#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h> 
#include <sys/socket.h>
#include <netinet/in.h>
#include <time.h>

// from daq.h
#define DAQ_EVTYPE_START_RUN 1
#define DAQ_EVTYPE_STOP_RUN 2

#define	PORT	31337
#define OUT_FILE	"junk"
//#define	HOST	192.
//#define	flen	53851
#define	BUFLEN	65536		//65536-20 is the maximum udp packet size, looks like a nice maximum for server.

//#define DEBUG

/**
 * TODO:
 * 	Make sure data is fetched from same client.
 **/
int main(void){
	int sockHandle;
	//int port;
	struct sockaddr_in *sock_server, *sock_client;
	char buf[BUFLEN];
	unsigned char *bufp,evtype;
	unsigned int downloaded=0;
	unsigned int sequence=0;
	unsigned long fileSize=0;
	unsigned long transSize=0,evsize=0;
	int packetCount=-1;
	int received=0;
	FILE *fileHandle;
	time_t timv;
	struct tm *ltm;
	char filename[40];
	struct timeval tv_start, tv_finish;
	double diff_msec;

	socklen_t socklen=sizeof(struct sockaddr_in);
    printf("datasink\n");
	sock_server = malloc(socklen);
	sock_client = malloc(socklen);
	if(!sock_server || !sock_client){
		printf("Cannot allocate memory for socket.\n");
	}

	sockHandle=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
	if(sockHandle<0){
		printf("Cannot get socket\n");
		return 0;
	}
	
	sock_server->sin_family = AF_INET;
	sock_server->sin_addr.s_addr=htonl(INADDR_ANY);
	sock_server->sin_port = htons(PORT);
	if(bind(sockHandle, (struct sockaddr *)sock_server, socklen)<0){
		printf("Error, cannot bind socket\n");
		return 0;
	}
	printf("ready for data\n");
	while(1){
		received=recvfrom(sockHandle, buf, BUFLEN, 0, (struct sockaddr *)sock_client, &socklen);
		if(received<0){
			printf("Error, cannot receive data\n");
			return 0;
		}
		if(packetCount==-1){
			sequence = buf[0]<<8;
			sequence |= buf[1];
			sequence &= 0x0000ffff;
			if(sequence!=0){
				printf("Caught packet in middle of stream, ignoring\n");
				continue;
			}else{
				#ifdef DEBUG
				printf("Caught first packet, starting capture.\n");
				#endif
				packetCount=0;
				transSize = (buf[2] & 0x000000ff)<<8;
				transSize |= buf[3] & 0x000000ff;
				transSize &= 0x0000ffff;
				#ifdef DEBUG
				printf("s%u, p%u packet/ransfer size =0x%x/%x\n", sequence, packetCount, received,transSize);
				#endif
				//check for correct n3c format
				bufp = (unsigned char*)buf+4;
				evtype  = *bufp;
				evsize  = (bufp[1] & 0xff)<<16;
				evsize |= (bufp[2] & 0xff)<<8 ;
				evsize |= (bufp[3] & 0xff);
				if(sequence==0 && (evsize != received - 4))
				{
					bufp = (unsigned char*)buf+4;
					printf("Not n3c event. Size=0x%x, evSize=0x%x, evtype=0x%x, body=%02x%02x%02x%02x\n",
					transSize, evsize, evtype, bufp[0],bufp[1],bufp[2],bufp[3]);
				}
				else packetCount=-1; // all packets of this transfer have been received
				switch (evtype)
				{
				case DAQ_EVTYPE_START_RUN:
					timv = time(0);
					ltm = localtime(&timv);
					sprintf(filename,"%02i%02i%02i%02i%02i%02i.dq0",
						ltm->tm_year%100,ltm->tm_mon+1,ltm->tm_mday,
						ltm->tm_hour,ltm->tm_min,ltm->tm_sec);
					printf("Start Run %s\n",filename);
					fileHandle=fopen(filename, "wb");
					if(fileHandle==NULL)
					{
						printf("Cannot open file for writing\n");
						return 0;
					}
					downloaded = 0;
					packetCount=-1;
					gettimeofday(&tv_start,0);
					break;
				case DAQ_EVTYPE_STOP_RUN:
					gettimeofday(&tv_finish,0);
					printf("Stop Run. Downloaded %i bytes. ",downloaded);
					diff_msec = (tv_finish.tv_sec - tv_start.tv_sec)*1000. 
						+ (double)(tv_finish.tv_usec - tv_start.tv_usec)/1000.;
					printf("@ %g KBytes/s\n",downloaded/diff_msec);
					if(fileHandle) fclose(fileHandle);
					fileHandle=NULL;
					printf("continue..\n");
					break;
				default:
					fwrite(buf+4, 1, received-4, fileHandle);
					downloaded += received-4;
				}
			}
		}else{
			sequence = buf[0]<<8;
			sequence |= buf[1];
			sequence &= 0x0000ffff;
			if(sequence!=packetCount+1){
				printf("Missed a packet, bumping sequence. Expecting %u, got %u. Waiting for new sequence.\n", packetCount+1, sequence);
				fseek(fileHandle, 0, SEEK_SET);
				packetCount=0;
				downloaded=0;
			}else{
				fwrite(buf+2, 1, received-2, fileHandle);
				packetCount++;
				downloaded += received-2;
				printf("Downloaded: %i\n", downloaded);
			}
		}
		//if(downloaded>=fileSize){
		//printf("Download complete. %i out of %i bytes.\n", 
		//	downloaded, fileSize);
		//	break;
	}
	if(fileHandle) fclose(fileHandle);
	//listen(sockHandle)
}