chat.js

import React, { Component } from 'react'
import './chat.css'
import io from "socket.io-client";
import { connect } from 'react-redux';
import { saveAuthor } from '../../store/actions/authorAction'
import { saveMessages } from '../../store/actions/messageAction'
import { deleteAuthor } from '../../store/actions/deleteAuthorAction'
import { fetchUsers } from '../../store/actions/userAction'
 
class Chat extends Component {

    constructor(props){
        super(props);

        this.state = {
            message: '',
            date: '',
            author: '',
            messages: []
        };
        this.sendMessage = this.sendMessage.bind(this);
        this.addMessage = this.addMessage.bind(this);

        this.socket = io('localhost:5000');
        this.socket.emit('LOGGEDIN_USER', { user1: this.props.match.params.user});
    }

    componentDidMount() {
      this.props.fetchUsers();
      this.socket.on('RECEIVE_MESSAGE', data => {
          console.log(data);
          this.addMessage(data);
      });
      
      this.socket.emit('LOGGEDIN_USER', { user1: this.props.match.params.user});
    }

    sendMessage(event) {
      event.preventDefault();

      if(this.state.message !== ''){
        this.socket.emit('SEND_MESSAGE', {
            author: this.props.match.params.user,
            message: this.state.message,
            date: Date.now()
        });
      }
    };

    addMessage(data) {
      console.log(data);
      this.props.saveAuthor(this.props.match.params.user)
      this.props.saveMessages(data)
    
      this.setState({
        message: ''
      });
      
    };

    handleClick = (userName) => {
        this.socket.emit('GET_USER', { user2: userName });
    }

    render() {
        return (
        <div>
            <h2>Hello {this.props.match.params.user}</h2>
            <div className="container">
                <div id="chat">
                    <div className="card">
                        <div id="messages" className="card-block">
                            { this.props.messages && this.props.messages.map((message, index) => {

                                if(message.author === this.props.match.params.user){
                                    return (
                                        <div key={index} className="msgBoxRight"><p className="msgTextRight">{message.message}</p></div>
                                    )
                                }else{
                                    return (
                                        <div key={index} className="msgBoxLeft"><p className="msgTextLeft">{message.message}</p></div>
                                    ) 
                                }  
                            })}
                        </div>
                        <div id="feedback"></div>
                            <div className="row">
                            <div className="column">
                                <input id="inputmsg" type="text" placeholder="Enter Message...."
                                value={this.state.message} onChange={ev => this.setState({message: ev.target.value})}/>
                            </div>
                            <div className="column2">
                                <button id="send" className="button" onClick={this.sendMessage}>Send</button>
                            </div>
                            <div className="upload">
                                
                            </div>
                        </div>
                    </div>
                </div>
                <div className="userlist">
                <div>
                    <h3>All users:</h3>
                    {this.props.match.params.user ? this.props.allusers.map((val,index) => {
              
                    if(this.props.match.params.user === val.username){
                        return null
                    }else {
                        return <div className="usernameList" key={index}><button onClick={() => this.handleClick(val.username)} type="button">{val.username}</button></div>
                    }
                    }) : ""}
                </div>
                </div>
            </div>
        </div>
        )
    }
}


const mapStateToProps = state => ({
    author: state.chat.author,
    messages: state.chat.messages,
    allusers: state.allusers.items
})

export default connect (mapStateToProps, { saveAuthor, saveMessages, deleteAuthor, fetchUsers })(Chat);

server.js

const express = require('express');
const mongoose = require('mongoose');
const bodyParser = require('body-parser');
const socket = require('socket.io');
const path = require('path');
const message = require('./model/message');
const Conversation = require('./model/conversation');
const User = require('./model/user');

const app = express();
app.use(bodyParser.json());

const mongoURI = require('./config/keys').mongoURI;

mongoose.connect(mongoURI, {useNewUrlParser: true}, function (err,res) {

    if(err){
      console.log("There is error: " + err);
    }else{
      console.log("Connected to mongo database") 
    }

})

app.use(function(req, res, next) {
 //to allow cross domain requests to send cookie information.
res.header('Access-Control-Allow-Credentials', true);

// origin can not be '*' when crendentials are enabled. so need to set it to the request origin
res.header('Access-Control-Allow-Origin',  req.headers.origin);

// list of methods that are supported by the server
res.header('Access-Control-Allow-Methods','OPTIONS,GET,PUT,POST,DELETE');

res.header('Access-Control-Allow-Headers', 'X-Requested-With, X-HTTP-Method-Override, Content-Type, Accept, X-XSRF-TOKEN');

next();

});

app.post('/api/users', (req, res) => {

    const user = new User({
      _id: new mongoose.Types.ObjectId(),
      firstName: req.body.firstName,
      username: req.body.username,
      email: req.body.email
    });

    user.save().then( result => {
      console.log(result);
    }).catch( err => console.log(err))

    res.status(200).json({
      message: 'Handling POST req for users at api/users',
      userCreated: user
    });
    
})

app.get('/api/users', (req, res) => {

  User.find({}).then(eachOne => {
		
		res.json(eachOne);
	
  });

})

let db = mongoose.connection;

db.once('open', function() {
  console.log("Database is now connected");

  let io =  socket(server);

io.on("connection", function(socket){
  console.log("Socket Connection Established with ID :"+ socket.id)
  
  socket.on('disconnect', function(){
    console.log('User Disconnected');
  });

  let chat = db.collection('chat');
  let conversation = db.collection('conversation'); 
  let user1,user2;

      const waitForUser2 = new Promise((resolve, reject) => {
        socket.on("GET_USER", function (data) {
            console.log(data)
            resolve(data.user2);
        });
      });

      const waitForUser1 = new Promise((resolve, reject) => {
          socket.on("LOGGEDIN_USER", function (data) {
              resolve(data.user1);
          });
      });

      Promise.all([
        waitForUser1,
        waitForUser2
        ]).then(([user1, user2]) => {
            console.log("This is user1 " + user1);
            console.log("This is user2 " + user2);
            conversation.find({
                $and: [
                    {user1: user1},
                    {user2: user2}
                ]
            }).toArray(function (err, res) {
                if (err) {
                    throw err;
                }
                console.log(res);
                // Emit the messages
                io.emit("RECEIVE_MESSAGE", res);
            });
        });

      socket.on('SEND_MESSAGE', function(data){
        
        let author = data.author;
        let message = data.message;
        let date = data.date;

        // Check for name and message
        if(author !== '' || message !== '' || date !== ''){

            conversation.findOne({ $and :[{user1: user1}, {user2: user2}] }, function (err, existingConversation){
                if(existingConversation === null){
                  conversation.insert({user1: user1, user2: user2, conversation: [{author: author, message: message, date:date}] }, function (){
                    io.emit('RECEIVE_MESSAGE', [data]);
                  })
                }else{
                  conversation.update({user1: user1, user2: user2}, 
                    {$push: {conversation : { author : author ,message : message,date : date }}  })
                }
            })


        }
      });
  }) 
	
});
  

const port = 5000;

let server = app.listen(5000, function(){
  console.log('server is running on port 5000')
});