#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#include <poll.h>

int main(void) {
    int fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY);
    if (fd < 0) { perror("open"); return 1; }

    // Configure serial port
    struct termios tty;
    tcgetattr(fd, &tty);
    cfmakeraw(&tty);
    cfsetspeed(&tty, B115200);
    tty.c_cflag |= CLOCAL | CREAD;
    tty.c_cc[VMIN] = 0;
    tty.c_cc[VTIME] = 1;
    tcsetattr(fd, TCSANOW, &tty);

    // Set stdin to raw mode
    struct termios old_stdin, raw_stdin;
    tcgetattr(STDIN_FILENO, &old_stdin);
    raw_stdin = old_stdin;
    cfmakeraw(&raw_stdin);
    tcsetattr(STDIN_FILENO, TCSANOW, &raw_stdin);

    write(STDOUT_FILENO, "Holcks minitty - ctrl-d to exit\r\n", 33);

    struct pollfd fds[2] = {
        { .fd = STDIN_FILENO, .events = POLLIN },
        { .fd = fd,           .events = POLLIN },
    };

    char buf[256];
    while (1) {
        poll(fds, 2, -1);
        if (fds[0].revents & POLLIN) {
            int n = read(STDIN_FILENO, buf, sizeof(buf));
            if (n > 0) {
                for (int i = 0; i < n; i++)
                    if (buf[i] == 4) goto done; // Ctrl-D
                write(fd, buf, n);
            }
        }
        if (fds[1].revents & POLLIN) {
            int n = read(fd, buf, sizeof(buf));
            if (n > 0) write(STDOUT_FILENO, buf, n);
        }
    }

done:
    tcsetattr(STDIN_FILENO, TCSANOW, &old_stdin);
    close(fd);
    return 0;
}