index.js

const express = require('express');
const http = require('http');
const path = require('path');
const {Server} = require('socket.io');
const port = 4000;
const sqlite3 = require('sqlite3');
const { open } = require('sqlite');

//databases
async function main(){
    const db = await open({
    filename: 'chat.db',
    driver: sqlite3.Database
  });

  // create our 'messages' table (you can ignore the 'client_offset' column for now)
  await db.exec(`
  CREATE TABLE IF NOT EXISTS messages (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      sender TEXT,
      receiver TEXT,
      content TEXT
  );
`);

//initialization
const app = express();
const myserver = http.createServer(app);
const io = new Server(myserver);

const users = {};



//middlewares
app.use(express.urlencoded({extended : false})); 
app.use(express.json());
app.use(express.static('templates'));
app.use(express.static('public'));

//routes
app.get('/', (req, res)=>{
    return res.sendFile(path.join(__dirname, 'templates/message.html'));
})

io.on('connection', async (socket)=>{
    console.log('a user connected');
    socket.on('disconnect', ()=>{
        if (socket.name) {
            delete users[socket.name];
        }
        console.log('user disconnected');
    })
    socket.on('chat message', async ({ to, message }) => {
        result = await db.run(
            'INSERT INTO messages (sender, receiver, content) VALUES (?, ?, ?)',
            [socket.name, to, message]
        );
        const targetSocketId = users[to];
        if (targetSocketId) {
            io.to(targetSocketId).emit('chat message', {
                from: socket.name,
                to: to,
                message,
                serveroffset: result.lastID,

            });
        } else {
             socket.emit('chat message', {
                from: 'System',
                message: `User "${to}" is offline. Message saved.`,
            });
        }
    });
    socket.on('registration', async (name) => {
    users[name] = socket.id;
    socket.name = name;
    console.log(`${name} registered with ID ${socket.id}`);

    try {
        // Fetch messages where the user is the receiver or sender
        const messages = await db.all(
            `SELECT sender, receiver, content FROM messages
             WHERE sender = ? OR receiver = ?
             ORDER BY id ASC`,
            [name, name]
        );

        for (const msg of messages) {
            // Determine the direction: 'sent' or 'received'
            const direction = msg.sender === name ? 'sent' : 'received';

            // Emit the message with direction
            socket.emit('chat message', {
                from: msg.sender,
                to: msg.receiver,
                message: msg.content,
                serveroffset: msg.id // if needed
            });
        }
    } catch (err) {
        console.error('Error fetching messages:', err);
    }
});

})


//setting up a http server
myserver.listen(port, ()=>{
    console.log('server has started listening');

})
}

main();