/* jslint node: true */
'use strict';

//  ENiGMA½
const Log                   = require('../../logger.js').log;
const { ServerModule }      = require('../../server_module.js');
const Config                = require('../../config.js').get;
const { Errors }            = require('../../enig_error.js');
const SysProps              = require('../../system_property.js');
const StatLog               = require('../../stat_log.js');

//  deps
const net                   = require('net');
const _                     = require('lodash');
const os                    = require('os');


// MRC
const protocolVersion   = '1.2.9';
const lineDelimiter     = new RegExp('\r\n|\r|\n');

const ModuleInfo = exports.moduleInfo = {
    name        : 'MRC',
    desc        : 'An MRC Chat Multiplexer',
    author      : 'RiPuk',
    packageName : 'codes.l33t.enigma.mrc.server',
    notes       : 'https://bbswiki.bottomlessabyss.net/index.php?title=MRC_Chat_platform',
};

const connectedSockets = new Set();

exports.getModule = class MrcModule extends ServerModule {
    constructor() {
        super();

        this.log            = Log.child( { server : 'MRC' } );

        const config        = Config();
        this.mrcConnectOpts = {
            host         : config.chatServers.mrc.serverHostname || 'mrc.bottomlessabyss.net',
            port         : config.chatServers.mrc.serverPort || 5000,
            retryDelay   : config.chatServers.mrc.retryDelay || 10000
        };
    }

    _connectionHandler() {
        const config = Config();
        const boardName  = config.general.prettyBoardName || config.general.boardName;
        const enigmaVersion = 'ENiGMA½-BBS_' + require('../../../package.json').version;

        const handshake = `${boardName}~${enigmaVersion}/${os.platform()}.${os.arch()}/${protocolVersion}`;
        this.log.debug({ handshake : handshake }, 'Handshaking with MRC server');

        this.sendRaw(handshake);
        this.log.info(this.mrcConnectOpts, 'Connected to MRC server');
    }

    createServer(cb) {

        if (!this.enabled) {
            return cb(null);
        }

        this.connectToMrc();
        this.createLocalListener();

        return cb(null);
    }

    listen(cb) {
        if (!this.enabled) {
            return cb(null);
        }

        const config = Config();

        const port = parseInt(config.chatServers.mrc.multiplexerPort);
        if(isNaN(port)) {
            this.log.warn( { port : config.chatServers.mrc.multiplexerPort, server : ModuleInfo.name }, 'Invalid port' );
            return cb(Errors.Invalid(`Invalid port: ${config.chatServers.mrc.multiplexerPort}`));
        }
        Log.info( { server : ModuleInfo.name, port : config.chatServers.mrc.multiplexerPort }, 'MRC multiplexer starting up');
        return this.server.listen(port, cb);
    }

    /**
     * Handles connecting to to the MRC server
     */
    connectToMrc() {
        const self = this;

        // create connection to MRC server
        this.mrcClient = net.createConnection(this.mrcConnectOpts, self._connectionHandler.bind(self));

        this.mrcClient.requestedDisconnect = false;

        // do things when we get data from MRC central
        let buffer = new Buffer.from('');

        function handleData(chunk) {
            if(_.isString(chunk)) {
                buffer += chunk;
            } else {
                buffer = Buffer.concat([buffer, chunk]);
            }

            let lines = buffer.toString().split(lineDelimiter);

            if (lines.pop()) {
                // if buffer is not ended with \r\n, there's more chunks.
                return;
            } else {
                // else, initialize the buffer.
                buffer = new Buffer.from('');
            }

            lines.forEach( line => {
                if (line.length) {
                    let message = self.parseMessage(line);
                    if (message) {
                        self.receiveFromMRC(message);
                    }
                }
            });
        }

        this.mrcClient.on('data', (data) => {
            handleData(data);
        });

        this.mrcClient.on('end', () => {
            this.log.info(this.mrcConnectOpts, 'Disconnected from MRC server');
        });

        this.mrcClient.on('close', () => {

            if (this.mrcClient && this.mrcClient.requestedDisconnect)
                return;

            this.log.info(this.mrcConnectOpts, 'Disconnected from MRC server, reconnecting');
            this.log.debug('Waiting ' + this.mrcConnectOpts.retryDelay + 'ms before retrying');

            setTimeout(function() {
                self.connectToMrc();
            }, this.mrcConnectOpts.retryDelay);
        });

        this.mrcClient.on('error', err => {
            this.log.info( { error : err.message }, 'MRC server error');
        });
    }

    createLocalListener() {
        // start a local server for clients to connect to

        this.server = net.createServer( socket => {
            socket.setEncoding('ascii');

            socket.on('data', data => {
                // split on \n to deal with getting messages in batches
                data.toString().split(lineDelimiter).forEach( item => {
                    if (item == '') return;

                    // save username with socket
                    if(item.startsWith('--DUDE-ITS--')) {
                        connectedSockets.add(socket);
                        socket.username = item.split('|')[1];
                        Log.debug( { server : 'MRC', user: socket.username } , 'User connected');
                    } else {
                        this.receiveFromClient(socket.username, item);
                    }
                });
            });

            socket.on('end', function() {
                connectedSockets.delete(socket);
            });

            socket.on('error', err => {
                if('ECONNRESET' !== err.code) { //  normal
                    this.log.error( { error: err.message }, 'MRC error' );
                }
            });
        });
    }

    get enabled() {
        return _.get(Config(), 'chatServers.mrc.enabled', false) && this.isConfigured();
    }

    isConfigured() {
        const config = Config();
        return _.isNumber(_.get(config, 'chatServers.mrc.multiplexerPort'));
    }

    /**
     * Sends received messages to local clients
     */
    sendToClient(message) {
        connectedSockets.forEach( (client) => {
            if (message.to_user == '' || message.to_user == client.username || message.to_user == 'CLIENT' || message.from_user == client.username || message.to_user == 'NOTME' ) {
                // this.log.debug({ server : 'MRC', username : client.username, message : message }, 'Forwarding message to connected user');
                client.write(JSON.stringify(message) + '\n');
            }
        });
    }

    /**
     * Processes messages received from the central MRC server
     */
    receiveFromMRC(message) {

        const config = Config();
        const siteName = slugify(config.general.boardName);

        if (message.from_user == 'SERVER' && message.body == 'HELLO') {
            // reply with extra bbs info
            this.sendToMrcServer('CLIENT', '', 'SERVER', 'ALL', '', `INFOSYS:${StatLog.getSystemStat(SysProps.SysOpUsername)}`);
            this.sendToMrcServer('CLIENT', '', 'SERVER', 'ALL', '', `INFOWEB:${config.general.website}`);
            this.sendToMrcServer('CLIENT', '', 'SERVER', 'ALL', '', `INFOTEL:${config.general.telnetHostname}`);
            this.sendToMrcServer('CLIENT', '', 'SERVER', 'ALL', '', `INFOSSH:${config.general.sshHostname}`);
            this.sendToMrcServer('CLIENT', '', 'SERVER', 'ALL', '', `INFODSC:${config.general.description}`);

        } else if (message.from_user == 'SERVER' && message.body.toUpperCase() == 'PING') {
            // reply to heartbeat
            this.sendToMrcServer('CLIENT', '', 'SERVER', 'ALL', '', `IMALIVE:${siteName}`);

        } else {
            // if not a heartbeat, and we have clients then we need to send something to them
            this.sendToClient(message);
        }
    }

    /**
     * Takes an MRC message and parses it into something usable
     */
    parseMessage(line) {

        const [from_user, from_site, from_room, to_user, to_site, to_room, body ] = line.split('~');

        // const msg = line.split('~');
        // if (msg.length < 7) {
        //     return;
        // }

        return { from_user, from_site, from_room, to_user, to_site, to_room, body };
    }

    /**
     * Receives a message from a local client and sanity checks before sending on to the central MRC server
     */
    receiveFromClient(username, message) {
        try {
            message = JSON.parse(message);
        } catch (e) {
            Log.debug({ server : 'MRC', user : username, message : message }, 'Dodgy message received from client');
        }

        this.sendToMrcServer(message.from_user, message.from_room, message.to_user, message.to_site, message.to_room, message.body);
    }

    /**
     * Converts a message back into the MRC format and sends it to the central MRC server
     */
    sendToMrcServer(fromUser, fromRoom, toUser, toSite, toRoom, messageBody) {
        const config = Config();
        const siteName = slugify(config.general.boardName);

        const line = [
            fromUser,
            siteName,
            sanitiseRoomName(fromRoom),
            sanitiseName(toUser || ''),
            sanitiseName(toSite || ''),
            sanitiseRoomName(toRoom || ''),
            sanitiseMessage(messageBody)
        ].join('~') + '~';

        // Log.debug({ server : 'MRC', data : line }, 'Sending data');
        this.sendRaw(line);
    }

    sendRaw(message) {
        // optionally log messages here
        this.mrcClient.write(message + '\n');
    }
};

/**
 * User / site name must be ASCII 33-125, no MCI, 30 chars max, underscores
 */
function sanitiseName(str) {
    return str.replace(
        /\s/g, '_'
    ).replace(
        /[^\x21-\x7D]|(\|\w\w)/g, '' // Non-printable & MCI
    ).substr(
        0, 30
    );
}

function sanitiseRoomName(message) {
    return message.replace(/[^\x21-\x7D]|(\|\w\w)/g, '').substr(0, 30);
}

function sanitiseMessage(message) {
    return message.replace(/[^\x20-\x7D]/g, '');
}

/**
 * SLugifies the BBS name for use as an MRC "site name"
 */
function slugify(text) {
    return text.toString()
        .replace(/\s+/g, '_')           // Replace spaces with _
        .replace(/[^\w\-]+/g, '')       // Remove all non-word chars
        .replace(/\-\-+/g, '_')         // Replace multiple - with single -
        .replace(/^-+/, '')             // Trim - from start of text
        .replace(/-+$/, '');            // Trim - from end of text
}