#!/usr/bin/env node
const fs=require("fs");
const net=require("net");
const https=require("https");
const WebSocket=require("uWebSockets.js");

let listenport=null;

let upstream=null;

function parseUpstream(arg){
	const [host, port]=arg.split(":");
	return {host, port};
}


let httpsConfig=null;
if(process.argv.length==6){
	upstream=parseUpstream(process.argv[2]);
	listenport=+process.argv[3];
	console.log("Reading keys for https");
	httpsConfig={
		key_file_name: process.argv[4],
		cert_file_name: process.argv[5],
	};
} else if(process.argv.length==4){
	upstream=parseUpstream(process.argv[2]);
	listenport=+process.argv[3];
	console.log("WARNING: Running without SSL!");
} else {
	console.error("Usage: ./server.js <host:port> <port>                        # proxy without SSL");
	console.error("       ./server.js <host:port> <port> <key.pem> <cert.pem>   # proxy with SSL");
	console.error("'<host:port>' indicates the plain-tcp tomsg server to proxy to.");
	console.error("'<port>' indicates the port to listen for websocket connections on.");
	process.exit(1);
}

if(process.getuid()==0){
	console.log(`Old uid: ${process.getuid()}, old gid: ${process.getgid()}; setting to nobody...`);
	process.setgid("nobody");
	process.setuid("nobody");
	console.log(`New uid: ${process.getuid()}, new gid: ${process.getgid()}`);
}


let wsServer;
if(httpsConfig){
	wsServer=WebSocket.SSLApp(httpsConfig);
} else {
	wsServer=WebSocket.App();
}

wsServer=wsServer.ws("/*",{
	open: sock=>{
		const stateobj={netconn: null, buffer: [], sock_closed: false};
		sock["tomsgdata"]=stateobj;
		let linebuf="";

		stateobj.netconn=net.connect(upstream.port,upstream.host,()=>{
			for(const item of stateobj.buffer){
				stateobj.netconn.write(item);
				stateobj.netconn.write("\n");
			}
			stateobj.buffer=[];
		});
		stateobj.netconn.on("close",()=>{
			if(!stateobj.sock_closed)sock.close();
		});
		stateobj.netconn.on("data",(data)=>{
			linebuf+=data;
			let idx;
			while((idx=linebuf.indexOf("\n"))!=-1){
				sock.send(linebuf.slice(0,idx));
				linebuf=linebuf.slice(idx+1);
			}
		});
		stateobj.netconn.on("error",()=>{
			if(!stateobj.sock_closed)sock.close();
		});
	},
	message: (sock,data,isBinary)=>{
		const stateobj=sock["tomsgdata"];
		data=new Uint8Array(data);
		if(stateobj.netconn.connecting){
			stateobj.buffer.push(data);
		} else {
			stateobj.netconn.write(data);
			stateobj.netconn.write("\n");
		}
	},
	close: sock=>{
		const stateobj=sock["tomsgdata"];
		stateobj.sock_closed=true;
		try {stateobj.netconn.end();}
		catch (e) {}
	}
});

wsServer=wsServer.listen(listenport,listenSocket=>{
	if(listenSocket){
		console.log(`Websocket server${httpsConfig?" (SSL)":""} bound on port ${listenport}`);
	}
});