From 1555e9071f1c040cd3e902093f3994abaaec2f24 Mon Sep 17 00:00:00 2001
From: ndwarshuis <ndwar@yavin4.ch>
Date: Mon, 29 May 2023 16:46:20 -0400
Subject: [PATCH] FIX actually throw error when folding periods/days

---
 lib/Internal/Budget.hs | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/lib/Internal/Budget.hs b/lib/Internal/Budget.hs
index 088d533..d343d6a 100644
--- a/lib/Internal/Budget.hs
+++ b/lib/Internal/Budget.hs
@@ -1,6 +1,7 @@
 module Internal.Budget (insertBudget) where
 
 import Control.Monad.Except
+import Data.Foldable
 import Database.Persist.Monad
 import Internal.Database.Ops
 import Internal.Types.Main
@@ -235,19 +236,23 @@ workingDays wds start end = fromIntegral $ daysFull + daysTail
     wds' = L.sort $ (\x -> diff (fromWeekday x) startDay) <$> L.nub wds
     diff a b = fromIntegral $ mod (fromEnum a - fromEnum b) 7
 
+-- ASSUME days is a sorted list
 foldDays
   :: MonadInsertError m
   => (Day -> Day -> m a)
   -> Day
   -> [Day]
   -> m [a]
-foldDays f start days
-  -- TODO throw real error here
-  | any (start >) days = throwError undefined
-  | otherwise =
-      combineErrors $
-        snd $
-          L.mapAccumL (\prevDay day -> (day, f prevDay day)) start days
+foldDays f start days = case NE.nonEmpty days of
+  Nothing -> return []
+  Just ds
+    | any (start >) ds ->
+        throwError $
+          InsertException [PeriodError start $ minimum ds]
+    | otherwise ->
+        combineErrors $
+          snd $
+            L.mapAccumL (\prevDay day -> (day, f prevDay day)) start days
 
 checkAcntType
   :: (MonadInsertError m, MonadFinance m)