var process = require('process')
var net = require('net')
// Handle SIGINT
process.on('SIGINT', () => {
    console.info("SIGINT Received, exiting...")
    process.exit(0)
})

// Handle SIGTERM
process.on('SIGTERM', () => {
    console.info("SIGTERM Received, exiting...")
    process.exit(0)
})

// Handle APP ERRORS
process.on('uncaughtException', (error, origin) => {
    console.log('----- Uncaught exception -----')
    console.log(error)
    console.log('----- Exception origin -----')
    console.log(origin)
})
process.on('unhandledRejection', (reason, promise) => {
    console.log('----- Unhandled Rejection at -----')
    console.log(promise)
    console.log('----- Reason -----')
    console.log(reason)
})

const express = require('express');
const RateLimit = require('express-rate-limit');
const http = require('http');

const limiter = RateLimit({
	windowMs: 5 * 60 * 1000, // 5 minutes
	max: 100, // Limit each IP to 100 requests per `window` (here, per 5 minutes)
	message: 'Too many requests from this IP Address, please try again after 5 minutes.',
	standardHeaders: true, // Return rate limit info in the `RateLimit-*` headers
	legacyHeaders: false, // Disable the `X-RateLimit-*` headers
})

const app = express();
const port = process.env.PORT || 3000;

app.use(limiter);

app.use(express.static('public'));

app.use(function(req, res) {
    res.redirect('/');
});

app.get('/', (req, res) => {
    res.sendFile('index.html');
});

const server = http.createServer(app);
server.listen(port);

const parser = require('ua-parser-js');
const { uniqueNamesGenerator, animals, colors } = require('unique-names-generator');

class SnapdropServer {

    constructor() {
        const WebSocket = require('ws');
        this._wss = new WebSocket.Server({ server });
        this._wss.on('connection', (socket, request) => this._onConnection(new Peer(socket, request)));
        this._wss.on('headers', (headers, response) => this._onHeaders(headers, response));

        this._rooms = {};

        console.log('Snapdrop is running on port', port);
    }

    _onConnection(peer) {
        this._joinRoom(peer);
        peer.socket.on('message', message => this._onMessage(peer, message));
        peer.socket.on('error', console.error);
        this._keepAlive(peer);

        // send displayName
        this._send(peer, {
            type: 'display-name',
            message: {
                displayName: peer.name.displayName,
                deviceName: peer.name.deviceName
            }
        });
    }

    _onHeaders(headers, request) {
        if (request.headers.cookie && request.headers.cookie.indexOf('peerid=') > -1) return;
        request.peerId = Peer.uuid();
        headers.push('Set-Cookie: peerid=' + request.peerId + "; SameSite=Strict; Secure");
    }

    _onMessage(sender, message) {
        // Try to parse message
        try {
            message = JSON.parse(message);
        } catch (e) {
            return; // TODO: handle malformed JSON
        }

        switch (message.type) {
            case 'disconnect':
                this._leaveRoom(sender);
                break;
            case 'pong':
                sender.lastBeat = Date.now();
                break;
        }

        // relay message to recipient
        if (message.to && this._rooms[sender.ip]) {
            const recipientId = message.to; // TODO: sanitize
            const recipient = this._rooms[sender.ip][recipientId];
            delete message.to;
            // add sender id
            message.sender = sender.id;
            this._send(recipient, message);
            return;
        }
    }

    _joinRoom(peer) {
        // if room doesn't exist, create it
        if (!this._rooms[peer.ip]) {
            this._rooms[peer.ip] = {};
        }

        // notify all other peers
        for (const otherPeerId in this._rooms[peer.ip]) {
            if (otherPeerId === peer.id) continue;
            const otherPeer = this._rooms[peer.ip][otherPeerId];
            this._send(otherPeer, {
                type: 'peer-joined',
                peer: peer.getInfo()
            });
        }

        // notify peer about the other peers
        const otherPeers = [];
        for (const otherPeerId in this._rooms[peer.ip]) {
            if (otherPeerId === peer.id) continue;
            otherPeers.push(this._rooms[peer.ip][otherPeerId].getInfo());
        }

        this._send(peer, {
            type: 'peers',
            peers: otherPeers
        });

        // add peer to room
        this._rooms[peer.ip][peer.id] = peer;
    }

    _leaveRoom(peer) {
        if (!this._rooms[peer.ip] || !this._rooms[peer.ip][peer.id]) return;
        this._cancelKeepAlive(this._rooms[peer.ip][peer.id]);

        // delete the peer
        delete this._rooms[peer.ip][peer.id];

        peer.socket.terminate();
        //if room is empty, delete the room
        if (!Object.keys(this._rooms[peer.ip]).length) {
            delete this._rooms[peer.ip];
        } else {
            // notify all other peers
            for (const otherPeerId in this._rooms[peer.ip]) {
                const otherPeer = this._rooms[peer.ip][otherPeerId];
                this._send(otherPeer, { type: 'peer-left', peerId: peer.id });
            }
        }
    }

    _send(peer, message) {
        if (!peer) return;
        if (this._wss.readyState !== this._wss.OPEN) return;
        message = JSON.stringify(message);
        peer.socket.send(message, error => '');
    }

    _keepAlive(peer) {
        this._cancelKeepAlive(peer);
        var timeout = 500;
        if (!peer.lastBeat) {
            peer.lastBeat = Date.now();
        }
        if (Date.now() - peer.lastBeat > 2 * timeout) {
            this._leaveRoom(peer);
            return;
        }

        this._send(peer, { type: 'ping' });

        peer.timerId = setTimeout(() => this._keepAlive(peer), timeout);
    }

    _cancelKeepAlive(peer) {
        if (peer && peer.timerId) {
            clearTimeout(peer.timerId);
        }
    }
}



class Peer {

    constructor(socket, request) {
        // set socket
        this.socket = socket;


        // set remote ip
        this._setIP(request);

        // set peer id
        this._setPeerId(request)
        // is WebRTC supported ?
        this.rtcSupported = request.url.indexOf('webrtc') > -1;
        // set name
        this._setName(request);
        // for keepalive
        this.timerId = 0;
        this.lastBeat = Date.now();
        console.debug(this.name.displayName)
    }

    _setIP(request) {
        if (request.headers['cf-connecting-ip']) {
            this.ip = request.headers['cf-connecting-ip'].split(/\s*,\s*/)[0];
        } else if (request.headers['x-forwarded-for']) {
            this.ip = request.headers['x-forwarded-for'].split(/\s*,\s*/)[0];
        } else {
            this.ip = request.connection.remoteAddress;
        }
        // IPv4 and IPv6 use different values to refer to localhost
        // put all peers on the same network as the server into the same room as well
        if (this.ip === '::1' || this.ip === '::ffff:127.0.0.1' || this.ip === '::1' || this.ipIsPrivate(this.ip)) {
            this.ip = '127.0.0.1';
        }
        console.debug(this.ip)
    }

    ipIsPrivate(ip) {
        if (ip.substring(0,7) === "::ffff:")
            ip = ip.substring(7);

        if (net.isIPv4(ip)) {
            //         10.0.0.0 - 10.255.255.255        ||   172.16.0.0 - 172.31.255.255                          ||    192.168.0.0 - 192.168.255.255
            return  /^(10)\.(.*)\.(.*)\.(.*)$/.test(ip) || /^(172)\.(1[6-9]|2[0-9]|3[0-1])\.(.*)\.(.*)$/.test(ip) || /^(192)\.(168)\.(.*)\.(.*)$/.test(ip)
        }

        // else: ip is IPv6
        const firstWord = ip.split(":").find(el => !!el); //get first not empty word

        // The original IPv6 Site Local addresses (fec0::/10) are deprecated. Range: fec0 - feff
        if (/^fe[c-f][0-f]$/.test(firstWord))
            return true;

            // These days Unique Local Addresses (ULA) are used in place of Site Local.
        // Range: fc00 - fcff
        else if (/^fc[0-f]{2}$/.test(firstWord))
            return true;

        // Range: fd00 - fcff
        else if (/^fd[0-f]{2}$/.test(firstWord))
            return true;

        // Link local addresses (prefixed with fe80) are not routable
        else if (firstWord === "fe80")
            return true;

        // Discard Prefix
        else if (firstWord === "100")
            return true;

        // Any other IP address is not Unique Local Address (ULA)
        return false;
    }

    _setPeerId(request) {
        if (request.peerId) {
            this.id = request.peerId;
        } else {
            this.id = request.headers.cookie.replace('peerid=', '');
        }
    }

    toString() {
        return `<Peer id=${this.id} ip=${this.ip} rtcSupported=${this.rtcSupported}>`
    }

    _setName(req) {
        let ua = parser(req.headers['user-agent']);


        let deviceName = '';

        if (ua.os && ua.os.name) {
            deviceName = ua.os.name.replace('Mac OS', 'Mac') + ' ';
        }

        if (ua.device.model) {
            deviceName += ua.device.model;
        } else {
            deviceName += ua.browser.name;
        }

        if(!deviceName)
            deviceName = 'Unknown Device';

        const displayName = uniqueNamesGenerator({
            length: 2,
            separator: ' ',
            dictionaries: [colors, animals],
            style: 'capital',
            seed: this.id.hashCode()
        })

        this.name = {
            model: ua.device.model,
            os: ua.os.name,
            browser: ua.browser.name,
            type: ua.device.type,
            deviceName,
            displayName
        };
    }

    getInfo() {
        return {
            id: this.id,
            name: this.name,
            rtcSupported: this.rtcSupported
        }
    }

    // return uuid of form xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
    static uuid() {
        let uuid = '',
            ii;
        for (ii = 0; ii < 32; ii += 1) {
            switch (ii) {
                case 8:
                case 20:
                    uuid += '-';
                    uuid += (Math.random() * 16 | 0).toString(16);
                    break;
                case 12:
                    uuid += '-';
                    uuid += '4';
                    break;
                case 16:
                    uuid += '-';
                    uuid += (Math.random() * 4 | 8).toString(16);
                    break;
                default:
                    uuid += (Math.random() * 16 | 0).toString(16);
            }
        }
        return uuid;
    };
}

Object.defineProperty(String.prototype, 'hashCode', {
    value: function() {
        var hash = 0, i, chr;
        for (i = 0; i < this.length; i++) {
            chr   = this.charCodeAt(i);
            hash  = ((hash << 5) - hash) + chr;
            hash |= 0; // Convert to 32bit integer
        }
        return hash;
    }
});

new SnapdropServer();