From 8c24464a4bd0a486cd0ddf846d3b5a323a7aaa9a Mon Sep 17 00:00:00 2001
From: Joris
Date: Sun, 4 Oct 2015 20:48:32 +0200
Subject: Using incomes to compute a fair computation to designate the payer

---
 src/server/Model/Payer/Income.hs | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644 src/server/Model/Payer/Income.hs

(limited to 'src/server/Model/Payer/Income.hs')

diff --git a/src/server/Model/Payer/Income.hs b/src/server/Model/Payer/Income.hs
new file mode 100644
index 0000000..f4bc9fd
--- /dev/null
+++ b/src/server/Model/Payer/Income.hs
@@ -0,0 +1,22 @@
+module Model.Payer.Income
+  ( incomeDefinedForAll
+  ) where
+
+import Data.Time.Clock (UTCTime)
+import Data.List (sort)
+import Data.Maybe
+
+import Database.Persist
+
+import Model.Database
+import Model.User (getUsers)
+import Model.Income (getFirstIncome)
+
+incomeDefinedForAll :: Persist (Maybe UTCTime)
+incomeDefinedForAll = do
+  userIds <- map entityKey <$> getUsers
+  firstIncomes <- mapM getFirstIncome userIds
+  return $
+    if all isJust firstIncomes
+      then listToMaybe . reverse . sort . map incomeCreation . catMaybes $ firstIncomes
+      else Nothing
-- 
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