[TASK] Use TSFE API methods for checking workspace preview

Instead of using the public "workspacePreview" parameter in TSFE,
which is only set when a sys_preview keyword is used, the parameter
from the BE User can be used instead directly (which is used anyways
when using the API methods TSFE->whichWorkspace()).

The TSFE method doWorkspacePreview() is adapted accordingly to be in line
with the rest of the code.

Resolves: #84038
Releases: master
Change-Id: Ic819e099abf36bda867bb2235d6aa23fbbfe19a4
Reviewed-on: https://review.typo3.org/55895
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Tested-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>

typo3/sysext/frontend/Classes/Controller/TypoScriptFrontendController.php

@@ -227,6 +227,7 @@ class TypoScriptFrontendController implements LoggerAwareInterface
 
     /**
      * Integer, that indicates which workspace is being previewed.
+     * Not in use anymore, as this is part of the workspace preview functionality, use $TSFE->whichWorkspace() instead.
      * @var int
      */
     public $workspacePreview = 0;
@@ -3167,7 +3168,7 @@ public function clearPageCacheContent_pidList($pidList)
     public function setSysLastChanged()
     {
         // We only update the info if browsing the live workspace
-        if ($this->whichWorkspace() === 0 && $this->page['SYS_LASTCHANGED'] < (int)$this->register['SYS_LASTCHANGED']) {
+        if (!$this->doWorkspacePreview() && $this->page['SYS_LASTCHANGED'] < (int)$this->register['SYS_LASTCHANGED']) {
             $connection = GeneralUtility::makeInstance(ConnectionPool::class)
                 ->getConnectionForTable('pages');
             $connection->update(
@@ -3945,23 +3946,17 @@ public function logDeprecatedTyposcript($typoScriptProperty, $explanation = '')
      */
     public function doWorkspacePreview()
     {
-        return $this->workspacePreview !== 0;
+        return $this->whichWorkspace() > 0;
     }
 
     /**
      * Returns the uid of the current workspace
      *
-     * @return int|null returns workspace integer for which workspace is being preview. NULL if none.
+     * @return int returns workspace integer for which workspace is being preview. 0 if none (= live workspace).
      */
     public function whichWorkspace()
     {
-        $ws = null;
-        if ($this->doWorkspacePreview()) {
-            $ws = (int)$this->workspacePreview;
-        } elseif ($this->beUserLogin) {
-            $ws = $this->getBackendUser()->workspace;
-        }
-        return $ws;
+        return $this->beUserLogin ? $this->getBackendUser()->workspace : 0;
     }
 
     /********************************************

typo3/sysext/workspaces/Classes/Hook/PreviewHook.php

@@ -116,6 +116,7 @@ public function initializePreviewUser(&$params, &$pObj)
                 $BE_USER->groupList = $tempBackendUser->groupList;
                 $BE_USER->userGroups = $tempBackendUser->userGroups;
                 $BE_USER->userGroupsUID = $tempBackendUser->userGroupsUID;
+                $BE_USER->workspace = (int)$workspaceUid;
                 $pObj->beUserLogin = true;
             } else {
                 $BE_USER = null;
@@ -124,27 +125,12 @@ public function initializePreviewUser(&$params, &$pObj)
             unset($tempBackendUser);
             $params['BE_USER'] = $BE_USER;
         }
-        if ($pObj->isBackendUserLoggedIn()
-            && is_object($params['BE_USER'])
-            && $workspaceUid > 0
-        ) {
-            // Check Access to workspace
-            if ($params['BE_USER']->checkWorkspace($workspaceRecord ?: $workspaceUid)
-                && $params['BE_USER']->isInWebMount($pObj->id)
-            ) {
-                $pObj->workspacePreview = (int)$workspaceUid;
-            } else {
-                // No preview, will fallback to "Live" at the moment
-                $pObj->workspacePreview = 0;
-            }
-        }
 
         // Now, if "ADMCMD_noBeUser" is set, then ensure that there is no workspace preview and no BE User logged in.
         // This option is solely used to ensure that a be user can preview the live version of a page in the
         // workspace preview module.
         if (GeneralUtility::_GET('ADMCMD_noBeUser')) {
             $params['BE_USER'] = null;
-            $pObj->workspacePreview = 0;
             $pObj->beUserLogin = false;
             // Caching is disabled, because otherwise generated URLs could include the ADMCMD_noBeUser parameter
             $pObj->set_no_cache('GET Parameter ADMCMD_noBeUser was given', true);