server.js~

//camera server idea:
//https://www.youtube.com/watch?v=qexy4Ph66JE

var express = require('express');//host public site files
const fs = require('fs');//used for reading files
const cv = require('opencv4nodejs');
var app = express();
var PORT = 3000;
var server = app.listen(PORT);
var settingsObject;
var cams = [];
var camindex = 0;

for(let i = 0; i < 25; i++){
  try{
    let wCap = new cv.VideoCapture(i);
    console.log('Yes! camera found at ' + i);
    wCap.set(cv.CAP_PROP_FRAME_WIDTH,400);
    wCap.set(cv.CAP_PROP_FRAME_HEIGHT,400);
    wCap.set(cv.CAP_PROP_BUFFERSIZE, 4);
    cams.push(wCap);
  }
  catch{
    // console.log('camera not found at ' + i);
  }
}
console.log(cams.length);
app.use(express.static('public'));

console.log("server running on port: " + PORT)

var socket = require('socket.io');
var io = socket(server);

io.sockets.on('connection', function(socket){
  console.log('made connection');
  //get settings from json and send to client
  fs.readFile('settings.json', (err, data) => {
    if (err) throw err;
    settingsObject = JSON.parse(data);
    socket.emit('settings',settingsObject);
    console.log('current settings on server: ' + JSON.stringify(settingsObject));
  });

  //widgets client to server
  socket.on('WCTS', function(data){
    try{
      settingsObject['widgets'] = data;
    }
    catch(e){
      console.log(e);
    }
    fs.writeFileSync('settings.json', JSON.stringify(settingsObject));
    console.log('recieved updated settings from client');
  });

  //ROS client to server
  socket.on('ROSCTS', function(data){
    settingsObject['widgets'] = data;
    var topic = data.topic;
    delete data.topic;
    console.log('Publish Ros Message on topic ' + topic + ', data = ' + JSON.stringify(data))
  });
  socket.on('setCam', function(data){
    camindex = data;
    console.log(`Change Camera to ${data}`);
  });
});

//video server
// var counter = 0;
let frame, image;
function sendCamStream(){
  try{
    frame = cams[camindex].read();
    image = cv.imencode('.jpg',frame).toString('base64');
    io.emit('image',image);
  }
  catch(e){
      console.log(e);
  }
  // io.emit('telem',counter);
  // counter++[];
  setTimeout(sendCamStream,70);
}
sendCamStream();