/* client.c
 * Greatly inspired from examples written by tmouse, July 2005
 * http://cboard.cprogramming.com/showthread.php?t=67469
 * Modified to run multi-platform by Christian Beier <dontmind@freeshell.org>.
 */

#ifndef __MINGW32__
#include <unistd.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include "msock.h" 

#define MULTICAST_RECV_BUF 10240
#define MULTICAST_SO_RCVBUF 425984
#define DEFAULT_MCAST_IP_STR "ff02::114"
#define DEFAULT_PORT_STR "9000"

/* Cmdline Arguments */
char *prog_name = NULL;
char *mcast_ip = NULL; 
char *port = NULL;

/* Sockets as global, used everywhere, even in die() */
SOCKET mcast_sock = (SOCKET) -1; /* Multicast socket for receiving data */
SOCKET ucast_sock = (SOCKET) -1; /* Unicast socket for give feedback to server */

/* Buffer used for earch recvfrom() */
char recvbuf[MULTICAST_RECV_BUF];

/* Strings to print out representation of various states of the program */
const char * const state_str[] = {
	"exiting",
	"wait_hello_and_connect_back",
	"wait_start_and_start_job",
	"receive_data",
	"finalize_job",
	"is_there_more_job"
};

/* Some boring funcs you didn't want to read now */
void die(char* msg);
void usage(char *msg);
void arg_parse(int argc, char* argv[]);

/* Parts of the "protocol", definitions are after main() */
int wait_hello_and_connect_back();
int wait_start_and_start_job();
int receive_data();
int finalize_job();
int is_there_more_job();


int main(int argc, char* argv[]) {
	int state = 1; /* state of the "protocol" state machine */
	int res;

	arg_parse(argc, argv);

	/* Finite state machine */
	while ( state > 0 ) {
		fprintf(stderr, "Now in %s state\n", state_str[state]);
		switch ( state ) {
			case 1: state = (wait_hello_and_connect_back() == 0)?2:1; break;
			case 2: state = (wait_start_and_start_job() == 0)?2:3; break;
			case 3: res = receive_data();
							if (res==0) state = 4;
							else if (res==1) state=3;
							else state = -1;
							break;
			case 4: state = (finalize_job() == 0)?5:-2; break;
			case 5: state = (is_there_more_job() == 0)?2:0; break;
		}
	}

	if ( mcast_sock > 0 ) {
		close(mcast_sock);
	}

	if ( state < 0 )
		return -state;

	return EXIT_SUCCESS;
}


int wait_hello_and_connect_back() {
	/* Buffers for host and service strings after resolve */
	char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
	/* Server address, filled by system after first recvfrom */
	struct sockaddr_storage peer_addr;
	socklen_t peer_addr_len;
	/* Various needed variables */
	ssize_t nread;
	int res;

	/* Setup mcast_sock */
	if ( mcast_sock > 0 ) {
		close(mcast_sock);
		mcast_sock = 0;
	}
	mcast_sock = mcast_recv_socket(mcast_ip, port, MULTICAST_SO_RCVBUF);
	if(mcast_sock < 0)
			usage("Could not setup multicast socket. Wrong args given ?");

	/* Wait for a single datagram from the server (for sync, no check on contain) */
	peer_addr_len = sizeof(struct sockaddr_storage);
	nread = recvfrom(mcast_sock, recvbuf, MULTICAST_RECV_BUF, 0, (struct sockaddr *) &peer_addr, &peer_addr_len);
 	if (nread < 0 ) {	
		perror("recvfrom() failed");
		return -1;	
	}
	/* Get peer informations as strings from peer_addr */
	res = getnameinfo((struct sockaddr *) &peer_addr, peer_addr_len,
			 hbuf, NI_MAXHOST, sbuf, NI_MAXSERV, NI_NUMERICSERV);
	if ( res != 0 ) {
		fprintf(stderr, "getnameinfo: %s\n", gai_strerror(res));
		return -2;	
	}
	/* Connect back to the server, with reliable unicast */
	if ( ucast_sock > 0 ) {
		close(ucast_sock);
	}
	ucast_sock = ucast_client_socket(hbuf,port);
	if(ucast_sock < 0) {
		fprintf(stderr, "Could not setup unicast socket or connect to %s:%s\n", hbuf, port);
		return -3;	
	}

	return 0;
}

int wait_start_and_start_job() {
	ssize_t nread, nwrite;

	/* Wait for a "start" datagram from the server */
	nread = recvfrom(mcast_sock, recvbuf, MULTICAST_RECV_BUF, 0, NULL, 0);
 	if (nread < 0 ) {	
		perror("recvfrom() failed");
		return -1;	
	}
	if ( nread >= 5 && strncmp("start", recvbuf, 5) == 0 ) {

		nwrite = write(ucast_sock, "ready", 5);
		if ( nwrite < 0 ) {
			fprintf(stderr, "write() failed\n");
			return -2;
		}
		if (nwrite != 5) {
			fprintf(stderr, "write() short\n");
			return -3;
		}

		return 1;
	}

	return 0;	
}

int receive_data() {
	ssize_t nread;
	uint32_t seq;
	uint16_t datalen;

	/* Wait for a "dataN" datagram from the server */
	nread = recvfrom(mcast_sock, recvbuf, MULTICAST_RECV_BUF, 0, NULL, 0);
 	if (nread < 0 ) {	
		perror("recvfrom() failed");
		return -1;	
	}
	if ( nread >= 10 && strncmp("data", recvbuf, 4) == 0 ) {
		seq = ntohl( *( (uint32_t *) recvbuf+1 ) );
		datalen = ntohs( *( (uint16_t *) recvbuf+4 ) );
		//fprintf(stderr, "debug seq==%i, datalen==%hi\n", seq, datalen);
		if ( nread != (10 + datalen) ) {
			fprintf(stderr, "debug nread==%zi, (10 + datalen)==%i\n", nread, (10 + datalen));
			//TODO nack ?
			return -2;
		}
		fprintf(stdout, "data #%i, ", seq);
		fwrite(recvbuf+10, datalen, 1, stdout);
		fflush(stdout);
		//TODO buffer zero copy, ack
		return 1;
	}

	return 0;
}

int finalize_job() {
	return 0;	
}
int is_there_more_job() {
	return 1;
}




void die(char* msg) {
	fprintf(stderr, "%s\n", msg);
	if (mcast_sock > 0)
		close(mcast_sock);
	if (ucast_sock > 0)
		close(ucast_sock);
	exit(EXIT_FAILURE);
}

void usage(char *msg) {
	char ubuf[256];
	if ( msg != NULL )
		fprintf(stderr, "%s\n", msg);
	ubuf[0] = '\0';
	snprintf(ubuf, 255, "Usage: %s [port] [mcast_ip]\n", prog_name);
	die(ubuf);
}

void arg_parse(int argc, char* argv[]) {
	prog_name = argv[0];
	if ( argc > 3 )
		usage("Too many arguments");	
	port = (argc >= 2)?argv[1]:DEFAULT_PORT_STR;
	mcast_ip = (argc >= 3)?argv[2]:DEFAULT_MCAST_IP_STR;
}