/*
 *  LimoX - The Linux on mobile XMPP chat client
 *  Copyright (C) 2022  xengineering
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */


#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h>


/*
 * Get the domainpart of the Jabber ID (JID)
 *
 * See https://datatracker.ietf.org/doc/html/rfc7622#section-3.2 for details.
 */
char *get_domainpart(char *jid)
{
	int start = 0;           // inclusive
	int stop = strlen(jid);  // exclusive

	for(int i=0; i<strlen(jid); i++) {
		if (jid[i] == '/') {
			stop = i;
			break;
		}
	}

	for(int i=0; i<strlen(jid); i++) {
		if (jid[i] == '@') {
			start = i + 1;
			break;
		}
	}

	char *retval = (char *)malloc((stop-start+1) * sizeof(char));
	memcpy(retval, jid+start, (stop-start) * sizeof(char));
	retval[stop] = '\0';

	return retval;
}

/*
 * Return the preferred struct addrinfo * or NULL
 *
 * This handles DNS resolution. It returns the first valid addrinfo which is
 * returned by getaddrinfo. Mind that the addrinfo could use IPv6 instead of
 * IPv4.
 *
 * FIXME this just takes the first received IPv4 address (by far not compliant
 *       to RFC 6120!)
 * FIXME This function contains a memory leak! Free the linked list servinfo!
 */
struct addrinfo *get_addrinfo(char *domain)
{
	struct addrinfo hints;
	struct addrinfo *servinfo;
	void *addr;
	char ipstr[INET6_ADDRSTRLEN];
	memset(&hints, 0, sizeof hints);
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;
	if (getaddrinfo(domain, "xmpp-client", &hints, &servinfo) != 0) {
		printf("Failed to resolve hostname '%s'.\n", domain);
		return NULL;
	}
	struct addrinfo *p;
	for(p=servinfo; p!=NULL; p=p->ai_next) {
		if (p->ai_family == AF_INET) {
			struct sockaddr_in *ipv4 = (struct sockaddr_in *)p->ai_addr;
			addr = &(ipv4->sin_addr);
			inet_ntop(p->ai_family, addr, ipstr, sizeof ipstr);
			printf("Got compatible IPv4 address %s from DNS.\n", ipstr);
			return p;
		} else if (p->ai_family == AF_INET6) {
			printf("Ignored IPv6 DNS entry which is not supported.\n");
		} else {
			printf("Ignored unknown addrinfo address type.\n");
		}
	}
	printf("No suitable IP address found via DNS!\n");
	return NULL;
}

/*
 * Initialize the network connection to the XMPP server
 *
 * TODO: Error handling is missing.
 */
void xmpp_connect(void)
{
	printf("net_init()\n");

	char *jid = getenv("LIMOX_USER");
	char *pwd = getenv("LIMOX_PWD");
	printf("Trying to connect as '%s' with '%s'.\n", jid, pwd);

	char *domain = get_domainpart(jid);
	printf("Domainpart is '%s'.\n", domain);

	struct addrinfo *addr = get_addrinfo(domain);

	int sock = socket(addr->ai_family, addr->ai_socktype, addr->ai_protocol);
	if (sock == -1) {
		printf("Failed to get socket from OS!.");
		return;
	} else {
		printf("Got socket number %d from OS.\n", sock);
	}
}