// Function for obtaining an interface pointer to a COM shell object
//
// paths:	absolute paths to the files/folders comprising the object
// riid:	the interface to return, eg. IID_IDropSource
// pObject:	the address to receive the interface pointer, caller must Release()

bool UIObjectFromPaths (std::vector<wstring> paths, const GUID riid, void** pObject)
{
	if (paths.empty())
		return false;

	// test for naked drive
	wchar_t buf [MAX_PATH];
	bool drive = false;

	wcscpy (buf, paths[0].c_str());
	if (buf [wcslen (buf) - 1] == L':')
	{
		drive = true;
		wcscat (buf, L"\\");
	}
	else if (buf [wcslen (buf) - 2] == L':')
		drive = true;

	// test for files with single parent folder
	bool singledir = false;
	if (!drive)
	{
		wchar_t* slash = wcsrchr (buf, L'\\');
		if (slash)
			*slash = L'\0';

		singledir = true;
		wchar_t dir [MAX_PATH];
		for (UINT i = 0; i < paths.size(); ++i)
		{
			wcscpy (dir, paths[i].c_str());
			slash = wcsrchr (dir, L'\\');
			if (slash)
				*slash = L'\0';
			if (wcscmp (dir, buf) != 0)
			{
				singledir = false;
				break;
			}
		}
	}

	// the COM part
	HRESULT hr = 0;
	IMalloc* pMalloc = 0;

	hr = ::SHGetMalloc (&pMalloc);
	if (hr != NOERROR)
		return false;

	IShellFolder* psfDesktop = 0;
	hr = ::SHGetDesktopFolder(&psfDesktop);
	if (hr != NOERROR)
	{
		pMalloc->Release();
		return false;
	}

	IShellFolder* psfFolder = 0;

	if (singledir)
	{
		// naked drive must have trailing backslash
		if (buf [wcslen (buf) - 1] == L':')
			wcscat (buf, L"\\");

		ITEMIDLIST* pidldir = 0;
		ULONG chEaten = 0;
		ULONG attributes = 0;

		hr = psfDesktop->ParseDisplayName (NULL, NULL, buf, &chEaten, &pidldir, &attributes);

		if (hr != NOERROR)
		{
			psfDesktop->Release();
			pMalloc->Release ();
			return false;
		}

		hr = psfDesktop->BindToObject (pidldir, NULL, IID_IShellFolder, (void**)&psfFolder);

		pMalloc->Free (pidldir);
		psfDesktop->Release();
		psfDesktop = 0;

		if (hr != NOERROR)
		{
			pMalloc->Release ();
			return false;
		}
	}

	// build pidl[]
	ITEMIDLIST* pidl [paths.size()];
	ULONG chEaten = 0;
	ULONG attributes = 0;

	for (UINT i = 0; i < paths.size(); ++i)
	{
		wcscpy (buf, paths[i].c_str());

		if (singledir)
		{
			wchar_t* name = wcsrchr (buf, L'\\');			// name[1] ok if not drive
			hr = psfFolder->ParseDisplayName (NULL, NULL, &name[1], &chEaten, &pidl [i], &attributes);
		}
		else
		{
			if (buf [wcslen (buf) - 1] == L':')
				wcscat (buf, L"\\");

			hr = psfDesktop->ParseDisplayName (NULL, NULL, buf, &chEaten, &pidl [i], &attributes);
		}

		if (hr != NOERROR)
		{
			for (UINT j = 0; j < i; ++j)	// free pidls assigned so far
				pMalloc->Free (pidl[j]);
			if (psfDesktop)
				psfDesktop->Release();
			if (psfFolder)
				psfFolder->Release();
			pMalloc->Release ();
			return false;
		}
	}

	// get the object - for a single IShellFolder* (shellfolder interface)
	*pObject = NULL;
	if (singledir)
		hr = psfFolder->GetUIObjectOf (NULL, paths.size(), (LPCITEMIDLIST*)pidl, riid, NULL, pObject);
	else
		hr = psfDesktop->GetUIObjectOf (NULL, paths.size(), (LPCITEMIDLIST*)pidl, riid, NULL, pObject);

	// cleanup
	for (UINT i = 0; i < paths.size(); ++i)
		pMalloc->Free (pidl[i]);
	if (psfDesktop)
		psfDesktop->Release();
	if (psfFolder)
		psfFolder->Release();
	pMalloc->Release ();

	return SUCCEEDED(hr);
}