diff --git a/messages/uniworx/de.msg b/messages/uniworx/de.msg
index e3d6da26f..91eb63eeb 100644
--- a/messages/uniworx/de.msg
+++ b/messages/uniworx/de.msg
@@ -148,8 +148,8 @@ SheetNewOk         tid@TermId ssh@SchoolId csh@CourseShorthand sheetName@SheetNa
 SheetTitle         tid@TermId ssh@SchoolId csh@CourseShorthand sheetName@SheetName: #{display tid}-#{display ssh}-#{csh} #{sheetName}
 SheetTitleNew      tid@TermId ssh@SchoolId csh@CourseShorthand                    : #{display tid}-#{display ssh}-#{csh}: Neues Übungsblatt
 SheetEditHead      tid@TermId ssh@SchoolId csh@CourseShorthand sheetName@SheetName: #{display tid}-#{display ssh}-#{csh} #{sheetName} editieren
-SheetEditOk        tid@TermId ssh@SchoolId csh@CourseShorthand sheetName@SheetName: Übungsblatt #{sheetName} aus Kurs #{display tid}-#{display ssh}-#{csh} wurde gespeichert.
-SheetNameDup       tid@TermId ssh@SchoolId csh@CourseShorthand sheetName@SheetName: Es gibt bereits ein Übungsblatt #{sheetName} in diesem Kurs #{display tid}-#{display ssh}-#{csh}.
+SheetEditOk        tid@TermId ssh@SchoolId csh@CourseShorthand sheetName@SheetName: Übungsblatt #{sheetName} wurde gespeichert in Kurs #{display tid}-#{display ssh}-#{csh}
+SheetNameDup       tid@TermId ssh@SchoolId csh@CourseShorthand sheetName@SheetName: Es gibt bereits ein Übungsblatt #{sheetName} in diesem Kurs #{display tid}-#{display ssh}-#{csh}
 SheetDelHead       tid@TermId ssh@SchoolId csh@CourseShorthand sheetName@SheetName: #{sheetName} wirklich aus Kurs #{display tid}-#{display ssh}-#{csh} herauslöschen? Alle assoziierten Abgaben und Korrekturen gehen ebenfalls verloren!
 SheetDelOk         tid@TermId ssh@SchoolId csh@CourseShorthand sheetName@SheetName: #{display tid}-#{display ssh}-#{csh}: #{sheetName} gelöscht.
 SheetDelHasSubmissions objs@Int: Inkl. #{tshow objs} #{pluralDE objs "Abgabe" "Abgaben"}!
@@ -172,7 +172,7 @@ SheetName: Name
 SheetDescription: Hinweise für Teilnehmer
 SheetGroup: Gruppenabgabe
 SheetVisibleFrom: Sichtbar für Teilnehmer ab
-SheetVisibleFromTip: Ohne Datum nie sichtbar und keine Abgabe möglich; nur für unfertige Blätter leer lassen, deren Fristen/Bewertung sich noch ändern kann
+SheetVisibleFromTip: Ohne Datum nie sichtbar und keine Abgabe möglich; nur für unfertige Blätter leer lassen, deren Bewertung/Fristen sich noch ändern können
 SheetActiveFrom: Beginn Abgabezeitraum
 SheetActiveFromTip: Download der Aufgabenstellung erst ab diesem Datum möglich
 SheetActiveTo: Ende Abgabezeitraum
@@ -214,6 +214,29 @@ CourseCorrectionsTitle: Korrekturen für diesen Kurs
 CorrectorsHead sheetName@SheetName: Korrektoren für #{sheetName}
 CorrectorAssignTitle: Korrektor zuweisen
 
+MaterialName: Name
+MaterialType: Art
+MaterialTypePlaceholder: Folien, Code, Beispiel, ...
+MaterialTypeSlides: Folien
+MaterialTypeCode: Code
+MaterialTypeExample: Beispiel
+MaterialDescription: Beschreibung
+MaterialVisibleFrom: Sichtbar für Teilnehmer ab
+MaterialVisibleFromTip: Ohne Datum nie sichtbar für Teilnehmer; leer lassen ist nur sinnvoll für unfertige Materialien oder zur ausschließlichen Verteilung an Korrektoren
+MaterialInvisible: Dieses Material ist für Teilnehmer momentan unsichtbar!
+MaterialInvisibleUntil date@Text: Dieses Material ist für Teilnehmer momentan unsichtbar bis #{date}!
+MaterialFiles: Dateien
+MaterialHeading materialName@MaterialName: Material "#{materialName}"
+MaterialListHeading: Materialien
+MaterialNewHeading: Neues Material veröffentlichen
+MaterialNewTitle: Neues Material
+MaterialEditHeading materialName@MaterialName: Material "#{materialName}" editieren
+MaterialEditTitle materialName@MaterialName: Material "#{materialName}" editieren
+MaterialSaveOk  tid@TermId ssh@SchoolId csh@CourseShorthand materialName@MaterialName: Material "#{materialName}" erfolgreich gespeichert in Kurs #{display tid}-#{display ssh}-#{csh}
+MaterialNameDup tid@TermId ssh@SchoolId csh@CourseShorthand materialName@MaterialName: Es gibt bereits Material mit Namen "#{materialName}" in diesem Kurs #{display tid}-#{display ssh}-#{csh}
+MaterialDeleteQuestion: Wollen Sie das unten aufgeführte Material wirklich löschen?
+MaterialDeleted materialName@MaterialName: Material "#{materialName}" gelöscht
+
 
 Unauthorized: Sie haben hierfür keine explizite Berechtigung.
 UnauthorizedAnd l@Text r@Text: (#{l} UND #{r})
@@ -237,6 +260,7 @@ UnauthorizedRegistered: Sie sind nicht als Teilnehmer für diese Veranstaltung r
 UnauthorizedParticipant: Angegebener Benutzer ist nicht als Teilnehmer dieser Veranstaltung registriert.
 UnauthorizedCourseTime: Dieses Kurs erlaubt momentan keine Anmeldungen.
 UnauthorizedSheetTime: Dieses Übungsblatt ist momentan nicht freigegeben.
+UnauthorizedMaterialTime: Dieses Material ist momentan nicht freigegeben.
 UnauthorizedTutorialTime: Dieses Tutorium erlaubt momentan keine Anmeldungen.
 UnauthorizedSubmissionOwner: Sie sind an dieser Abgabe nicht beteiligt.
 UnauthorizedSubmissionRated: Diese Abgabe ist noch nicht korrigiert.
@@ -382,6 +406,8 @@ Pseudonyms: Pseudonyme
 
 FileTitle: Dateiname
 FileModified: Letzte Änderung
+VisibleFrom: Veröffentlicht
+AccessibleSince: Verfügbar seit
 
 
 Corrected: Korrigiert
@@ -591,6 +617,7 @@ SheetGroupNoGroups: Keine Gruppenabgabe
 SheetGroupMaxGroupsize: Maximale Gruppengröße
 
 SheetFiles: Übungsblatt-Dateien
+SheetFileTypeHeader: Zugehörigkeit
 
 NotificationTriggerSubmissionRatedGraded: Meine Abgabe in einem gewerteten Übungsblatt wurde korrigiert
 NotificationTriggerSubmissionRated: Meine Abgabe wurde korrigiert
@@ -727,6 +754,10 @@ MenuCorrections: Korrekturen
 MenuCorrectionsOwn: Meine Korrekturen
 MenuSubmissions: Abgaben
 MenuSheetList: Übungsblätter
+MenuMaterialList: Material
+MenuMaterialNew: Neues Material veröffentlichen
+MenuMaterialEdit: Material bearbeiten
+MenuMaterialDelete: Material löschen
 MenuTutorialList: Tutorien
 MenuTutorialNew: Neues Tutorium anlegen
 MenuSheetNew: Neues Übungsblatt anlegen
diff --git a/models/materials b/models/materials
new file mode 100644
index 000000000..062ab3232
--- /dev/null
+++ b/models/materials
@@ -0,0 +1,12 @@
+Material -- course material for disemination to course participants
+  course          CourseId
+  name            (CI Text)
+  type            Text Maybe
+  description     Html Maybe
+  visibleFrom     UTCTime Maybe    -- Invisible to enrolled participants before
+  lastEdit        UTCTime
+  UniqueMaterial course name
+  deriving Generic
+MaterialFile -- a file that is part of a material distribution
+  material MaterialId
+  file     FileId
\ No newline at end of file
diff --git a/routes b/routes
index 17ed427ad..c98fd9131 100644
--- a/routes
+++ b/routes
@@ -39,87 +39,94 @@
 /favicon.ico FaviconR GET                                     !free
 /robots.txt RobotsR GET                                       !free
 
-/                             HomeR             GET           !free
-/users                        UsersR            GET           -- no tags, i.e. admins only
-/users/#CryptoUUIDUser        AdminUserR        GET POST
-/users/#CryptoUUIDUser/delete AdminUserDeleteR      POST
-/users/#CryptoUUIDUser/hijack AdminHijackUserR  POST          !adminANDno-escalation
-/users/#CryptoUUIDUser/notifications UserNotificationR GET POST      !self
-/admin                        AdminR            GET
-/admin/features               AdminFeaturesR    GET POST
-/admin/test                   AdminTestR        GET POST
-/admin/errMsg                 AdminErrMsgR      GET POST
+/                             HomeR            GET            !free
+/users                        UsersR           GET            -- no tags, i.e. admins only
+/users/#CryptoUUIDUser        AdminUserR       GET POST
+/users/#CryptoUUIDUser/delete AdminUserDeleteR     POST
+/users/#CryptoUUIDUser/hijack AdminHijackUserR     POST       !adminANDno-escalation
+/users/#CryptoUUIDUser/notifications UserNotificationR GET POST   !self
+/admin                        AdminR           GET
+/admin/features               AdminFeaturesR   GET POST
+/admin/test                   AdminTestR       GET POST
+/admin/errMsg                 AdminErrMsgR     GET POST
 
-/health                       HealthR           GET            !free
-/instance                     InstanceR         GET            !free
-/info                         InfoR             GET            !free
-/info/lecturer                InfoLecturerR     GET            !lecturer
-/info/data                    DataProtR         GET            !free
-/impressum                    ImpressumR        GET            !free
-/version                      VersionR          GET            !free
+/health                       HealthR          GET             !free
+/instance                     InstanceR        GET             !free
+/info                         InfoR            GET             !free
+/info/lecturer                InfoLecturerR    GET             !lecturer
+/info/data                    DataProtR        GET             !free
+/impressum                    ImpressumR       GET             !free
+/version                      VersionR         GET             !free
 
-/help                         HelpR             GET POST       !free
+/help                         HelpR            GET POST        !free
 
-/user                      ProfileR          GET POST        !free
-/user/profile              ProfileDataR      GET             !free
-/user/authpreds            AuthPredsR        GET POST        !free
+/user                      ProfileR            GET POST        !free
+/user/profile              ProfileDataR        GET             !free
+/user/authpreds            AuthPredsR          GET POST        !free
 
-/term                      TermShowR         GET             !free
-/term/current              TermCurrentR      GET             !free
-/term/edit                 TermEditR         GET POST
-/term/#TermId/edit         TermEditExistR    GET POST
-!/term/#TermId             TermCourseListR   GET             !free
-!/term/#TermId/#SchoolId   TermSchoolCourseListR  GET        !free
+/term                      TermShowR           GET             !free
+/term/current              TermCurrentR        GET             !free
+/term/edit                 TermEditR           GET POST
+/term/#TermId/edit         TermEditExistR      GET POST
+!/term/#TermId             TermCourseListR     GET             !free
+!/term/#TermId/#SchoolId   TermSchoolCourseListR  GET          !free
 
-/school                    SchoolListR       GET             !development
-/school/#SchoolId          SchoolShowR       GET             !development
+/school                    SchoolListR         GET             !development
+/school/#SchoolId          SchoolShowR         GET             !development
 
 
 -- For Pattern Synonyms see Foundation
-/course/                    CourseListR       GET             !free
-!/course/new                CourseNewR        GET POST        !lecturer
-/course/#TermId/#SchoolId/#CourseShorthand CourseR          !lecturer:
-  /                           CShowR          GET             !free
-  /register                   CRegisterR      GET POST        !timeANDcapacity
-  /edit                       CEditR          GET POST
-  /lecturer-invite/#UserEmail CLecInviteR     GET POST
-  /delete                     CDeleteR        GET POST        !lecturerANDempty
-  /users                      CUsersR         GET POST
-  /users/#CryptoUUIDUser      CUserR          GET POST        !lecturerANDparticipant
-  /correctors                 CHiWisR         GET
-  /communication              CCommR          GET POST
-  /notes                      CNotesR         GET POST        !corrector
-  /subs                       CCorrectionsR   GET POST
-  /ex                         SheetListR      GET             !course-registered !materials !corrector
-  /ex/new                     SheetNewR       GET POST
-  /ex/current                 SheetCurrentR   GET             !course-registered !materials !corrector
-  /ex/unassigned              SheetOldUnassigned GET
+/course/                    CourseListR        GET             !free
+!/course/new                CourseNewR         GET POST        !lecturer
+/course/#TermId/#SchoolId/#CourseShorthand CourseR             !lecturer:
+  /                           CShowR           GET             !free
+  /register                   CRegisterR       GET POST        !timeANDcapacity
+  /edit                       CEditR           GET POST
+  /lecturer-invite/#UserEmail CLecInviteR      GET POST
+  /delete                     CDeleteR         GET POST        !lecturerANDempty
+  /users                      CUsersR          GET POST
+  /users/#CryptoUUIDUser      CUserR           GET POST        !lecturerANDparticipant
+  /correctors                 CHiWisR          GET
+  /communication              CCommR           GET POST
+  /notes                      CNotesR          GET POST        !corrector
+  /subs                       CCorrectionsR    GET POST
+  /ex                         SheetListR       GET             !course-registered !materials !corrector
+  /ex/new                     SheetNewR        GET POST
+  /ex/current                 SheetCurrentR    GET             !course-registered !materials !corrector
+  /ex/unassigned              SheetOldUnassigned    GET
   /ex/#SheetName SheetR:
-    /show                       SShowR        GET             !timeANDcourse-registered !timeANDmaterials !corrector
-    /edit                       SEditR        GET POST
-    /delete                     SDelR         GET POST
-    /subs                       SSubsR        GET POST        -- for lecturer only
-    !/subs/new                  SubmissionNewR GET POST       !timeANDcourse-registeredANDuser-submissions
-    !/subs/own                  SubmissionOwnR GET            !free -- just redirect
+    /show                       SShowR         GET             !timeANDcourse-registered !timeANDmaterials !corrector
+    /edit                       SEditR         GET POST
+    /delete                     SDelR          GET POST
+    /subs                       SSubsR         GET POST        -- for lecturer only
+    !/subs/new                  SubmissionNewR GET POST        !timeANDcourse-registeredANDuser-submissions
+    !/subs/own                  SubmissionOwnR GET             !free -- just redirect
     /subs/#CryptoFileNameSubmission SubmissionR:
-      /                         SubShowR      GET POST        !ownerANDtime !ownerANDread !correctorANDread
-      /archive/#{ZIPArchiveName SubmissionFileType} SubArchiveR                GET      !owner !corrector
-      /delete                   SubDelR       GET POST        !ownerANDtime
-      /assign                   SAssignR      GET POST	      !lecturerANDtime
-      /correction               CorrectionR   GET POST        !corrector !ownerANDreadANDrated
-      !/#SubmissionFileType/*FilePath SubDownloadR           GET      !owner !corrector
-    /correctors                 SCorrR        GET POST
-    /pseudonym                  SPseudonymR   GET POST        !course-registeredANDcorrector-submissions
-    /corrector-invite/#UserEmail SCorrInviteR     GET POST
-    !/#SheetFileType/*FilePath  SFileR        GET             !timeANDcourse-registered !timeANDmaterials !corrector
-  /tuts                         CTutorialListR GET            !tutor
+      /                         SubShowR       GET POST        !ownerANDtime !ownerANDread !correctorANDread
+      /archive/#{ZIPArchiveName SubmissionFileType} SubArchiveR     GET      !owner !corrector
+      /delete                   SubDelR        GET POST        !ownerANDtime
+      /assign                   SAssignR       GET POST        !lecturerANDtime
+      /correction               CorrectionR    GET POST        !corrector !ownerANDreadANDrated
+      !/#SubmissionFileType/*FilePath SubDownloadR  GET        !owner !corrector
+    /correctors                 SCorrR         GET POST
+    /pseudonym                  SPseudonymR    GET POST        !course-registeredANDcorrector-submissions
+    /corrector-invite/#UserEmail SCorrInviteR  GET POST
+    !/#SheetFileType/*FilePath  SFileR         GET             !timeANDcourse-registered !timeANDmaterials !corrector
+  /file                          MaterialListR GET             !course-registered !materials !corrector !tutor
+  /file/new                      MaterialNewR  GET POST
+  /file/#MaterialName MaterialR:
+    /edit                       MEditR         GET POST
+    /delete                     MDelR          GET POST
+    /show                       MShowR         GET             !timeANDcourse-registered !timeANDmaterials !corrector !tutor
+    /load/*FilePath             MFileR         GET             !timeANDcourse-registered !timeANDmaterials !corrector !tutor
+  /tuts                         CTutorialListR GET             !tutor
   /tuts/new                     CTutorialNewR  GET POST
   /tuts/#TutorialName TutorialR:
-    /edit                     TEditR          GET POST
-    /delete                   TDeleteR        GET POST
-    /participants             TUsersR         GET POST        !tutor
-    /register                 TRegisterR          POST        !timeANDcapacityANDcourse-registeredANDregister-group !timeANDtutorial-registered
-    /communication            TCommR          GET POST        !tutor
+    /edit                     TEditR           GET POST
+    /delete                   TDeleteR         GET POST
+    /participants             TUsersR          GET POST        !tutor
+    /register                 TRegisterR           POST        !timeANDcapacityANDcourse-registeredANDregister-group !timeANDtutorial-registered
+    /communication            TCommR           GET POST        !tutor
 
 
 /subs  CorrectionsR GET POST !corrector !lecturer
diff --git a/src/Application.hs b/src/Application.hs
index 11eb60210..cc8843303 100644
--- a/src/Application.hs
+++ b/src/Application.hs
@@ -80,7 +80,7 @@ import System.Environment (lookupEnv)
 import System.Posix.Process (getProcessID)
 
 import Control.Monad.Trans.State (execStateT)
-  
+
 -- Import all relevant handler modules here.
 -- (HPack takes care to add new modules to our cabal file nowadays.)
 import Handler.Common
@@ -97,6 +97,7 @@ import Handler.Sheet
 import Handler.Submission
 import Handler.Tutorial
 import Handler.Corrections
+import Handler.Material
 import Handler.CryptoIDDispatch
 import Handler.SystemMessage
 import Handler.Health
@@ -189,7 +190,7 @@ makeFoundation appSettings'@AppSettings{..} = do
       ldapPool <- for appLdapConf $ \LdapConf{..} -> do
         $logDebugS "setup" "LDAP-Pool"
         createLdapPool ldapHost ldapPort (poolStripes ldapPool) (poolTimeout ldapPool) ldapTimeout (poolLimit ldapPool)
-    
+
       -- Perform database migration using our application's logging settings.
       $logDebugS "setup" "Migration"
       migrateAll `runSqlPool` sqlPool
@@ -231,7 +232,7 @@ clusterSetting proxy@(knownClusterSetting -> key) = do
       new <- initClusterSetting proxy
       void . insert $ ClusterConfig key (Aeson.toJSON new)
       return new
-  
+
 readInstanceIDFile :: MonadIO m => FilePath -> m UUID
 readInstanceIDFile idFile = liftIO . handle generateInstead $ LBS.readFile idFile >>= parseBS
   where
@@ -252,7 +253,7 @@ createSmtpPool SmtpConf{ smtpPool = ResourcePoolConf{..}, .. } = do
   let
     withLogging :: LoggingT IO a -> IO a
     withLogging = flip runLoggingT logFunc
-    
+
     mkConnection = withLogging $ do
       $logInfoS "SMTP" "Opening new connection"
       liftIO mkConnection'
@@ -353,7 +354,7 @@ adjustSettings = execStateT $ do
     Just wInterval
       | maybe True (== myProcessID) watchdogProcess
         -> _appHealthCheckInterval %= min (fromRational $ (toRational wInterval / 1e6) / 2)
-    _other -> return () 
+    _other -> return ()
 
 -- | main function for use by yesod devel
 develMain :: IO ()
@@ -373,7 +374,7 @@ appMain = runResourceT $ do
 
     -- Generate the foundation from the settings
     foundation <- makeFoundation settings
-  
+
     runAppLoggingT foundation $ do
       $logDebugS "setup" "Job-Handling"
       handleJobs foundation
@@ -406,7 +407,7 @@ appMain = runResourceT $ do
 --------------------------------------------------------------
 foundationStoreNum :: Word32
 foundationStoreNum = 2
-  
+
 getApplicationRepl :: (MonadResource m, MonadBaseControl IO m) => m (Int, UniWorX, Application)
 getApplicationRepl = do
     settings <- getAppDevSettings
@@ -418,7 +419,7 @@ getApplicationRepl = do
     let foundationStore = Store foundationStoreNum
     liftIO $ deleteStore foundationStore
     liftIO $ writeStore foundationStore foundation
-  
+
     return (getPort wsettings, foundation, app1)
 
 shutdownApp :: MonadIO m => UniWorX -> m ()
diff --git a/src/Database/Esqueleto/Utils.hs b/src/Database/Esqueleto/Utils.hs
index 990c782ff..38105a37a 100644
--- a/src/Database/Esqueleto/Utils.hs
+++ b/src/Database/Esqueleto/Utils.hs
@@ -19,9 +19,9 @@ import Database.Esqueleto.Utils.TH
 
 
 --
--- Description : Convenience for using @Esqueleto@,
+-- Description : Convenience for using `Esqueleto`,
 --               intended to be imported qualified
---               just like Esqueleto
+--               just like @Esqueleto@
 
 
 -- ezero = E.val (0 :: Int64)
@@ -44,13 +44,13 @@ hasInfix :: (E.Esqueleto query expr backend, E.SqlString s2) =>
 hasInfix = flip isInfixOf
 
 -- | Given a test and a set of values, check whether anyone succeeds the test
---   WARNING: SQL leaves it explicitely unspecified whether || is short curcuited (i.e. lazily evaluated)
+--   WARNING: SQL leaves it explicitely unspecified whether `||` is short curcuited (i.e. lazily evaluated)
 any :: Foldable f =>
   (a -> E.SqlExpr (E.Value Bool)) -> f a -> E.SqlExpr (E.Value Bool)
 any test = F.foldr (\needle acc -> acc E.||. test needle) false
 
 -- | Given a test and a set of values, check whether all succeeds the test
---   WARNING: SQL leaves it explicitely unspecified whether && is short curcuited (i.e. lazily evaluated)
+--   WARNING: SQL leaves it explicitely unspecified whether `&&` is short curcuited (i.e. lazily evaluated)
 all :: Foldable f =>
   (a -> E.SqlExpr (E.Value Bool)) -> f a -> E.SqlExpr (E.Value Bool)
 all test = F.foldr (\needle acc -> acc E.&&. test needle) true
@@ -82,7 +82,7 @@ mkExactFilter :: (PersistField a)
   -> E.SqlExpr (E.Value Bool)
 mkExactFilter = mkExactFilterWith id
 
--- | like @mkExactFiler@ but allows for conversion; convenient in conjunction with @anyFilter@ and @allFilter@
+-- | like `mkExactFiler` but allows for conversion; convenient in conjunction with `anyFilter` and `allFilter`
 mkExactFilterWith :: (PersistField b)
   => (a -> b)                      -- ^ type conversion
   -> (t -> E.SqlExpr (E.Value b))  -- ^ getter from query to searched element
diff --git a/src/Foundation.hs b/src/Foundation.hs
index 8ce8987de..0e99aba6b 100644
--- a/src/Foundation.hs
+++ b/src/Foundation.hs
@@ -163,9 +163,13 @@ pattern CSheetR :: TermId -> SchoolId -> CourseShorthand -> SheetName -> SheetR
 pattern CSheetR tid ssh csh shn ptn
   = CourseR tid ssh csh (SheetR shn ptn)
 
+pattern CMaterialR :: TermId -> SchoolId -> CourseShorthand -> MaterialName -> MaterialR -> Route UniWorX
+pattern CMaterialR tid ssh csh mnm ptn
+  = CourseR tid ssh csh (MaterialR mnm ptn)
+
 pattern CTutorialR :: TermId -> SchoolId -> CourseShorthand -> TutorialName -> TutorialR -> Route UniWorX
-pattern CTutorialR tid ssh csh shn ptn
-  = CourseR tid ssh csh (TutorialR shn ptn)
+pattern CTutorialR tid ssh csh tnm ptn
+  = CourseR tid ssh csh (TutorialR tnm ptn)
 
 pattern CSubmissionR :: TermId -> SchoolId -> CourseShorthand -> SheetName -> CryptoFileNameSubmission -> SubmissionR -> Route UniWorX
 pattern CSubmissionR tid ssh csh shn cid ptn
@@ -638,9 +642,9 @@ tagAccessPredicate AuthTime = APDB $ \mAuthId route _ -> case route of
         -> return Authorized
       | otherwise
         -> mzero
-     
+
   CSheetR tid ssh csh shn subRoute -> maybeT (unauthorizedI MsgUnauthorizedSheetTime) $ do
-    Entity cid _ <- MaybeT . getBy $ TermSchoolCourseShort tid ssh csh
+    cid <- MaybeT . getKeyBy $ TermSchoolCourseShort tid ssh csh
     Entity _sid Sheet{..} <- MaybeT . getBy $ CourseSheet cid shn
     cTime <- liftIO getCurrentTime
     let
@@ -662,6 +666,14 @@ tagAccessPredicate AuthTime = APDB $ \mAuthId route _ -> case route of
 
     return Authorized
 
+  CourseR tid ssh csh (MaterialR mnm _) -> maybeT (unauthorizedI MsgUnauthorizedMaterialTime) $ do
+    cid <- MaybeT . getKeyBy $ TermSchoolCourseShort tid ssh csh
+    Entity _mid Material{materialVisibleFrom} <- MaybeT . getBy $ UniqueMaterial cid mnm
+    cTime <- liftIO getCurrentTime
+    let visible = NTop materialVisibleFrom <= NTop (Just cTime)
+    guard visible
+    return Authorized
+
   CourseR tid ssh csh CRegisterR -> do
     now <- liftIO getCurrentTime
     mbc <- getBy $ TermSchoolCourseShort tid ssh csh
@@ -1397,6 +1409,14 @@ instance YesodBreadcrumbs UniWorX where
 --           (CSubmissionR tid ssh csh shn _ SubDownloadR) -- just for Download
   breadcrumb (CSheetR tid ssh csh shn SCorrR) = return ("Korrektoren", Just $ CSheetR tid ssh csh shn SShowR)
   --         (CSheetR tid ssh csh shn SFileR) -- just for Downloads
+
+  breadcrumb (CourseR tid ssh csh MaterialListR) = return ("Material"     , Just $ CourseR tid ssh csh CShowR)
+  breadcrumb (CourseR tid ssh csh MaterialNewR ) = return ("Neu"          , Just $ CourseR tid ssh csh MaterialListR)
+  breadcrumb (CMaterialR tid ssh csh mnm MShowR) = return (CI.original mnm, Just $ CourseR tid ssh csh MaterialListR)
+  breadcrumb (CMaterialR tid ssh csh mnm MEditR) = return ("Bearbeiten"   , Just $ CMaterialR tid ssh csh mnm MShowR)
+  breadcrumb (CMaterialR tid ssh csh mnm MDelR)  = return ("Löschen"      , Just $ CMaterialR tid ssh csh mnm MShowR)
+  --         (CMaterialR tid ssh csh mnm MFileR) -- just for Downloads
+
   -- Others
   breadcrumb (CorrectionsR)       = return ("Korrekturen", Just HomeR)
   breadcrumb (CorrectionsUploadR) = return ("Hochladen", Just CorrectionsR)
@@ -1755,6 +1775,14 @@ pageActions (CourseNewR) = [
   ]
 pageActions (CourseR tid ssh csh CShowR) =
   [ MenuItem
+      { menuItemType  = PageActionPrime
+      , menuItemLabel = MsgMenuMaterialList
+      , menuItemIcon  = Nothing
+      , menuItemRoute = SomeRoute $ CourseR tid ssh csh MaterialListR
+      , menuItemModal = False
+      , menuItemAccessCallback' = return True
+      }
+  , MenuItem
       { menuItemType = PageActionPrime
       , menuItemLabel = MsgMenuSheetList
       , menuItemIcon  = Nothing
@@ -1883,6 +1911,34 @@ pageActions (CourseR tid ssh csh SheetListR) =
       , menuItemAccessCallback' = return True
       }
   ]
+pageActions (CourseR tid ssh csh MaterialListR) =
+  [ MenuItem
+      { menuItemType  = PageActionPrime
+      , menuItemLabel = MsgMenuMaterialNew
+      , menuItemIcon  = Nothing
+      , menuItemRoute = SomeRoute $ CourseR tid ssh csh MaterialNewR
+      , menuItemModal = False
+      , menuItemAccessCallback' = return True
+      }
+  ]
+pageActions (CMaterialR tid ssh csh mnm MShowR) =
+  [ MenuItem
+      { menuItemType  = PageActionPrime
+      , menuItemLabel = MsgMenuMaterialEdit
+      , menuItemIcon  = Nothing
+      , menuItemRoute = SomeRoute $ CMaterialR tid ssh csh mnm MEditR
+      , menuItemModal = False
+      , menuItemAccessCallback' = return True
+      }
+  , MenuItem
+      { menuItemType  = PageActionPrime
+      , menuItemLabel = MsgMenuMaterialDelete
+      , menuItemIcon  = Nothing
+      , menuItemRoute = SomeRoute $ CMaterialR tid ssh csh mnm MDelR
+      , menuItemModal = False
+      , menuItemAccessCallback' = return True
+      }
+  ]
 pageActions (CourseR tid ssh csh CTutorialListR) =
   [ MenuItem
       { menuItemType  = PageActionPrime
@@ -2212,6 +2268,7 @@ pageHeading (CourseR tid ssh csh SheetNewR)
   = Just $ i18nHeading $ MsgSheetNewHeading tid ssh csh
 pageHeading (CSheetR tid ssh csh shn SShowR)
   = Just $ i18nHeading $ MsgSheetTitle tid ssh csh shn
+  -- = Just $ i18nHeading $ prependCourseTitle tid ssh csh $ SomeMessage shn -- TODO: for consistency use prependCourseTitle throughout ERROR: circularity
 pageHeading (CSheetR tid ssh csh shn SEditR)
   = Just $ i18nHeading $ MsgSheetEditHead tid ssh csh shn
 pageHeading (CSheetR tid ssh csh shn SDelR)
diff --git a/src/Handler/Material.hs b/src/Handler/Material.hs
new file mode 100644
index 000000000..56e696daf
--- /dev/null
+++ b/src/Handler/Material.hs
@@ -0,0 +1,302 @@
+module Handler.Material where
+
+import Import
+
+import Data.Monoid (Any(..))
+import Data.Set (Set)
+import qualified Data.Set as Set
+-- import Data.Map (Map)
+import qualified Data.Map as Map
+import qualified Data.Conduit.List as C
+-- import qualified Data.CaseInsensitive as CI
+
+import qualified Database.Esqueleto as E
+import Database.Esqueleto.Utils.TH
+
+import Utils.Lens
+import Utils.Form
+import Handler.Utils
+-- import Handler.Utils.Delete
+import Handler.Utils.Table.Cells
+import Handler.Utils.Table.Columns
+
+import Control.Monad.Writer (MonadWriter(..), execWriterT)
+
+
+
+
+data MaterialForm = MaterialForm
+      { mfName         :: MaterialName
+      , mfType         :: Maybe Text
+      , mfDescription  :: Maybe Html
+      , mfVisibleFrom  :: Maybe UTCTime
+      , mfFiles        :: Maybe (Source Handler (Either FileId File))
+      }
+
+makeMaterialForm :: CourseId -> Maybe MaterialForm -> Form MaterialForm
+makeMaterialForm cid template = identifyForm FIDmaterial $ \html -> do
+  MsgRenderer mr <- getMsgRenderer
+  let setIds :: Either FileId File -> Set FileId
+      setIds = either Set.singleton $ const Set.empty
+      oldFileIds
+        | Just source <- template >>= mfFiles
+                    = runConduit $ source .| C.foldMap setIds
+        | otherwise = return Set.empty
+      typeOptions :: WidgetT UniWorX IO (Set Text)
+      typeOptions = do
+        let defaults = Set.fromList $ map mr [MsgMaterialTypeSlides,MsgMaterialTypeCode,MsgMaterialTypeExample]
+        previouslyUsed <- liftHandlerT . runDB $
+          E.select $ E.from $ \material ->
+            E.distinctOnOrderBy [E.asc $ material E.^. MaterialType] $ do
+              E.where_ $ (material E.^. MaterialCourse E.==. E.val cid)
+                  E.&&.  (E.not_ $ E.isNothing $ material E.^. MaterialType)
+              return $ material E.^. MaterialType
+        return $ defaults <> (Set.fromList $ mapMaybe E.unValue previouslyUsed)
+
+  ctime <- ceilingQuarterHour <$> liftIO getCurrentTime
+  flip (renderAForm FormStandard) html $ MaterialForm
+      <$> areq ciField        (fslI MsgMaterialName)         (mfName        <$> template)
+      <*> aopt (textField & addDatalist typeOptions)
+                              (fslpI MsgMaterialType $ mr MsgMaterialTypePlaceholder)
+                                                             (mfType        <$> template)
+      <*> aopt htmlField      (fslpI MsgMaterialDescription "Html")
+                                                             (mfDescription <$> template)
+      <*> aopt utcTimeField   (fslI MsgMaterialVisibleFrom
+            & setTooltip MsgMaterialVisibleFromTip)         ((mfVisibleFrom  <$> template) <|> pure (Just ctime))
+      <*> aopt (multiFileField oldFileIds)
+                              (fslI MsgMaterialFiles)        (mfFiles <$> template)
+
+fetchMaterial :: TermId -> SchoolId -> CourseShorthand -> MaterialName -> DB (Entity Material)
+fetchMaterial tid ssh csh mnm = do
+  [matEnt] <- E.select . E.from  $ -- uniqueness guaranteed by DB constraints
+    \(course `E.InnerJoin` material) -> do
+      E.on     $ course   E.^. CourseId   E.==.   material E.^. MaterialCourse
+      E.where_ $ course   E.^. CourseTerm      E.==. E.val tid
+          E.&&.  course   E.^. CourseSchool    E.==. E.val ssh
+          E.&&.  course   E.^. CourseShorthand E.==. E.val csh
+          E.&&.  material E.^. MaterialName    E.==. E.val mnm
+      return material
+  return matEnt
+
+
+getMaterialListR :: TermId -> SchoolId -> CourseShorthand -> Handler Html
+getMaterialListR tid ssh csh = do
+  let matLink :: MaterialName -> Route UniWorX
+      matLink = CourseR tid ssh csh . flip MaterialR MShowR
+  now <- liftIO getCurrentTime
+  table <- runDB $ do
+    cid <- getKeyBy404 $ TermSchoolCourseShort tid ssh csh
+    let row2material = entityVal . dbrOutput -- no inner join, just Entity Material
+        psValidator  = def & defaultSorting [SortDescBy "last-edit"]
+    table <- dbTableWidget' psValidator DBTable
+      { dbtIdent     = "material-list" :: Text
+      , dbtStyle     = def
+      , dbtParams    = def
+      , dbtSQLQuery  = \material -> do
+            E.where_ $ material E.^. MaterialCourse  E.==.  E.val cid
+            return material
+      , dbtRowKey    = (E.^. MaterialId)
+      -- , dbtProj      = \dbr -> guardAuthorizedFor (matLink . materialName $ dbr ^. _dbrOutput . _entityVal) dbr
+      , dbtProj      = guardAuthorizedFor =<< matLink . materialName . row2material -- Moand: (a ->)
+      , dbtColonnade = widgetColonnade $ mconcat
+            [ dbRow
+            , sortable (Just "type") (i18nCell MsgMaterialType)
+                $ foldMap textCell . materialType . row2material
+            , sortable (Just "name") (i18nCell MsgMaterialName)
+                $ liftA2 anchorCell matLink toWgt . materialName . row2material
+            , sortable (toNothingS "description") mempty
+                $ foldMap modalCell . materialDescription . row2material
+            , sortable (Just "visble-from") (i18nCell MsgAccessibleSince)
+                $ foldMap (dateTimeCellVisible now) . materialVisibleFrom . row2material
+            , sortable (Just "last-edit") (i18nCell MsgFileModified)
+                $ dateTimeCell . materialLastEdit . row2material
+            ]
+      , dbtSorting   = Map.fromList
+            [ ( "type"         , SortColumn (E.^. MaterialType)        )
+            , ( "name"         , SortColumn (E.^. MaterialName)        )
+            , ( "visible-from" , SortColumn (E.^. MaterialVisibleFrom) )
+            , ( "last-edit"    , SortColumn (E.^. MaterialLastEdit)    )
+            ]
+      , dbtFilter    = mempty
+      , dbtFilterUI  = mempty
+      }
+    return table
+
+  let headingLong  = prependCourseTitle tid ssh csh $ MsgMaterialListHeading
+      headingShort = prependCourseTitle tid ssh csh $ MsgMaterialListHeading
+  siteLayoutMsg headingLong $ do
+    setTitleI headingShort
+    $(widgetFile "material-list")
+
+
+getMFileR :: TermId -> SchoolId -> CourseShorthand -> MaterialName -> FilePath -> Handler TypedContent
+getMFileR tid ssh csh mnm title = serveOneFile fileQuery
+  where
+    fileQuery = E.select $ E.from $
+      \(course `E.InnerJoin` material `E.InnerJoin` matFile `E.InnerJoin` file) -> do
+        -- Restrict to consistent rows that correspond to each other
+        E.on (file     E.^. FileId               E.==. matFile  E.^. MaterialFileFile)
+        E.on (matFile  E.^. MaterialFileMaterial E.==. material E.^. MaterialId)
+        E.on (material E.^. MaterialCourse       E.==. course   E.^. CourseId)
+        -- filter to requested file
+        E.where_ ((file      E.^. FileTitle       E.==. E.val title)
+          E.&&.   (material  E.^. MaterialName    E.==. E.val mnm  )
+          E.&&.   (course    E.^. CourseShorthand E.==. E.val csh  )
+          E.&&.   (course    E.^. CourseSchool    E.==. E.val ssh  )
+          E.&&.   (course    E.^. CourseTerm      E.==. E.val tid  )
+          )
+        -- return file entity
+        return file
+
+getMShowR :: TermId -> SchoolId -> CourseShorthand -> MaterialName -> Handler Html
+getMShowR tid ssh csh mnm = do
+  let matLink :: FilePath -> Route UniWorX
+      matLink = CourseR tid ssh csh . MaterialR mnm . MFileR
+  ( (Entity _mid material@Material{materialType, materialDescription})
+    , (Any hasFiles,fileTable)) <- runDB $ do
+    matEnt <- fetchMaterial tid ssh csh mnm
+    let psValidator = def & defaultSortingByFileTitle
+    fileTable' <- dbTable psValidator DBTable
+      { dbtSQLQuery = \(matFile `E.InnerJoin` file) -> do
+            E.on     $ matFile E.^. MaterialFileFile     E.==. file E.^. FileId
+            E.where_ $ matFile E.^. MaterialFileMaterial E.==. E.val (entityKey matEnt)
+                E.&&.  E.not_ (E.isNothing $ file E.^. FileContent) -- don't show directories
+            return (file E.^. FileTitle, file E.^. FileModified)
+      , dbtRowKey = \(_ `E.InnerJoin` file) -> file E.^. FileId
+      , dbtColonnade = widgetColonnade $ mconcat
+            [ dbRowIndicator -- important: contains writer to indicate that the tables is not empty
+            , colFilePathSimple   (view $ _dbrOutput . _1) matLink
+            , colFileModification (view $ _dbrOutput . _2)
+            ]
+      , dbtProj = \dbr -> guardAuthorizedFor (matLink $ dbr ^. _dbrOutput . _1 . _Value) dbr
+      , dbtStyle    = def
+      , dbtParams   = def
+      , dbtFilter   = mempty
+      , dbtFilterUI = mempty
+      , dbtIdent    = "material-files" :: Text
+      , dbtSorting  = Map.fromList
+            [ sortFilePath         $(sqlIJproj 2 2)
+            , sortFileModification $(sqlIJproj 2 2)
+            ]
+      }
+    return (matEnt,fileTable')
+
+  let matVisFro = materialVisibleFrom material
+  now <- liftIO $ getCurrentTime
+  materialLastEdit    <-           formatTime SelFormatDateTime  $ materialLastEdit    material
+  materialVisibleFrom <- traverse (formatTime SelFormatDateTime) matVisFro
+  when (NTop matVisFro >= NTop (Just now)) $ addMessageI Warning $
+    maybe MsgMaterialInvisible MsgMaterialInvisibleUntil materialVisibleFrom
+
+  let headingLong  = prependCourseTitle tid ssh csh $ MsgMaterialHeading mnm
+      headingShort = prependCourseTitle tid ssh csh $ SomeMessage mnm
+  siteLayoutMsg headingLong $ do
+    setTitleI headingShort
+    $(widgetFile "material-show")
+
+
+getMEditR, postMEditR :: TermId -> SchoolId -> CourseShorthand -> MaterialName -> Handler Html
+getMEditR = postMEditR
+postMEditR tid ssh csh mnm = do
+  (Entity mid Material{..}, files) <- runDB $ do
+    matEnt <- fetchMaterial tid ssh csh mnm
+    fileIds <- E.select . E.from $ \(matFile `E.InnerJoin` file) -> do
+      E.on     $ matFile  E.^. MaterialFileFile     E.==. file E.^. FileId
+      E.where_ $ matFile  E.^. MaterialFileMaterial E.==. E.val (entityKey matEnt)
+      return $ file E.^. FileId
+    return (matEnt, (Left . E.unValue) <$> fileIds)
+  -- let cid = materialCourse
+  let template = Just $ MaterialForm
+        { mfName         = materialName
+        , mfType         = materialType
+        , mfDescription  = materialDescription
+        , mfVisibleFrom  = materialVisibleFrom
+        , mfFiles        = Just $ yieldMany files
+        }
+  editWidget <- handleMaterialEdit tid ssh csh materialCourse template $ uniqueReplace mid
+  let headingLong  = prependCourseTitle tid ssh csh $ MsgMaterialEditHeading mnm
+      headingShort = prependCourseTitle tid ssh csh $ MsgMaterialEditTitle   mnm
+  siteLayoutMsg headingLong $ do
+    setTitleI headingShort
+    editWidget
+
+
+getMaterialNewR, postMaterialNewR :: TermId -> SchoolId -> CourseShorthand -> Handler Html
+getMaterialNewR = postMaterialNewR
+postMaterialNewR tid ssh csh = do
+  Entity cid _ <- runDB . getBy404 $ TermSchoolCourseShort tid ssh csh
+  editWidget <- handleMaterialEdit tid ssh csh cid Nothing insertUnique
+  let headingLong  = prependCourseTitle tid ssh csh MsgMaterialNewHeading
+      headingShort = prependCourseTitle tid ssh csh MsgMaterialNewTitle
+  siteLayoutMsg headingLong $ do
+    setTitleI headingShort
+    editWidget
+
+handleMaterialEdit :: TermId -> SchoolId -> CourseShorthand -> CourseId -> Maybe MaterialForm -> (Material -> DB (Maybe MaterialId)) -> Handler Widget
+handleMaterialEdit tid ssh csh cid template dbMaterial = do
+    ((res,formWidget), formEnctype) <- runFormPost $ makeMaterialForm cid template
+    formResult res saveMaterial
+    -- actionUrl <- fromMaybe (CourseR tid ssh csh MaterialNewR) <$> getCurrentRoute
+    return $ wrapForm formWidget def
+        { formAction   = Nothing -- Just $ SomeRoute actionUrl
+        , formEncoding = formEnctype
+        }
+  where
+    saveMaterial :: MaterialForm -> Handler ()
+    saveMaterial MaterialForm{..} = do
+      _aid <- requireAuthId
+      now <- liftIO getCurrentTime
+      let newMaterial = Material
+            { materialCourse      = cid
+            , materialName        = mfName
+            , materialType        = mfType
+            , materialDescription = mfDescription
+            , materialVisibleFrom = mfVisibleFrom
+            , materialLastEdit    = now
+            }
+      saveOk <- runDB $ do
+        mbmid <- dbMaterial newMaterial
+        case mbmid of
+          Nothing -> False <$ addMessageI Error (MsgMaterialNameDup tid ssh csh mfName)
+          (Just mid) -> do -- save files in DB
+            whenIsJust mfFiles $ insertMaterialFile' mid
+            addMessageI Success $ MsgMaterialSaveOk tid ssh csh mfName
+            -- more info/warnings could go here
+            return True
+      when saveOk $ redirect -- redirect must happen outside of runDB
+        $ CourseR tid ssh csh (MaterialR mfName MShowR)
+
+    insertMaterialFile' :: MaterialId -> Source Handler (Either FileId File) -> DB ()
+    insertMaterialFile' mid fs = do
+        oldFileIdVals <- E.select . E.from $ \(file `E.InnerJoin` materialFile) -> do
+          E.on     $  materialFile E.^. MaterialFileFile E.==. file E.^. FileId
+          E.where_ $  materialFile E.^. MaterialFileMaterial E.==. E.val mid
+          return $ file E.^. FileId
+        let oldFileIds = setFromList $ map E.unValue oldFileIdVals
+        keep <- execWriterT . runConduit $ transPipe (lift . lift) fs =$= C.mapM_ finsert
+        mapM_ deleteCascade $ (oldFileIds \\ keep :: Set FileId)
+      where
+        finsert (Left fileId) = tell $ singleton fileId
+        finsert (Right file) = lift $ do
+          fid <- insert file
+          void . insert $ MaterialFile mid fid -- cannot fail due to uniqueness, since we generated a fresh FileId in the previous step
+
+
+getMDelR, postMDelR :: TermId -> SchoolId -> CourseShorthand ->  MaterialName -> Handler Html
+getMDelR = postMDelR
+postMDelR tid ssh csh mnm = do
+  _matEnt <- runDB $ fetchMaterial tid ssh csh mnm
+  error "todo" -- CONTINUE HERE
+  {-
+  deleteR DeleteRoute
+    { drRecords = Set.singleton $ entityKey matEnt
+    , drGetInfo = error "todo"
+    , drUnjoin  = error "todo"
+    , drRenderRecord = error "todo"
+    , drRecordConfirmString = error "todo"
+    , drCaption        = SomeMessage   MsgMaterialDeleteQuestion
+    , drSuccessMessage = SomeMessage $ MsgMaterialDeleted mnm
+    , drSuccess = SomeRoute $ CourseR tid ssh csh   MaterialListR
+    , drAbort   = SomeRoute $ CourseR tid ssh csh $ MaterialR mnm MShowR
+    }
+  -}
\ No newline at end of file
diff --git a/src/Handler/Sheet.hs b/src/Handler/Sheet.hs
index c454b4e06..e5c86ed26 100644
--- a/src/Handler/Sheet.hs
+++ b/src/Handler/Sheet.hs
@@ -4,12 +4,12 @@ import Import
 
 import Jobs.Queue
 
-import System.FilePath (takeFileName)
-
+-- import Utils.Lens
 import Utils.Sheet
 import Handler.Utils
 -- import Handler.Utils.Zip
 import Handler.Utils.Table.Cells
+-- import Handler.Utils.Table.Columns
 import Handler.Utils.SheetType
 import Handler.Utils.Delete
 import Handler.Utils.Form.MassInput
@@ -38,8 +38,6 @@ import Control.Monad.Writer (MonadWriter(..), execWriterT)
 
 import Control.Monad.Trans.Except (runExceptT, mapExceptT, throwE)
 
-import Network.Mime
-
 import Data.Set (Set)
 import qualified Data.Set as Set
 import qualified Data.Map as Map
@@ -96,10 +94,11 @@ makeSheetForm msId template = identifyForm FIDsheet $ \html -> do
       Nothing    -> return $ partitionFileType mempty
       (Just sId) -> liftHandlerT $ runDB $ getFtIdMap sId
     mr <- getMsgRenderer
-    ctime <- liftIO $ getCurrentTime
+    ctime <- ceilingQuarterHour <$> liftIO getCurrentTime
     (result, widget) <- flip (renderAForm FormStandard) html $ SheetForm
       <$> areq ciField        (fslI MsgSheetName)         (sfName        <$> template)
-      <*> aopt htmlField      (fslI MsgSheetDescription)  (sfDescription <$> template)
+      <*> aopt htmlField      (fslpI MsgSheetDescription "Html")
+                                                          (sfDescription <$> template)
       <*> sheetTypeAFormReq   (fslI MsgSheetType
             & setTooltip (uniworxMessages [MsgSheetTypeInfoBonus,MsgSheetTypeInfoNotGraded]))
                                                           (sfType        <$> template)
@@ -155,7 +154,8 @@ getSheetOldUnassigned tid ssh csh = runDB $ do
 getSheetListR :: TermId -> SchoolId -> CourseShorthand -> Handler Html
 getSheetListR tid ssh csh = do
   muid <- maybeAuthId
-  Entity cid _ <- runDB . getBy404 $ TermSchoolCourseShort tid ssh csh
+  now <- liftIO getCurrentTime
+  cid <- runDB . getKeyBy404 $ TermSchoolCourseShort tid ssh csh
   let
     lastSheetEdit sheet = E.sub_select . E.from $ \sheetEdit -> do
         E.where_ $ sheetEdit E.^. SheetEditSheet E.==. sheet E.^. SheetId
@@ -176,9 +176,9 @@ getSheetListR tid ssh csh = do
       , sortable (Just "name") (i18nCell MsgSheet)
           $ \DBRow{dbrOutput=(Entity _ Sheet{..}, _, _)} -> anchorCell (CSheetR tid ssh csh sheetName SShowR) (toWidget sheetName)
       , sortable (Just "last-edit") (i18nCell MsgLastEdit)
-          $ \DBRow{dbrOutput=(_, E.Value mEditTime, _)} -> maybe mempty dateTimeCell mEditTime
-      , sortable (Just "visible-from") (i18nCell MsgSheetVisibleFrom)
-          $ \DBRow{dbrOutput=(Entity _ Sheet{..}, _, _)} -> maybe mempty dateTimeCell sheetVisibleFrom
+          $ \DBRow{dbrOutput=(_, E.Value mEditTime, _)} -> foldMap dateTimeCell mEditTime
+      , sortable (Just "visible-from") (i18nCell MsgAccessibleSince)
+          $ \DBRow{dbrOutput=(Entity _ Sheet{..}, _, _)} -> foldMap (dateTimeCellVisible now) sheetVisibleFrom
       , sortable (Just "submission-since") (i18nCell MsgSheetActiveFrom)
           $ \DBRow{dbrOutput=(Entity _ Sheet{..}, _, _)} -> dateTimeCell sheetActiveFrom
       , sortable (Just "submission-until") (i18nCell MsgSheetActiveTo)
@@ -304,43 +304,43 @@ getSShowR tid ssh csh shn = do
 --   let fileLinks = map (\(E.Value fName, E.Value modified, E.Value fType) -> (CSheetR tid ssh csh (SheetFileR shn fType fName),modified)) fileNameTypes
   -- with Colonnade
 
-  let fileData (sheet' `E.InnerJoin` sheetFile `E.InnerJoin` file) = do
+  let fileData (sheetFile `E.InnerJoin` file) = do
         -- Restrict to consistent rows that correspond to each other
-        E.on (file      E.^. FileId           E.==. sheetFile E.^. SheetFileFile)
-        E.on (sheetFile E.^. SheetFileSheet   E.==. sheet'    E.^. SheetId)
+        E.on (sheetFile E.^. SheetFileFile  E.==.  file E.^. FileId)
         -- filter to requested file
-        E.where_ $  sheet'    E.^. SheetId      E.==. E.val sid
-              E.&&. E.not_ (E.isNothing $ file E.^. FileContent)
+        E.where_ $  sheetFile E.^. SheetFileSheet  E.==.  E.val sid
+              E.&&. E.not_ (E.isNothing $ file E.^. FileContent) -- don't show directories
         -- return desired columns
         return $ (file E.^. FileTitle, file E.^. FileModified, sheetFile E.^. SheetFileType)
   let colonnadeFiles = widgetColonnade $ mconcat
-        [ sortable (Just "type") "Typ" $ \(_,_, E.Value ftype) -> i18nCell ftype & cellContents %~ (\act -> act <* tell (Any True))
-        , sortable (Just "path") "Dateiname" $ \(E.Value fName,_,E.Value fType) -> anchorCell
-            (CSheetR tid ssh csh shn (SFileR fType fName))
-            (str2widget fName)
-        , sortable (Just "time") "Modifikation" $ \(_,E.Value modified,_) -> cell $ formatTime SelFormatDateTime (modified :: UTCTime) >>= toWidget
+        [ sortable (Just "type") (i18nCell MsgSheetFileTypeHeader) $ \(_,_, E.Value ftype) -> i18nCell ftype & cellContents %~ (\act -> act <* tell (Any True))
+        , sortable (Just "path") (i18nCell MsgFileTitle) $ \(E.Value fName,_,E.Value fType) -> anchorCell
+             (CSheetR tid ssh csh shn (SFileR fType fName))
+             (str2widget fName)
+        -- , colFilePath (view _1) (\row -> let fType = view _3 row in let fName = view _1 row in (CSheetR tid ssh csh shn (SFileR (E.unValue fType) (E.unValue fName))))
+        -- , colFileModification (view _2)
+        , sortable (Just "time") (i18nCell MsgFileModified) $ \(_,E.Value modified,_) -> dateTimeCell modified
         ]
-  let psValidator = def
-        & defaultSorting [SortAscBy "type", SortAscBy "path"]
+  let psValidator = def & defaultSorting [SortAscBy "type", SortAscBy "path"]
   (Any hasFiles, fileTable) <- runDB $ dbTable psValidator DBTable
     { dbtSQLQuery = fileData
-    , dbtRowKey = \(_ `E.InnerJoin` _ `E.InnerJoin` file) -> file E.^. FileId
+    , dbtRowKey = \(_ `E.InnerJoin` file) -> file E.^. FileId
     , dbtColonnade = colonnadeFiles
     , dbtProj = \DBRow{ dbrOutput = dbrOutput@(E.Value fName, _, E.Value fType) }
-                   -> dbrOutput <$ guardM (lift $ (== Authorized) <$> evalAccessDB (CSheetR tid ssh csh shn $ SFileR fType fName) False)
+                   -> guardAuthorizedFor (CSheetR tid ssh csh shn $ SFileR fType fName) dbrOutput
     , dbtStyle = def
     , dbtFilter = mempty
     , dbtFilterUI = mempty
     , dbtIdent = "files" :: Text
     , dbtSorting = Map.fromList
       [ ( "type"
-        , SortColumn $ \(_sheet `E.InnerJoin` sheetFile `E.InnerJoin` _file) -> sheetFile E.^. SheetFileType
+        , SortColumn $ \(sheetFile `E.InnerJoin` _file) -> sheetFile E.^. SheetFileType
         )
       , ( "path"
-        , SortColumn $ \(_sheet `E.InnerJoin` _sheetFile `E.InnerJoin` file) -> file E.^. FileTitle
+        , SortColumn $ \(_sheetFile `E.InnerJoin` file) -> file E.^. FileTitle
         )
       , ( "time"
-        , SortColumn $ \(_sheet `E.InnerJoin` _sheetFile `E.InnerJoin` file) -> file E.^. FileModified
+        , SortColumn $ \(_sheetFile `E.InnerJoin` file) -> file E.^. FileModified
         )
       ]
     , dbtParams = def
@@ -365,7 +365,7 @@ getSShowR tid ssh csh shn = do
         , formSubmit = FormNoSubmit
         }
   defaultLayout $ do
-    setTitleI $ MsgSheetTitle tid ssh csh shn
+    setTitleI $ prependCourseTitle tid ssh csh $ SomeMessage shn
     sheetFrom    <-           formatTime SelFormatDateTime  $ sheetActiveFrom   sheet
     sheetTo      <-           formatTime SelFormatDateTime  $ sheetActiveTo     sheet
     hintsFrom    <- traverse (formatTime SelFormatDateTime) $ sheetHintFrom     sheet
@@ -399,34 +399,24 @@ postSPseudonymR tid ssh csh shn = do
 
 
 getSFileR :: TermId -> SchoolId -> CourseShorthand -> SheetName -> SheetFileType -> FilePath -> Handler TypedContent
-getSFileR tid ssh csh shn typ title = do
-  results <- runDB $ E.select $ E.from $
-    \(course `E.InnerJoin` sheet `E.InnerJoin` sheetFile `E.InnerJoin` file) -> do
-      -- Restrict to consistent rows that correspond to each other
-      E.on (file      E.^. FileId         E.==. sheetFile E.^. SheetFileFile)
-      E.on (sheetFile E.^. SheetFileSheet E.==. sheet     E.^. SheetId)
-      E.on (sheet     E.^. SheetCourse    E.==. course    E.^. CourseId)
-      -- filter to requested file
-      E.where_ ((file      E.^. FileTitle       E.==. E.val title)
-        E.&&.   (sheetFile E.^. SheetFileType   E.==. E.val typ  )
-        E.&&.   (sheet     E.^. SheetName       E.==. E.val shn  )
-        E.&&.   (course    E.^. CourseShorthand E.==. E.val csh  )
-        E.&&.   (course    E.^. CourseSchool    E.==. E.val ssh  )
-        E.&&.   (course    E.^. CourseTerm      E.==. E.val tid  )
-        )
-      -- return desired columns
-      return $ (file E.^. FileTitle, file E.^. FileContent)
-  case results of
-    [(E.Value fileTitle, E.Value fileContent)]
-      | Just fileContent' <- fileContent -> do
-          whenM downloadFiles $
-            addHeader "Content-Disposition" [st|attachment; filename="#{takeFileName fileTitle}"|]
-          return $ TypedContent (defaultMimeLookup (pack fileTitle) <> "; charset=utf-8") (toContent fileContent')
-      | otherwise -> sendResponseStatus noContent204 ()
-    [] -> notFound
-    other -> do
-      $logErrorS "SFileR" $ "Multiple matching files: " <> tshow other
-      error "Multiple matching files found."
+getSFileR tid ssh csh shn typ title = serveOneFile fileQuery
+  where
+    fileQuery = E.select $ E.from $
+       \(course `E.InnerJoin` sheet `E.InnerJoin` sheetFile `E.InnerJoin` file) -> do
+        -- Restrict to consistent rows that correspond to each other
+        E.on (file      E.^. FileId         E.==. sheetFile E.^. SheetFileFile)
+        E.on (sheetFile E.^. SheetFileSheet E.==. sheet     E.^. SheetId)
+        E.on (sheet     E.^. SheetCourse    E.==. course    E.^. CourseId)
+        -- filter to requested file
+        E.where_ ((file      E.^. FileTitle       E.==. E.val title)
+          E.&&.   (sheetFile E.^. SheetFileType   E.==. E.val typ  )
+          E.&&.   (sheet     E.^. SheetName       E.==. E.val shn  )
+          E.&&.   (course    E.^. CourseShorthand E.==. E.val csh  )
+          E.&&.   (course    E.^. CourseSchool    E.==. E.val ssh  )
+          E.&&.   (course    E.^. CourseTerm      E.==. E.val tid  )
+          )
+        -- return file entity
+        return file
 
 getSheetNewR :: TermId -> SchoolId -> CourseShorthand -> Handler Html
 getSheetNewR tid ssh csh = do
@@ -502,11 +492,7 @@ getSEditR tid ssh csh shn = do
         , sfMarkingF     = Just . yieldMany . map Left . Set.elems $ sheetFileIds SheetMarking
         , sfMarkingText  = sheetMarkingText
         }
-  let action newSheet = do
-        replaceRes <- myReplaceUnique sid $ newSheet
-        case replaceRes of
-          Nothing     -> return $ Just sid
-          (Just _err) -> return $ Nothing -- More specific error message for edit old sheet could go here
+  let action = uniqueReplace sid -- More specific error message for edit old sheet could go here by using myReplaceUnique instead
   handleSheetEdit tid ssh csh (Just sid) template action
 
 postSEditR :: TermId -> SchoolId -> CourseShorthand -> SheetName -> Handler Html
diff --git a/src/Handler/Utils.hs b/src/Handler/Utils.hs
index 46c4e8631..dfca11b4c 100644
--- a/src/Handler/Utils.hs
+++ b/src/Handler/Utils.hs
@@ -30,7 +30,9 @@ import Handler.Utils.Sheet      as Handler.Utils
 import Handler.Utils.Mail       as Handler.Utils
 
 import System.Directory (listDirectory)
-import System.FilePath.Posix (takeBaseName)
+import System.FilePath.Posix (takeBaseName, takeFileName)
+
+import Network.Mime
 
 import qualified Data.List as List
 import qualified Data.List.NonEmpty as NonEmpty
@@ -45,6 +47,22 @@ downloadFiles = do
       UserDefaultConf{..} <- getsYesod $ view _appUserDefaults
       return userDefaultDownloadFiles
 
+-- | Serve a single file, identified through a given DB query
+serveOneFile :: DB [Entity File] -> Handler TypedContent
+serveOneFile query = do
+  results <- runDB query
+  case results of
+    [(Entity _fileId File{fileTitle, fileContent})]
+      | Just fileContent' <- fileContent -> do
+          whenM downloadFiles $
+            addHeader "Content-Disposition" [st|attachment; filename="#{takeFileName fileTitle}"|]
+          return $ TypedContent (defaultMimeLookup (pack fileTitle) <> "; charset=utf-8") (toContent fileContent')
+      | otherwise -> sendResponseStatus noContent204 ()
+    [] -> notFound
+    other -> do
+      $logErrorS "SFileR" $ "Multiple matching files: " <> tshow other
+      error "Multiple matching files found."
+
 tidFromText :: Text -> Maybe TermId
 tidFromText = fmap TermKey . maybeRight . termFromText
 
@@ -171,3 +189,12 @@ i18nWidgetFile basename = do
                 | l <- unpack <$> NonEmpty.toList availableTranslations' -- One function definition for every available language
                 ] ++ [ clause [wildP] (normalB [e| error "selectLanguage returned an invalid translation" |]) [] ] -- Fallback mostly there so compiler does not complain about non-exhaustive pattern match
     ] [e|selectLanguage availableTranslations' >>= $(varE ws)|]
+
+
+
+-- | return a value only if the current user ist authorized for a given route
+guardAuthorizedFor :: ( HandlerSite h ~ UniWorX, MonadHandler h, MonadLogger h
+                      , MonadTrans m, MonadPlus (m (ReaderT SqlBackend h)))
+  => Route UniWorX -> a -> m (ReaderT SqlBackend h) a
+guardAuthorizedFor link val =
+  val <$ guardM (lift $ (== Authorized) <$> evalAccessDB link False)
diff --git a/src/Handler/Utils/DateTime.hs b/src/Handler/Utils/DateTime.hs
index dc5a59c06..2b8e5af46 100644
--- a/src/Handler/Utils/DateTime.hs
+++ b/src/Handler/Utils/DateTime.hs
@@ -9,6 +9,7 @@ module Handler.Utils.DateTime
   , addOneWeek, addWeeks
   , weeksToAdd
   , setYear
+  , ceilingQuarterHour
   ) where
 
 import Import
@@ -190,3 +191,17 @@ weeksToAdd old new = loop 0 old
     loop n t
       | t > new   = n
       | otherwise = loop (succ n) (addOneWeek t)
+
+-- | round up the next full quarter hour with a margin of at least 5 minutes
+ceilingQuarterHour :: UTCTime -> UTCTime
+ceilingQuarterHour = ceilingMinuteBy 5 15
+
+-- | round up the next full @roundto@ minutes with a margin of at least @margin@ minutes
+ceilingMinuteBy :: Int -> Int -> UTCTime -> UTCTime
+ceilingMinuteBy margin roundto utct = addUTCTime bonus utct
+  where
+    oldTime = localTimeOfDay $ utcToLocalTime utct
+    oldMin  = todMin  oldTime
+    newMin  = roundToNearestMultiple roundto $ oldMin + margin
+    newTime = oldTime { todMin = newMin, todSec = 0} -- might be invalid, but correctly treated by `timeOfDayToTime`
+    bonus   = realToFrac $ (timeOfDayToTime newTime) - (timeOfDayToTime oldTime)
\ No newline at end of file
diff --git a/src/Handler/Utils/Table/Cells.hs b/src/Handler/Utils/Table/Cells.hs
index 5b0cd1eee..5f7a29e52 100644
--- a/src/Handler/Utils/Table/Cells.hs
+++ b/src/Handler/Utils/Table/Cells.hs
@@ -53,6 +53,13 @@ pathPieceCell = cell . toWidget . toPathPiece
 sqlCell :: (IsDBTable (YesodDB UniWorX) a) => YesodDB UniWorX Widget -> DBCell (YesodDB UniWorX) a
 sqlCell act = mempty & cellContents .~ lift act
 
+markCell :: (IsDBTable m a) => (a -> Bool) -> (a -> DBCell m a) -> a -> DBCell m a
+markCell condition normal x
+  | condition x = (normal x) <> (cell $ isVisibleWidget False)
+  | otherwise   = normal x
+
+
+-- Recall: for line numbers, use dbRow
 
 ---------------------
 -- Icon cells
@@ -75,6 +82,9 @@ commentCell Nothing     = mempty
 commentCell (Just link) = anchorCell link icon
   where icon = toWidget $ hasComment True
 
+-- | Display an icon that opens a modal upon clicking
+modalCell :: (IsDBTable m a, ToWidget UniWorX w) => w -> DBCell m a
+modalCell content = cell $ modal (toWidget $ hasComment True) (Right $ toWidget content)
 
 -----------------
 -- Datatype cells
@@ -87,6 +97,12 @@ dateCell t = cell $ formatTime SelFormatDate t >>= toWidget
 dateTimeCell :: IsDBTable m a => UTCTime -> DBCell m a
 dateTimeCell t = cell $ formatTime SelFormatDateTime t >>= toWidget
 
+dateTimeCellVisible :: IsDBTable m a => UTCTime -> UTCTime -> DBCell m a
+dateTimeCellVisible watershed t = cell $ do
+    tfw <- formatTime SelFormatDateTime t >>= toWidget
+    icn <- bool mempty (toWidget $ isVisible False) $ watershed < t
+    return $ tfw <> icn
+
 userCell :: IsDBTable m a => Text -> Text -> DBCell m a
 userCell displayName surname = cell $ nameWidget displayName surname
 
diff --git a/src/Handler/Utils/Table/Columns.hs b/src/Handler/Utils/Table/Columns.hs
index 25279fb96..1c125344b 100644
--- a/src/Handler/Utils/Table/Columns.hs
+++ b/src/Handler/Utils/Table/Columns.hs
@@ -11,6 +11,7 @@ import Import
 
 -- import Text.Blaze (ToMarkup(..))
 
+import Data.Monoid (Any(..))
 import qualified Database.Esqueleto as E
 import Database.Esqueleto.Utils as E
 
@@ -34,6 +35,54 @@ import Handler.Utils.Table.Cells
 --  * additional helper, such as default sorting
 
 
+-----------------------
+-- Numbers and Indices
+
+-- | Simple index column, also indicating whether there is a row at all
+-- For a version without indication, use `Handler.Utils.Pagination.dbRow` instead.
+dbRowIndicator :: IsDBTable m Any => Colonnade Sortable (DBRow r) (DBCell m Any)
+dbRowIndicator = sortable Nothing (i18nCell MsgNrColumn) $ \DBRow{ dbrIndex } ->  tellCell (Any True) $ textCell $ tshow dbrIndex
+
+
+---------------
+-- Files
+
+-- | Generic column for links to FilePaths, where the link depends on the entire table row
+colFilePath :: (IsDBTable m c) => (t -> E.Value FilePath) -> (t -> Route UniWorX) -> Colonnade Sortable t  (DBCell m c)
+colFilePath row2path row2link = sortable (Just "path") (i18nCell MsgFileTitle) makeCell
+  where
+    makeCell row =
+      let filePath = E.unValue $ row2path row
+          link     = row2link row
+      in  anchorCell link $ str2widget filePath
+
+-- | Generic column for links to FilePaths, where the link only depends on the FilePath itself
+colFilePathSimple :: (IsDBTable m c) => (t -> E.Value FilePath) -> (FilePath -> Route UniWorX) -> Colonnade Sortable t (DBCell m c)
+colFilePathSimple row2path row2link = sortable (Just "path") (i18nCell MsgFileTitle) makeCell
+  where
+    makeCell row =
+      let filePath = E.unValue $ row2path row
+          link     = row2link filePath
+      in  anchorCell link $ str2widget filePath
+
+-- | Generic column for File Modification
+colFileModification :: (IsDBTable m c) => (t -> E.Value UTCTime) -> Colonnade Sortable t (DBCell m c)
+colFileModification row2time = sortable (Just "time") (i18nCell MsgFileModified) (dateTimeCell . E.unValue . row2time)
+
+sortFilePath :: IsString s => (r -> E.SqlExpr (Entity File)) -> (s, SortColumn r)
+sortFilePath queryPath = ("path", SortColumn $ queryPath >>> (E.^. FileTitle))
+
+sortFileModification :: IsString s => (r -> E.SqlExpr (Entity File)) -> (s, SortColumn r)
+sortFileModification queryModification = ("time", SortColumn $ queryModification >>> (E.^. FileModified))
+
+defaultSortingByFileTitle :: PSValidator m x -> PSValidator m x
+defaultSortingByFileTitle = defaultSorting [SortAscBy "path"]
+
+defaultSortingByFileModification :: PSValidator m x -> PSValidator m x
+defaultSortingByFileModification = defaultSorting [SortAscBy "time"]
+
+
+
 ---------------
 -- User names
 
diff --git a/src/Handler/Utils/Table/Pagination.hs b/src/Handler/Utils/Table/Pagination.hs
index 3e32e7028..36d2cfaca 100644
--- a/src/Handler/Utils/Table/Pagination.hs
+++ b/src/Handler/Utils/Table/Pagination.hs
@@ -931,7 +931,7 @@ formCell formCellLens genIndex genForm input@(DBRow{dbrKey}) = FormCell
 
 -- Predefined colonnades
 
---Number column?
+-- | Simple number column, also see Handler.Utils.Table.Columns.dbRowIndicator
 dbRow :: forall h r m a. (Headedness h, IsDBTable m a) => Colonnade h (DBRow r) (DBCell m a)
 dbRow = Colonnade.singleton (headednessPure $ i18nCell MsgNrColumn) $ \DBRow{ dbrIndex } -> textCell $ tshow dbrIndex
 
diff --git a/src/Model.hs b/src/Model.hs
index 6ae0a2f0c..1ee1c9530 100644
--- a/src/Model.hs
+++ b/src/Model.hs
@@ -32,10 +32,11 @@ import Data.Binary (Binary)
 share [mkPersist sqlSettings, mkDeleteCascade sqlSettings, mkMigrate "migrateAll'", mkSave "currentModel"]
     $(persistDirectoryWith lowerCaseSettings "models")
 
--- (Eq Course) is impossible so we derive it for the Uniqueness Constraint only
-deriving instance Eq (Unique Course)
-deriving instance Eq (Unique Sheet)
-deriving instance Eq (Unique Tutorial)
+-- (Eq Course) is impossible so we derive it for the Uniqueness Constraint only; comments helpful for searching in code
+deriving instance Eq (Unique Course)    -- instance Eq TermSchoolCourseShort; instance Eq TermSchoolCourseName
+deriving instance Eq (Unique Sheet)     -- instance Eq CourseSheet
+deriving instance Eq (Unique Material)  -- instance Eq UniqueMaterial
+deriving instance Eq (Unique Tutorial)  -- instance Eq Tutorial
 
 -- Primary keys mentioned in dbtable row-keys must be Binary
 -- Automatically generated (i.e. numeric) ids are already taken care of
diff --git a/src/Model/Types.hs b/src/Model/Types.hs
index 50335333d..0791bb218 100644
--- a/src/Model/Types.hs
+++ b/src/Model/Types.hs
@@ -90,7 +90,7 @@ import Data.Time.LocalTime (LocalTime, TimeOfDay)
 import Data.Semigroup (Min(..))
 import Control.Monad.Trans.Writer (execWriter)
 import Control.Monad.Writer.Class (MonadWriter(..))
-  
+
 
 instance PathPiece UUID where
   fromPathPiece = UUID.fromString . unpack
@@ -357,7 +357,7 @@ classifySubmissionMode (SubmissionMode False Nothing ) = SubmissionModeNone
 classifySubmissionMode (SubmissionMode True  Nothing ) = SubmissionModeCorrector
 classifySubmissionMode (SubmissionMode False (Just _)) = SubmissionModeUser
 classifySubmissionMode (SubmissionMode True  (Just _)) = SubmissionModeBoth
-  
+
 
 data ExamStatus = Attended | NoShow | Voided
   deriving (Show, Read, Eq, Ord, Enum, Bounded, Generic)
@@ -880,11 +880,11 @@ derivePersistFieldJSON ''LecturerType
 
 instance Hashable LecturerType
 
-  
+
 deriveJSON defaultOptions
   { constructorTagModifier = camelToPathPiece
   } ''WeekDay
-  
+
 data OccurenceSchedule = ScheduleWeekly
                          { scheduleDayOfWeek :: WeekDay
                          , scheduleStart     :: TimeOfDay
@@ -984,6 +984,7 @@ type SchoolShorthand = CI Text
 type CourseName      = CI Text
 type CourseShorthand = CI Text
 type SheetName       = CI Text
+type MaterialName    = CI Text
 type UserEmail       = CI Email
 type TutorialName    = CI Text
 
diff --git a/src/Utils.hs b/src/Utils.hs
index 0d656c1fd..b96684358 100644
--- a/src/Utils.hs
+++ b/src/Utils.hs
@@ -168,12 +168,18 @@ boolSymbol False = [shamlet|<i .fas .fa-times>|]
 
 -- DEPRECATED: use hasTickmark instead;
 -- maybe reinstate if needed for @bewertung.txt@ files
-
 -- tickmark :: IsString a => a
 -- tickmark = fromString "✔"
 
+-- | Convert text as it is to Html, may prevent ambiguous types
+-- This function definition is mainly for documentation purposes
 text2Html :: Text -> Html
-text2Html = toHtml -- prevents ambiguous types
+text2Html = toHtml
+
+-- | Convert text as it is to Message, may prevent ambiguous types
+-- This function definition is mainly for documentation purposes
+text2message :: Text -> SomeMessage site
+text2message = SomeMessage
 
 toWgt :: (ToMarkup a, MonadBaseControl IO m, MonadThrow m, MonadIO m)
       => a -> WidgetT site m ()
@@ -278,6 +284,17 @@ notUsedT = notUsed
 
 
 
+-------------
+-- Numeric --
+-------------
+
+-- | round n to nearest multiple of m
+roundToNearestMultiple :: Int -> Int -> Int
+roundToNearestMultiple m n = (n `div` m + 1) * m
+
+
+
+
 ------------
 -- Monoid --
 ------------
@@ -403,6 +420,12 @@ toNothing = const Nothing
 toNothingS :: String -> Maybe b
 toNothingS = const Nothing
 
+-- MOVED TO UTILS.DB due to cyclic dependency
+--  Swap 'Nothing' for 'Just' and vice versa
+-- flipMaybe :: b -> Maybe b -> Maybe b
+-- flipMaybe x Nothing  = Just x
+-- flipMaybe _ (Just _) = Nothing
+
 maybeAdd :: Num a => Maybe a -> Maybe a -> Maybe a -- treats Nothing as neutral/zero, unlike fmap/ap
 maybeAdd (Just x) (Just y) = Just (x + y)
 maybeAdd Nothing y  = y
@@ -504,7 +527,7 @@ maybeMExceptT err act = lift act >>= maybe (lift err >>= throwE) return
 
 maybeTExceptT :: Monad m => e -> MaybeT m b -> ExceptT e m b
 maybeTExceptT err act = maybeExceptT err $ runMaybeT act
-  
+
 maybeTMExceptT :: Monad m => m e -> MaybeT m b -> ExceptT e m b
 maybeTMExceptT err act = maybeMExceptT err $ runMaybeT act
 
diff --git a/src/Utils/DB.hs b/src/Utils/DB.hs
index 9700dd88f..b6e7b9950 100644
--- a/src/Utils/DB.hs
+++ b/src/Utils/DB.hs
@@ -10,8 +10,18 @@ import qualified Data.Set as Set
 import qualified Database.Esqueleto as E
 -- import Database.Persist -- currently not needed here
 
-emptyOrIn :: PersistField typ =>
-  E.SqlExpr (E.Value typ) -> Set typ -> E.SqlExpr (E.Value Bool)
+
+-- | Swap 'Nothing' for 'Just' and vice versa
+-- This belongs into Module 'Utils' but we have a weird cyclic
+-- dependency
+flipMaybe :: b -> Maybe a -> Maybe b
+flipMaybe x Nothing  = Just x
+flipMaybe _ (Just _) = Nothing
+
+
+
+emptyOrIn :: PersistField typ
+          => E.SqlExpr (E.Value typ) -> Set typ -> E.SqlExpr (E.Value Bool)
 emptyOrIn criterion testSet
   | Set.null testSet = E.val True
   | otherwise        = criterion `E.in_` E.valList (Set.toList testSet)
@@ -20,33 +30,44 @@ entities2map :: PersistEntity record => [Entity record] -> Map (Key record) reco
 entities2map = foldl' (\m entity -> Map.insert (entityKey entity) (entityVal entity) m) Map.empty
 
 getKeyBy :: (PersistEntityBackend record ~ BaseBackend backend, PersistEntity record, PersistUniqueRead backend, MonadIO m)
-  => Unique record -> ReaderT backend m (Maybe (Key record))
+         => Unique record -> ReaderT backend m (Maybe (Key record))
 getKeyBy u = fmap entityKey <$> getBy u -- TODO optimize this, so that DB does not deliver entire record!
 
 getKeyBy404 :: (PersistEntityBackend record ~ BaseBackend backend, PersistEntity record, PersistUniqueRead backend, MonadIO m)
-  => Unique record -> ReaderT backend m (Key record)
+            => Unique record -> ReaderT backend m (Key record)
 getKeyBy404 = fmap entityKey . getBy404 -- TODO optimize this, so that DB does not deliver entire record!
 
 existsBy :: (PersistEntityBackend record ~ BaseBackend backend, PersistEntity record, PersistUniqueRead backend, MonadIO m)
-  => Unique record -> ReaderT backend m Bool
+         => Unique record -> ReaderT backend m Bool
 existsBy = fmap isJust . getBy -- TODO optimize, so that DB does not deliver entire record
 
 existsKey :: (PersistEntityBackend record ~ BaseBackend backend, PersistEntity record, PersistStoreRead backend, MonadIO m)
-  => Key record -> ReaderT backend m Bool
+          => Key record -> ReaderT backend m Bool
 existsKey = fmap isJust . get -- TODO optimize, so that DB does not deliver entire record
 
 updateBy :: (PersistUniqueRead backend, PersistStoreWrite backend, MonadIO m, PersistRecordBackend record backend )
-  => Unique record -> [Update record] -> ReaderT backend m ()
+         => Unique record -> [Update record] -> ReaderT backend m ()
 updateBy uniq updates = do
   key <- getKeyBy uniq
   for_ key $ flip update updates
 
-myReplaceUnique -- Identical to Database.Persist.Class, except for the better type signature (original requires Eq  record which is not needed anyway)
-    :: (MonadIO m
-       ,Eq (Unique record)
-       ,PersistRecordBackend record backend
-       ,PersistUniqueWrite backend)
-    => Key record -> record -> ReaderT backend m (Maybe (Unique record))
+-- | Like 'myReplaceUnique' or 'replaceUnique' but with reversed result: returns 'Nothing' if the replacement was not possible,
+--   and 'Just key' for the successfully replaced record
+uniqueReplace :: ( MonadIO m
+                 , Eq (Unique record)
+                 , PersistRecordBackend record backend
+                 , PersistUniqueWrite backend
+                 )
+              => Key record -> record -> ReaderT backend m (Maybe (Key record))
+uniqueReplace key datumNew = flipMaybe key <$> myReplaceUnique key datumNew
+
+-- | Identical to 'Database.Persist.Class', except for the better type signature (original requires Eq  record which is not needed anyway)
+myReplaceUnique :: ( MonadIO m
+                   , Eq (Unique record)
+                   , PersistRecordBackend record backend
+                   , PersistUniqueWrite backend
+                   )
+                => Key record -> record -> ReaderT backend m (Maybe (Unique record))
 myReplaceUnique key datumNew = getJust key >>= replaceOriginal
   where
     uniqueKeysNew = persistUniqueKeys datumNew
@@ -59,12 +80,12 @@ myReplaceUnique key datumNew = getJust key >>= replaceOriginal
         changedKeys = uniqueKeysNew List.\\ uniqueKeysOriginal
         uniqueKeysOriginal = persistUniqueKeys original
 
-checkUniqueKeys
-    :: (MonadIO m
-       ,PersistEntity record
-       ,PersistUniqueRead backend
-       ,PersistRecordBackend record backend)
-    => [Unique record] -> ReaderT backend m (Maybe (Unique record))
+checkUniqueKeys :: ( MonadIO m
+                   , PersistEntity record
+                   , PersistUniqueRead backend
+                   , PersistRecordBackend record backend
+                   )
+                => [Unique record] -> ReaderT backend m (Maybe (Unique record))
 checkUniqueKeys [] = return Nothing
 checkUniqueKeys (x:xs) = do
     y <- getBy x
diff --git a/src/Utils/Form.hs b/src/Utils/Form.hs
index 1fa6de74f..d4d0ba97e 100644
--- a/src/Utils/Form.hs
+++ b/src/Utils/Form.hs
@@ -169,6 +169,7 @@ data FormIdentifier
   = FIDcourse
   | FIDcourseRegister
   | FIDsheet
+  | FIDmaterial
   | FIDsubmission
   | FIDsettings
   | FIDcorrectors
@@ -574,7 +575,7 @@ formFailure errs' = do
   mr <- getMessageRender
   return . FormFailure $ map mr errs'
 
-
+-- | Turns errors into alerts, ignores missing forms and applies processing function
 formResult :: MonadHandler m => FormResult a -> (a -> m ()) -> m ()
 formResult res f = void . formResultMaybe res $ \x -> Nothing <$ f x
 
diff --git a/templates/material-list.hamlet b/templates/material-list.hamlet
new file mode 100644
index 000000000..503a88d43
--- /dev/null
+++ b/templates/material-list.hamlet
@@ -0,0 +1,2 @@
+<section>
+  ^{table}
diff --git a/templates/material-show.hamlet b/templates/material-show.hamlet
new file mode 100644
index 000000000..92dba855e
--- /dev/null
+++ b/templates/material-show.hamlet
@@ -0,0 +1,22 @@
+$newline never
+$maybe descr <- materialDescription
+  <section>
+    <h2 #description>_{MsgMaterialDescription}
+    <p>
+      #{descr}
+
+<section>
+  <dl .deflist>
+    $maybe matKind <- materialType
+      <dt .deflist__dt>_{MsgMaterialType}
+      <dd .deflist__dd>#{matKind}
+    $maybe matVisible <- materialVisibleFrom
+      <dt .deflist__dt>_{MsgVisibleFrom}
+      <dd .deflist__dd>#{matVisible}
+    <dt .deflist__dt>_{MsgFileModified}
+    <dd .deflist__dd>#{materialLastEdit}
+
+$if hasFiles || True
+  <section>
+    <h2>_{MsgMaterialFiles}
+    ^{fileTable}