package console

import (
	"fmt"
	"os"
	"unsafe"

	"golang.org/x/sys/unix"
)

const (
	cmdTcGet = unix.TCGETS
	cmdTcSet = unix.TCSETS
)

func ioctl(fd, flag, data uintptr) error {
	if _, _, err := unix.Syscall(unix.SYS_IOCTL, fd, flag, data); err != 0 {
		return err
	}
	return nil
}

// unlockpt unlocks the slave pseudoterminal device corresponding to the master pseudoterminal referred to by f.
// unlockpt should be called before opening the slave side of a pty.
func unlockpt(f *os.File) error {
	var u int32
	return ioctl(f.Fd(), unix.TIOCSPTLCK, uintptr(unsafe.Pointer(&u)))
}

// ptsname retrieves the name of the first available pts for the given master.
func ptsname(f *os.File) (string, error) {
	n, err := unix.IoctlGetInt(int(f.Fd()), unix.TIOCGPTN)
	if err != nil {
		return "", err
	}
	return fmt.Sprintf("/dev/pts/%d", n), nil
}