feat(course-visibility): add invisible icon to CShowR title

src/Handler/Course/Show.hs

@@ -210,6 +210,8 @@ getCShowR tid ssh csh = do
 
   (Any hasExams, examTable) <- runDB . mkExamTable $ Entity cid course
 
+  now <- liftIO getCurrentTime
+
   let visibleNews = any (view _3) news
       showNewsFiles fs = and
         [ not $ null fs
@@ -219,11 +221,22 @@ getCShowR tid ssh csh = do
       hiddenEventNotes = all (\(_,CourseEvent{..}) -> is _Nothing courseEventNote) events
       courseVisFrom = courseVisibleFrom course
       courseVisTo   = courseVisibleTo course
+      courseIsVisible
+        | Just visFrom <- courseVisFrom, Just visTo <- courseVisTo = visFrom <= now && now <= visTo
+        | Just visFrom <- courseVisFrom = visFrom <= now
+        | otherwise = False
   mayCreateNews <- hasWriteAccessTo $ CourseR tid ssh csh CNewsNewR
   mayCreateEvents <- hasWriteAccessTo $ CourseR tid ssh csh CEventsNewR
   mayEditCourse <- hasWriteAccessTo $ CourseR tid ssh csh CEditR
 
-  siteLayout (toWgt $ courseName course) $ do
+  let heading = [whamlet|
+          $newline never
+          ^{courseName course}
+          $if not courseIsVisible
+            \ #{iconInvisible}
+        |]
+
+  siteLayout heading $ do
     setTitleI $ prependCourseTitle tid ssh csh (""::Text)
     $(widgetFile "course")