#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <limits.h>
#include <unistd.h>
#include <netdb.h>
#include <sys/socket.h>
#include <arpa/inet.h>

int main(const int argc, const char **argv) {
	unsigned int f_flag = 0;
	unsigned int d_flag = 0;
	unsigned int i_flag = 0;

	int i;
	for (i = 1; i < argc; i++) {
		if (argv[i][0] != '-')
			break;

		else if (!strcmp(argv[i], "-f"))
			f_flag = 1;

		else if (!strcmp(argv[i], "-d"))
			d_flag = 1;

		else if (!strcmp(argv[i], "-i"))
			i_flag = 1;

		else if (!strcmp(argv[i], "--help")) {
			printf("hostname [-f (Display the FQDN)] [-d (Display domainname)] [-i (Addresses for the hostname)]/ [hostname (Set new hostname)]\n");
			return 0;
		}
	}


	/* Set hostname */
	if (argc - i == 1) {
		if (sethostname(argv[argc - 1], strlen(argv[argc - 1])) < 0) {
			fprintf(stderr, "hostname: %s\n", strerror(errno));
			return 1;
		}

		return 0;
	}

	/* Get info */
	char hostname[HOST_NAME_MAX];
	if (gethostname(hostname, sizeof(hostname)) < 0) {
		fprintf(stderr, "hostname: %s\n", strerror(errno));
		return 1;
	}


	struct hostent *hp = gethostbyname(hostname);
	if (!hp) {
		fprintf(stderr, "hostname: %s\n", strerror(errno));
		return 1;
	}

	/* Print info */
	if (f_flag)
		puts(hp->h_name);

	else if (d_flag) {
		char *ptr = strchr(hp->h_name, '.');
		if (ptr)
			puts(ptr + 1);
	}

	else if (i_flag) {
		while (hp->h_addr_list[0])
			printf("%s ", inet_ntoa( *(struct in_addr *) *(hp->h_addr_list++) ));
		printf("\n");
	}

	else
		puts(hostname);

	return 0;
}