// 7 february 2014
package main

import (
	"syscall"
	"unsafe"
)

// MessageBox button types.
const (
	MB_ABORTRETRYIGNORE = 0x00000002
	MB_CANCELTRYCONTINUE = 0x00000006
	MB_HELP = 0x00004000
	MB_OK = 0x00000000
	MB_OKCANCEL = 0x00000001
	MB_RETRYCANCEL = 0x00000005
	MB_YESNO = 0x00000004
	MB_YESNOCANCEL = 0x00000003
)

// MessageBox icon types.
const (
	MB_ICONEXCLAMATION = 0x00000030
	MB_ICONWARNING = 0x00000030
	MB_ICONINFORMATION = 0x00000040
	MB_ICONASTERISK = 0x00000040
	MB_ICONQUESTION = 0x00000020
	MB_ICONSTOP = 0x00000010
	MB_ICONERROR = 0x00000010
	MB_ICONHAND = 0x00000010
)

// MessageBox default button types.
const (
	MB_DEFBUTTON1 = 0x00000000
	MB_DEFBUTTON2 = 0x00000100
	MB_DEFBUTTON3 = 0x00000200
	MB_DEFBUTTON4 = 0x00000300
)

// MessageBox modality types.
const (
	MB_APPLMODAL = 0x00000000
	MB_SYSTEMMODAL = 0x00001000
	MB_TASKMODAL = 0x00002000
)

// MessageBox miscellaneous types.
const (
	MB_DEFAULT_DESKTOP_ONLY = 0x00020000
	MB_RIGHT = 0x00080000
	MB_RTLREADING = 0x00100000
	MB_SETFOREGROUND = 0x00010000
	MB_TOPMOST = 0x00040000
	MB_SERVICE_NOTIFICATION = 0x00200000 
)

// MessageBox return values.
const (
	IDABORT = 3
	IDCANCEL = 2
	IDCONTINUE = 11
	IDIGNORE = 5
	IDNO = 7
	IDOK = 1
	IDRETRY = 4
	IDTRYAGAIN = 10
	IDYES = 6
)

var (
	messageBox = user32.NewProc("MessageBoxW")
)

func MessageBox(hWnd HWND, lpText string, lpCaption string, uType uint32) (result int, err error) {
	r1, _, err := messageBox.Call(
		uintptr(unsafe.Pointer(hWnd)),
		uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(lpText))),
		uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(lpCaption))),
		uintptr(uType))
	if r1 == 0 {		// failure
		return 0, err
	}
	return int(r1), nil
}