#!/usr/bin/env node

var fs=require("fs"),
    path=require("path"),
    app=require("express")(),
    bodyParser=require("body-parser"),
    crypto=require("crypto"),
    Persist=require("node-persist"),
    glob=require("glob");

var HTTPPORT=42420;

Persist.initSync({});

var challenge=null;

function renewChallenge(){
	var entropy=crypto.randomBytes(512);
	var hasher=crypto.createHash("sha256");
	hasher.update(entropy);
	challenge=hasher.digest("hex");
}
setInterval(renewChallenge,8000);
renewChallenge();

var gencode=(function(){
	const startn=42424242;
	const alphabet="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
	var lastn=Persist.getItemSync("gencode_lastn");
	if(lastn==null)lastn=startn;
	return function gencode(){
		var code="",coden=lastn;
		while(coden){
			code+=alphabet[coden%alphabet.length];
			coden=~~(coden/alphabet.length);
		}
		if(lastn==0x7fffffff)lastn=0; //maximum value of a 32-bit int
		else lastn++;
		Persist.setItemSync("gencode_lastn",lastn);
		if(lastn==startn)throw new Error("RUN OUT OF INDICES PANIC PANIC");
		while(code.length<6)code+="a";
		return code;
	};
})();


app.use(bodyParser.raw({
	limit:"3mb",
	type:"image/*"
}));

app.use(bodyParser.text({
	type:"text/plain"
}));


app.get("/challenge",function(req,res){
	res.end(challenge);
});


app.param("userid",function(req,res,next,userid){
	var password=Persist.getItemSync("user_"+userid);
	if(!password){
		res.sendStatus(404);
		res.end("Non-existent userid");
		return;
	}
	req.ssuser=[userid,password];
	next();
});
app.param("authhash",function(req,res,next,authhash){
	var s=challenge+req.ssuser[1];
	var hasher=crypto.createHash("sha256");
	hasher.update(s);
	var hashres=hasher.digest("hex");
	if(hashres!=authhash){
		res.sendStatus(403);
		res.end("Invalid answer to challenge");
		return;
	}
	next();
});
app.param("fname",function(req,res,next,fname){
	req.sscode=gencode();
	req.ssfname=req.sscode+"_"+fname.replace(/[\x00-\x1F\/]/g,"").replace(/^\.+/,"");
	next();
});
app.post("/image/:userid/:authhash/:fname",function(req,res){
	try {
		if(!fs.statSync("images").isDirectory())throw new Error;
	} catch(e){
		fs.mkdirSync("images");
		if(!fs.statSync("images").isDirectory())throw new Error;
	}
	if(!fs.existsSync("images/"+req.ssuser[0])){
		fs.mkdirSync("images/"+req.ssuser[0]);
	}
	fs.writeFileSync("images/"+req.ssuser[0]+"/"+req.ssfname,req.body);
	res.end("http://"+req.hostname+(HTTPPORT!=80?":"+HTTPPORT:"")+"/ssimg/"+req.ssuser[0]+"/"+req.sscode);
});


app.param("reguserid",function(req,res,next,reguserid){
	req.ssreguserid=reguserid;
	next();
});
app.post("/registerx/:reguserid",function(req,res){ //pass password in body
	var password=req.body;
	if(Persist.getItemSync("user_"+req.ssreguserid)){
		res.sendStatus(409); //Conflict
		res.end("That userid already exists");
		return;
	}
	Persist.setItemSync("user_"+req.ssreguserid,password);
	res.sendStatus(200);
	res.end();
});


app.get("/exists/:reguserid",function(req,res){
	res.sendStatus(Persist.getItemSync("user_"+req.ssreguserid)?200:404);
	res.end();
});

app.get("/checklogin/:userid/:authhash",function(req,res){
	res.sendStatus(200);
	res.end();
});


app.param("ssimgcode",function(req,res,next,ssimgcode){
	req.ssimgcode=ssimgcode.replace(/[^a-zA-Z0-9]/g,"");
	if(req.ssimgcode.length!=6){
		res.sendStatus(404);
		res.end("Invalid or unknown image code");
		return;
	}
	next();
});
app.get("/ssimg/:userid/:ssimgcode",function(req,res){
	var files=glob.sync(__dirname+"/images/"+req.ssuser[0]+"/"+req.ssimgcode+"*");
	if(files.length==0){
		res.sendStatus(404);
		res.end("Unknown image code");
		return;
	}
	if(files.length>1){
		console.log("More than one file matched; internal error");
		console.log(files);
		res.sendStatus(500);
		res.end("More than one file matched; internal error");
		return;
	}
	res.sendFile(files[0]);
});


app.listen(42420,function(){
	console.log("Server started.");
});