server.js

const express = require('express')
const http = require('http')
const fs = require('fs')

const webpack = require('webpack')
const webpackDevMiddleware = require('webpack-dev-middleware')
const webpackConfig = require('./webpack.config.js')

const app = express()
const server = http.createServer(app)

app.use(webpackDevMiddleware(webpack(webpackConfig)))

function readFiles(dirname, onFileContent, onError) {
	fs.readdir(dirname, function(err, filenames) {
		if (err) {
			onError(err);
			return;
		}
		filenames.forEach(function(filename) {
			fs.readFile(dirname + filename, 'utf-8', function(err, content) {
				if (err) {
					onError(err);
					return;
				}
				onFileContent(filename, content);
			});
		});
	});
}

let data = [];
readFiles('raw-data/', function(filename, content) {
	let waypointStrArr = content.split('\n')
    waypointStrArr.pop()
    let waypoints = []
	waypointStrArr.forEach(waypointStr => {
        let waypointArr = waypointStr.split('	')
        let waypointObj = {
            time_stamp: waypointArr[0],
            lat: waypointArr[1],
            lng: waypointArr[2],
            alt: waypointArr[3]
        }
        waypoints.push(waypointObj)
	})
    let splitName = filename.split('_')
    console.log('splitName', splitName)
    data.push({
        device_id: splitName[0],
        session_id: splitName[1].substr(0, splitName[1].indexOf('.')),
        waypoints: waypoints
    })

}, function(err) {
	throw err;
});

function consolidateData (data) {
    let devices = data
        .map(item => item['device_id'])
        .filter((el, i, arr) => arr.indexOf(el) === i)
     
    return devices
        .map(device => data.filter(session => device === session['device_id']))
        .map(device => { 
            return {
                device_id: device[0]['device_id'],
                sessions: device.reduce((crt, nxt) => {
                    return crt.concat([{
                        session_id: nxt['session_id'],
                        waypoints: nxt['waypoints']
                    }])
                }, [])
            }
        })
}

app.get('/click', (req, res) => {
    let formatedData = consolidateData(data)
    res.json(formatedData)
})

app.use(express.static(__dirname + '/public'))

server.listen(3000, () => console.log('Listening on 3000'))