#define FD_SET_MAX(fd, set, maxfd) do { \
		FD_SET(fd, set);        \
		if (fd > maxfd)         \
			maxfd = fd;     \
	} while (0)

static Client *client_malloc(int socket) {
	Client *c = calloc(1, sizeof(Client));
	if (!c)
		return NULL;
	c->socket = socket;
	return c;
}

static void client_free(Client *c) {
	if (c && c->socket > 0)
		close(c->socket);
	free(c);
}

static int server_mark_socket_exec(bool exec) {
	struct stat sb;
	if (stat(sockaddr.sun_path, &sb) == -1)
		return -1;
	mode_t mode = sb.st_mode;
	if (exec)
		mode |= S_IXUSR;
	else
		mode &= ~S_IXUSR;
	return chmod(sockaddr.sun_path, mode);
}

static int server_create_socket(const char *name) {
	int socket = create_socket(name);
	if (socket == -1)
		return -1;
	socklen_t socklen = offsetof(struct sockaddr_un, sun_path) + strlen(sockaddr.sun_path) + 1;
	mode_t mode = S_IRUSR|S_IWUSR;
	fchmod(socket, mode);
	if (bind(socket, (struct sockaddr*)&sockaddr, socklen) == -1)
		return -1;
	if (fchmod(socket, mode) == -1 && chmod(sockaddr.sun_path, mode) == -1)
		goto error;
	if (listen(socket, 5) == -1)
		goto error;
	debug("old: %d new: %d\n", server.socket, socket);
	return socket;
error:
	unlink(sockaddr.sun_path);
	return -1;
}

static int server_set_socket_non_blocking(int sock) {
	int flags;
	if ((flags = fcntl(sock, F_GETFL, 0)) == -1)
		flags = 0;
    	return fcntl(sock, F_SETFL, flags | O_NONBLOCK);
}

static Client *server_accept_client(time_t now) {
	int newfd = accept(server.socket, NULL, NULL);
	if (newfd == -1)
		return NULL;
	Client *c = client_malloc(newfd);
	if (!c)
		return NULL;
	if (!server.clients)
		server_mark_socket_exec(true);
	server_set_socket_non_blocking(newfd);
	c->socket = newfd;
	c->state = STATE_CONNECTED;
	c->last_activity = now;
	c->next = server.clients;
	server.clients = c;
	server.client_count++;
	return c;
}

static bool server_read_pty(Packet *pkt) {
	pkt->type = MSG_CONTENT;
	ssize_t len = read(server.pty, pkt->u.msg, sizeof(pkt->u.msg));
	if (len != -1)
		pkt->len = len;
	else if (errno != EAGAIN && errno != EINTR)
		server.running = false;
	print_packet("server-read-pty:", pkt);
	return len > 0;
}

static bool server_write_pty(ClientPacketState *pkt) {
	size_t count = pkt->pkt.len - pkt->off;
	ssize_t len = write(server.pty, pkt->pkt.u.msg + pkt->off, count);
	if (len == -1) {
		if (errno != EAGAIN && errno != EINTR)
			server.running = false;
	} else { 
		pkt->off += len;
	}
	print_client_packet_state("server-write-pty:", pkt);
	return len == count;
}

static void server_place_packet(Client *c, Packet *pkt) {
	c->output.pkt = pkt;
	c->output.off = 0;
}

static bool server_recv_packet_header(Client *c) {
	ClientPacketState *pkt = &c->input;
	if (pkt->off >= packet_header_size())
		return true;
	size_t count = packet_header_size() - pkt->off;
	ssize_t len = recv(c->socket, ((char *)&pkt->pkt) + pkt->off, count, 0);
	switch (len) {
	case -1:
		if (errno != EAGAIN && errno != EWOULDBLOCK && errno != EINTR) {
	case 0:
			c->state = STATE_DISCONNECTED;
		}
		break;
	default:
		pkt->off += len;
		break;
	}
	print_client_packet_state("server-recv:", pkt);
	return len == count;
}

static bool server_recv_packet(Client *c) {
	ClientPacketState *pkt = &c->input;
	if (is_client_packet_complete(pkt))
		return true;
	if (!server_recv_packet_header(c))
		return false;
	size_t count = packet_size(&pkt->pkt) - pkt->off;
	ssize_t len = recv(c->socket, ((char *)&pkt->pkt) + pkt->off, count, 0);
	switch (len) {
	case -1:
		if (errno != EAGAIN && errno != EWOULDBLOCK && errno != EINTR) {
	case 0:
			c->state = STATE_DISCONNECTED;
		}
		break;
	default:
		pkt->off += len;
		break;
	}
	print_client_packet_state("server-recv:", pkt);
	return len == count;
}

static bool server_send_packet(Client *c) {
	ServerPacketState *pkt = &c->output;
	if (is_server_packet_complete(pkt))
		return true;
	size_t count = packet_size(pkt->pkt) - pkt->off;
	ssize_t len = send(c->socket, (char*)pkt->pkt + pkt->off, count, 0);
	switch (len) {
	case -1:
		if (errno != EAGAIN && errno != EWOULDBLOCK && errno != EINTR) {
	case 0:
			c->state = STATE_DISCONNECTED;
		}
		break;
	default:
		pkt->off += len;
		break;
	}
	print_server_packet_state("server-send:", pkt);
	return len == count;
}

static void server_pty_died_handler(int sig) {
	int errsv = errno;
	pid_t pid;

	while ((pid = waitpid(-1, &server.exit_status, WNOHANG)) != 0) {
		if (pid == -1)
			break;
		server.exit_status = WEXITSTATUS(server.exit_status);
	}

	debug("server pty died: %d\n", server.exit_status);
	errno = errsv;
}

static void server_sigterm_handler(int sig) {
	exit(EXIT_FAILURE); /* invoke atexit handler */
}

static void server_sigusr1_handler(int sig) {
	int socket = server_create_socket(server.session_name);
	if (socket != -1) {
		if (server.socket)
			close(server.socket);
		server.socket = socket;
	}
}

static void server_atexit_handler() {
	unlink(sockaddr.sun_path);
}

static bool server_queue_empty() {
	return server.queue_count == 0;
}

static bool server_queue_packet(Packet *pkt) {
	if (server.queue_count >= countof(server.queue))
		return false;
	server.queue[server.queue_insert] = *pkt;
	server.queue_insert++;
	server.queue_insert %= countof(server.queue);
	server.queue_count++;
	return true;
}

static Packet *server_peek_packet() {
	return &server.queue[server.queue_remove];
}

static void server_dequeue_packet() {
	server.queue_remove++;
	server.queue_remove %= countof(server.queue);
	server.queue_count--;
}

static void server_mainloop() {
	atexit(server_atexit_handler);
	fd_set new_readfds, new_writefds;
	FD_ZERO(&new_readfds);
	FD_ZERO(&new_writefds);
	FD_SET(server.socket, &new_readfds);
	int new_fdmax = server.socket;

	for (;;) {
		int fdmax = new_fdmax;
		fd_set readfds = new_readfds;
		fd_set writefds = new_writefds;
		FD_SET_MAX(server.socket, &readfds, fdmax);

		if (!server.running && server.exit_status != -1 && server.clients) { /* application terminated */
			Packet pkt = { .type = MSG_EXIT, .len = sizeof(int), .u.i = server.exit_status };
			server.pty_output = pkt;
			time_t now = time(NULL);
			for (Client *c = server.clients; c; c = c->next) {
				server_place_packet(c, &server.pty_output);
				c->last_activity = now;
				FD_SET_MAX(c->socket, &writefds, fdmax);
			}
			server.exit_status = -1;
		}

		if (select(fdmax+1, &readfds, &writefds, NULL, NULL) == -1) {
			if (errno == EINTR)
				continue;
			die("server-mainloop");
		}

		FD_ZERO(&new_readfds);
		FD_ZERO(&new_writefds);
		new_fdmax = server.socket;

		time_t now = time(NULL);
		time_t timeout = now - CLIENT_TIMEOUT;
		bool pty_data = false, clients_ready = true, exit_sent = false;

		if (FD_ISSET(server.socket, &readfds))
			server_accept_client(now);

		if (FD_ISSET(server.pty, &readfds))
			pty_data = server_read_pty(&server.pty_output);

		for (Client **prev_next = &server.clients, *c = server.clients; c;) {
			if (c->state == STATE_DISCONNECTED) {
				Client *t = c->next;
				client_free(c);
				*prev_next = c = t;
				if (--server.client_count == 0)
					server_mark_socket_exec(false);
				continue;
			}

			if (FD_ISSET(c->socket, &readfds))
				server_recv_packet(c);
			if (is_client_packet_complete(&c->input)) {
				bool packet_handled = true;
				switch (c->input.pkt.type) {
				case MSG_CONTENT:
					packet_handled = server_queue_packet(&c->input.pkt);
					break;
				case MSG_ATTACH:
				case MSG_RESIZE:
					c->state = STATE_ATTACHED;
				case MSG_REDRAW:
					if (c->input.pkt.type == MSG_REDRAW || c == server.clients)
						ioctl(server.pty, TIOCSWINSZ, &c->input.pkt.u.ws);
					kill(-server.pid, SIGWINCH);
					break;
				case MSG_DETACH:
					c->state = STATE_DETACHED;
					break;
				default: /* ignore package */
					break;
				}

				if (packet_handled) {
					c->input.off = 0;
					FD_SET_MAX(c->socket, &new_readfds, new_fdmax);
				}
			} else {
				FD_SET_MAX(c->socket, &new_readfds, new_fdmax);
			}

			if (pty_data) {
				server_place_packet(c, &server.pty_output);
				c->last_activity = now;
			}
	
			if (FD_ISSET(c->socket, &writefds)) {
				server_send_packet(c);
				c->last_activity = now;
			}

			if (!is_server_packet_complete(&c->output)) {
				if (c->last_activity < timeout) {
					c->state = STATE_DISCONNECTED;
				} else if (is_server_packet_nonempty(&c->output)) {
					clients_ready = false;
					FD_SET_MAX(c->socket, &new_writefds, new_fdmax);
				}
			} else {
				exit_sent = (c->output.pkt && c->output.pkt->type == MSG_EXIT);
			}

			if (c->state != STATE_ATTACHED)
				clients_ready = false;
			prev_next = &c->next;
			c = c->next;
		}

		if (server.running && clients_ready)
			FD_SET_MAX(server.pty, &new_readfds, new_fdmax);

		if (FD_ISSET(server.pty, &writefds)) {
			while (!server_queue_empty()) {
				if (!server.pty_input.off)
					server.pty_input.pkt = *server_peek_packet();
				if (!server_write_pty(&server.pty_input))
					break;
				server_dequeue_packet();
				server.pty_input.off = 0;
			}
		}

		if (!server_queue_empty())
			FD_SET_MAX(server.pty, &new_writefds, new_fdmax);

		if (exit_sent)
			break;
	}

	exit(EXIT_SUCCESS);
}