From 78004194a4d9dfabd5e64d72751f3270d3034217 Mon Sep 17 00:00:00 2001
From: Igor Pashev <pashev.igor@gmail.com>
Date: Tue, 27 Jun 2017 05:37:41 +0300
Subject: Remove I/O format knowledge from library functions

---
 cmd/Main.hs            |  5 +++--
 cmd/Main/Output.hs     | 29 +++++++++++++++++++++++++++++
 lib/Malodivo/Budget.hs | 31 ++++++++-----------------------
 malodivo.cabal         |  1 +
 4 files changed, 41 insertions(+), 25 deletions(-)
 create mode 100644 cmd/Main/Output.hs

diff --git a/cmd/Main.hs b/cmd/Main.hs
index 69ce114..35a42a6 100644
--- a/cmd/Main.hs
+++ b/cmd/Main.hs
@@ -18,8 +18,9 @@ import Text.InterpolatedString.Perl6 (qc)
 
 import Malodivo.Budget (manyToMany)
 
-import Malodivo.Types.District (di2df)
 import qualified Main.Input as I
+import qualified Main.Output as O
+import Malodivo.Types.District (di2df)
 import Paths_malodivo (version) -- from cabal
 
 usageHelp :: String
@@ -49,7 +50,7 @@ process = do
       let allBills = I.bills si
           suppliedFunds = di2df $ I.districts si
       in do when (HM.null suppliedFunds) $ die "We needs at least one district"
-            L.putStr . encode $ manyToMany suppliedFunds allBills
+            L.putStr . encode . O.encode $ manyToMany suppliedFunds allBills
 
 main :: IO ()
 main = do
diff --git a/cmd/Main/Output.hs b/cmd/Main/Output.hs
new file mode 100644
index 0000000..107e8fd
--- /dev/null
+++ b/cmd/Main/Output.hs
@@ -0,0 +1,29 @@
+{-
+This modules describes output data for the command line utlity.
+-}
+{-# LANGUAGE DeriveAnyClass #-}
+{-# LANGUAGE DeriveGeneric #-}
+
+module Main.Output
+  ( Output
+  , encode
+  ) where
+
+import GHC.Generics (Generic)
+
+import Data.Aeson (ToJSON)
+
+import Malodivo.Types.Bill (Bill)
+import Malodivo.Types.District (DistrictFunds, DistrictInfo, df2di)
+
+type Output = [BillBudget]
+
+-- | JSON-friendly type. It describes contribution of each district into a bill.
+data BillBudget = BillBudget
+  { bill :: Bill
+  , districts :: [DistrictInfo]
+  } deriving (Generic, ToJSON)
+
+-- | Translate into JSON-friendly format.
+encode :: [(Bill, DistrictFunds)] -> Output
+encode = map (\(b, df) -> BillBudget {bill = b, districts = df2di df})
diff --git a/lib/Malodivo/Budget.hs b/lib/Malodivo/Budget.hs
index 8d70629..935f86c 100644
--- a/lib/Malodivo/Budget.hs
+++ b/lib/Malodivo/Budget.hs
@@ -3,12 +3,8 @@
 Budget planning in the Kingdom of Malodivo.
 
 -}
-{-# LANGUAGE DeriveAnyClass #-}
-{-# LANGUAGE DeriveGeneric #-}
-
 module Malodivo.Budget
-  ( BillBudget
-  , billsByMinistry
+  ( billsByMinistry
   , manyToOne
   , manyToMany
   , manyToManyLimited
@@ -16,24 +12,13 @@ module Malodivo.Budget
   ) where
 
 import Control.Arrow ((&&&))
-import GHC.Generics (Generic)
 
-import Data.Aeson (ToJSON)
 import qualified Data.HashMap.Strict as HM
 
 import qualified Malodivo.Types.Bill as B
 import qualified Malodivo.Types.District as D
 import qualified Malodivo.Types.Ministry as M
 
--- | This is output type. It describes contribution of each district into a bill.
-data BillBudget = BillBudget
-  { bill :: B.Bill
-  , districts :: [D.DistrictInfo]
-  } deriving (Generic, ToJSON)
-
-zipBills :: [B.Bill] -> [D.DistrictFunds] -> [BillBudget]
-zipBills = zipWith $ \b df -> BillBudget {bill = b, districts = D.df2di df}
-
 {-|
 Group bills by ministry.
 
@@ -195,12 +180,12 @@ Districts funding multiple bills. No constraints.
 manyToMany ::
      D.DistrictFunds -- ^ Amounts of available funds per district.
   -> [B.Bill] -- ^ Bills requiring funding.
-  -> [BillBudget] -- ^ Contribution of each district to each bill.
-manyToMany df bills = zipBills bills allocated
+  -> [(B.Bill, D.DistrictFunds)] -- ^ Contribution of each district to each bill.
+manyToMany funds bills = zipWith (\b df -> (b, df)) bills allocated
   where
     billAmounts = B.amount <$> bills
-    fundsTotal = sum $ HM.elems df
-    allocated = flip fundRaising df <$> normalizeDown fundsTotal billAmounts
+    fundsTotal = sum $ HM.elems funds
+    allocated = flip fundRaising funds <$> normalizeDown fundsTotal billAmounts
 
 {-|
 Districts funding multiple bills. But each ministry may have been limited
@@ -226,8 +211,8 @@ in the amount of funds it can get.
 >>> let allBills = scienceBills ++ welfareBills
 
 >>> let funds = HM.fromList [(D.Lakos, 1000)]
->>> let findBill b = find (\bb -> B.name (bill bb) == B.name b)
->>> let amounts budget = map (B.amount . bill . fromJust) $ map (\b -> findBill b budget) allBills
+>>> let findBill b = find (\bb -> B.name (fst bb) == B.name b)
+>>> let amounts budget = map (B.amount . fst . fromJust) $ map (\b -> findBill b budget) allBills
 
 
 If all bills of the specific ministry can't get enough funds due to limits imposed on the ministry,
@@ -247,7 +232,7 @@ manyToManyLimited ::
      D.DistrictFunds -- ^ Amounts of available funds per district.
   -> M.MinistryLimits -- ^ Maximum funds ministries can get.
   -> [B.Bill] -- ^ Bills requiring funding.
-  -> [BillBudget] -- ^ Contribution of each district to each bill.
+  -> [(B.Bill, D.DistrictFunds)] -- ^ Contribution of each district to each bill.
 manyToManyLimited df ml bills = manyToMany df . concat $ HM.elems byMinistry'
   where
     byMinistry = billsByMinistry bills
diff --git a/malodivo.cabal b/malodivo.cabal
index 0f68889..9b8a191 100644
--- a/malodivo.cabal
+++ b/malodivo.cabal
@@ -57,6 +57,7 @@ executable malodivo
   main-is: Main.hs
   other-modules:
     Main.Input
+    Main.Output
   build-depends:
       base >= 4.9 && < 5
     , aeson
-- 
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