binoculars/aws-sigv4

#!/usr/bin/env node

'use strict';

const fs = require('fs');
const https = require('https');
const path = require('path');
const unzip = require('unzip');
const url = require('url');

const fixturesDir = path.join(__dirname, '..', 'test', 'fixtures');

function promisify(func) {
    return function() {
        const args = [].slice.call(arguments);

        return new Promise((resolve, reject) => {
            args.push((err, data) =>
                err ? reject(err) : resolve(data)
            );

            func.apply(this, args);
        });
    }
}

const exists = promisify(fs.stat);
const readFile = promisify(fs.readFile);
const unlink = promisify(fs.unlink);
const writeFile = promisify(fs.writeFile);

function request(options) {
    return new Promise((resolve, reject) => {
        const req = https.request(options, res => {
            let body = '';
            res.on('data', chunk => body += chunk);
            res.on('end', () => resolve(
                Object.assign(res, {body})
            ));
        });

        req.on('error', reject);
        req.end();
    });
}

function getRemoteETag(parsedUrl) {
    const options = Object.assign(
        {
            method: 'HEAD'
        },
        parsedUrl
    );

    return request(options)
        .then(res => res.headers.etag);
}

function downloadAndUnzipFile(parsedUrl, path) {
    return new Promise((resolve, reject) => {
        const req = https.request(parsedUrl, res => {
            res.pipe(unzip.Extract({path}));
            res.on('end', () => resolve(res));
        });

        req.on('error', reject);
        req.end();
    });
}

// Ref: https://docs.aws.amazon.com/general/latest/gr/signature-v4-test-suite.html
const fixtureName = 'aws4_testsuite';
const fixtureURL = 'https://docs.aws.amazon.com/general/latest/gr/samples/aws-sig-v4-test-suite.zip';

const fixtureDir = path.join(fixturesDir, fixtureName);
const fixtureEtagFile = path.join(fixturesDir, `${fixtureName}.ETag`);
const fixtureUrlParsed = url.parse(fixtureURL);

const files = [
    fixtureDir,
    fixtureEtagFile
];

return Promise.all(files.map(file => exists(file)))
    .catch(() => Promise.reject('ETag or Fixtures directory does not exist'))
    .then(() => Promise.all([
        readFile(fixtureEtagFile, {encoding: 'utf8'}),
        getRemoteETag(fixtureUrlParsed)
    ]))
    .then(arr => arr[0] !== arr[1] ?
        Promise.reject('Invalid cached ETag') :
        'Valid ETag, using cached version'
    )
    .then(console.log)
    .catch(err => {
        console.error(`${err}, downloading new version`);
        return Promise.all(files.map(file => unlink(file)))
            .catch(() => {})
            .then(() => downloadAndUnzipFile(fixtureUrlParsed, fixtureDir))
            .then(res => writeFile(fixtureEtagFile, res.headers.etag));
    });