const express = require('express');
const path = require('path');
const http = require('http');
const fs = require('fs');
const { WebSocketServer } = require('ws');
const { v4: uuidv4 } = require('uuid');
const { defaultState } = require('./defaultState');

const app = express();
const port = process.env.PORT || 3001;
const subfolder = '/ag-beats';
const distPath = path.join(__dirname, 'dist');

// --- Helper function for random colors ---
const COLORS = ['#F94144', '#F3722C', '#F8961E', '#F9C74F', '#90BE6D', '#43AA8B', '#4D908E', '#577590', '#277DA1'];
const getRandomColor = () => COLORS[Math.floor(Math.random() * COLORS.length)];

// --- HTTP and Static Server Setup ---
app.use(subfolder, express.static(distPath));
app.get(subfolder + '/*', (req, res) => {
    res.sendFile(path.join(distPath, 'index.html'));
});
app.get('/', (req, res) => {
    res.redirect(subfolder);
});

const httpServer = http.createServer(app);

// --- WebSocket Server ---
const wss = new WebSocketServer({ path: '/ag-beats', server: httpServer });
const sessions = new Map();

wss.on('connection', (ws, req) => {
    const url = new URL(req.url, `http://${req.headers.host}`);
    const sessionId = url.searchParams.get('sessionId');
    const clientId = uuidv4();
    const clientColor = getRandomColor();

    if (!sessionId) {
        return ws.close(1008, 'Session ID required');
    }

    if (!sessions.has(sessionId)) {
        // Deep copy the default state to ensure each session has its own mutable state
        const initialState = JSON.parse(JSON.stringify(defaultState));
        sessions.set(sessionId, { clients: new Map(), state: initialState });
    }
    const session = sessions.get(sessionId);
    session.clients.set(clientId, { ws, color: clientColor });

    console.log(`Client ${clientId} connected to session ${sessionId}`);

    // Welcome message with client's own ID
    ws.send(JSON.stringify({
        type: 'welcome',
        payload: {
            clientId,
        }
    }));

    // Inform all clients about the current users
    const userList = Array.from(session.clients.entries()).map(([id, { color }]) => ({ id, color }));
    const userUpdateMessage = JSON.stringify({ type: 'user-update', payload: { users: userList } });
    session.clients.forEach(({ ws: clientWs }) => clientWs.send(userUpdateMessage));


    ws.on('message', (messageBuffer) => {
        const message = messageBuffer.toString();
        const parsedMessage = JSON.parse(message);

        // Handle state requests
        if (parsedMessage.type === 'get_state') {
            ws.send(JSON.stringify({
                type: 'session_state',
                payload: session.state
            }));
            return;
        }

        // Add sender's ID to the message for client-side identification
        const messageToSend = JSON.stringify({ ...parsedMessage, senderId: clientId });

        // Persist state on the server, excluding cursor movements
        if (parsedMessage.type !== 'cursor-move') {
            session.state = { ...session.state, ...parsedMessage.payload };
        }

        // Broadcast to all clients in the session, including the sender
        session.clients.forEach(({ ws: clientWs }) => {
            if (clientWs.readyState === clientWs.OPEN) {
                clientWs.send(messageToSend);
            }
        });
    });

    ws.on('close', () => {
        console.log(`Client ${clientId} disconnected from session ${sessionId}`);
        session.clients.delete(clientId);

        if (session.clients.size === 0) {
            sessions.delete(sessionId);
            console.log(`Session ${sessionId} closed.`);
        } else {
            // Inform remaining clients that a user has left
            const userList = Array.from(session.clients.keys()).map(id => ({ id, color: session.clients.get(id).color }));
            const userUpdateMessage = JSON.stringify({ type: 'user-update', payload: { users: userList } });
            session.clients.forEach(({ ws: clientWs }) => clientWs.send(userUpdateMessage));
        }
    });

    ws.on('error', (error) => console.error(`WebSocket error for client ${clientId}:`, error));
});

httpServer.listen(port, '0.0.0.0', () => {
    console.log(`AG Beats server started on port ${port} with HTTP.`);
    if (process.send) {
        process.send('ready');
    }
});