handy batch download of 3d-tiles tileset.json from bim360 (using batchPromises for threads)

pull-tiles-offline.mjs

// PURPOSE: download 3d-tiles files from BIM360, to local drive
// INSTALL: npm install node-fetch
// RUN: add your BIM360 access-token and the base url, then type 
// > node pull-tiles-offline.mjs myOutputFolder

import fetch from 'node-fetch';
import fs from 'fs';
import util from 'util';
import stream from 'stream';

const token = "eyJh...DV-OCgxNcjnIp-3bNk7Sc8ZE..ISKykb5Q";
const URN = "dXJuOm...yc2lvbj0x";
const url = `https://cdn.derivative.autodesk.com/derivativeservice/v2/derivatives/urn:adsk.viewing:fs.file:${URN}/output/`
const NUMTHREADS = 64;

const uris = ["tileset.json"];

//-----------UTILS
function recurveNode(node) {
	uris.push(node.content.uri);
	for (var n in node.children) {
		recurveNode(node.children[n]);
	};
	return node;
}

// https://github.com/Nicktho/batch-promises/blob/3b73b218b165b974d116b2cc5a7720895af489db/index.js#L4
async function batchPromises(batchSize, collection, callback) {
	const arr = await Promise.resolve(collection);
	return arr
		.map((_, i) => (i % batchSize ? [] : arr.slice(i, i + batchSize)))
		.map((group) => (res) => Promise.all(group.map(callback)).then((r) => res.concat(r)))
		.reduce((chain, work) => chain.then(work), Promise.resolve([]));
}

// download each tile
const streamPipeline = util.promisify(stream.pipeline);

//end----------- UTILS


async function downloadFile (url, szFile, outfolder) {
	console.log(`downloading... ${szFile}`)
	const response = await fetch(url + szFile, { headers:{ 'Authorization':`Bearer ${token}`}});
	if (!response.ok) return;//skip it... throw new Error(`unexpected response ${response.statusText}`)
	await streamPipeline(response.body, fs.createWriteStream(`${outfolder}/${szFile}`));
}

async function main (outfolder) {
	fs.promises.mkdir(outfolder, { recursive: true }); // make destination folder, if not exist
	// download tileset.json file
	const jsonTileset = await (await fetch(url + "tileset.json", { headers:{ 'Authorization':`Bearer ${token}`} })).json();
  // decode all it's uri's 
	recurveNode(jsonTileset.root);

	// now wget those uri's, using 64 threads
	console.log(`downloading ${uris.length} files`)
	await batchPromises(NUMTHREADS, uris, (szFile) => 
		downloadFile(url, szFile, outfolder 
	))
};

await main(process.argv.slice(2)[0] || 'result');
console.log('done');