package client

import (
	"syscall"
	"unsafe"
)

type Termios struct {
	Iflag  uintptr
	Oflag  uintptr
	Cflag  uintptr
	Lflag  uintptr
	Cc     [20]byte
	Ispeed uintptr
	Ospeed uintptr
}


const (
	// Input flags
	inpck  = 0x010
	istrip = 0x020
	icrnl  = 0x100
	ixon   = 0x200

	// Output flags
	opost = 0x1

	// Control flags
	cs8 = 0x300

	// Local flags
	icanon = 0x100
	iexten = 0x400
)

const (
        HUPCL                             = 0x4000 
        ICANON                            = 0x100 
        ICRNL                             = 0x100 
        IEXTEN                            = 0x400
        BRKINT                            = 0x2 
        CFLUSH                            = 0xf 
        CLOCAL                            = 0x8000 
        CREAD                             = 0x800 
        CS5                               = 0x0 
        CS6                               = 0x100 
        CS7                               = 0x200 
        CS8                               = 0x300 
        CSIZE                             = 0x300 
        CSTART                            = 0x11 
        CSTATUS                           = 0x14 
        CSTOP                             = 0x13 
        CSTOPB                            = 0x400 
        CSUSP                             = 0x1a 
        IGNBRK                            = 0x1 
        IGNCR                             = 0x80 
        IGNPAR                            = 0x4 
        IMAXBEL                           = 0x2000 
        INLCR                             = 0x40 
        INPCK                             = 0x10 
        ISIG                              = 0x80 
        ISTRIP                            = 0x20 
        IUTF8                             = 0x4000 
        IXANY                             = 0x800 
        IXOFF                             = 0x400 
        IXON                              = 0x200 
        NOFLSH                            = 0x80000000 
        OCRNL                             = 0x10 
        OFDEL                             = 0x20000 
        OFILL                             = 0x80 
        ONLCR                             = 0x2 
        ONLRET                            = 0x40 
        ONOCR                             = 0x20 
        ONOEOT                            = 0x8 
        OPOST                             = 0x1 
RENB                            = 0x1000 
        PARMRK                            = 0x8 
        PARODD                            = 0x2000 

        TOSTOP                            = 0x400000 
        VDISCARD                          = 0xf 
        VDSUSP                            = 0xb 
        VEOF                              = 0x0 
        VEOL                              = 0x1 
        VEOL2                             = 0x2 
        VERASE                            = 0x3 
        VINTR                             = 0x8 
        VKILL                             = 0x5 
        VLNEXT                            = 0xe 
        VMIN                              = 0x10 
        VQUIT                             = 0x9 
        VREPRINT                          = 0x6 
        VSTART                            = 0xc 
        VSTATUS                           = 0x12 
        VSTOP                             = 0xd 
        VSUSP                             = 0xa 
        VT0                               = 0x0 
        VT1                               = 0x10000 
        VTDLY                             = 0x10000 
        VTIME                             = 0x11 
	ECHO				  = 0x00000008

        PENDIN                            = 0x20000000 
)

type State struct {
       termios Termios
}

// IsTerminal returns true if the given file descriptor is a terminal.
func IsTerminal(fd int) bool {
        var termios Termios
        _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), uintptr(getTermios), uintptr(unsafe.Pointer(&termios)), 0, 0, 0)
        return err == 0
}

// MakeRaw put the terminal connected to the given file descriptor into raw
// mode and returns the previous state of the terminal so that it can be
// restored.
func MakeRaw(fd int) (*State, error) {
        var oldState State
        if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), uintptr(getTermios), uintptr(unsafe.Pointer(&oldState.termios)), 0, 0, 0); err != 0 {
                return nil, err
        }

        newState := oldState.termios
        newState.Iflag &^= istrip | INLCR | ICRNL | IGNCR | IXON | IXOFF
        newState.Lflag &^= ECHO | ICANON | ISIG
        if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), uintptr(setTermios), uintptr(unsafe.Pointer(&newState)), 0, 0, 0); err != 0 {
                return nil, err
        }

        return &oldState, nil
}


// Restore restores the terminal connected to the given file descriptor to a
// previous state.
func Restore(fd int, state *State) error {
        _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), uintptr(setTermios), uintptr(unsafe.Pointer(&state.termios)), 0, 0, 0)
        return err
}