Refactor server side code

index.js

-var config = require('./config');
-var express = require('express');
-var app = express();
-var server = require('http').createServer(app);
-var io = require('socket.io')(server);
-var path = require('path');
-var fs = require('fs')
-var port = config.port || 3000;
-var filename = config.filename || 'knowledge.json';
-var filepath = path.join('/tmp', filename);
-
-//asking server to listen to 3000
+// const fs = require('fs');
+
+const express = require('express');
+
+const app = express();
+const server = require('http').createServer(app);
+const io = require('socket.io')(server);
+const path = require('path');
+
+const config = require('./config');
+
+const port = config.port || 3000;
+// const filename = config.filename || 'knowledge.json';
+// const filepath = path.join('/tmp', filename);
+
+// asking server to listen to 3000
 server.listen(port, () => {
-    console.log('Server listening at port %d', port);
+  console.log('Server listening at port %d', port);
 });
 
-//assign static path to public folder
+// assign static path to public folder
 app.use(express.static(path.join(__dirname, '/public/')));
 
 app.get('/mod_en', (req, res) => {
-    res.sendFile(__dirname + '/public/mod.html');
+  res.sendFile(path.join(__dirname, '/public/mod.html'));
 });
 
 app.get('/', (req, res) => {
-    res.sendFile(__dirname + '/index.html');
+  res.sendFile(path.join(__dirname, '/index.html'));
 });
 
-const user_en = io.of('/user_en');
-const mod_en = io.of('/mod_en');
+const enUserNamespace = io.of('/user_en');
+const enModNamespace = io.of('/mod_en'); // set auth
 
-const leafids = [];
-for (let i=7; i<332; i++) {
-    leafID = "path" + i.toString();
-    i += 3;
-    leafids.push(leafID);
+const leafIds = [];
+for (let i = 7; i < 332; i += 1) {
+  const leafId = `path${i.toString()}`;
+  i += 3;
+  leafIds.push(leafId);
 }
 
-var leavesdata = {}; //object of structure {socketid1: {leaftext:"text",leafid:"leafid"}, ...}
-var leafno = 0;
-var socketids = [];
-
-user_en.on('connection', (socket) => {
-    let id = socket.id;
-    socket.emit('leaves data', leavesdata);
-
-    socket.on('leaf text', (leafdata) => {
-        console.log(leafdata);
-        if(!socketids.includes(id)) { //checks if socketid is already assigned with leafid
-            socketids.push(id);
-            leafdata["leafid"] = leafids[leafno]; //if not assign leafid
-            leafno = leafno+1;
-            leavesdata[id] = leafdata;
-        } else {
-            leavesdata[id]["leaftext"] = leafdata["leaftext"]; //if yes update the message
-            leafdata = leavesdata[id];
-        };
-        console.log(leafdata);
-        user_en.emit('leaf data', leafdata);
-        mod_en.emit('leaves data', leavesdata);
-                console.log(leavesdata);
-
-        fs.writeFileSync(filepath, JSON.stringify(leavesdata), function(err) {
-            if(err) return console.error(err);
-        });
-    });
+const leavesData = {};
+// object of structure {socketid1: {userName:"", leafText:"",leafId:""}, ...}
+
+const notifyEveryone = function notifyUserStateChangeToEveryone() {
+  enUserNamespace.emit('leaves data', leavesData);
+  enModNamespace.emit('leaves data', leavesData);
+};
+
+const updateLeavesData = function udateLeavesDataAndNotify(socketId, leafData) {
+  leavesData[socketId] = { ...leavesData[socketId], ...leafData };
+  notifyEveryone();
+};
+
+enUserNamespace.on('connection', (socket) => {
+  const socketId = socket.id;
+  leavesData[socketId] = { userName: socket.handshake.query.userName }; // user
+  socket.emit('leaves data', leavesData);
+
+  socket.on('leaf text', (leafText) => {
+    const leafData = {};
+    leafData.leafText = leafText;
+    if (!(leavesData[socketId].leafText)) {
+      leafData.leafNo = leafIds.shift();
+    }
+
+    updateLeavesData(socketId, leafData);
+
+    // fs.writeFileSync(filepath, JSON.stringify(leavesData), (err) => {
+    //   if (err) return console.error(err);
+    // });
+  });
 });
 
-mod_en.on('connection', (socket) => {
-    io.of('mod').emit('leaves data', leavesdata);
-    socket.on('message delete', id => {
-        console.log(leavesdata);
-        mod_en.emit('delete text', leavesdata[id]["leafid"]);
-        delete leavesdata[id];
-        const index = socketids.indexOf(id);
-        if (index > -1) {
-            socketids.splice(index, 1);
-        }
-        io.of('mod').emit('leaves data', leavesdata);
-    });
-    socket.on('save exit', filename => {
-        console.log("nsdiisd");
-        leavesdata = {};
-        leafno = 0;
-        socketids = [];
-        io.emit('leaves data', leavesdata);
-        io.of('mod').emit('leaves data', leavesdata);
+enModNamespace.on('connection', (socket) => {
+  enModNamespace.emit('leaves data', leavesData);
+  socket.on('leaf delete', (socketId) => {
+    leafIds.push(leavesData[socketId].leafId);
+    delete leavesData[socketId].leafText;
+    delete leavesData[socketId].leafId;
+    notifyEveryone();
+  });
+  socket.on('leaf update', (leafData) => updateLeavesData(socket.id, leafData));
+  socket.on('user delete', (socketId) => {
+    leafIds.push(leavesData[socketId].leafId);
+    enUserNamespace.sockets.get(socketId).disconnect();
+    delete leavesData[socketId];
+    notifyEveryone();
+  });
+  socket.on('save exit', () => { // save data into file
+    enUserNamespace.disconnectSockets();
+    Object.keys(leavesData).forEach((key) => {
+      delete leavesData[key];
     });
+    notifyEveryone();
+  });
 });