersion, url = ELECTRON_VERSIONS_URL) {

    return axios.get(url, {timeout: 5000})
        .then(response => {
            if (response.status !== 200) {
                throw `Bad request: Status code ${response.status}`;
            }

            const data = response.data;
            const electronVersionToChromeVersion = _.zipObject(data.map(d => d.version), data.map(d => d.chrome));

            if (!(electronVersion in electronVersionToChromeVersion)) {
                throw `Electron version '${ electronVersion }' not found in retrieved version list!`;
            }

            return electronVersionToChromeVersion[electronVersion];
        });
}

export function getUserAgentString(chromeVersion, platform) {
    let userAgent;
    switch (platform) {
        case 'darwin':
            userAgent = `Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/${ chromeVersion } Safari/537.36`;
            break;
        case 'win32':
            userAgent = `Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/${ chromeVersion } Safari/537.36`;
            break;
        case 'linux':
            userAgent = `Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/${ chromeVersion } Safari/537.36`;
            break;
        default:
            throw 'Error invalid platform specified to getUserAgentString()';
    }
    return userAgent;
}

function inferUserAgent(electronVersion, platform, url = ELECTRON_VERSIONS_URL) {
    return getChromeVersionForElectronVersion(electronVersion, url)
        .then(chromeVersion => {
            return getUserAgentString(chromeVersion, platform);
        })
        .catch(() => {
            // console.warn(`Unable to infer chrome version for user agent, using ${DEFAULT_CHROME_VERSION}`);
            return getUserAgentString(DEFAULT_CHROME_VERSION, platform);
        });
}

export default inferUserAgent;