//Prog.c
//usage: prog [-t|-u][-x][-h|-n] hostname servicename
//	-t TCP (def)
//	-u UDP
//	-x HEX
//	-h host byte order (def)
//	-n network byte order

//povratne vrijednosti: 0 - sve OK; neki broj za krivi unos argumenata, neki broj za nepostojeci servis/host
//ispisati std. error (postoji funkcija)


#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <err.h>
#include <netinet/in.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <string.h>
#include <arpa/inet.h>


int main(int argc, char *argv[]) {
	int err, option, TCPFlag = 1, UDPFlag = 0, HEXFlag = 0, HBOFlag = 1, NBOFlag = 0;
	int type, mysocket;
	char addrstr[100], *error;
	struct sockaddr_in myaddr;
	struct addrinfo hints, *result;
	struct servent *server;

	if (argc < 3) {																		//inicijalna provjera ulaznih argumenata
		printf("Usage: prog [-t|-u][-x][-h|-n] hostname servicename\n");
		return 2;
	}

	//Provjera zastavica
	while((option = getopt(argc, argv, "tuxhn")) != -1) {
		switch (option) {
			case 't': 	TCPFlag = 1;
						break;
			case 'u':	UDPFlag = 1;
						break;
			case 'x':	HEXFlag = 1;
						break;
			case 'h':	HBOFlag = 1;
						break;
			case 'n':	NBOFlag = 1;
						break;
			default:	printf("Usage: prog [-t|-u][-x][-h|-n] hostname servicename\n");				//dana nepoznata opcija
						return 2;
		}
	}

	if (argc - optind != 2) {																			//nisu dani svi nuzni argumenti
		printf("Usage: prog [-t|-u][-x][-h|-n] hostname servicename\n");
		return 2;
	}

	if (UDPFlag)
		type = SOCK_DGRAM;
	else
		type = SOCK_STREAM;

	//Stvori socket
	mysocket = socket(PF_INET, type, 0);								// 0 za def. IP; mozda 6 za TCP i 17 za UDP
	if (mysocket == -1)	{
		//errx(24, "%s", gai_strerror(err));
		error = strerror(errno);
		printf("%s\n", error);
		return 24;
	}


	//Moji podaci (IP i port)
	myaddr.sin_family = AF_INET;
	myaddr.sin_port = htons(0);
	myaddr.sin_addr.s_addr = htonl(INADDR_ANY);

	//Povezi socket sa svoje strane
	err = bind(mysocket, (struct sockaddr *) &myaddr, sizeof(myaddr));
	if (err) {
		error = strerror(errno);
		printf("%s\n", error);
		//errx(24, "%s", gai_strerror(err));
		return 24;
	}


	memset(&hints, 0, sizeof(hints));
	hints.ai_family = AF_INET;
	hints.ai_flags |= AI_CANONNAME;
	err = getaddrinfo(argv[argc-2], argv[argc-1], &hints, &result);				//povezi se i provjeri
	if (err) {
		error = strerror(errno);
		printf("%s\n", error);
		//errx(25, "%s", gai_strerror(err));
		return 25;
	}


	inet_ntop(result->ai_family, &((struct sockaddr_in *) result->ai_addr)->sin_addr, addrstr, 100);

	//Koji protokol
	if (UDPFlag)
		server = getservbyname(argv[argc-1], "udp");					//dobiva u network byte orderu
	else
		server = getservbyname(argv[argc-1], "tcp");

	if (server == NULL) {
		printf("servname not supported for ai_socktype\n");				//TODO: kako dobiti pravi error
		return 25;
	}
	//Koji redosljed ispisa rezultata
	if (!NBOFlag)
		server->s_port = ntohs(server->s_port);


	//Hex ili Dec
	if (HEXFlag)
		printf("%s (%s) %x\n", addrstr, result->ai_canonname, server->s_port);	//hex vrijednost
	else
		printf("%s (%s) %d\n", addrstr, result->ai_canonname, server->s_port);	//dec vrijednost

	//Ciscenje
	freeaddrinfo(result);
	close(mysocket);
	return 0;
}