[FEATURE] Mark broken file links in RTE

Broken file links are now marked in RTE with yellow background and red
border.

This patch uses the previously introduced event
:php:`BrokenLinkAnalysisEvent`.

The broken links are only detected if linkvalidator is installed and
has checked for broken links (e.g. via scheduler).

Resolves: #84990
Releases: master
Change-Id: Iddebe7f9358901c70f90f9751298ce2905684662
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/62091

Tested-by: Daniel Goerz <daniel.goerz@posteo.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Sybille Peters <sypets@gmx.de>
Tested-by: Riccardo De Contardi <erredeco@gmail.com>
Tested-by: Susanne Moog <look@susi.dev>
Reviewed-by: Sybille Peters <sypets@gmx.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Daniel Goerz <daniel.goerz@posteo.de>
Reviewed-by: Susanne Moog <look@susi.dev>

typo3/sysext/core/Documentation/Changelog/master/Feature-84990-MarkBrokenFileLinksInRTE.rst

+.. include:: ../../Includes.txt
+
+===============================================
+Feature: #84990 - Mark broken file links in RTE
+===============================================
+
+See :issue:`84990`
+
+Description
+===========
+
+Links to files that were detected as broken by the system extension
+`linkvalidator` are now marked accordingly in the RTE via
+:php:`TYPO3\CMS\Core\Html\Event\BrokenLinkAnalysisEvent`.
+
+Those links are now marked with extra markup (yellow background with
+red border) in RTE.
+
+The procedure for marking the broken links in the RTE is as follow:
+
+#. RTE content is fetched from the database. Before it is displayed in
+   the edit form, RTE transformations are performed.
+#. The transformation function parses the text and detects links.
+#. For each link, a new PSR-14 event is dispatched.
+#. If a listener is attached, it may set the link as broken and will set
+   the link as "checked".
+#. If a link is detected as broken, RTE will mark it as broken.
+
+The implementation for checking file links is supplied by the system
+extension `linkvalidator`.
+
+Other extensions can use the event to override the default behaviour.
+
+
+Impact
+======
+
+The behaviour stays the same as before unless the system extension `linkvalidator`
+is installed.
+
+If `linkvalidator` is installed and regularly checks for broken file links, those
+links will be marked in the RTE.
+
+If `linkvalidator` is used, it is recommended to use the scheduler to regularly
+check for broken links.
+
+
+.. index:: RTE, ext:linkvalidator

typo3/sysext/linkvalidator/Classes/EventListener/CheckBrokenRteLinkEventListener.php

@@ -18,6 +18,7 @@ namespace TYPO3\CMS\Linkvalidator\EventListener;
 use TYPO3\CMS\Backend\Utility\BackendUtility;
 use TYPO3\CMS\Core\Html\Event\BrokenLinkAnalysisEvent;
 use TYPO3\CMS\Core\LinkHandling\LinkService;
+use TYPO3\CMS\Core\Resource\FileInterface;
 use TYPO3\CMS\Linkvalidator\Repository\BrokenLinkRepository;
 
 /**
@@ -67,4 +68,29 @@ final class CheckBrokenRteLinkEventListener
         }
         $event->markAsCheckedLink();
     }
+
+    public function checkFileLink(BrokenLinkAnalysisEvent $event): void
+    {
+        if ($event->getLinkType() !== LinkService::TYPE_FILE) {
+            return;
+        }
+        $event->markAsCheckedLink();
+
+        $hrefInformation = $event->getLinkData();
+        $file = $hrefInformation['file'] ?? null;
+        if (!$file instanceof FileInterface) {
+            $event->markAsBrokenLink('File link is broken');
+            return;
+        }
+
+        if (!$file->hasProperty('uid') || (int)$file->getProperty('uid') === 0) {
+            $event->markAsBrokenLink('File link is broken');
+            return;
+        }
+
+        $count = $this->brokenLinkRepository->getNumberOfBrokenLinks('file:' . $file->getProperty('uid'));
+        if ($count) {
+            $event->markAsBrokenLink('File with ID ' . $file->getProperty('uid') . ' not found');
+        }
+    }
 }

typo3/sysext/linkvalidator/Configuration/Services.yaml

@@ -20,3 +20,7 @@ services:
           identifier: 'rte-check-link-to-page',
           event: TYPO3\CMS\Core\Html\Event\BrokenLinkAnalysisEvent,
           method: 'checkPageLink' }
+      - { name: event.listener,
+          identifier: 'rte-check-link-to-file',
+          event: TYPO3\CMS\Core\Html\Event\BrokenLinkAnalysisEvent,
+          method: 'checkFileLink' }