a simple and incomplete wget for node

wget.js

const fs = require('fs');
const fetch = require('node-fetch');
const progress = require('progress-stream');
const crypto = require('crypto');

function wgetNext(url, progStrem, hash, tracking, retry) {
    console.log(`bt-wgetNext length=${tracking.length} pipedLength=${tracking.pipedLength} retry=${retry}`);
    const options =  {
        headers: {
            Range: `bytes=${tracking.pipedLength}-${tracking.length}`
        }
    }; 
    return fetch(url,options)
    .then((res) => {
        console.log('wgetNext fetch res ', res);
        if (!res.ok) { 
            throw new fetch.FetchError(`request failed with ${res.status}`, 'request'); 
        }
        const srcStream = res.body;
        srcStream.on('data', chunk => {
            tracking.pipedLength = tracking.pipedLength + chunk.length;
            hash.update(chunk);
        });
        srcStream.on('error', err => reject(err));
        srcStream.pipe(progStrem,{ end: false }); 
        srcStream.on('end', () => {
            console.log(`srcStream ${retry} end length=${tracking.length} pipedLength=${tracking.pipedLength}`);
            if(tracking.pipedLength >= tracking.length) {
                progStrem.end();
                return;    
            }    
            return wgetNext(url, progStrem, hash, tracking, retry + 1);
        });    
    })
    .catch((err) => {
        console.log(`wgetNext catch`, err);
    });
}

function wget(url, filename, onProgress) {
    console.log(`bt-wget ${url} => ${filename}`);
    return fetch(url)
    .then((res) => {
        if (!res.ok) { 
            throw new fetch.FetchError(`request failed with ${res.status}`, 'request'); 
        }
        const hash = crypto.createHash('sha256');
        const length = res.headers.get('content-length');
        const destStream = fs.createWriteStream(filename);
        const srcStream = res.body;
        const progStream = progress({time:100, length:length }, onProgress);
        const tracking = {length, pipedLength:0 };
        return new Promise((resolve, reject) => {
            srcStream.on('data', chunk => {
                tracking.pipedLength = tracking.pipedLength + chunk.length;
                hash.update(chunk);
            });
            srcStream.on('error', err => reject(err));
		    destStream.on('error', err => reject(err));
            destStream.on('finish', () => {
                console.log(`destStream finish length=${tracking.length} pipedLength=${tracking.pipedLength}`);
                resolve({ filename, hash: hash.digest('hex') })
            });            
            srcStream.on('end', () => {
                console.log(`srcStream end length=${tracking.length} pipedLength=${tracking.pipedLength}`);
                if(tracking.pipedLength >= tracking.length) {
                    progStream.end();
                    return;    
                }    
                wgetNext(url, progStream, hash, tracking, 1)
                .catch((err) => {
                    reject(err);    
                })
            });          
            srcStream.pipe(progStream,{ end: false }).pipe(destStream);
        })
    });
}


module.exports = wget;