Remove I/O format knowledge from library functions

2 files changed, 32 insertions, 2 deletions

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})