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#ifndef tcptimesync_h
#define tcptimesync_h

struct SYNC_PACKET {
	unsigned char type;
	union {
		struct {
			Uint32 s;
			Uint32 c;
		} u;
		struct {
			Sint32 s;
			Sint32 c;
		} s;
	} data;
};

typedef struct SYNC_PACKET SyncPacket;

void sendSyncPacket(TCPsocket sock, SyncPacket *sp)
{
	char tmp[8];
	SDLNet_TCP_Send(sock,&sp->type,1);
	SDLNet_Write32(sp->data.u.s,tmp);
	SDLNet_Write32(sp->data.u.c,tmp+4);
	SDLNet_TCP_Send(sock,tmp,8);
}

void recvSyncPacket(TCPsocket sock, SyncPacket *sp)
{
	char tmp[8];
	SDLNet_TCP_Recv(sock,&sp->type,1);
	SDLNet_TCP_Recv(sock,tmp,8);
	sp->data.u.s=SDLNet_Read32(tmp);
	sp->data.u.c=SDLNet_Read32(tmp+4);
}

void printSyncPacket(SyncPacket *sp)
{
	printf("SyncPacket %8p:\n",sp);
	printf("\ttype=%d\n",sp->type);
	printf("\tdata.u.s=%u\n",sp->data.u.s);
	printf("\tdata.u.c=%u\n",sp->data.u.c);
	printf("\tdata.s.s=%d\n",sp->data.s.s);
	printf("\tdata.s.c=%d\n",sp->data.s.c);
}

#endif

#include 
#ifndef _MSC_VER
#include 
#endif
#include "SDL.h"
#include "SDL_net.h"

int main(int argc, char **argv)
{
	IPaddress ip,*remoteip;
	TCPsocket server=NULL,client=NULL,sock=NULL;
	char *hostname;
	int simlag;
	Uint32 ipaddr,t[2],base,now;
	float lag;
	Uint16 port;
	
	// check our commandline
	if(argc<3)
	{
		printf("%s lag port [hostname]\n",argv[0]);
		exit(0);
	}
	
	// initialize SDL
	if(SDL_Init(0)==-1)
	{
		printf("SDL_Init: %s\n",SDL_GetError());
		exit(1);
	}

	// initialize SDL_net
	if(SDLNet_Init()==-1)
	{
		printf("SDLNet_Init: %s\n",SDLNet_GetError());
		exit(2);
	}

	// get the desired simulated lag from the commandline
	simlag=strtol(argv[1],NULL,0);
	
	// get the port from the commandline
	port=(Uint16) strtol(argv[2],NULL,0);

	// get the hostname from commandline (for client)
	hostname=argc>3?argv[3]:NULL;
	
	// Resolve the argument into an IPaddress type
	if(SDLNet_ResolveHost(&ip,hostname,port)==-1)
	{
		printf("SDLNet_ResolveHost: %s\n",SDLNet_GetError());
		exit(3);
	}

	lag=-1;
	if(!hostname)
	{
		// open the server socket
		server=SDLNet_TCP_Open(&ip);
		if(!server)
		{
			printf("SDLNet_TCP_Open: %s\n",SDLNet_GetError());
			exit(4);
		}

		client=NULL;
		while(!client)
		{ // no connection accepted
			client=SDLNet_TCP_Accept(server);
			if(!client)
				SDL_Delay(100); //sleep 1/10th of a second
		}
		
		// get the clients IP and port number
		remoteip=SDLNet_TCP_GetPeerAddress(client);
		if(!remoteip)
		{
			printf("SDLNet_TCP_GetPeerAddress: %s\n",SDLNet_GetError());
			goto endS;
		}

		// print out the clients IP and port number
		ipaddr=SDL_SwapBE32(remoteip->host);
		printf("Accepted a connection from %d.%d.%d.%d port %hu\n",
			ipaddr>>24,
			(ipaddr>>16)&0xff,
			(ipaddr>>8)&0xff,
			ipaddr&0xff,
			remoteip->port);

		base=SDL_GetTicks();
		t[0]=SDL_SwapBE32(0);
		t[1]=SDL_SwapBE32(~0L);
		SDLNet_TCP_Send(client,t,sizeof(t));
		
		SDLNet_TCP_Recv(client,t,sizeof(t));
		now=SDL_GetTicks()-base;
		t[0]=SDL_SwapBE32(t[0]);
		t[1]=SDL_SwapBE32(t[1]);
		lag=(now-t[0])/2.0f;
		printf("S1) now=%u t[0]=%u t[1]=%u (lag=%f)\n",
				now ,t[0], t[1], lag);

		t[0]=SDL_SwapBE32(SDL_GetTicks()-base+(Uint32)lag);
		t[1]=SDL_SwapBE32(t[1]);
		SDLNet_TCP_Send(client,t,sizeof(t));

		SDLNet_TCP_Recv(client,t,sizeof(t));
		now=SDL_GetTicks()-base;
		t[0]=SDL_SwapBE32(t[0]);
		t[1]=SDL_SwapBE32(t[1]);
		lag+=(Sint32)t[0];
		printf("S2) now=%u t[0]=%d t[1]=%u (lag=%f)\n",
				now ,t[0], t[1], lag);

		t[0]=SDL_GetTicks()-base+(Uint32) lag;
		t[0]=SDL_SwapBE32(t[0]);
		t[1]=((Sint32)(now-t[1]))/2;
		t[1]=SDL_SwapBE32(t[1]);
		SDLNet_TCP_Send(client,t,sizeof(t));
		/*for(i=0; i<20; i++)
		{
			printf("Server time : %u\n", SDL_GetTicks()-base);
			fflush(stdout);
			SDL_Delay(50);
		}*/
endS:
		SDLNet_TCP_Close(client);
		SDLNet_TCP_Close(server);
	}
	else
	{
		// open the server socket
		sock=SDLNet_TCP_Open(&ip);
		if(!sock)
		{
			printf("SDLNet_TCP_Open: %s\n",SDLNet_GetError());
			goto endC;
		}

		SDLNet_TCP_Recv(sock,t,sizeof(t));
		if(simlag) SDL_Delay(simlag);
		base=SDL_GetTicks();
		t[0]=SDL_SwapBE32(t[0]);
		printf("C1) t[0]=%u\n",t[0]);

		
		t[0]=SDL_SwapBE32(t[0]);
		t[1]=SDL_SwapBE32(SDL_GetTicks()-base);
		if(simlag) SDL_Delay(simlag);
		SDLNet_TCP_Send(sock,t,sizeof(t));
		
		SDLNet_TCP_Recv(sock,t,sizeof(t));
		if(simlag) SDL_Delay(simlag);
		now=SDL_GetTicks()-base;
		t[0]=SDL_SwapBE32(t[0]);
		t[1]=SDL_SwapBE32(t[1]);
		lag=(now-t[1])/2.0f;
		base-=(Uint32) lag;
		now+=(Uint32) lag;
		printf("C2) now=%u t[0]=%u t[1]=%u (lag=%f)\n",
				now, t[0], t[1], lag);

		t[0]=((Sint32)(now-t[0]))/2;
		t[0]=SDL_SwapBE32(t[0]);
		t[1]=(SDL_GetTicks()-base+(Uint32) lag);
		t[1]=SDL_SwapBE32(t[1]);
		if(simlag) SDL_Delay(simlag);
		SDLNet_TCP_Send(sock,t,sizeof(t));
		
		SDLNet_TCP_Recv(sock,t,sizeof(t));
		if(simlag) SDL_Delay(simlag);
		now=SDL_GetTicks()-base;
		t[0]=SDL_SwapBE32(t[0]);
		t[1]=SDL_SwapBE32(t[1]);
		lag+=(Sint32)t[1];
		base-=(Sint32)t[1];
		now+=(Sint32)t[1];
		printf("C3) now=%u t[0]=%u t[1]=%d (lag=%f)\n",
				now, t[0], t[1], lag);
		/*for(i=0; i<20; i++)
		{
			printf("Client time : %u\n", SDL_GetTicks()-base);
			fflush(stdout);
			SDL_Delay(50);
		}*/
endC:
		SDLNet_TCP_Close(sock);
	}
	
	// shutdown SDL_net
	SDLNet_Quit();

	// shutdown SDL
	SDL_Quit();

	return(0);
}

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