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/Payment.hs | 40 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 src/server/Model/Payer/Payment.hs

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

diff --git a/src/server/Model/Payer/Payment.hs b/src/server/Model/Payer/Payment.hs
new file mode 100644
index 0000000..6efc38d
--- /dev/null
+++ b/src/server/Model/Payer/Payment.hs
@@ -0,0 +1,40 @@
+module Model.Payer.Payment
+  ( getTotalPaymentsBefore
+  , getTotalPaymentsAfter
+  ) where
+
+import Data.Time.Clock (UTCTime)
+import Data.Maybe (catMaybes)
+
+import Database.Persist
+import Database.Esqueleto
+import qualified Database.Esqueleto as E
+
+import Model.Database
+import Model.Frequency
+
+getTotalPaymentsBefore :: UTCTime -> Persist [(UserId, Int)]
+getTotalPaymentsBefore time =
+  getTotalPayments (\p -> p ^. PaymentCreation E.<. val time)
+
+getTotalPaymentsAfter :: UTCTime -> Persist [(UserId, Int)]
+getTotalPaymentsAfter time =
+  getTotalPayments (\p -> p ^. PaymentCreation E.>=. val time)
+
+getTotalPayments :: (SqlExpr (Entity Payment) -> SqlExpr (Value Bool)) -> Persist [(UserId, Int)]
+getTotalPayments paymentWhere = do
+  values <- select $
+            from $ \payment -> do
+              where_ (isNothing (payment ^. PaymentDeletedAt))
+              where_ (payment ^. PaymentFrequency E.==. val Punctual)
+              where_ (paymentWhere payment)
+              groupBy (payment ^. PaymentUserId)
+              return (payment ^. PaymentUserId, sum_ (payment ^. PaymentCost))
+  return $ catMaybes . map (unMaybe . unValueTuple) $ values
+
+unValueTuple :: (Value a, Value b) -> (a, b)
+unValueTuple (Value a, Value b) = (a, b)
+
+unMaybe :: (a, Maybe b) -> Maybe (a, b)
+unMaybe (a, Just b) = Just (a, b)
+unMaybe _ = Nothing
-- 
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