// server.cpp: little more than enhanced multicaster
// runs dedicated or as client coroutine

#include "engine.h"

#define LOGSTRLEN 512

void logoutf(const char *fmt, ...) {
	va_list args;
	va_start(args, fmt);
	logoutfv(fmt, args);
	va_end(args);
}

static void writelog(FILE *file, const char *buf) {
	static uchar ubuf[512];
	size_t len = strlen(buf), carry = 0;
	while(carry < len) {
		size_t numu = encodeutf8(ubuf, sizeof(ubuf)-1, &((const uchar *)buf)[carry], len - carry, &carry);
		if(carry >= len) ubuf[numu++] = '\n';
		fwrite(ubuf, 1, numu, file);
	}
}

static void writelogv(FILE *file, const char *fmt, va_list args) {
	static char buf[LOGSTRLEN];
	vformatstring(buf, fmt, args, sizeof(buf));
	writelog(file, buf);
}

#ifdef STANDALONE
void fatal(const char *fmt, ...) {
	void cleanupserver();
	cleanupserver();
	defvformatstring(msg,fmt,fmt);
	logoutf("%s", msg);
	fprintf(stderr, "server error: %s\n", msg);
	exit(EXIT_FAILURE);
}

void conoutfv(int type, const char *fmt, va_list args) {
	(void) type;
	logoutfv(fmt, args);
}
#endif

#define DEFAULTCLIENTS 8

enum { ST_EMPTY, ST_LOCAL, ST_TCPIP };

struct client {				   // server side version of "dynent" type {
	int type;
	int num;
	ENetPeer *peer;
	string hostname;
	void *info;
};

vector<client *> clients;

ENetHost *serverhost = NULL;
int laststatus = 0;
ENetSocket pongsock = ENET_SOCKET_NULL, lansock = ENET_SOCKET_NULL;

int localclients = 0, nonlocalclients = 0;

bool hasnonlocalclients() { return nonlocalclients!=0; }
bool haslocalclients() { return localclients!=0; }

client &addclient(int type) {
	client *c = NULL;
	loopv(clients) if(clients[i]->type==ST_EMPTY) {
		c = clients[i];
		break;
	}
	if(!c) {
		c = new client;
		c->num = clients.length();
		clients.add(c);
	}
	c->info = server::newclientinfo();
	c->type = type;
	switch(type) {
		case ST_TCPIP: nonlocalclients++; break;
		case ST_LOCAL: localclients++; break;
	}
	return *c;
}

void delclient(client *c) {
	if(!c) return;
	switch(c->type) {
		case ST_TCPIP: nonlocalclients--; if(c->peer) c->peer->data = NULL; break;
		case ST_LOCAL: localclients--; break;
		case ST_EMPTY: return;
	}
	c->type = ST_EMPTY;
	c->peer = NULL;
	if(c->info) {
		server::deleteclientinfo(c->info);
		c->info = NULL;
	}
}

void cleanupserver() {
	if(serverhost) enet_host_destroy(serverhost);
	serverhost = NULL;
	if(pongsock != ENET_SOCKET_NULL) enet_socket_destroy(pongsock);
	if(lansock != ENET_SOCKET_NULL) enet_socket_destroy(lansock);
	pongsock = lansock = ENET_SOCKET_NULL;
}

VARF(maxclients, 0, DEFAULTCLIENTS, MAXCLIENTS, { if(!maxclients) maxclients = DEFAULTCLIENTS; });
VARF(maxdupclients, 0, 0, MAXCLIENTS, { if(serverhost) serverhost->duplicatePeers = maxdupclients ? maxdupclients : MAXCLIENTS; });

void process(ENetPacket *packet, int sender, int chan);
//void disconnect_client(int n, int reason);

int getservermtu() { return serverhost ? serverhost->mtu : -1; }
void *getclientinfo(int i) { return !clients.inrange(i) || clients[i]->type==ST_EMPTY ? NULL : clients[i]->info; }
ENetPeer *getclientpeer(int i) { return clients.inrange(i) && clients[i]->type==ST_TCPIP ? clients[i]->peer : NULL; }
int getnumclients()		{ return clients.length(); }
uint getclientip(int n)	{ return clients.inrange(n) && clients[n]->type==ST_TCPIP ? clients[n]->peer->address.host : 0; }

void sendpacket(int n, int chan, ENetPacket *packet, int exclude) {
	if(n<0) {
		server::recordpacket(chan, packet->data, packet->dataLength);
		loopv(clients) if(i!=exclude && server::allowbroadcast(i)) sendpacket(i, chan, packet);
		return;
	}
	switch(clients[n]->type) {
		case ST_TCPIP: {
			enet_peer_send(clients[n]->peer, chan, packet);
			break;
		}

#ifndef STANDALONE
		case ST_LOCAL:
			localservertoclient(chan, packet);
			break;
#endif
	}
}

ENetPacket *sendf(int cn, int chan, const char *format, ...) {
	int exclude = -1;
	bool reliable = false;
	if(*format=='r') { reliable = true; ++format; }
	packetbuf p(MAXTRANS, reliable ? ENET_PACKET_FLAG_RELIABLE : 0);
	va_list args;
	va_start(args, format);
	while(*format) switch(*format++) {
		case 'x':
			exclude = va_arg(args, int);
			break;
		case 'v': {
			int n = va_arg(args, int);
			int *v = va_arg(args, int *);
			loopi(n) putint(p, v[i]);
			break;
		}
		case 'i': {
			int n = isdigit(*format) ? *format++-'0' : 1;
			loopi(n) putint(p, va_arg(args, int));
			break;
		}
		case 'f': {
			int n = isdigit(*format) ? *format++-'0' : 1;
			loopi(n) putfloat(p, (float)va_arg(args, double));
			break;
		}
		case 's': sendstring(va_arg(args, const char *), p); break;
		case 'm': {
			int n = va_arg(args, int);
			p.put(va_arg(args, uchar *), n);
			break;
		}
	}
	va_end(args);
	ENetPacket *packet = p.finalize();
	sendpacket(cn, chan, packet, exclude);
	return packet->referenceCount > 0 ? packet : NULL;
}

ENetPacket *sendfile(int cn, int chan, stream *file, const char *format, ...) {
	if(cn < 0) {
#ifdef STANDALONE
		return NULL;
#endif
	}
	else if(!clients.inrange(cn)) return NULL;
	int len = (int)min(file->size(), stream::offset(INT_MAX));
	if(len <= 0 || len > 16<<20) return NULL;
	packetbuf p(MAXTRANS+len, ENET_PACKET_FLAG_RELIABLE);
	va_list args;
	va_start(args, format);
	while(*format) switch(*format++) {
		case 'i': {
			int n = isdigit(*format) ? *format++-'0' : 1;
			loopi(n) putint(p, va_arg(args, int));
			break;
		}
		case 's': sendstring(va_arg(args, const char *), p); break;
		case 'l': putint(p, len); break;
	}
	va_end(args);
	file->seek(0, SEEK_SET);
	file->read(p.subbuf(len).buf, len);
	ENetPacket *packet = p.finalize();
	if(cn >= 0) sendpacket(cn, chan, packet, -1);
#ifndef STANDALONE
	else sendclientpacket(packet, chan);
#endif
	return packet->referenceCount > 0 ? packet : NULL;
}

const char *disconnectreason(int reason) {
	switch(reason) {
		case DISC_EOP: return "end of packet";
		case DISC_LOCAL: return "server is in local mode";
		case DISC_KICK: return "kicked/banned";
		case DISC_MSGERR: return "message error";
		case DISC_IPBAN: return "ip is banned";
		case DISC_PRIVATE: return "server is in private mode";
		case DISC_MAXCLIENTS: return "server FULL";
		case DISC_TIMEOUT: return "connection timed out";
		case DISC_OVERFLOW: return "overflow";
		case DISC_PASSWORD: return "invalid password";
		default: return NULL;
	}
}

void disconnect_client(int n, int reason) {
	if(!clients.inrange(n) || clients[n]->type!=ST_TCPIP) return;
	enet_peer_disconnect(clients[n]->peer, reason);
	server::clientdisconnect(n);
	delclient(clients[n]);
	const char *msg = disconnectreason(reason);
	string s;
	if(msg) formatstring(s, "client (%s) disconnected because: %s", clients[n]->hostname, msg);
	else formatstring(s, "client (%s) disconnected", clients[n]->hostname);
	logoutf("%s", s);
	server::sendservmsg(s);
}

void kicknonlocalclients(int reason) {
	loopv(clients) if(clients[i]->type==ST_TCPIP) disconnect_client(i, reason);
}

void process(ENetPacket *packet, int sender, int chan) {   // sender may be -1 {
	packetbuf p(packet);
	server::parsepacket(sender, chan, p);
	if(p.overread()) { disconnect_client(sender, DISC_EOP); return; }
}

void localclienttoserver(int chan, ENetPacket *packet) {
	client *c = NULL;
	loopv(clients) if(clients[i]->type==ST_LOCAL) { c = clients[i]; break; }
	if(c) process(packet, c->num, chan);
}

#ifdef STANDALONE
bool resolverwait(const char *name, ENetAddress *address) {
	return enet_address_set_host(address, name) >= 0;
}

int connectwithtimeout(ENetSocket sock, const ENetAddress &remoteaddress) {
	return enet_socket_connect(sock, &remoteaddress);
}
#endif

ENetSocket mastersock = ENET_SOCKET_NULL;
ENetAddress masteraddress = { ENET_HOST_ANY, ENET_PORT_ANY }, serveraddress = { ENET_HOST_ANY, ENET_PORT_ANY };
int lastupdatemaster = 0, lastconnectmaster = 0, masterconnecting = 0, masterconnected = 0;
vector<char> masterout, masterin;
int masteroutpos = 0, masterinpos = 0;
VARN(updatemaster, allowupdatemaster, 0, 1, 1);

void disconnectmaster() {
	if(mastersock != ENET_SOCKET_NULL) {
		server::masterdisconnected();
		enet_socket_destroy(mastersock);
		mastersock = ENET_SOCKET_NULL;
	}
	masterout.setsize(0);
	masterin.setsize(0);
	masteroutpos = masterinpos = 0;
	masteraddress.host = ENET_HOST_ANY;
	masteraddress.port = ENET_PORT_ANY;
	lastupdatemaster = masterconnecting = masterconnected = 0;
}

SVARF(mastername, server::defaultmaster(), disconnectmaster());
VARF(masterport, 1, server::masterport(), 0xFFFF, disconnectmaster());

ENetSocket connectmaster(bool wait) {
	if(!mastername[0]) return ENET_SOCKET_NULL;
	if(masteraddress.host == ENET_HOST_ANY) {
		if(isdedicatedserver()) logoutf("looking up %s...", mastername);
		masteraddress.port = masterport;
		if(!resolverwait(mastername, &masteraddress)) return ENET_SOCKET_NULL;
	}
	ENetSocket sock = enet_socket_create(ENET_SOCKET_TYPE_STREAM);
	if(sock == ENET_SOCKET_NULL) {
		if(isdedicatedserver()) logoutf("could not open master server socket");
		return ENET_SOCKET_NULL;
	}
	if(wait || serveraddress.host == ENET_HOST_ANY || !enet_socket_bind(sock, &serveraddress)) {
		enet_socket_set_option(sock, ENET_SOCKOPT_NONBLOCK, 1);
		if(wait) {
			if(!connectwithtimeout(sock, masteraddress)) return sock;
		}
		else if(!enet_socket_connect(sock, &masteraddress)) return sock;
	}
	enet_socket_destroy(sock);
	if(isdedicatedserver()) logoutf("could not connect to master server");
	return ENET_SOCKET_NULL;
}

bool requestmaster(const char *req) {
	if(mastersock == ENET_SOCKET_NULL) {
		mastersock = connectmaster(false);
		if(mastersock == ENET_SOCKET_NULL) return false;
		lastconnectmaster = masterconnecting = totalmillis ? totalmillis : 1;
	}
	if(masterout.length() >= 4096) return false;
	masterout.put(req, strlen(req));
	return true;
}

bool requestmasterf(const char *fmt, ...) {
	defvformatstring(req, fmt, fmt);
	return requestmaster(req);
}

void processmasterinput() {
	if(masterinpos >= masterin.length()) return;
	char *input = &masterin[masterinpos], *end = (char *)memchr(input, '\n', masterin.length() - masterinpos);
	while(end) {
		*end = '\0';
		const char *args = input;
		while(args < end && !iscubespace(*args)) args++;
		int cmdlen = args - input;
		while(args < end && iscubespace(*args)) args++;
		if(matchstring(input, cmdlen, "failreg"))
			conoutf(CON_ERROR, "master server registration failed: %s", args);
		else if(matchstring(input, cmdlen, "succreg"))
			conoutf("master server registration succeeded");
		else server::processmasterinput(input, cmdlen);
		end++;
		masterinpos = end - masterin.getbuf();
		input = end;
		end = (char *)memchr(input, '\n', masterin.length() - masterinpos);
	}
	if(masterinpos >= masterin.length()) {
		masterin.setsize(0);
		masterinpos = 0;
	}
}

void flushmasteroutput() {
	if(masterconnecting && totalmillis - masterconnecting >= 60000) {
		logoutf("could not connect to master server");
		disconnectmaster();
	}
	if(masterout.empty() || !masterconnected) return;
	ENetBuffer buf;
	buf.data = &masterout[masteroutpos];
	buf.dataLength = masterout.length() - masteroutpos;
	int sent = enet_socket_send(mastersock, NULL, &buf, 1);
	if(sent >= 0) {
		masteroutpos += sent;
		if(masteroutpos >= masterout.length()) {
			masterout.setsize(0);
			masteroutpos = 0;
		}
	}
	else disconnectmaster();
}

void flushmasterinput() {
	if(masterin.length() >= masterin.capacity())
		masterin.reserve(4096);
	ENetBuffer buf;
	buf.data = masterin.getbuf() + masterin.length();
	buf.dataLength = masterin.capacity() - masterin.length();
	int recv = enet_socket_receive(mastersock, NULL, &buf, 1);
	if(recv > 0) {
		masterin.advance(recv);
		processmasterinput();
	}
	else disconnectmaster();
}

static ENetAddress pongaddr;

void sendserverinforeply(ucharbuf &p) {
	ENetBuffer buf;
	buf.data = p.buf;
	buf.dataLength = p.length();
	enet_socket_send(pongsock, &pongaddr, &buf, 1);
}

#define MAXPINGDATA 32

void checkserversockets() {		// reply all server info requests {
	static ENetSocketSet readset, writeset;
	ENET_SOCKETSET_EMPTY(readset);
	ENET_SOCKETSET_EMPTY(writeset);
	ENetSocket maxsock = pongsock;
	ENET_SOCKETSET_ADD(readset, pongsock);
	if(mastersock != ENET_SOCKET_NULL) {
		maxsock = max(maxsock, mastersock);
		ENET_SOCKETSET_ADD(readset, mastersock);
		if(!masterconnected) ENET_SOCKETSET_ADD(writeset, mastersock);
	}
	if(lansock != ENET_SOCKET_NULL) {
		maxsock = max(maxsock, lansock);
		ENET_SOCKETSET_ADD(readset, lansock);
	}
	if(enet_socketset_select(maxsock, &readset, &writeset, 0) <= 0) return;
	ENetBuffer buf;
	uchar pong[MAXTRANS];
	loopi(2) {
		ENetSocket sock = i ? lansock : pongsock;
		if(sock == ENET_SOCKET_NULL || !ENET_SOCKETSET_CHECK(readset, sock)) continue;
		buf.data = pong;
		buf.dataLength = sizeof(pong);
		int len = enet_socket_receive(sock, &pongaddr, &buf, 1);
		if(len < 0 || len > MAXPINGDATA) continue;
		ucharbuf req(pong, len), p(pong, sizeof(pong));
		p.len += len;
		server::serverinforeply(req, p);
	}
	if(mastersock != ENET_SOCKET_NULL) {
		if(!masterconnected) {
			if(ENET_SOCKETSET_CHECK(readset, mastersock) || ENET_SOCKETSET_CHECK(writeset, mastersock)) {
				int error = 0;
				if(enet_socket_get_option(mastersock, ENET_SOCKOPT_ERROR, &error) < 0 || error) {
					logoutf("could not connect to master server");
					disconnectmaster();
				}
				else {
					masterconnecting = 0;
					masterconnected = totalmillis ? totalmillis : 1;
					server::masterconnected();
				}
			}
		}
		if(mastersock != ENET_SOCKET_NULL && ENET_SOCKETSET_CHECK(readset, mastersock)) flushmasterinput();
	}
}

VAR(serveruprate, 0, 0, INT_MAX);
SVAR(serverip, "");
VARF(serverport, 0, server::serverport(), 0xFFFF-1, { if(!serverport) serverport = server::serverport(); });

#ifdef STANDALONE
int curtime = 0, lastmillis = 0, elapsedtime = 0, totalmillis = 0;
#endif

void updatemasterserver() {
	if(!masterconnected && lastconnectmaster && totalmillis-lastconnectmaster <= 5*60*1000) return;
	if(mastername[0] && allowupdatemaster) requestmasterf("regserv %d\n", serverport);
	lastupdatemaster = totalmillis ? totalmillis : 1;
}

uint totalsecs = 0;

void updatetime() {
	static int lastsec = 0;
	if(totalmillis - lastsec >= 1000) {
		int cursecs = (totalmillis - lastsec) / 1000;
		totalsecs += cursecs;
		lastsec += cursecs * 1000;
	}
}

void serverslice(bool dedicated, uint timeout) {   // main server update, called from main loop in sp, or from below in dedicated server {
	if(!serverhost) {
		server::serverupdate();
		server::sendpackets();
		return;
	}
	// below is network only
	if(dedicated) {
		int millis = (int)enet_time_get();
		elapsedtime = millis - totalmillis;
		static int timeerr = 0;
		int scaledtime = server::scaletime(elapsedtime) + timeerr;
		curtime = scaledtime/100;
		timeerr = scaledtime%100;
		if(server::ispaused()) curtime = 0;
		lastmillis += curtime;
		totalmillis = millis;
		updatetime();
	}
	server::serverupdate();
	flushmasteroutput();
	checkserversockets();
	if(!lastupdatemaster || totalmillis-lastupdatemaster>60*60*1000)	   // send alive signal to masterserver every hour of uptime
		updatemasterserver();
	if(totalmillis-laststatus>60*1000) {   // display bandwidth stats, useful for server ops {
		laststatus = totalmillis;
		if(nonlocalclients || serverhost->totalSentData || serverhost->totalReceivedData) logoutf("status: %d remote clients, %.1f send, %.1f rec (K/sec)", nonlocalclients, serverhost->totalSentData/60.0f/1024, serverhost->totalReceivedData/60.0f/1024);
		serverhost->totalSentData = serverhost->totalReceivedData = 0;
	}
	ENetEvent event;
	bool serviced = false;
	while(!serviced) {
		if(enet_host_check_events(serverhost, &event) <= 0) {
			if(enet_host_service(serverhost, &event, timeout) <= 0) break;
			serviced = true;
		}
		switch(event.type) {
			case ENET_EVENT_TYPE_CONNECT: {
				client &c = addclient(ST_TCPIP);
				c.peer = event.peer;
				c.peer->data = &c;
				string hn;
				copystring(c.hostname, (enet_address_get_host_ip(&c.peer->address, hn, sizeof(hn))==0) ? hn : "unknown");
				logoutf("client connected (%s)", c.hostname);
				int reason = server::clientconnect(c.num);
				if(reason) disconnect_client(c.num, reason);
				break;
			}
			case ENET_EVENT_TYPE_RECEIVE: {
				client *c = (client *)event.peer->data;
				if(c) process(event.packet, c->num, event.channelID);
				if(event.packet->referenceCount==0) enet_packet_destroy(event.packet);
				break;
			}
			case ENET_EVENT_TYPE_DISCONNECT: {
				client *c = (client *)event.peer->data;
				if(!c) break;
				logoutf("disconnected client (%s)", c->hostname);
				server::clientdisconnect(c->num);
				delclient(c);
				break;
			}
			default:
				break;
		}
	}
	if(server::sendpackets()) enet_host_flush(serverhost);
}

void flushserver(bool force) {
	if(server::sendpackets(force) && serverhost) enet_host_flush(serverhost);
}

#ifndef STANDALONE
void localdisconnect(bool cleanup) {
	bool disconnected = false;
	loopv(clients) if(clients[i]->type==ST_LOCAL) {
		server::localdisconnect(i);
		delclient(clients[i]);
		disconnected = true;
	}
	if(!disconnected) return;
	game::gamedisconnect(cleanup);
	mainmenu = 1;
}

void localconnect() {
	if(initing) return;
	client &c = addclient(ST_LOCAL);
	copystring(c.hostname, "local");
	game::gameconnect(false);
	server::localconnect(c.num);
}
#endif

void logoutfv(const char *fmt, va_list args) {
	FILE *f = stdout;
	if(f) writelogv(f, fmt, args);
}

static bool dedicatedserver = false;

bool isdedicatedserver() { return dedicatedserver; }

void rundedicatedserver() {
	dedicatedserver = true;
	logoutf("dedicated server started, waiting for clients...");
	for(;;) serverslice(true, 5);
	dedicatedserver = false;
}

bool servererror(bool dedicated, const char *desc) {
	(void) dedicated;
#ifndef STANDALONE
	if(!dedicated) {
		conoutf(CON_ERROR, "%s", desc);
		cleanupserver();
	}
	else
#endif
		fatal("%s", desc);
	return false;
}

bool setuplistenserver(bool dedicated) {
	ENetAddress address = { ENET_HOST_ANY, enet_uint16(serverport <= 0 ? server::serverport() : serverport) };
	if(*serverip) {
		if(enet_address_set_host(&address, serverip)<0) conoutf(CON_WARN, "WARNING: server ip not resolved");
		else serveraddress.host = address.host;
	}
	serverhost = enet_host_create(&address, min(maxclients + server::reserveclients(), MAXCLIENTS), server::numchannels(), 0, serveruprate);
	if(!serverhost) return servererror(dedicated, "could not create server host");
	serverhost->duplicatePeers = maxdupclients ? maxdupclients : MAXCLIENTS;
	address.port = server::serverinfoport(serverport > 0 ? serverport : -1);
	pongsock = enet_socket_create(ENET_SOCKET_TYPE_DATAGRAM);
	if(pongsock != ENET_SOCKET_NULL && enet_socket_bind(pongsock, &address) < 0) {
		enet_socket_destroy(pongsock);
		pongsock = ENET_SOCKET_NULL;
	}
	if(pongsock == ENET_SOCKET_NULL) return servererror(dedicated, "could not create server info socket");
	else enet_socket_set_option(pongsock, ENET_SOCKOPT_NONBLOCK, 1);
	address.port = server::laninfoport();
	lansock = enet_socket_create(ENET_SOCKET_TYPE_DATAGRAM);
	if(lansock != ENET_SOCKET_NULL && (enet_socket_set_option(lansock, ENET_SOCKOPT_REUSEADDR, 1) < 0 || enet_socket_bind(lansock, &address) < 0)) {
		enet_socket_destroy(lansock);
		lansock = ENET_SOCKET_NULL;
	}
	if(lansock == ENET_SOCKET_NULL) conoutf(CON_WARN, "WARNING: could not create LAN server info socket");
	else enet_socket_set_option(lansock, ENET_SOCKOPT_NONBLOCK, 1);
	return true;
}

void initserver(bool listen, bool dedicated) {
	execfile("server-init.cfg", false);
	if(listen) setuplistenserver(dedicated);
	server::serverinit();
	if(listen) {
		dedicatedserver = dedicated;
		updatemasterserver();
		if(dedicated) rundedicatedserver(); // never returns
#ifndef STANDALONE
		else conoutf("listen server started");
#endif
	}
}

#ifndef STANDALONE
void startlistenserver(int *usemaster) {
	if(serverhost) { conoutf(CON_ERROR, "listen server is already running"); return; }
	allowupdatemaster = *usemaster>0 ? 1 : 0;
	if(!setuplistenserver(false)) return;
	updatemasterserver();
	conoutf("listen server started for %d clients%s", maxclients, allowupdatemaster ? " and listed with master server" : "");
}
COMMAND(startlistenserver, "i");

void stoplistenserver() {
	if(!serverhost) { conoutf(CON_ERROR, "listen server is not running"); return; }
	kicknonlocalclients();
	enet_host_flush(serverhost);
	cleanupserver();
	conoutf("listen server stopped");
}
COMMAND(stoplistenserver, "");
#endif

#ifdef STANDALONE
int main(void) {
	if(enet_initialize()<0) fatal("Unable to initialise network module");
	atexit(enet_deinitialize);
	enet_time_set(0);
	initserver(true, true);
	return EXIT_SUCCESS;
}
#endif