// +build windows

// +build !appengine

package isatty

import (

	"strings"

	"syscall"

	"unicode/utf16"

	"unsafe"

)

const (

	fileNameInfo uintptr = 2

	fileTypePipe         = 3

)

var (

	kernel32                         = syscall.NewLazyDLL("kernel32.dll")

	procGetConsoleMode               = kernel32.NewProc("GetConsoleMode")

	procGetFileInformationByHandleEx = kernel32.NewProc("GetFileInformationByHandleEx")

	procGetFileType                  = kernel32.NewProc("GetFileType")

)

func init() {

	// Check if GetFileInformationByHandleEx is available.

	if procGetFileInformationByHandleEx.Find() != nil {

		procGetFileInformationByHandleEx = nil

	}

}

// IsTerminal return true if the file descriptor is terminal.

func IsTerminal(fd uintptr) bool {

	var st uint32

	r, _, e := syscall.Syscall(procGetConsoleMode.Addr(), 2, fd, uintptr(unsafe.Pointer(&st)), 0)

	return r != 0 && e == 0

}

// Check pipe name is used for cygwin/msys2 pty.

// Cygwin/MSYS2 PTY has a name like:

//   \{cygwin,msys}-XXXXXXXXXXXXXXXX-ptyN-{from,to}-master

func isCygwinPipeName(name string) bool {

	token := strings.Split(name, "-")

	if len(token) < 5 {

		return false

	}

	if token[0] != `\msys` && token[0] != `\cygwin` {

		return false

	}

	if token[1] == "" {

		return false

	}

	if !strings.HasPrefix(token[2], "pty") {

		return false

	}

	if token[3] != `from` && token[3] != `to` {

		return false

	}

	if token[4] != "master" {

		return false

	}

	return true

}

// IsCygwinTerminal() return true if the file descriptor is a cygwin or msys2

// terminal.

func IsCygwinTerminal(fd uintptr) bool {

	if procGetFileInformationByHandleEx == nil {

		return false

	}

	// Cygwin/msys's pty is a pipe.

	ft, _, e := syscall.Syscall(procGetFileType.Addr(), 1, fd, 0, 0)

	if ft != fileTypePipe || e != 0 {

		return false

	}

	var buf [2 + syscall.MAX_PATH]uint16

	r, _, e := syscall.Syscall6(procGetFileInformationByHandleEx.Addr(),

		4, fd, fileNameInfo, uintptr(unsafe.Pointer(&buf)),

		uintptr(len(buf)*2), 0, 0)

	if r == 0 || e != 0 {

		return false

	}

	l := *(*uint32)(unsafe.Pointer(&buf))

	return isCygwinPipeName(string(utf16.Decode(buf[2 : 2+l/2])))

}