package win32api

import (
	"errors"
	"syscall"
	"unsafe"
)

func Keybd_event(keyname string, keydown bool) error {
	var key int
	var down uintptr
	if !keydown {
		down = KEYEVENTF_KEYUP
	}
	switch keyname {
	case "shift":
		key = VK_SHIFT
	case "lshift":
		key = VK_LSHIFT
	case "rshift":
		key = VK_RSHIFT
	case "a":
		key = VK_A
	}
	user32, err := syscall.LoadLibrary("user32.dll")
	if err != nil {
		return errors.New("Can't Load User32 API")
	}
	defer syscall.FreeLibrary(user32)
	keyevent, err := syscall.GetProcAddress(syscall.Handle(user32), "keybd_event")
	if err != nil {
		return errors.New("Can't Load Keybd_event API")
	}
	syscall.Syscall6(keyevent, 4, uintptr(key), uintptr(key), down, 0, 0, 0)
	return nil
}

func Keybd_event_origin(key, keyenv, down, extra uintptr) error {
	user32, err := syscall.LoadLibrary("user32.dll")
	if err != nil {
		return errors.New("Can't Load User32 API")
	}
	defer syscall.FreeLibrary(user32)
	keyevent, err := syscall.GetProcAddress(syscall.Handle(user32), "keybd_event")
	if err != nil {
		return errors.New("Can't Load Keybd_event API")
	}
	syscall.Syscall6(keyevent, 4, key, keyenv, down, extra, 0, 0)
	return nil
}

func OpenClipboard(hWnd HWND) error {
	user32, err := syscall.LoadLibrary("user32.dll")
	if err != nil {
		return errors.New("Can't Load User32 API")
	}
	defer syscall.FreeLibrary(user32)
	oc, err := syscall.GetProcAddress(syscall.Handle(user32), "OpenClipboard")
	if err != nil {
		return errors.New("Can't Load OpenClipboard API")
	}
	if hWnd != 0 {
		if r, _, errno := syscall.Syscall(oc, 1, uintptr(hWnd), 0, 0); r == 0 {
			return error(errno)
		}
		return nil
	}
	if r, _, errno := syscall.Syscall(oc, 0, 0, 0, 0); r == 0 {
		return error(errno)
	}
	return nil
}

func CloseClipboard() error {
	user32, err := syscall.LoadLibrary("user32.dll")
	if err != nil {
		return errors.New("Can't Load User32 API")
	}
	defer syscall.FreeLibrary(user32)
	cc, err := syscall.GetProcAddress(syscall.Handle(user32), "CloseClipboard")
	if err != nil {
		return errors.New("Can't Load CloseClipboard API")
	}
	if r, _, errno := syscall.Syscall(cc, 0, 0, 0, 0); r == 0 {
		return error(errno)
	}
	return nil
}

func GetClipboardData(uFormat DWORD) (HGLOBAL, error) {
	user32, err := syscall.LoadLibrary("user32.dll")
	if err != nil {
		return 0, errors.New("Can't Load User32 API")
	}
	defer syscall.FreeLibrary(user32)
	gcd, err := syscall.GetProcAddress(syscall.Handle(user32), "GetClipboardData")
	if err != nil {
		return 0, errors.New("Can't Load GetClipboardData API")
	}
	r, _, errno := syscall.Syscall(gcd, 1, uintptr(uFormat), 0, 0)
	if r == 0 {
		return 0, error(errno)
	}
	return HGLOBAL(r), nil
}

func EnumClipboardFormats(uFormat DWORD) (DWORD, error) {
	user32, err := syscall.LoadLibrary("user32.dll")
	if err != nil {
		return 0, errors.New("Can't Load User32 API")
	}
	defer syscall.FreeLibrary(user32)
	ecf, err := syscall.GetProcAddress(syscall.Handle(user32), "EnumClipboardFormats")
	if err != nil {
		return 0, errors.New("Can't Load EnumClipboardFormats API")
	}
	r, _, errno := syscall.Syscall(ecf, 1, uintptr(uFormat), 0, 0)
	if r == 0 {
		return 0, error(errno)
	}
	return DWORD(r), nil
}

func EnumAllClipboardFormats() ([]DWORD, error) {
	var formats []DWORD
	for i := 0; ; i++ {
		format, err := EnumClipboardFormats(DWORD(i))
		if err != nil {
			break
		}
		formats = append(formats, format)
	}
	return formats, nil
}

func GetClipboardFormatName(uFormat DWORD) (string, error) {
	user32, err := syscall.LoadLibrary("user32.dll")
	if err != nil {
		return "", errors.New("Can't Load User32 API")
	}
	defer syscall.FreeLibrary(user32)
	gcfn, err := syscall.GetProcAddress(syscall.Handle(user32), "GetClipboardFormatNameW")
	if err != nil {
		return "", errors.New("Can't Load GetClipboardFormatName API")
	}
	var buffer [256]uint16
	r, _, errno := syscall.Syscall6(gcfn, 3, uintptr(uFormat), uintptr(unsafe.Pointer(&buffer)), uintptr(len(buffer)), 0, 0, 0)
	if r == 0 {
		return "", error(errno)
	}
	return syscall.UTF16ToString(buffer[:]), nil
}

func RegisterClipboardFormat(lpszFormat string) DWORD {
	user32, err := syscall.LoadLibrary("user32.dll")
	if err != nil {
		return 0
	}
	defer syscall.FreeLibrary(user32)
	rcf, err := syscall.GetProcAddress(syscall.Handle(user32), "RegisterClipboardFormatW")
	if err != nil {
		return 0
	}
	r, _, _ := syscall.Syscall(rcf, 1, uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(lpszFormat))), 0, 0)
	return DWORD(r)
}