From 94b4ff2e7e8b097e55335d30c93af8b48d47843d Mon Sep 17 00:00:00 2001
From: Steffen Jost <jost@cip.ifi.lmu.de>
Date: Fri, 24 Sep 2021 12:34:27 +0200
Subject: [PATCH] chore(term): generalize termToRational by using Enum
 instances

---
 src/Model/Types/DateTime.hs | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/src/Model/Types/DateTime.hs b/src/Model/Types/DateTime.hs
index 218dd202b..d96f71f14 100644
--- a/src/Model/Types/DateTime.hs
+++ b/src/Model/Types/DateTime.hs
@@ -110,24 +110,16 @@ termFromText t
     (~=) = (==) `on` CI.mk
 
 termToRational :: TermIdentifier -> Rational
-termToRational TermIdentifier{..} = fromInteger year + seasonOffset
+termToRational TermIdentifier{..} = toRational year + seasonOffset
   where
-    seasonOffset
-      | Q1 <- season = 0
-      | Q2 <- season = 0.25
-      | Q3 <- season = 0.5
-      | Q4 <- season = 0.75
+    seasonOffset = fromIntegral (fromEnum season) % fromIntegral numSeasons
 
 termFromRational :: Rational -> TermIdentifier
 termFromRational n = TermIdentifier{..}
   where
-    year = floor n
-    remainder = n - fromInteger (floor n)
-    season
-      | remainder == 0    = Q1
-      | remainder == 0.25 = Q2
-      | remainder == 0.5  = Q3
-      | otherwise         = Q4
+    year = floor n 
+    remainder = n - fromInteger (floor n)  -- properFraction problematic for negative year values 
+    season = toEnum $ floor $ remainder * fromIntegral numSeasons
 
 instance PersistField TermIdentifier where
   toPersistValue = PersistRational . termToRational