#include <netinet/in.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/select.h>
#include <sys/socket.h>
#include <unistd.h>

#define BUFSIZE 200000

typedef struct {
	int	  id;
	char *msg;
} client_t;

client_t clients[FD_SETSIZE];

char recv_buf[BUFSIZE];
char send_buf[BUFSIZE];

int maxfd = 0;
int lastid = -1;
int sockfd = -1;

fd_set main_fd, read_fd, write_fd;

int extract_message(char **buf, char **msg) {
	char *newbuf;
	int	  i;

	*msg = 0;
	if (*buf == 0)
		return (0);
	i = 0;
	while ((*buf)[i]) {
		if ((*buf)[i] == '\n') {
			newbuf = calloc(1, sizeof(*newbuf) * (strlen(*buf + i + 1) + 1));
			if (newbuf == 0)
				return (-1);
			strcpy(newbuf, *buf + i + 1);
			*msg = *buf;
			(*msg)[i + 1] = 0;
			*buf = newbuf;
			return (1);
		}
		i++;
	}
	return (0);
}

char *str_join(char *buf, char *add) {
	char *newbuf;
	int	  len;

	if (buf == 0)
		len = 0;
	else
		len = strlen(buf);
	newbuf = malloc(sizeof(*newbuf) * (len + strlen(add) + 1));
	if (newbuf == 0)
		return (0);
	newbuf[0] = 0;
	if (buf != 0)
		strcat(newbuf, buf);
	free(buf);
	strcat(newbuf, add);
	return (newbuf);
}

void send_all(int cli_fd) {
	for (int i = 0; i <= maxfd; i++)
		if (FD_ISSET(i, &main_fd) && i != sockfd && i != cli_fd)
			send(i, send_buf, strlen(send_buf), 0);
}

void append_client(int cli_fd) {
	lastid++;
	clients[cli_fd].id = lastid;
	clients[cli_fd].msg = NULL;
	FD_SET(cli_fd, &main_fd);
	bzero(send_buf, BUFSIZE);
	sprintf(send_buf, "server: client %d just arrived\n", lastid);
	send_all(cli_fd);
}

void rm_client(int cli_fd) {
	bzero(send_buf, BUFSIZE);
	sprintf(send_buf, "server: client %d, just left\n", clients[cli_fd].id);
	send_all(cli_fd);
	clients[cli_fd].id = -1;
	if (clients[cli_fd].msg != NULL) {
		free(clients[cli_fd].msg);
		clients[cli_fd].msg = NULL;
	}
	FD_CLR(cli_fd, &main_fd);
	close(cli_fd);
}

int read_client(int cli_fd) {
	bzero(recv_buf, BUFSIZE);
	int bytes = recv(cli_fd, recv_buf, BUFSIZE, 0);

	if (bytes <= 0) {
		if (strlen(clients[cli_fd].msg) > 0) {
			for (int i = 0; i < maxfd; i++)
				if (FD_ISSET(i, &main_fd) && i != sockfd && i != cli_fd)
					send(i, clients[cli_fd].msg, strlen(clients[cli_fd].msg), 0);
		}
		rm_client(cli_fd);
		return (0);
	}

	recv_buf[bytes] = 0;
	clients[cli_fd].msg = str_join(clients[cli_fd].msg, recv_buf);
	char *line = NULL;
	while (extract_message(&clients[cli_fd].msg, &line)) {
		bzero(send_buf, BUFSIZE);
		sprintf(send_buf, "client %d: %s", clients[cli_fd].id, line);
		send_all(cli_fd);
		free(line);
	}
	return (1);
}

int send_error(void) {
	for (int i = 0; i < maxfd; i++)
		if (FD_ISSET(i, &main_fd))
			close(i);
	close(sockfd);
	write(STDERR_FILENO, "Fatal error\n", 12);
	return (EXIT_FAILURE);
}

int main(int ac, char **av) {
	if (ac != 2) {
		write(STDERR_FILENO, "Wrong number of argument\n", 25);
		return (EXIT_FAILURE);
	}

	socklen_t		   len;
	struct sockaddr_in servaddr, cli;

	sockfd = socket(AF_INET, SOCK_STREAM, 0);
	if (sockfd == -1)
		return (send_error());

	servaddr.sin_family = AF_INET;
	servaddr.sin_addr.s_addr = htonl(2130706433); // 127.0.0.1
	servaddr.sin_port = htons(atoi(av[1]));

	if (bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) != 0)
		return (send_error());

	if (listen(sockfd, SOMAXCONN) != 0)
		return (send_error());

	FD_ZERO(&main_fd);
	FD_SET(sockfd, &main_fd);
	maxfd = sockfd;

	while (1) {
		read_fd = write_fd = main_fd;
		int ret = select(maxfd + 1, &read_fd, &write_fd, NULL, NULL);
		if (ret < 0)
			return (send_error());

		for (int i = 0; i <= maxfd; i++) {
			if (FD_ISSET(i, &read_fd)) {
				if (i == sockfd) {
					len = sizeof(cli);
					int cli_fd = accept(i, (struct sockaddr *)&cli, &len);
					if (cli_fd < 0)
						return (send_error());

					if (cli_fd > maxfd)
						maxfd = cli_fd;
					append_client(cli_fd);
					break;
				} else {
					if (!read_client(i))
						break;
				}
			}
		}
	}
}