// Copied from https://github.com/secur30nly/go-self-delete
// with modification to suitable for ctrld usage.

/*
   License: MIT Licence

   References:
       - https://github.com/LloydLabs/delete-self-poc
       - https://twitter.com/jonasLyk/status/1350401461985955840
*/

package cli

import (
	"unsafe"

	"golang.org/x/sys/windows"
)

var supportedSelfDelete = false

type FILE_RENAME_INFO struct {
	Union struct {
		ReplaceIfExists bool
		Flags           uint32
	}
	RootDirectory  windows.Handle
	FileNameLength uint32
	FileName       [1]uint16
}

type FILE_DISPOSITION_INFO struct {
	DeleteFile bool
}

func dsOpenHandle(pwPath *uint16) (windows.Handle, error) {
	handle, err := windows.CreateFile(
		pwPath,
		windows.DELETE,
		0,
		nil,
		windows.OPEN_EXISTING,
		windows.FILE_ATTRIBUTE_NORMAL,
		0,
	)

	if err != nil {
		return 0, err
	}

	return handle, nil
}

func dsRenameHandle(hHandle windows.Handle) error {
	var fRename FILE_RENAME_INFO
	DS_STREAM_RENAME, err := windows.UTF16FromString(":deadbeef")

	if err != nil {
		return err
	}

	lpwStream := &DS_STREAM_RENAME[0]
	fRename.FileNameLength = uint32(unsafe.Sizeof(lpwStream))

	windows.NewLazyDLL("kernel32.dll").NewProc("RtlCopyMemory").Call(
		uintptr(unsafe.Pointer(&fRename.FileName[0])),
		uintptr(unsafe.Pointer(lpwStream)),
		unsafe.Sizeof(lpwStream),
	)

	err = windows.SetFileInformationByHandle(
		hHandle,
		windows.FileRenameInfo,
		(*byte)(unsafe.Pointer(&fRename)),
		uint32(unsafe.Sizeof(fRename)+unsafe.Sizeof(lpwStream)),
	)

	if err != nil {
		return err
	}

	return nil
}

func dsDepositeHandle(hHandle windows.Handle) error {
	var fDelete FILE_DISPOSITION_INFO
	fDelete.DeleteFile = true

	err := windows.SetFileInformationByHandle(
		hHandle,
		windows.FileDispositionInfo,
		(*byte)(unsafe.Pointer(&fDelete)),
		uint32(unsafe.Sizeof(fDelete)),
	)

	if err != nil {
		return err
	}

	return nil
}

func selfDeleteExe() error {
	var wcPath [windows.MAX_PATH + 1]uint16
	var hCurrent windows.Handle

	_, err := windows.GetModuleFileName(0, &wcPath[0], windows.MAX_PATH)
	if err != nil {
		return err
	}

	hCurrent, err = dsOpenHandle(&wcPath[0])
	if err != nil || hCurrent == windows.InvalidHandle {
		return err
	}

	if err := dsRenameHandle(hCurrent); err != nil {
		_ = windows.CloseHandle(hCurrent)
		return err
	}
	_ = windows.CloseHandle(hCurrent)

	hCurrent, err = dsOpenHandle(&wcPath[0])
	if err != nil || hCurrent == windows.InvalidHandle {
		return err
	}

	if err := dsDepositeHandle(hCurrent); err != nil {
		_ = windows.CloseHandle(hCurrent)
		return err
	}

	return windows.CloseHandle(hCurrent)
}