/**
 * Connections
 * Pokemon Showdown - http://pokemonshowdown.com/
 *
 * Abstraction layer for multi-process SockJS connections.
 *
 * This file handles all the communications between the users'
 * browsers, the networking processes, and users.js in the
 * main process.
 *
 * @license MIT license
 */

'use strict';

const cluster = require('cluster');
global.Config = require('./config/config');

if (cluster.isMaster) {
	cluster.setupMaster({
		exec: require('path').resolve(__dirname, 'sockets'),
	});

	const workers = exports.workers = new Map();

	const spawnWorker = exports.spawnWorker = function () {
		let worker = cluster.fork({PSPORT: Config.port, PSBINDADDR: Config.bindaddress || '0.0.0.0', PSNOSSL: Config.ssl ? 0 : 1});
		let id = worker.id;
		workers.set(id, worker);
		worker.on('message', data => {
			// console.log('master received: ' + data);
			switch (data.charAt(0)) {
			case '*': {
				// *socketid, ip, protocol
				// connect
				let nlPos = data.indexOf('\n');
				let nlPos2 = data.indexOf('\n', nlPos + 1);
				Users.socketConnect(worker, id, data.slice(1, nlPos), data.slice(nlPos + 1, nlPos2), data.slice(nlPos2 + 1));
				break;
			}

			case '!': {
				// !socketid
				// disconnect
				Users.socketDisconnect(worker, id, data.substr(1));
				break;
			}

			case '<': {
				// <socketid, message
				// message
				let nlPos = data.indexOf('\n');
				Users.socketReceive(worker, id, data.substr(1, nlPos - 1), data.substr(nlPos + 1));
				break;
			}

			default:
			// unhandled
			}
		});

		return worker;
	};

	cluster.on('exit', (worker, code, signal) => {
		if (code === null && signal === 'SIGTERM') {
			// worker was killed by Sockets.killWorker or Sockets.killPid
		} else {
			// worker crashed, try our best to clean up
			require('./crashlogger')(new Error(`Worker ${worker.id} abruptly died`), "The main process");

			// this could get called during cleanup; prevent it from crashing
			// note: overwriting Worker#send is unnecessary in Node.js v7.0.0 and above
			// see https://github.com/nodejs/node/commit/8c53d2fe9f102944cc1889c4efcac7a86224cf0a
			worker.send = () => {};

			let count = 0;
			Users.connections.forEach(connection => {
				if (connection.worker === worker) {
					Users.socketDisconnect(worker, worker.id, connection.socketid);
					count++;
				}
			});
			console.error(`${count} connections were lost.`);
		}

		// don't delete the worker, so we can investigate it if necessary.

		// attempt to recover
		spawnWorker();
	});

	exports.listen = function (port, bindAddress, workerCount) {
		if (port !== undefined && !isNaN(port)) {
			Config.port = port;
			Config.ssl = null;
		} else {
			port = Config.port;

			// Autoconfigure when running in cloud environments.
			try {
				const cloudenv = require('cloud-env');
				bindAddress = cloudenv.get('IP', bindAddress);
				port = cloudenv.get('PORT', port);
			} catch (e) {}
		}
		if (bindAddress !== undefined) {
			Config.bindaddress = bindAddress;
		}
		if (workerCount === undefined) {
			workerCount = (Config.workers !== undefined ? Config.workers : 1);
		}
		for (let i = 0; i < workerCount; i++) {
			spawnWorker();
		}
	};

	exports.killWorker = function (worker) {
		let count = 0;
		Users.connections.forEach(connection => {
			if (connection.worker === worker) {
				Users.socketDisconnect(worker, worker.id, connection.socketid);
				count++;
			}
		});
		console.log(`${count} connections were lost.`);

		try {
			worker.disconnect();
			worker.kill('SIGTERM');
		} catch (e) {}
		workers.delete(worker.id);

		return count;
	};

	exports.killPid = function (pid) {
		pid = '' + pid;
		for (let [workerid, worker] of workers) { // eslint-disable-line no-unused-vars
			if (pid === '' + worker.process.pid) {
				return this.killWorker(worker);
			}
		}
		return false;
	};

	exports.socketSend = function (worker, socketid, message) {
		worker.send(`>${socketid}\n${message}`);
	};
	exports.socketDisconnect = function (worker, socketid) {
		worker.send(`!${socketid}`);
	};

	exports.channelBroadcast = function (channelid, message) {
		workers.forEach(worker => {
			worker.send(`#${channelid}\n${message}`);
		});
	};
	exports.channelSend = function (worker, channelid, message) {
		worker.send(`#${channelid}\n${message}`);
	};
	exports.channelAdd = function (worker, channelid, socketid) {
		worker.send(`+${channelid}\n${socketid}`);
	};
	exports.channelRemove = function (worker, channelid, socketid) {
		worker.send(`-${channelid}\n${socketid}`);
	};

	exports.subchannelBroadcast = function (channelid, message) {
		workers.forEach(worker => {
			worker.send(`:${channelid}\n${message}`);
		});
	};
	exports.subchannelMove = function (worker, channelid, subchannelid, socketid) {
		worker.send(`.${channelid}\n${subchannelid}\n${socketid}`);
	};
} else {
	// is worker

	if (process.env.PSPORT) Config.port = +process.env.PSPORT;
	if (process.env.PSBINDADDR) Config.bindaddress = process.env.PSBINDADDR;
	if (+process.env.PSNOSSL) Config.ssl = null;

	if (Config.ofe) {
		try {
			require.resolve('ofe');
		} catch (e) {
			if (e.code !== 'MODULE_NOT_FOUND') throw e; // should never happen
			throw new Error(
				'ofe is not installed, but it is a required dependency if Config.ofe is set to true! ' +
				'Run npm install ofe and restart the server.'
			);
		}

		// Create a heapdump if the process runs out of memory.
		require('ofe').call();
	}

	// Static HTTP server

	// This handles the custom CSS and custom avatar features, and also
	// redirects yourserver:8001 to yourserver-8001.psim.us

	// It's optional if you don't need these features.

	global.Dnsbl = require('./dnsbl');

	if (Config.crashguard) {
		// graceful crash
		process.on('uncaughtException', err => {
			require('./crashlogger')(err, `Socket process ${cluster.worker.id} (${process.pid})`, true);
		});
	}

	let app = require('http').createServer();
	let appssl = Config.ssl ? require('https').createServer(Config.ssl.options) : null;

	// Static server
	const StaticServer = require('node-static').Server;
	const roomidRegex = /^\/(?:[A-Za-z0-9][A-Za-z0-9-]*)\/?$/;
	const cssServer = new StaticServer('./config');
	const avatarServer = new StaticServer('./config/avatars');
	const staticServer = new StaticServer('./static');
	const staticRequestHandler = (req, res) => {
		// console.log(`static rq: ${req.socket.remoteAddress}:${req.socket.remotePort} -> ${req.socket.localAddress}:${req.socket.localPort} - ${req.method} ${req.url} ${req.httpVersion} - ${req.rawHeaders.join('|')}`);
		req.resume();
		req.addListener('end', () => {
			if (Config.customhttpresponse &&
					Config.customhttpresponse(req, res)) {
				return;
			}

			let server = staticServer;
			if (req.url === '/custom.css') {
				server = cssServer;
			} else if (req.url.startsWith('/avatars/')) {
				req.url = req.url.substr(8);
				server = avatarServer;
			} else if (roomidRegex.test(req.url)) {
				req.url = '/';
			}

			server.serve(req, res, e => {
				if (e && (e.status === 404)) {
					staticServer.serveFile('404.html', 404, {}, req, res);
				}
			});
		});
	};

	app.on('request', staticRequestHandler);
	if (appssl) appssl.on('request', staticRequestHandler);

	// SockJS server

	// This is the main server that handles users connecting to our server
	// and doing things on our server.

	const sockjs = require('sockjs');
	const server = sockjs.createServer({
		sockjs_url: "//play.pokemonshowdown.com/js/lib/sockjs-1.1.1-nwjsfix.min.js",
		log: (severity, message) => {
			if (severity === 'error') console.log('ERROR: ' + message);
		},
		prefix: '/showdown',
	});

	const sockets = new Map();
	const channels = new Map();
	const subchannels = new Map();

	// Deal with phantom connections.
	const sweepClosedSockets = () => {
		sockets.forEach(socket => {
			if (socket.protocol === 'xhr-streaming' &&
				socket._session &&
				socket._session.recv) {
				socket._session.recv.didClose();
			}

			// A ghost connection's `_session.to_tref._idlePrev` (and `_idleNext`) property is `null` while
			// it is an object for normal users. Under normal circumstances, those properties should only be
			// `null` when the timeout has already been called, but somehow it's not happening for some connections.
			// Simply calling `_session.timeout_cb` (the function bound to the aformentioned timeout) manually
			// on those connections kills those connections. For a bit of background, this timeout is the timeout
			// that sockjs sets to wait for users to reconnect within that time to continue their session.
			if (socket._session &&
				socket._session.to_tref &&
				!socket._session.to_tref._idlePrev) {
				socket._session.timeout_cb();
			}
		});
	};
	const interval = setInterval(sweepClosedSockets, 1000 * 60 * 10); // eslint-disable-line no-unused-vars

	process.on('message', data => {
		// console.log('worker received: ' + data);
		let socket = null;
		let socketid = '';
		let channel = null;
		let channelid = '';
		let subchannel = null;
		let subchannelid = '';
		let nlLoc = -1;
		let message = '';

		switch (data.charAt(0)) {
		case '$': // $code
			eval(data.substr(1));
			break;

		case '!': // !socketid
			// destroy
			socketid = data.substr(1);
			socket = sockets.get(socketid);
			if (!socket) return;
			socket.end();
			// After sending the FIN packet, we make sure the I/O is totally blocked for this socket
			socket.destroy();
			sockets.delete(socketid);
			channels.forEach(channel => channel.delete(socketid));
			break;

		case '>':
			// >socketid, message
			// message
			nlLoc = data.indexOf('\n');
			socketid = data.substr(1, nlLoc - 1);
			socket = sockets.get(socketid);
			if (!socket) return;
			message = data.substr(nlLoc + 1);
			socket.write(message);
			break;

		case '#':
			// #channelid, message
			// message to channel
			nlLoc = data.indexOf('\n');
			channelid = data.substr(1, nlLoc - 1);
			channel = channels.get(channelid);
			if (!channel) return;
			message = data.substr(nlLoc + 1);
			channel.forEach(socket => socket.write(message));
			break;

		case '+':
			// +channelid, socketid
			// add to channel
			nlLoc = data.indexOf('\n');
			socketid = data.substr(nlLoc + 1);
			socket = sockets.get(socketid);
			if (!socket) return;
			channelid = data.substr(1, nlLoc - 1);
			channel = channels.get(channelid);
			if (!channel) {
				channel = new Map();
				channels.set(channelid, channel);
			}
			channel.set(socketid, socket);
			break;

		case '-':
			// -channelid, socketid
			// remove from channel
			nlLoc = data.indexOf('\n');
			channelid = data.slice(1, nlLoc);
			channel = channels.get(channelid);
			if (!channel) return;
			socketid = data.slice(nlLoc + 1);
			channel.delete(socketid);
			subchannel = subchannels.get(channelid);
			if (subchannel) subchannel.delete(socketid);
			if (!channel.size) {
				channels.delete(channelid);
				if (subchannel) subchannels.delete(channelid);
			}
			break;

		case '.':
			// .channelid, subchannelid, socketid
			// move subchannel
			nlLoc = data.indexOf('\n');
			channelid = data.slice(1, nlLoc);
			let nlLoc2 = data.indexOf('\n', nlLoc + 1);
			subchannelid = data.slice(nlLoc + 1, nlLoc2);
			socketid = data.slice(nlLoc2 + 1);

			subchannel = subchannels.get(channelid);
			if (!subchannel) {
				subchannel = new Map();
				subchannels.set(channelid, subchannel);
			}
			if (subchannelid === '0') {
				subchannel.delete(socketid);
			} else {
				subchannel.set(socketid, subchannelid);
			}
			break;

		case ':':
			// :channelid, message
			// message to subchannel
			nlLoc = data.indexOf('\n');
			channelid = data.slice(1, nlLoc);
			channel = channels.get(channelid);
			if (!channel) return;

			let messages = [null, null, null];
			message = data.substr(nlLoc + 1);
			subchannel = subchannels.get(channelid);
			channel.forEach((socket, socketid) => {
				switch (subchannel ? subchannel.get(socketid) : '0') {
				case '1':
					if (!messages[1]) {
						messages[1] = message.replace(/\n\|split\n[^\n]*\n([^\n]*)\n[^\n]*\n[^\n]*/g, '\n$1');
					}
					socket.write(messages[1]);
					break;
				case '2':
					if (!messages[2]) {
						messages[2] = message.replace(/\n\|split\n[^\n]*\n[^\n]*\n([^\n]*)\n[^\n]*/g, '\n$1');
					}
					socket.write(messages[2]);
					break;
				default:
					if (!messages[0]) {
						messages[0] = message.replace(/\n\|split\n([^\n]*)\n[^\n]*\n[^\n]*\n[^\n]*/g, '\n$1');
					}
					socket.write(messages[0]);
					break;
				}
			});
			break;
		}
	});

	// Clean up any remaining connections on disconnect. If this isn't done,
	// the process will not exit until any remaining connections have been destroyed.
	// Afterwards, the worker process will die on its own.
	process.once('disconnect', () => {
		sockets.forEach(socket => {
			try {
				socket.end();
				socket.destroy();
			} catch (e) {}
		});
		sockets.clear();
		channels.clear();
		subchannels.clear();
		app.close();
		if (appssl) appssl.close();
	});

	// this is global so it can be hotpatched if necessary
	let isTrustedProxyIp = Dnsbl.checker(Config.proxyip);
	let socketCounter = 0;
	server.on('connection', socket => {
		if (!socket) {
			// For reasons that are not entirely clear, SockJS sometimes triggers
			// this event with a null `socket` argument.
			return;
		} else if (!socket.remoteAddress) {
			// This condition occurs several times per day. It may be a SockJS bug.
			try {
				socket.end();
			} catch (e) {}
			return;
		}

		let socketid = socket.id = '' + (++socketCounter);
		sockets.set(socketid, socket);

		if (isTrustedProxyIp(socket.remoteAddress)) {
			let ips = (socket.headers['x-forwarded-for'] || '').split(',');
			let ip;
			while ((ip = ips.pop())) {
				ip = ip.trim();
				if (!isTrustedProxyIp(ip)) {
					socket.remoteAddress = ip;
					break;
				}
			}
		}

		process.send(`*${socketid}\n${socket.remoteAddress}\n${socket.protocol}`);

		socket.on('data', message => {
			// drop empty messages (DDoS?)
			if (!message) return;
			// drop messages over 100KB
			if (message.length > 100000) {
				console.log(`Dropping client message ${message.length / 1024} KB...`);
				console.log(message.slice(0, 160));
				return;
			}
			// drop legacy JSON messages
			if (typeof message !== 'string' || message.startsWith('{')) return;
			// drop blank messages (DDoS?)
			let pipeIndex = message.indexOf('|');
			if (pipeIndex < 0 || pipeIndex === message.length - 1) return;

			process.send(`<${socketid}\n${message}`);
		});

		socket.on('close', () => {
			process.send(`!${socketid}`);
			sockets.delete(socketid);
			channels.forEach(channel => channel.delete(socketid));
		});
	});
	server.installHandlers(app, {});
	app.listen(Config.port, Config.bindaddress);
	console.log(`Worker ${cluster.worker.id} now listening on ${Config.bindaddress}:${Config.port}`);

	if (appssl) {
		server.installHandlers(appssl, {});
		appssl.listen(Config.ssl.port, Config.bindaddress);
		console.log(`Worker ${cluster.worker.id} now listening for SSL on port ${Config.ssl.port}`);
	}

	console.log(`Test your server at http://${Config.bindaddress === '0.0.0.0' ? 'localhost' : Config.bindaddress}:${Config.port}`);

	require('./repl').start(`sockets-${cluster.worker.id}-${process.pid}`, cmd => eval(cmd));
}