use objects instead of idstic-4946

27 files changed, 144 insertions, 140 deletions

diff --git a/app/controllers/file.php b/app/controllers/file.php
index c21fb89..982ef41 100644
--- a/app/controllers/file.php
+++ b/app/controllers/file.php
@@ -387,8 +387,8 @@ class FileController extends AuthenticatedController
             }
 
             $this->file = $plugin->getPreparedFile($file_id);
+            $this->file_ref = $this->file->getFileRef();
             $this->from_plugin = Request::get("from_plugin");
-
         } else {
             $this->file_ref = FileRef::find($file_ref_id);
             $this->file = $this->file_ref->getFileType();
@@ -396,7 +396,10 @@ class FileController extends AuthenticatedController
 
         $this->folder = $this->file->getFoldertype();
 
-        if (!$this->folder || !$this->folder->isFileEditable($this->file->getId(), $GLOBALS['user']->id)) {
+        if (
+            !$this->folder
+            || !$this->folder->isFileEditable($this->file_ref, $GLOBALS['user']->id)
+        ) {
             throw new AccessDeniedException();
         }
 
@@ -538,7 +541,7 @@ class FileController extends AuthenticatedController
 
         if (
             !$this->folder
-            || !$this->folder->isFileEditable($this->file->getId(), $GLOBALS['user']->id)
+            || !$this->folder->isFileEditable($this->file_ref, $GLOBALS['user']->id)
             || !$GLOBALS['perm']->have_perm(Config::get()->OER_PUBLIC_STATUS)
         ) {
             throw new AccessDeniedException();
@@ -626,7 +629,7 @@ class FileController extends AuthenticatedController
         $this->file = $this->file_ref->getFileType();
         $this->folder = $this->file_ref->foldertype;
 
-        if (!$this->folder || !$this->folder->isFileEditable($this->file_ref->id, $GLOBALS['user']->id)) {
+        if (!$this->folder || !$this->folder->isFileEditable($this->file_ref, $GLOBALS['user']->id)) {
             throw new AccessDeniedException();
         }
 
diff --git a/app/controllers/files_dashboard/helpers.php b/app/controllers/files_dashboard/helpers.php
index 4489e04..dc759a1 100644
--- a/app/controllers/files_dashboard/helpers.php
+++ b/app/controllers/files_dashboard/helpers.php
@@ -10,9 +10,9 @@ trait Helpers
     /**
      * Create an action menu for a file. This method is used by the template.
      *
-     * @param FileRef    $fileRef the file whose action shall be created
-     * @param FolderType $folder  the file's folder
-     * @param User       $user    the user for whom the actions shall be created
+     * @param \FileRef    $fileRef the file whose action shall be created
+     * @param \FolderType $folder  the file's folder
+     * @param \User       $user    the user for whom the actions shall be created
      *
      * @return string the HTML fragment of the action menu
      */
@@ -37,7 +37,7 @@ trait Helpers
             );
         }
 
-        if ($folder->isFileEditable($fileRef->id, $user->id)) {
+        if ($folder->isFileEditable($fileRef, $user->id)) {
             $actionMenu->addLink(
                 URLHelper::getURL('dispatch.php/file/edit/'.$fileRef->id),
                 _('Datei bearbeiten'),
@@ -52,7 +52,7 @@ trait Helpers
             );
         }
 
-        if ($folder->isFileWritable($fileRef->id, $user->id)) {
+        if ($folder->isFileWritable($fileRef, $user->id)) {
             $actionMenu->addLink(
                 URLHelper::getURL('dispatch.php/file/choose_destination/move/'.$fileRef->id),
                 _('Datei verschieben'),
@@ -61,7 +61,7 @@ trait Helpers
             );
         }
 
-        if ($folder->isFileDownloadable($fileRef->id, $user->id)) {
+        if ($folder->isFileDownloadable($fileRef, $user->id)) {
             $actionMenu->addLink(
                 URLHelper::getURL('dispatch.php/file/choose_destination/copy/'.$fileRef->id),
                 _('Datei kopieren'),
@@ -70,7 +70,7 @@ trait Helpers
             );
         }
 
-        if ($folder->isFileWritable($fileRef->id, $user->id)) {
+        if ($folder->isFileWritable($fileRef, $user->id)) {
             $actionMenu->addLink(
                 URLHelper::getURL('dispatch.php/file/delete/'.$fileRef->id),
                 _('Datei löschen'),
diff --git a/app/controllers/profile.php b/app/controllers/profile.php
index b00c2b2..a656685 100644
--- a/app/controllers/profile.php
+++ b/app/controllers/profile.php
@@ -186,7 +186,7 @@ class ProfileController extends AuthenticatedController
                 //since we have collected all public folders above already.
                 $folder_file_refs = $one_public_folder->getFiles();
                 foreach ($folder_file_refs as $file_ref) {
-                    if ($one_public_folder->isFileDownloadable($file_ref->id, $GLOBALS['user']->id)) {
+                    if ($one_public_folder->isFileDownloadable($file_ref, $GLOBALS['user']->id)) {
                         $public_files[$file_ref->id] = $file_ref;
                     }
                 }
diff --git a/lib/activities/DocumentsProvider.php b/lib/activities/DocumentsProvider.php
index 0275c3f..bee3e22 100644
--- a/lib/activities/DocumentsProvider.php
+++ b/lib/activities/DocumentsProvider.php
@@ -26,7 +26,7 @@ class DocumentsProvider implements ActivityProvider
         if (
             !$document
             || !$activity->getContextObject()
-            || !$document->folder->getTypedFolder()->isFileDownloadable($document->id, $activity->getContextObject()->getObserver()->id)
+            || !$document->folder->getTypedFolder()->isFileDownloadable($document, $activity->getContextObject()->getObserver()->id)
         ) {
             return false;
         }
diff --git a/lib/classes/exportdocument/ExportPDF.php b/lib/classes/exportdocument/ExportPDF.php
index 1b2ec77..1519ba5 100644
--- a/lib/classes/exportdocument/ExportPDF.php
+++ b/lib/classes/exportdocument/ExportPDF.php
@@ -329,8 +329,8 @@ class ExportPDF extends TCPDF implements ExportDocument
                     $file_ref = FileRef::find($matches[1]);
                     $folder = isset($file_ref->folder) ? $file_ref->folder->getTypedFolder() : null;
                     if (
-                        isset($folder)
-                        && $folder->isFileDownloadable($file_ref->id, $GLOBALS['user']->id)
+                        isset($folder, $file_ref)
+                        && $folder->isFileDownloadable($file_ref, $GLOBALS['user']->id)
                     ) {
                         $convurl = $file_ref->file->getPath();
                     } else {
diff --git a/lib/filesystem/CoursePublicFolder.php b/lib/filesystem/CoursePublicFolder.php
index 0aabac4..5432709 100644
--- a/lib/filesystem/CoursePublicFolder.php
+++ b/lib/filesystem/CoursePublicFolder.php
@@ -138,12 +138,12 @@ class CoursePublicFolder extends StandardFolder
     /**
      * Files in CoursePublicFolders are downloadable for all logged in users.
      *
-     * @param string $file_ref_id The ID to a FileRef.
-     * @param string $user_id     The user who wishes to downlaod the file.
+     * @param FileRef $file_ref The ID to a FileRef.
+     * @param string  $user_id  The user who wishes to downlaod the file.
      *
      * @return bool
      */
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool
     {
         return $this->isVisible($user_id);
     }
diff --git a/lib/filesystem/ExerciseFolder.php b/lib/filesystem/ExerciseFolder.php
index e882de8..a2f5bec 100644
--- a/lib/filesystem/ExerciseFolder.php
+++ b/lib/filesystem/ExerciseFolder.php
@@ -58,17 +58,17 @@ class ExerciseFolder extends StandardFolder
         return false;
     }
 
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool
     {
         return $this->isReadable($user_id);
     }
 
-    public function isFileEditable(string $file_ref_id, string $user_id): bool
+    public function isFileEditable(FileRef $file_ref, string $user_id): bool
     {
         return $this->isWritable($user_id);
     }
 
-    public function isFileWritable(string $file_ref_id, string $user_id): bool
+    public function isFileWritable(FileRef $file_ref, string $user_id): bool
     {
         return $this->isWritable($user_id);
     }
diff --git a/lib/filesystem/FeedbackFolder.php b/lib/filesystem/FeedbackFolder.php
index db82a38..2a23101 100644
--- a/lib/filesystem/FeedbackFolder.php
+++ b/lib/filesystem/FeedbackFolder.php
@@ -43,17 +43,17 @@ class FeedbackFolder extends StandardFolder
         return false;
     }
 
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool
     {
         return $this->isReadable($user_id);
     }
 
-    public function isFileEditable(string $file_ref_id, string $user_id): bool
+    public function isFileEditable(FileRef $file_ref, string $user_id): bool
     {
         return $this->isWritable($user_id);
     }
 
-    public function isFileWritable(string $file_ref_id, string $user_id): bool
+    public function isFileWritable(FileRef $file_ref, string $user_id): bool
     {
         return $this->isWritable($user_id);
     }
diff --git a/lib/filesystem/FileManager.php b/lib/filesystem/FileManager.php
index 4328fcf..4ca5621 100644
--- a/lib/filesystem/FileManager.php
+++ b/lib/filesystem/FileManager.php
@@ -1250,7 +1250,7 @@ class FileManager
 
         // loop through all files and copy them to the folder path:
         foreach ($folder->getFiles() as $file_ref) {
-            if ($folder->isFileDownloadable($file_ref->id, $user_id) || $ignore_perms) {
+            if ($folder->isFileDownloadable($file_ref, $user_id) || $ignore_perms) {
                 //The user (given by user_id) has the required permissions
                 //to download the file or the permission checks are
                 //ignored.
@@ -1302,7 +1302,7 @@ class FileManager
                 //specified by $user_id:
                 if ($folder->isReadable($user_id)) {
                     foreach ($folder_files as $folder_file) {
-                        if ($folder->isFileDownloadable($folder_file->id, $user_id)) {
+                        if ($folder->isFileDownloadable($folder_file, $user_id)) {
                             $num_files++;
                         }
                     }
@@ -1316,7 +1316,7 @@ class FileManager
                     if ($user_id) {
                         //user-ID is set: only if the file is downloadable
                         //it will be counted!
-                        if ($folder->isFileDownloadable($file->id, $user_id)) {
+                        if ($folder->isFileDownloadable($file, $user_id)) {
                             $num_files++;
                         }
                     } else {
diff --git a/lib/filesystem/FolderType.php b/lib/filesystem/FolderType.php
index ef98af1..5eba268 100644
--- a/lib/filesystem/FolderType.php
+++ b/lib/filesystem/FolderType.php
@@ -225,29 +225,29 @@ interface FolderType
     /**
      * Determines if a user may download the file.
      *
-     * @param string $file_ref_id The ID of the FileRef object of a file that shall be downloaded.
-     * @param string $user_id     The user who wishes to download the file.
+     * @param FileRef $file_ref The FileRef object of a file that shall be downloaded.
+     * @param string  $user_id  The user who wishes to download the file.
      * @return boolean True, if the user is permitted to download the file, false otherwise.
      */
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool;
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool;
 
     /**
      * Determines if a user may edit the file.
      *
-     * @param string $file_ref_id The ID of the FileRef object of a file that shall be edited.
-     * @param string $user_id     The user who wishes to edit the file.
+     * @param FileRef $file_ref The FileRef object of a file that shall be edited.
+     * @param string $user_id   The user who wishes to edit the file.
      * @return boolean True, if the user is permitted to edit the file, false otherwise.
      */
-    public function isFileEditable(string $file_ref_id, string $user_id): bool;
+    public function isFileEditable(FileRef $file_ref, string $user_id): bool;
 
     /**
      * Determines if a user may write to the file.
      *
-     * @param string $file_ref_id The FileRef object of a file that shall be written.
-     * @param string $user_id The user who wishes to write to the file.
+     * @param FileRef $file_ref The FileRef object of a file that shall be written.
+     * @param string  $user_id     The user who wishes to write to the file.
      * @return boolean True, if the user is permitted to write to the file, false otherwise.
      */
-    public function isFileWritable(string $file_ref_id, string $user_id): bool;
+    public function isFileWritable(FileRef $file_ref, string $user_id): bool;
 
     /**
      * Returns an associative array of additional colums with the index the id of the column
diff --git a/lib/filesystem/HiddenFolder.php b/lib/filesystem/HiddenFolder.php
index df93517..c503e93 100644
--- a/lib/filesystem/HiddenFolder.php
+++ b/lib/filesystem/HiddenFolder.php
@@ -126,18 +126,14 @@ class HiddenFolder extends PermissionEnabledFolder
     }
 
     /**
-     * @param string $file_ref_id
-     * @param string $user_id
+     * @param FileRef $file_ref
+     * @param string  $user_id
      * @return bool
      */
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool
     {
-        $fileref = FileRef::find($file_ref_id);
-
-        if ($fileref) {
-            if ($this->download_allowed || Seminar_Perm::get()->have_studip_perm('tutor', $this->range_id, $user_id)) {
-                return $fileref->terms_of_use->isDownloadable($this->range_id, $this->range_type, true, $user_id);
-            }
+        if ($this->download_allowed || Seminar_Perm::get()->have_studip_perm('tutor', $this->range_id, $user_id)) {
+            return $file_ref->terms_of_use->isDownloadable($this->range_id, $this->range_type, true, $user_id);
         }
 
         return false;
diff --git a/lib/filesystem/HomeworkFolder.php b/lib/filesystem/HomeworkFolder.php
index 46b9f20..11f585c 100644
--- a/lib/filesystem/HomeworkFolder.php
+++ b/lib/filesystem/HomeworkFolder.php
@@ -109,11 +109,11 @@ class HomeworkFolder extends PermissionEnabledFolder
     }
 
     /**
-     * @param string $file_ref_id
-     * @param string $user_id
+     * @param FileRef $file_ref
+     * @param string  $user_id
      * @return bool
      */
-    public function isFileEditable(string $file_ref_id, string $user_id): bool
+    public function isFileEditable(FileRef $file_ref, string $user_id): bool
     {
         return $GLOBALS['perm']->have_studip_perm('tutor', $this->range_id, $user_id);
     }
@@ -126,11 +126,11 @@ class HomeworkFolder extends PermissionEnabledFolder
      * tutor permissions on the Stud.IP object specified by range_id
      * (such objects may be courses or institutes for example).
      *
-     * @param string $file_ref_id
-     * @param string $user_id
+     * @param FileRef $file_ref
+     * @param string  $user_id
      * @return bool
      */
-    public function isFileWritable(string $file_ref_id, string $user_id): bool
+    public function isFileWritable(FileRef $file_ref, string $user_id): bool
     {
         return $GLOBALS['perm']->have_studip_perm('tutor', $this->range_id, $user_id);
     }
diff --git a/lib/filesystem/InboxOutboxFolder.php b/lib/filesystem/InboxOutboxFolder.php
index bab9253..fe61573 100644
--- a/lib/filesystem/InboxOutboxFolder.php
+++ b/lib/filesystem/InboxOutboxFolder.php
@@ -235,7 +235,7 @@ class InboxOutboxFolder implements FolderType
     /**
      * Files are only downloadable for the owner.
      */
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool
     {
         return $this->user
             && $user_id === $this->user->id;
@@ -244,7 +244,7 @@ class InboxOutboxFolder implements FolderType
     /**
      * InboxOutboxFolders do not allow editing files.
      */
-    public function isFileEditable(string $file_ref_id, string $user_id): bool
+    public function isFileEditable(FileRef $file_ref, string $user_id): bool
     {
         //files shall be unchanged in here
         return false;
@@ -253,7 +253,7 @@ class InboxOutboxFolder implements FolderType
     /**
      * InboxOutboxFolders do not allow writing files.
      */
-    public function isFileWritable(string $file_ref_id, string $user_id): bool
+    public function isFileWritable(FileRef $file_ref, string $user_id): bool
     {
         //files shall be unchanged in here
         return false;
diff --git a/lib/filesystem/MVVFolder.php b/lib/filesystem/MVVFolder.php
index 73f237a..b75372f 100644
--- a/lib/filesystem/MVVFolder.php
+++ b/lib/filesystem/MVVFolder.php
@@ -32,7 +32,7 @@ class MVVFolder extends StandardFolder
     /**
      * See method MVVFolder::isReadable
      */
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool
     {
         return $this->isReadable($user_id);
     }
diff --git a/lib/filesystem/MessageFolder.php b/lib/filesystem/MessageFolder.php
index f0d5cf6..9f2d301 100644
--- a/lib/filesystem/MessageFolder.php
+++ b/lib/filesystem/MessageFolder.php
@@ -317,7 +317,7 @@ class MessageFolder extends StandardFolder
     /**
      * See method MessageFolder::isReadable
      */
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool
     {
         return $this->isReadable($user_id);
     }
@@ -325,7 +325,7 @@ class MessageFolder extends StandardFolder
     /**
      * Files inside MessageFolders are not editable.
      */
-    public function isFileEditable(string $file_ref_id, string $user_id): bool
+    public function isFileEditable(FileRef $file_ref, string $user_id): bool
     {
         //message attachments are never editable!
         return false;
@@ -334,7 +334,7 @@ class MessageFolder extends StandardFolder
     /**
      * Files inside MessageFolders are not writable.
      */
-    public function isFileWritable(string $file_ref_id, string $user_id): bool
+    public function isFileWritable(FileRef $file_ref, string $user_id): bool
     {
         //message attachments are never writable!
         return false;
diff --git a/lib/filesystem/PermissionEnabledFolder.php b/lib/filesystem/PermissionEnabledFolder.php
index 29acb65..36f98f6 100644
--- a/lib/filesystem/PermissionEnabledFolder.php
+++ b/lib/filesystem/PermissionEnabledFolder.php
@@ -134,13 +134,13 @@ class PermissionEnabledFolder extends StandardFolder
     }
 
     /**
-     * @param string $file_ref_id
-     * @param string $user_id
+     * @param FileRef $file_ref
+     * @param string  $user_id
      * @return bool
      */
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool
     {
-        $fileref = FileRef::find($file_ref_id);
+        $fileref = FileRef::find($file_ref);
 
         if ($fileref) {
             if ($this->isVisible($user_id) && $this->isFileVisible($fileref, $user_id)) {
diff --git a/lib/filesystem/PublicFolder.php b/lib/filesystem/PublicFolder.php
index 285a0df..439ab04 100644
--- a/lib/filesystem/PublicFolder.php
+++ b/lib/filesystem/PublicFolder.php
@@ -118,12 +118,12 @@ class PublicFolder extends StandardFolder
     /**
      * Files in PublicFolders are always downloadable.
      *
-     * @param string $file_ref_id The ID to a FileRef.
-     * @param string $user_id     The user who wishes to downlaod the file.
+     * @param FileRef $file_ref The ID to a FileRef.
+     * @param string  $user_id  The user who wishes to downlaod the file.
      *
      * @return bool True
      */
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool
     {
         //public folder => everyone can download a file
         return true;
@@ -132,12 +132,12 @@ class PublicFolder extends StandardFolder
     /**
      * Files in PublicFolders are editable for the owner only.
      *
-     * @param string $file_ref_id The ID to a FileRef.
-     * @param string $user_id     The user who wishes to edit the file.
+     * @param FileRef $file_ref The ID to a FileRef.
+     * @param string  $user_id  The user who wishes to edit the file.
      *
      * @return bool True, if the user is the owner of the file, false otherwise.
      */
-    public function isFileEditable(string $file_ref_id, string $user_id): bool
+    public function isFileEditable(FileRef $file_ref, string $user_id): bool
     {
         //only the owner may edit files
         return $this->range_id === $user_id;
@@ -146,12 +146,12 @@ class PublicFolder extends StandardFolder
     /**
      * Files in PublicFolders are writable for the owner only.
      *
-     * @param string $file_ref_id The ID to a FileRef.
-     * @param string $user_id     The user who wishes to write to the file.
+     * @param FileRef $file_ref The ID to a FileRef.
+     * @param string  $user_id  The user who wishes to write to the file.
      *
      * @return bool True, if the user is the owner of the file, false otherwise.
      */
-    public function isFileWritable(string $file_ref_id, string $user_id): bool
+    public function isFileWritable(FileRef $file_ref, string $user_id): bool
     {
         //only the owner may delete files
         return $this->range_id === $user_id;
diff --git a/lib/filesystem/ResourceFolder.php b/lib/filesystem/ResourceFolder.php
index edb7a48..1319040 100644
--- a/lib/filesystem/ResourceFolder.php
+++ b/lib/filesystem/ResourceFolder.php
@@ -127,17 +127,17 @@ class ResourceFolder extends StandardFolder
         return false;
     }
 
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool
     {
         return $this->isReadable($user_id);
     }
 
-    public function isFileEditable(string $file_ref_id, string $user_id): bool
+    public function isFileEditable(FileRef $file_ref, string $user_id): bool
     {
         return $this->isWritable($user_id);
     }
 
-    public function isFileWritable(string $file_ref_id, string $user_id): bool
+    public function isFileWritable(FileRef $file_ref, string $user_id): bool
     {
         return $this->isWritable($user_id);
     }
diff --git a/lib/filesystem/ResponseFolder.php b/lib/filesystem/ResponseFolder.php
index 169405e..cf2cf67 100644
--- a/lib/filesystem/ResponseFolder.php
+++ b/lib/filesystem/ResponseFolder.php
@@ -54,17 +54,17 @@ class ResponseFolder extends StandardFolder
         return false;
     }
 
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool
     {
         return $this->isReadable($user_id);
     }
 
-    public function isFileEditable(string $file_ref_id, string $user_id): bool
+    public function isFileEditable(FileRef $file_ref, string $user_id): bool
     {
         return $this->isWritable($user_id);
     }
 
-    public function isFileWritable(string $file_ref_id, string $user_id): bool
+    public function isFileWritable(FileRef $file_ref, string $user_id): bool
     {
         return $this->isWritable($user_id);
     }
diff --git a/lib/filesystem/StandardFile.php b/lib/filesystem/StandardFile.php
index f357b47..ad16023 100644
--- a/lib/filesystem/StandardFile.php
+++ b/lib/filesystem/StandardFile.php
@@ -379,7 +379,7 @@ class StandardFile implements FileType, ArrayAccess, StandardFileInterface
     {
         $user_id || $user_id = $GLOBALS['user']->id;
         return $this->getFolderType()->isFileDownloadable(
-            $this->fileref->getId(),
+            $this->fileref,
             $user_id
         );
     }
@@ -393,7 +393,7 @@ class StandardFile implements FileType, ArrayAccess, StandardFileInterface
     {
         $user_id || $user_id = $GLOBALS['user']->id;
         return $this->getFolderType()->isFileEditable(
-            $this->fileref->getId(),
+            $this->fileref,
             $user_id
         );
     }
@@ -407,7 +407,7 @@ class StandardFile implements FileType, ArrayAccess, StandardFileInterface
     {
         $user_id || $user_id = $GLOBALS['user']->id;
         return $this->getFolderType()->isFileWritable(
-            $this->fileref->getId(),
+            $this->fileref,
             $user_id
         );
     }
diff --git a/lib/filesystem/StandardFolder.php b/lib/filesystem/StandardFolder.php
index 6404dd8..524d68a 100644
--- a/lib/filesystem/StandardFolder.php
+++ b/lib/filesystem/StandardFolder.php
@@ -347,7 +347,11 @@ class StandardFolder implements FolderType
     {
         $file_ref = $this->folderdata->file_refs->find($file_ref_id);
 
-        if (!$this->isFileWritable($file_ref->id, $GLOBALS['user']->id)) {
+        if (!$file_ref) {
+            return 0;
+        }
+
+        if (!$this->isFileWritable($file_ref, $GLOBALS['user']->id)) {
             return [sprintf(
                 _('Ungenügende Berechtigungen zum Löschen der Datei %s in Ordner %s!'),
                 $file_ref->name,
@@ -355,11 +359,7 @@ class StandardFolder implements FolderType
             )];
         }
 
-        if ($file_ref) {
-            return $file_ref->delete();
-        }
-
-        return 0;
+        return $file_ref->delete();
     }
 
     /**
@@ -417,23 +417,21 @@ class StandardFolder implements FolderType
     }
 
     /**
-     * @param string $file_ref_id
-     * @param string $user_id
+     * @param FileRef $file_ref
+     * @param string  $user_id
      * @return bool
      */
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool
     {
         if ($this->range_type === 'user') {
             return $user_id === $this->range_id;
         }
 
         if (in_array($this->range_type, ['course', 'institute'])) {
-            $fileref = FileRef::find($file_ref_id);
-
-            if (is_object($fileref->terms_of_use)) {
+            if (is_object($file_ref->terms_of_use)) {
                 //terms of use are defined for this file!
                 return $this->isReadable($user_id)
-                    && $fileref->terms_of_use->isDownloadable($this->range_id, $this->range_type,true, $user_id);
+                    && $file_ref->terms_of_use->isDownloadable($this->range_id, $this->range_type,true, $user_id);
             } else {
                 return $this->isReadable($user_id)
                     && $GLOBALS['perm']->have_studip_perm('user', $this->range_id, $user_id);
@@ -444,19 +442,17 @@ class StandardFolder implements FolderType
     }
 
     /**
-     * @param string $file_ref_id
-     * @param string $user_id
+     * @param FileRef $file_ref
+     * @param string  $user_id
      * @return bool
      */
-    public function isFileEditable(string $file_ref_id, string $user_id): bool
+    public function isFileEditable(FileRef $file_ref, string $user_id): bool
     {
         if ($this->range_type === 'user') {
             return $user_id === $this->range_id;
         }
 
-        $fileref = FileRef::find($file_ref_id);
-
-        return $fileref->user_id === $user_id
+        return $file_ref->user_id === $user_id
             || $GLOBALS['perm']->have_studip_perm('tutor', $this->range_id, $user_id);
     }
 
@@ -468,13 +464,13 @@ class StandardFolder implements FolderType
      * tutor permissions on the Stud.IP object specified by range_id
      * (such objects may be courses or institutes for example).
      *
-     * @param string $file_ref_id
-     * @param string $user_id
+     * @param FileRef $file_ref
+     * @param string  $user_id
      * @return bool
      */
-    public function isFileWritable(string $file_ref_id, string $user_id): bool
+    public function isFileWritable(FileRef $file_ref, string $user_id): bool
     {
-        return $this->isFileEditable($file_ref_id, $user_id);
+        return $this->isFileEditable($file_ref, $user_id);
     }
 
     /**
diff --git a/lib/filesystem/TimedFolder.php b/lib/filesystem/TimedFolder.php
index b331f0d..9e04b44 100644
--- a/lib/filesystem/TimedFolder.php
+++ b/lib/filesystem/TimedFolder.php
@@ -211,36 +211,43 @@ class TimedFolder extends PermissionEnabledFolder
     }
 
     /**
-     * @param string $file_ref_id
-     * @param string $user_id
+     * @param FileRef $file_ref
+     * @param string  $user_id
      * @return bool
      */
-    public function isFileEditable(string $file_ref_id, string $user_id): bool
+    public function isFileEditable(FileRef $file_ref, string $user_id): bool
     {
-        //HomeworkFolder Style
-        if (!Seminar_Perm::get()->have_studip_perm('tutor', $this->range_id) &&
-            $this->isWritable($user_id) && !$this->isReadable($user_id)) {
+        // HomeworkFolder Style
+        if (
+            !Seminar_Perm::get()->have_studip_perm('tutor', $this->range_id)
+            && $this->isWritable($user_id)
+            && !$this->isReadable($user_id)
+        ) {
             return false;
         }
-        return parent::isFileEditable($file_ref_id, $user_id);
+        return parent::isFileEditable($file_ref, $user_id);
     }
 
     /**
      * Checks if a user has write permissions to a file.
      *
      *
-     * @param string $file_ref_id
-     * @param string $user_id
+     * @param FileRef $file_ref
+     * @param string  $user_id
      * @return bool
      */
-    public function isFileWritable(string $file_ref_id, string $user_id): bool
+    public function isFileWritable(FileRef $file_ref, string $user_id): bool
     {
-        //HomeworkFolder Style
-        if (!Seminar_Perm::get()->have_studip_perm('tutor', $this->range_id) &&
-            $this->isWritable($user_id) && !$this->isReadable($user_id)) {
+        // HomeworkFolder Style
+        if (
+            !Seminar_Perm::get()->have_studip_perm('tutor', $this->range_id)
+            && $this->isWritable($user_id)
+            && !$this->isReadable($user_id)
+        ) {
             return false;
         }
-        return parent::isFileWritable($file_ref_id, $user_id);
+
+        return parent::isFileWritable($file_ref, $user_id);
     }
 
 }
diff --git a/lib/filesystem/UnknownFolderType.php b/lib/filesystem/UnknownFolderType.php
index 2cd7fd2..4eba3bf 100644
--- a/lib/filesystem/UnknownFolderType.php
+++ b/lib/filesystem/UnknownFolderType.php
@@ -239,32 +239,32 @@ class UnknownFolderType implements FolderType
     }
 
     /**
-     * @param string $file_ref_id
-     * @param string $user_id
+     * @param FileRef $file_ref
+     * @param string  $user_id
      * @return bool
      */
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool
     {
         return false;
     }
 
 
     /**
-     * @param string $file_ref_id
-     * @param string $user_id
+     * @param FileRef $file_ref
+     * @param string  $user_id
      * @return bool
      */
-    public function isFileEditable(string $file_ref_id, string $user_id): bool
+    public function isFileEditable(FileRef $file_ref, string $user_id): bool
     {
         return false;
     }
 
     /**
-     * @param string $file_ref_id
-     * @param string $user_id
+     * @param FileRef $file_ref
+     * @param string  $user_id
      * @return bool
      */
-    public function isFileWritable(string $file_ref_id, string $user_id): bool
+    public function isFileWritable(FileRef $file_ref, string $user_id): bool
     {
         return false;
     }
diff --git a/lib/filesystem/VirtualFolderType.php b/lib/filesystem/VirtualFolderType.php
index 0e2c2b4..a83ec0a 100644
--- a/lib/filesystem/VirtualFolderType.php
+++ b/lib/filesystem/VirtualFolderType.php
@@ -266,31 +266,31 @@ class VirtualFolderType implements FolderType
     }
 
     /**
-     * @param string $file_ref_id
-     * @param string $user_id
+     * @param FileRef $file_ref
+     * @param string  $user_id
      * @return bool
      */
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool
     {
         return true;
     }
 
     /**
-     * @param string $file_ref_id
-     * @param string $user_id
+     * @param FileRef $file_ref
+     * @param string  $user_id
      * @return bool
      */
-    public function isFileEditable(string $file_ref_id, string $user_id): bool
+    public function isFileEditable(FileRef $file_ref, string $user_id): bool
     {
         return false;
     }
 
     /**
-     * @param string $file_ref_id
-     * @param string $user_id
+     * @param FileRef $file_ref
+     * @param string  $user_id
      * @return bool
      */
-    public function isFileWritable(string $file_ref_id, string $user_id): bool
+    public function isFileWritable(FileRef $file_ref, string $user_id): bool
     {
         return false;
     }
diff --git a/lib/models/Courseware/Filesystem/PublicFolder.php b/lib/models/Courseware/Filesystem/PublicFolder.php
index 10af85c..535b5f3 100644
--- a/lib/models/Courseware/Filesystem/PublicFolder.php
+++ b/lib/models/Courseware/Filesystem/PublicFolder.php
@@ -4,6 +4,8 @@ namespace Courseware\Filesystem;
 
 use ArrayAccess;
 use Courseware\Instance;
+use File;
+use FileRef;
 use FileType;
 use Flexi\Template;
 use Folder;
@@ -216,7 +218,7 @@ class PublicFolder extends StandardFolder
     /**
      * {@inheritdoc}
      */
-    public function isFileDownloadable(string $file_ref_id, string $user_id): bool
+    public function isFileDownloadable(FileRef $file_ref, string $user_id): bool
     {
         return true;
     }
@@ -224,7 +226,7 @@ class PublicFolder extends StandardFolder
     /**
      * {@inheritdoc}
      */
-    public function isFileEditable(string $file_ref_id, string $user_id): bool
+    public function isFileEditable(FileRef $file_ref, string $user_id): bool
     {
         return false;
     }
@@ -232,7 +234,7 @@ class PublicFolder extends StandardFolder
     /**
      * {@inheritdoc}
      */
-    public function isFileWritable(string $file_ref_id, string $user_id): bool
+    public function isFileWritable(FileRef $file_ref, string $user_id): bool
     {
         return false;
     }
diff --git a/lib/models/vips/Exercise.php b/lib/models/vips/Exercise.php
index bb142cc..9a5f5c1 100644
--- a/lib/models/vips/Exercise.php
+++ b/lib/models/vips/Exercise.php
@@ -814,7 +814,7 @@ abstract class Exercise extends SimpleORMap
                     if ($file_ref) {
                         $folder = $file_ref->folder->getTypedFolder();
 
-                        if ($folder->isFileDownloadable($file_ref->id, $GLOBALS['user']->id)) {
+                        if ($folder->isFileDownloadable($file_ref, $GLOBALS['user']->id)) {
                             if (!$this->folder->file_refs->find($file_id)) {
                                 $file = $file_ref->file;
                                 // $this->files->append($file);
diff --git a/lib/modules/CoreDocuments.php b/lib/modules/CoreDocuments.php
index 3accbbe..985db40 100644
--- a/lib/modules/CoreDocuments.php
+++ b/lib/modules/CoreDocuments.php
@@ -129,7 +129,7 @@ class CoreDocuments extends CorePlugin implements StudipModule, OERModule
         ]);
         foreach ($file_refs as $fileref) {
             $foldertype = $fileref->folder->getTypedFolder();
-            if ($foldertype->isFileDownloadable($fileref->getId(), $user_id)) {
+            if ($foldertype->isFileDownloadable($fileref, $user_id)) {
                 $navigation->setImage(Icon::create('files', Icon::ROLE_ATTENTION), [
                     'title' => _('Es gibt neue Dateien.'),
                 ]);