//#include <errno.h>
//#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h> //sprintf


// accept
// atoi
// bind
// bzero
// calloc
// close
// exit
// free
// listen
// malloc
// memset
// realloc
// recv
// select
// send
// socket
// sprintf
// strcat
// strcpy
// strlen
// strstr
// write

#define BUFSIZE 42000

void error(char *str) {
	write(2, str, strlen(str));
	exit(1);
}

int init_socket(struct sockaddr_in *addr, int len, int port) {
	int server_fd;

	if ( (server_fd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
		error("Fatal error2\n");
	bzero(addr, len);
	addr->sin_family = AF_INET;
	addr->sin_addr.s_addr = htonl(2130706433); //127.0.0.1
	addr->sin_port = htons(port);

	if (bind(server_fd, (const struct sockaddr *)addr, len) == -1)
		error("Fatal error3\n");
	if (listen(server_fd, 10) == -1)
		error("Fatal error4\n");

	return server_fd;
}

void broadcast(char *buf, fd_set *set, int max_fd, int server_fd, int sender_fd) {
	for(int i = 0; i <= max_fd; ++i) {
		if (i == server_fd)
			continue;
		if (i == sender_fd)
			continue;
		if (FD_ISSET(i, set))
			send(i, buf, strlen(buf), 0);
	}
}

int main(int ac, char **av) {
	int									server_fd;
	int									client_fd;
	int									client_id;

	int									port;
	int									max_fd;
	int									ret;
	int									clients[FD_SETSIZE];

	char								buf[BUFSIZE];
	char								tmpbuf[BUFSIZE];
	char								msg[BUFSIZE];

	struct sockaddr_in	addr;
	socklen_t						addr_len;
	fd_set							fdset;
	fd_set							rdset;

	if (ac != 2)
		error("Wrong number of arguments\n");
	if ( (port = atoi(av[1])) == -1)
		error("Fatal error1\n");
	addr_len = sizeof(addr);

	server_fd = init_socket(&addr, addr_len, port);

	FD_ZERO(&fdset);
	FD_SET(server_fd, &fdset);
	max_fd = server_fd;
	client_id = 0;

/*
*/
	while (1) {
		rdset = fdset;

		select(max_fd + 1, &rdset, NULL, NULL, NULL);

		// new connection
		if (FD_ISSET(server_fd, &rdset)) {
			client_fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len);
			FD_SET(client_fd, &fdset);
			clients[client_fd] = client_id;
			if (client_fd > max_fd)
				max_fd = client_fd;
			sprintf(msg, "server: client %d just arrived\n", client_id);
			broadcast(msg, &fdset, max_fd, server_fd, client_fd);
			client_id++;
		}

		// new message
		client_fd = 0;
		while(client_fd <= max_fd) {
			ret = 1;
			if (FD_ISSET(client_fd, &rdset)) {
				bzero(buf, BUFSIZE);
				ret = recv(client_fd, buf, BUFSIZE, 0);
				if (ret == 0) {
					sprintf(msg, "server: client %d just left\n", clients[client_fd]);
					broadcast(msg, &fdset, max_fd, server_fd, client_fd);
					FD_CLR(client_fd, &fdset);
				}
				else if (ret > 0) {

					for(int i = 0, j = 0; buf[i] != '\n'; ++i, ++j) {
						tmpbuf[j] = buf[i];
						if (buf[i] == '\n') {
							tmpbuf[j] = '\0';
							sprintf(msg, "client %d: %s\n", clients[client_fd], tmpbuf);
							broadcast(msg, &fdset, max_fd, server_fd, client_fd);
							bzero(tmpbuf, strlen(tmpbuf));
							j = -1;
						}
					}

				}
			}
			client_fd++;
		}
	}

	return (0);
}