ImportManager::recoverExtensionInName

protected function recoverExtensionInName($fileName, $mimeType)
{
	$specificMimeTypes = array(
		'application/vnd.google-apps.document' => 'docx',
		'application/vnd.google-apps.spreadsheet' => 'xlsx',
		'application/vnd.google-apps.presentation' => 'pptx',
	);
	if(isset($specificMimeTypes[$mimeType]))
	{
		$originalExtension = $specificMimeTypes[$mimeType];
	}
	else
	{
		$originalExtension = TypeFile::getExtensionByMimeType($mimeType);
	}

	$newExtension = mb_strtolower(trim(getFileExtension($fileName), '.'));
	if ($originalExtension !== $newExtension && $originalExtension !== null)
	{
		return getFileNameWithoutExtension($fileName) . '.' . $originalExtension;
	}

	return $fileName;
}