Check TYPO3 link type in fluid - typo3

Question

I want to render a typolink in fluid, but i need to check if it is a download file (t3://file?uid=1), a page link (t3://page?uid=1) or an external link (https://www.abc.de _blank).
Is there a way or viewhelper to check the linktype in fluid?
What i found were only via typoscript or a hacky way with VHS like
<f:if condition="{target -> v:math.round()} > 0">
It's for TYPO3 9.x

Answer 1

$linkService = $this->objectManager->get(LinkService::class);
$result = $linkService->resolve($linkValue);
That could help you in a custom ViewHelper
Possible Values for $linkValue:
t3://page?uid=1 => [string (pageuid), 'page']
info#example.com => [string (email), 'email']
https://typo3.org => [string (url), 'url']
t3://file?uid=226 => [TYPO3\CMS\Core\Resource\File, 'file']
$result returns an array. Every case has the argument "type". Depending on the type, another value or object is returned. I have listed this above.
The class is available from TYPO3 Version 8.

Answer 2

You could also check the linktype with the vhs extension, e.g. to set a different target:
{namespace v=FluidTYPO3\Vhs\ViewHelpers}
...
<f:variable name="target">_self</f:variable>
<v:condition.string.contains haystack="{url}" needle="t3://file?uid">
<f:variable name="target">_blank</f:variable>
</v:condition.string.contains>
<v:condition.string.contains haystack="{url}" needle="http">
<f:variable name="target">_blank</f:variable>
</v:condition.string.contains>
<v:condition.string.contains haystack="{url}" needle="www">
<f:variable name="target">_blank</f:variable>
</v:condition.string.contains>
<f:link.typolink parameter="{url}" target="{target}">the link</f:link.typolink>

Answer 3

This is the ViewHelper i am using now:
/**
* A view helper for rendering the linktype
*
* = Examples =
*
* <code>
* {nc:linkType(parameter: link)}
* </code>
* <output>
* page, file, url, email, folder, unknown
* </output>
*/
class LinkTypeViewHelper extends AbstractViewHelper
{
use CompileWithRenderStatic;
/**
* Initialize arguments
*/
public function initializeArguments()
{
$this->registerArgument('parameter', 'string', 'stdWrap.typolink style parameter string', true);
}
/**
* #param array $arguments
* #param \Closure $renderChildrenClosure
* #param RenderingContextInterface $renderingContext
* #return string Linktype (page, file, url, email, folder, unknown)
*/
public static function renderStatic(array $arguments, \Closure $renderChildrenClosure, RenderingContextInterface $renderingContext)
{
$parameter = $arguments['parameter'];
// workaround if parameter has _blank or other additional params
$arr = explode(' ',trim($parameter));
$firstparameter = $arr[0];
$linkService = GeneralUtility::makeInstance(LinkService::class);
$linkDetails = $linkService->resolve($firstparameter);
return $linkDetails['type'];
}
}