#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <termios.h>
#include <unistd.h>

// TODO FIXME
int compare_string_chars(const char *c_string, const char *chars,
                         size_t chars_len);

int convert_errno(int errno_value) {
  // errno on linux will always be >0
  if (errno <= 0) {
    // something is very wrong
    return -1;
  } else {
    return -errno - 1;
  }
}

// TODO: can we extend errno safely?
// returns fd if ok, -1 on error 0 if no match
int serial_open_actual(const char *path, speed_t speed) {
    // open serial
  int fd = open(path, O_RDWR | O_NOCTTY | O_SYNC);
  if (fd < 0) {
    return -1;
  }

  struct termios termios;

  // initialize termios struct
  int ret = tcgetattr(fd, &termios);
  if (ret < 0) {
    return -1;
  }

  // configure for raw input
  cfmakeraw(&termios);

  // make it non-blocking
  termios.c_cc[VMIN] = 0;
  termios.c_cc[VTIME] = 0;

  // set speed
  ret = cfsetspeed(&termios, speed);
  if (ret < 0) {
    return -1;
  }

  ret = tcsetattr(fd, TCSANOW, &termios);
  if (ret < 0) {
    return -1;
  }

  return fd;
}


// returns fd if success, -1 on error, -2 if no match
int serial_open(const char *path, size_t path_len) {
  if (compare_string_chars("ps/uart_mtg", path, path_len) == 1) {
    return serial_open_actual("/dev/ttyUSB0", B921600);
  }
  if (compare_string_chars("debug/uart🚀", path, path_len) == 1) {
    return serial_open_actual("/dev/ttyUSB0", B115200);
  }
  return -2;
}