#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <sys/wait.h>
#include <signal.h>

#define terminal_up "\x1b[A"

char *default_port = "2345";

void error(char *msg)
{
	perror(msg);
	exit(1);
}

void readsocket(FILE * sock)
{
	char buffer[256];

	while (1) {
		if (!fgets(buffer, sizeof(buffer), sock))
			break;
		fputs(buffer, stdout);
		fflush(stdout);
	}
	fclose(sock);
}

void writesocket(FILE * sock, char nick[])
{
	char buffer[256];
	fflush(stderr);
	fprintf(sock, "nick: %s\n\n", nick);
	fflush(sock);
	while (fgets(buffer, sizeof(buffer), stdin)) {
		fprintf(stderr, terminal_up);
		fputs(buffer, sock);
		fflush(sock);
	}
	fclose(sock);
}

char *user_env_vars[] = { "NICK", "nick", "USER", "LOGNAME", "USERNAME", "user", NULL };

char *guess_nick(void)
{
	char **p;
	char *nick = NULL;
	for (p = user_env_vars; *p; ++p) {
		nick = getenv(*p);
		if (nick)
			break;
	}
	if (!nick) {
		fprintf(stderr, "can't guess nick from environment variables\n");
		exit(1);
	}
	return nick;
}

int main(int argc, char *argv[])
{
	int sockfd;
	struct addrinfo *res, hints, *p;
	char *nick, *host, *port;

	if (argc < 1 || argc > 4 || (argc > 1 && argv[1][0] == '-')) {
		fprintf(stderr, "usage: chat [nick [host [port]]]\n");
		exit(1);
	}

	nick = argc < 2 ? guess_nick() : argv[1];
	host = argc < 3 ? "127.0.0.1" : argv[2];
	port = argc < 4 ? default_port : argv[3];

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;

	// TODO put this getaddrinfo into a function
	int result = getaddrinfo(host, port, &hints, &res);
	if (result != 0)
		error("ERROR getaddrinfo\n");

	for (p = res; p; p = p->ai_next) {

		sockfd =
		    socket(p->ai_family, p->ai_socktype, p->ai_protocol);
		if (sockfd < 0)
			continue;

		if (connect(sockfd, p->ai_addr, p->ai_addrlen) < 0)
			error("ERROR connecting");

		break;
	}

	FILE *io = fdopen(sockfd, "r+");

	pid_t pid;
	pid = fork();
	if (pid < 0) {
		perror("ERROR from fork()");
	} else if (pid == 0) {
		readsocket(io);
		kill(getppid(), SIGTERM);
	} else {
		writesocket(io, nick);
		kill(pid, SIGTERM);
		waitpid(pid, NULL, 0);
	}

	return 0;
}