com.go

package w32

import (
	"errors"
	"syscall"
	"unicode/utf16"
	"unsafe"
)

type pIUnknownVtbl struct {
	queryInterface uintptr
	addRef         uintptr
	release        uintptr
}

type IUnknown struct {
	lpVtbl *pIUnknownVtbl
}

func (u *IUnknown) QueryInterface(id *GUID) (*IDispatch, HRESULT) {
	return ComQueryInterface(u, id)
}

func (u *IUnknown) AddRef() int32 {
	return ComAddRef(u)
}

func (u *IUnknown) Release() int32 {
	return ComRelease(u)
}

type pIDispatchVtbl struct {
	queryInterface   uintptr
	addRef           uintptr
	release          uintptr
	getTypeInfoCount uintptr
	getTypeInfo      uintptr
	getIDsOfNames    uintptr
	invoke           uintptr
}

type IDispatch struct {
	lpVtbl *pIDispatchVtbl
}

func (d *IDispatch) QueryInterface(id *GUID) (*IDispatch, HRESULT) {
	return ComQueryInterface((*IUnknown)(unsafe.Pointer(d)), id)
}

func (d *IDispatch) AddRef() int32 {
	return ComAddRef((*IUnknown)(unsafe.Pointer(d)))
}

func (d *IDispatch) Release() int32 {
	return ComRelease((*IUnknown)(unsafe.Pointer(d)))
}

func (d *IDispatch) GetIDsOfName(names []string) ([]int32, HRESULT) {
	return ComGetIDsOfName(d, names)
}

func (d *IDispatch) Invoke(dispid int32, dispatch int16, params ...interface{}) (*VARIANT, error) {
	return ComInvoke(d, dispid, dispatch, params...)
}

type pIStreamVtbl struct {
	qeryInterface uintptr
	addRef        uintptr
	release       uintptr
}

type IStream struct {
	lpVtbl *pIStreamVtbl
}

func (s *IStream) QueryInterface(id *GUID) (*IDispatch, HRESULT) {
	return ComQueryInterface((*IUnknown)(unsafe.Pointer(s)), id)
}

func (s *IStream) AddRef() int32 {
	return ComAddRef((*IUnknown)(unsafe.Pointer(s)))
}

func (s *IStream) Release() int32 {
	return ComRelease((*IUnknown)(unsafe.Pointer(s)))
}

func ComAddRef(unknown *IUnknown) int32 {
	ret, _, _ := syscall.Syscall(unknown.lpVtbl.addRef, 1,
		uintptr(unsafe.Pointer(unknown)),
		0,
		0)
	return int32(ret)
}

func ComRelease(unknown *IUnknown) int32 {
	ret, _, _ := syscall.Syscall(unknown.lpVtbl.release, 1,
		uintptr(unsafe.Pointer(unknown)),
		0,
		0)
	return int32(ret)
}

func ComQueryInterface(unknown *IUnknown, id *GUID) (*IDispatch, HRESULT) {
	var disp *IDispatch
	hr, _, _ := syscall.Syscall(unknown.lpVtbl.queryInterface, 3,
		uintptr(unsafe.Pointer(unknown)),
		uintptr(unsafe.Pointer(id)),
		uintptr(unsafe.Pointer(&disp)),
	)
	return disp, HRESULT(hr)
}

func ComGetIDsOfName(disp *IDispatch, names []string) ([]int32, HRESULT) {
	wnames := make([]*uint16, len(names))
	dispid := make([]int32, len(names))
	for i := 0; i < len(names); i++ {
		wnames[i] = syscall.StringToUTF16Ptr(names[i])
	}
	hr, _, _ := syscall.Syscall6(disp.lpVtbl.getIDsOfNames, 6,
		uintptr(unsafe.Pointer(disp)),
		uintptr(unsafe.Pointer(IID_NULL)),
		uintptr(unsafe.Pointer(&wnames[0])),
		uintptr(len(names)),
		uintptr(GetUserDefaultLCID()),
		uintptr(unsafe.Pointer(&dispid[0])),
	)
	return dispid, HRESULT(hr)
}

func ComInvoke(disp *IDispatch, dispid int32, dispatch int16, params ...interface{}) (result *VARIANT, err error) {
	var dispparams DISPPARAMS

	if dispatch&DISPATCH_PROPERTYPUT != 0 {
		dispnames := [1]int32{DISPID_PROPERTYPUT}
		dispparams.RgdispidNamedArgs = uintptr(unsafe.Pointer(&dispnames[0]))
		dispparams.CNamedArgs = 1
	}
	var vargs []VARIANT
	if len(params) > 0 {
		vargs = make([]VARIANT, len(params))
		for i, v := range params {
			n := len(params) - i - 1
			VariantInit(&vargs[n])
			switch v.(type) {
			case bool:
				if v.(bool) {
					vargs[n] = VARIANT{VT_BOOL, 0, 0, 0, 0xffff}
				} else {
					vargs[n] = VARIANT{VT_BOOL, 0, 0, 0, 0}
				}
			case *bool:
				vargs[n] = VARIANT{VT_BOOL | VT_BYREF, 0, 0, 0, int64(uintptr(unsafe.Pointer(v.(*bool))))}
			case byte:
				vargs[n] = VARIANT{VT_I1, 0, 0, 0, int64(v.(byte))}
			case *byte:
				vargs[n] = VARIANT{VT_I1 | VT_BYREF, 0, 0, 0, int64(uintptr(unsafe.Pointer(v.(*byte))))}
			case int16:
				vargs[n] = VARIANT{VT_I2, 0, 0, 0, int64(v.(int16))}
			case *int16:
				vargs[n] = VARIANT{VT_I2 | VT_BYREF, 0, 0, 0, int64(uintptr(unsafe.Pointer(v.(*int16))))}
			case uint16:
				vargs[n] = VARIANT{VT_UI2, 0, 0, 0, int64(v.(int16))}
			case *uint16:
				vargs[n] = VARIANT{VT_UI2 | VT_BYREF, 0, 0, 0, int64(uintptr(unsafe.Pointer(v.(*uint16))))}
			case int, int32:
				vargs[n] = VARIANT{VT_UI4, 0, 0, 0, int64(v.(int))}
			case *int, *int32:
				vargs[n] = VARIANT{VT_I4 | VT_BYREF, 0, 0, 0, int64(uintptr(unsafe.Pointer(v.(*int))))}
			case uint, uint32:
				vargs[n] = VARIANT{VT_UI4, 0, 0, 0, int64(v.(uint))}
			case *uint, *uint32:
				vargs[n] = VARIANT{VT_UI4 | VT_BYREF, 0, 0, 0, int64(uintptr(unsafe.Pointer(v.(*uint))))}
			case int64:
				vargs[n] = VARIANT{VT_I8, 0, 0, 0, v.(int64)}
			case *int64:
				vargs[n] = VARIANT{VT_I8 | VT_BYREF, 0, 0, 0, int64(uintptr(unsafe.Pointer(v.(*int64))))}
			case uint64:
				vargs[n] = VARIANT{VT_UI8, 0, 0, 0, int64(v.(uint64))}
			case *uint64:
				vargs[n] = VARIANT{VT_UI8 | VT_BYREF, 0, 0, 0, int64(uintptr(unsafe.Pointer(v.(*uint64))))}
			case float32:
				vargs[n] = VARIANT{VT_R4, 0, 0, 0, int64(v.(float32))}
			case *float32:
				vargs[n] = VARIANT{VT_R4 | VT_BYREF, 0, 0, 0, int64(uintptr(unsafe.Pointer(v.(*float32))))}
			case float64:
				vargs[n] = VARIANT{VT_R8, 0, 0, 0, int64(v.(float64))}
			case *float64:
				vargs[n] = VARIANT{VT_R8 | VT_BYREF, 0, 0, 0, int64(uintptr(unsafe.Pointer(v.(*float64))))}
			case string:
				vargs[n] = VARIANT{VT_BSTR, 0, 0, 0, int64(uintptr(unsafe.Pointer(SysAllocString(v.(string)))))}
			case *string:
				vargs[n] = VARIANT{VT_BSTR | VT_BYREF, 0, 0, 0, int64(uintptr(unsafe.Pointer(v.(*string))))}
			case *IDispatch:
				vargs[n] = VARIANT{VT_DISPATCH, 0, 0, 0, int64(uintptr(unsafe.Pointer(v.(*IDispatch))))}
			case **IDispatch:
				vargs[n] = VARIANT{VT_DISPATCH | VT_BYREF, 0, 0, 0, int64(uintptr(unsafe.Pointer(v.(**IDispatch))))}
			case nil:
				vargs[n] = VARIANT{VT_NULL, 0, 0, 0, 0}
			case *VARIANT:
				vargs[n] = VARIANT{VT_VARIANT | VT_BYREF, 0, 0, 0, int64(uintptr(unsafe.Pointer(v.(*VARIANT))))}
			default:
				return nil, errors.New("w32.ComInvoke: unknown variant type")
			}
		}
		dispparams.Rgvarg = uintptr(unsafe.Pointer(&vargs[0]))
		dispparams.CArgs = uint32(len(params))
	}

	var ret VARIANT
	var excepInfo EXCEPINFO
	VariantInit(&ret)
	hr, _, _ := syscall.Syscall9(disp.lpVtbl.invoke, 8,
		uintptr(unsafe.Pointer(disp)),
		uintptr(dispid),
		uintptr(unsafe.Pointer(IID_NULL)),
		uintptr(GetUserDefaultLCID()),
		uintptr(dispatch),
		uintptr(unsafe.Pointer(&dispparams)),
		uintptr(unsafe.Pointer(&ret)),
		uintptr(unsafe.Pointer(&excepInfo)),
		0)
	if hr != 0 {
		if excepInfo.BstrDescription != nil {
			bs := UTF16PtrToString(excepInfo.BstrDescription)
			return nil, errors.New(bs)
		}
	}
	for _, varg := range vargs {
		if varg.VT == VT_BSTR && varg.Val != 0 {
			SysFreeString(((*int16)(unsafe.Pointer(uintptr(varg.Val)))))
		}
	}
	result = &ret
	return
}

func UTF16PtrToString(cstr *uint16) string {
	if cstr != nil {
		us := make([]uint16, 0, 256)
		for p := uintptr(unsafe.Pointer(cstr)); ; p += 2 {
			u := *(*uint16)(unsafe.Pointer(p))
			if u == 0 {
				return string(utf16.Decode(us))
			}
			us = append(us, u)
		}
	}

	return ""
}