#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#ifndef _MSC_VER
#include <unistd.h>
#endif
#include "SDL.h"
#include "SDL_net.h"

#define ERROR (0xff)
#define TIMEOUT (5000) /*five seconds */

int udpsend(UDPsocket sock, int channel, UDPpacket *out, UDPpacket *in, Uint32 delay, Uint8 expect, int timeout)
{
	Uint32 t,t2;
	int err;
	
	in->data[0]=0;
	t=SDL_GetTicks();
	do
	{
		t2=SDL_GetTicks();
		if(t2-t>(Uint32)timeout)
		{
			printf("timed out\n");
			return(0);
		}
		if(!SDLNet_UDP_Send(sock, channel, out))
		{
			printf("SDLNet_UDP_Send: %s\n",SDLNet_GetError());
			exit(1);
		}
		err=SDLNet_UDP_Recv(sock, in);
		if(!err)
			SDL_Delay(delay);
	} while(!err || (in->data[0]!=expect && in->data[0]!=ERROR));
	if(in->data[0]==ERROR)
		printf("received error code\n");
	return(in->data[0]==ERROR?-1:1);
}

int udprecv(UDPsocket sock, UDPpacket *in, Uint32 delay, Uint8 expect, int timeout)
{
	Uint32 t,t2;
	int err;
	
	in->data[0]=0;
	t=SDL_GetTicks();
	do
	{
		t2=SDL_GetTicks();
		if(t2-t>(Uint32)timeout)
		{
			printf("timed out\n");
			return(0);
		}
		err=SDLNet_UDP_Recv(sock, in);
		if(!err)
			SDL_Delay(delay);
	} while(!err || (in->data[0]!=expect && in->data[0]!=ERROR));
	if(in->data[0]==ERROR)
		printf("received error code\n");
	return(in->data[0]==ERROR?-1:1);
}

int main(int argc, char **argv)
{
	const char *host=NULL;
	char fname[65535];
	int len=1400, plen, err=0;
	Sint32 flen;
	Uint16 port;
	Uint32 ipnum,ack;
	IPaddress ip;
	UDPsocket sock;
	UDPpacket *out, *in, **packets, *outs[32];
	FILE *f=NULL;
	Sint32 p,p2,i;
	
	/* check our commandline */
	if(argc<2)
	{
		printf("%s port [packet-len]\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 port from the commandline */
	port=(Uint16)strtol(argv[1],NULL,0);
	if(!port)
	{
		printf("a server port cannot be 0.\n");
		exit(3);
	}
	
	if(argc>2)
		len=strtol(argv[2],NULL,0);
	
	/* open udp server socket */
	if(!(sock=SDLNet_UDP_Open(port)))
	{
		printf("SDLNet_UDP_Open: %s\n",SDLNet_GetError());
		exit(4);
	}
	printf("port %hd opened\n", port);

	/* allocate max packet */
	if(!(out=SDLNet_AllocPacket(65535)))
	{
		printf("SDLNet_AllocPacket: %s\n",SDLNet_GetError());
		exit(5);
	}
	if(!(in=SDLNet_AllocPacket(65535)))
	{
		printf("SDLNet_AllocPacket: %s\n",SDLNet_GetError());
		exit(5);
	}

	/* allocate 32 packets of size len */
	if(!(packets=SDLNet_AllocPacketV(32,len)))
	{
		printf("SDLNet_AllocPacket: %s\n",SDLNet_GetError());
		exit(6);
	}
	
	while(1)
	{
		if(f)
		{
			fclose(f);
			f=NULL;
		}
		SDLNet_UDP_Unbind(sock, 0);
		in->data[0]=0;
		printf("waiting...\n");
		while(!SDLNet_UDP_Recv(sock, in))
			SDL_Delay(100); /*1/10th of a second */
		if(in->data[0]!=1<<4)
		{
			in->data[0]=ERROR;
			in->len=1;
			SDLNet_UDP_Send(sock, -1, in);
			continue; /* not a request... */
		}
		memcpy(&ip,&in->address,sizeof(IPaddress));
		host=SDLNet_ResolveIP(&ip);
		ipnum=SDL_SwapBE32(ip.host);
		port=SDL_SwapBE16(ip.port);
		if(host)
			printf("request from host=%s port=%hd\n",host,port);
		else
			printf("request from host=%d.%d.%d.%d port=%hd\n",
					ipnum>>24,
					(ipnum>>16)&0xff,
					(ipnum>>8)&0xff,
					ipnum&0xff,
					port);
		if(SDLNet_UDP_Bind(sock, 0, &ip)==-1)
		{
			printf("SDLNet_UDP_Bind: %s\n",SDLNet_GetError());
			exit(7);
		}

		strcpy(fname,(char*)in->data+1);
		printf("fname=%s\n",fname);
		
		/* get actual filesize */
		{
			struct stat buf;

#ifndef _MSC_VER
			if(stat(fname, &buf)>=0 && S_ISREG(buf.st_mode) && (f=fopen(fname,"rb")))
#else
			/* window MSVC version has no check for a valid file except that it opens */
			if(stat(fname, &buf)>=0 && (f=fopen(fname,"rb")))
#endif
				flen=buf.st_size;
			else
				flen=-1;
		}

		/* send filesize / expect ready */
		printf("sending filesize=%d blocksize=%d\n",flen,len);
		out->data[0]=1;
		SDLNet_Write32(flen,out->data+1);
		SDLNet_Write32(len-6,out->data+5);
		out->len=9;
		if(udpsend(sock,0,out,in,10,2<<4,TIMEOUT)<1)
			continue;

		if(flen<0)
			continue; /* invalid file... */

		/* send file */
		printf("sending file\n");
		/*out->data[0]=2; */
		/*out->len=1; */
		/*SDLNet_UDP_Send(sock, -1, out); */

		plen=len-6;
		err=0;
		for(p=0;p<flen && !err;p+=32*plen)
		{
			while(SDLNet_UDP_Recv(sock, in)); /* flush input */
			printf("p=%d\n",p);
			/* fill packets */
			for(p2=0;p+p2*plen<flen && p2<32;p2++)
			{
				packets[p2]->data[0]=2;
				packets[p2]->data[1]=p2;
				SDLNet_Write32(p+p2*plen,packets[p2]->data+2);
				packets[p2]->len=len;
				packets[p2]->channel=0;
				if(p+(p2+1)*plen>=flen)
					packets[p2]->len=6+(flen-(p+p2*plen));
				if(!fread(packets[p2]->data+6, packets[p2]->len-6, 1, f))
				{
					perror("fread");
					continue; /* error on read */
				}
				outs[p2]=packets[p2];
			}
			
			/* setup the acks expected */
			ack=0;
			for(i=p2;i<32;i++)
				ack|=1<<i;

			/* send packets/expect ack */
			while(ack!=0xffffffff && !err)
			{
				do
				{
					printf("sending %d packets\n",p2);
					if(SDLNet_UDP_SendV(sock, outs, p2)<p2)
					{
						printf("SDLNet_UDP_SendV: %s\n",SDLNet_GetError());
						err=-1;
						continue;
					}
					err=udprecv(sock,in,10,3<<4,TIMEOUT);
				} while(err==1 && (Sint32) SDLNet_Read32(in->data+1)!=p);
				if(err<1)
				{
					err=1;
					continue; /* we have an error... */
				}
				err=0;
				ack|=SDLNet_Read32(in->data+5);
				printf("received ack 0x%08X\n",ack);
				for(p2=i=0;i<32;i++)
					if(!((ack>>i)&1))
						outs[p2++]=packets[i];
			}
		}
		if(!err)
			printf("done\n");
		else
			printf("finished with an error\n");

		fclose(f);
		f=NULL;
	}
	
	/* close the socket */
	SDLNet_UDP_Close(sock);
	
	/* free packet */
	SDLNet_FreePacket(out);
	SDLNet_FreePacket(in);
	SDLNet_FreePacketV(packets);
	
	/* shutdown SDL_net */
	SDLNet_Quit();

	/* shutdown SDL */
	SDL_Quit();

	return(0);
}