sensor-server.js

const http = require('http');
const ws = require('ws');
const Sensor = require("./Sensor.js");

const httpPort = process.env.npm_config_http_port ?? 5004;
const serialport = process.env.npm_config_serial_port ?? 'COM3';

let server = http.createServer((req, res) => {
    res.writeHead(200);
});
server.listen(httpPort, () => console.log('Started server on', httpPort));
const wss = new ws.Server({server, path: '/fluorescence-sensor'});
wss.on('connection', handleConnection);
let connections = new Array;

let sensor = new Sensor();
sensor.init(serialport);
sensor.parser.on('data', handleData);
sensor.port.pause();

let counter = 0;
let measurement = Array(4095).fill(0);
let startTime = getCurrentDate();

function handleData(buffer) {
    let numbers = JSON.parse(JSON.stringify(buffer)).data;
    let result = getResult(numbers);
    if (result === -1) {
        return;
    }

    measurement[result]++;
    counter++;

    // Broadcast result every 100 counts
    if(counter % 100 === 0) {
        broadcast(JSON.stringify(measurement));
        console.log('Broadcasted data');
        console.log('Start time: ' + startTime);
        console.log('Current time: ' + getCurrentDate());
        console.log('Total counts: ' + counter);
    }
}

function getResult(numbers) {
    let result = -1;
    // MCA returns total 5 numbers, first three are 77, 67, 65 and last two are measurement result
    if (numbers[0] === 77 && numbers[1] === 67 && numbers[2] === 65) {
        result = numbers[3] * 256 + numbers[4];
    }
    if (numbers[1] === 77 && numbers[2] === 67 && numbers[3] === 65) {
        result = numbers[4] * 256 + numbers[0];
    }
    if (numbers[2] === 77 && numbers[3] === 67 && numbers[4] === 65) {
        result = numbers[0] * 256 + numbers[1];
    }
    if (numbers[3] === 77 && numbers[4] === 67 && numbers[0] === 65) {
        result = numbers[1] * 256 + numbers[2];
    }
    if (numbers[4] === 77 && numbers[0] === 67 && numbers[1] === 65) {
        result = numbers[2] * 256 + numbers[3];
    }
    if (result > 4095) {
        result = -1;
    }
    return result;
}

function broadcast(data) {
    for (connection in connections) {
      connections[connection].send(data);
    }
}

function handleConnection(client) {
    console.log('New connection');
    connections.push(client);

    client.on('error', error => {
        console.log(error);
    });

    client.on('message', (message) => {
        handleCommand(message);
    });

    client.on('close', () => {
        console.log('Connection closed');
        let position = connections.indexOf(client);
        connections.splice(position, 1);
    });
}

async function handleCommand(message) {
    message = message.toString();
    message = message.replace(/['"]+/g, '');

    if (message === 'resume') {
        console.log('Message ', message);
        sensor.resume();
    }
    if (message === 'reset') {
        console.log('Message ', message);
        measurement = Array(4095).fill(0);
        counter = 0;
    }
    if (message === 'pause') {
        console.log('Message ', message);
        sensor.pause();
    }
}

function getCurrentDate() {
    var today = new Date();
    var date = today.getFullYear() + '-' + ('0' + (today.getMonth() + 1)).slice(-2) + '-' + ('0' + today.getDate()).slice(-2);
    var time = ('0' + today.getHours()).slice(-2) + ":" + ('0' + today.getMinutes()).slice(-2) + ":" + ('0' + today.getSeconds()).slice(-2);
    return date + ' ' + time
}