#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>

#define MSGSIZE 1024
#define BUFSIZE 120000

typedef struct s_client {
	int		id;
	char	msg[MSGSIZE];
} t_client;

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

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

int main(int ac, char **av) {
	int									server_fd;
	int									client_fd;
	int									id;
	int									ret;
	int									port;
	int									max_fd;
	char								buf[BUFSIZE];
	char								msg[BUFSIZE];
	struct sockaddr_in	addr; 
	socklen_t						addr_len;
	fd_set							fdset;
	fd_set							rdset;
	fd_set							wdset;
	t_client						clients[FD_SETSIZE];

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

	// socket create and verification 
	server_fd = socket(AF_INET, SOCK_STREAM, 0); 
	if (server_fd == -1)
		error("Fatal error2\n");

	// assign IP, PORT 
	addr.sin_family = AF_INET; 
	addr.sin_addr.s_addr = htonl(2130706433); //127.0.0.1
	addr.sin_port = htons(port); 

	// Binding newly created socket to given IP and verification 
	if ((bind(server_fd, (const struct sockaddr *)&addr, addr_len)) == -1)
		error("Fatal error3\n");
	if (listen(server_fd, 10) == -1)
		error("Fatal error4\n");

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

	while(1) {
		rdset = fdset;
		wdset = fdset;

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

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

		client_fd = 0;
		while(client_fd <= max_fd) {
			if (FD_ISSET(client_fd, &rdset)) {
				ret = recv(client_fd, buf, BUFSIZE, 0);
				if (ret == 0) {
					sprintf(msg, "server: client %d just left\n", clients[client_fd].id);
					broadcast(msg, &wdset, max_fd, client_fd);
					FD_CLR(client_fd, &fdset);
					close(client_fd);
					if (client_fd == max_fd) {
						for(; max_fd > 2; --max_fd) {
							if (FD_ISSET(max_fd, &fdset))
								break;
						}
					}
				}
				else if (ret > 0) {
					for(int i = 0, j = strlen(clients[client_fd].msg); i < ret; ++i, ++j) {
						clients[client_fd].msg[j] = buf[i];
						if (buf[i] == '\n') {
							clients[client_fd].msg[j] = '\0';
							sprintf(msg, "client %d: %s\n", clients[client_fd].id, clients[client_fd].msg);
							broadcast(msg, &wdset, max_fd, client_fd);
							bzero(clients[client_fd].msg, MSGSIZE);
							j = -1;
						}
					}
				}
			}
			++client_fd;
		}
	}

	return(0);
}