From 8e4cb0917db1098f5b19be0dfad4c6fafb900c49 Mon Sep 17 00:00:00 2001
From: Wolfgang Witt <Wolfgang.Witt@campus.lmu.de>
Date: Fri, 19 Feb 2021 15:03:13 +0100
Subject: [PATCH] fix: make sure unfortunate combination doesn't only produce
 0-9 ranges for matrikelnummer

---
 src/Handler/Utils/Exam.hs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/Handler/Utils/Exam.hs b/src/Handler/Utils/Exam.hs
index b3632453a..6dc50e878 100644
--- a/src/Handler/Utils/Exam.hs
+++ b/src/Handler/Utils/Exam.hs
@@ -567,6 +567,7 @@ examAutoOccurrence (hash -> seed) rule ExamAutoOccurrenceConfig{..} occurrences
                 go start borderLength acc ((_occurrenceId, []):t) = go start borderLength acc t
                 go start borderLength acc ((occurrenceId, userTags):t)
                   | matchMappingDescription mappingDescription userTags
+                    && (null t || Just (toNullable nextStart) > maybeEnd)
                   = go nextStart borderLength ((occurrenceId, mappingDescription) : acc) t
                   | borderLength < maxTagLength
                   = go (singleton $ head alphabet) (succ borderLength) [] result
@@ -586,6 +587,8 @@ examAutoOccurrence (hash -> seed) rule ExamAutoOccurrenceConfig{..} occurrences
                     -- | pre/suffix of largest user tag
                     maybeEnd :: Maybe [CI Char]
                     maybeEnd = case t of
+                      -- TODO account for special tags
+                      -- e.g. don't stop at T if Ù is in the special prefix set
                       [] -> Just $ replicate borderLength $ last alphabet
                       _nonEmpty -> transformTag borderLength . maximum <$> fromNullable alphabetTags
                     nextStart :: NonNull [CI Char]