Refactor

Mainly because further development will not preserve
bill order in lists and we'll need to maintain mapping
internally.

3 files changed, 80 insertions, 48 deletions

diff --git a/lib/Malodivo/Budget.hs b/lib/Malodivo/Budget.hs
index a707cec..657cf14 100644
--- a/lib/Malodivo/Budget.hs
+++ b/lib/Malodivo/Budget.hs
@@ -3,20 +3,32 @@
 Budget planning in the Kingdom of Malodivo.
 
 -}
+{-# LANGUAGE DeriveAnyClass #-}
+{-# LANGUAGE DeriveGeneric #-}
+
 module Malodivo.Budget
-  ( DistrictFunds
-  , normalizeDown
-  , manyToOne
+  ( BillBudget
   , manyToMany
+  , manyToOne
+  , normalizeDown
   ) where
 
+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
 
--- | Convenient type. Describes available or allocated funds per 'District'.
-type DistrictFunds = HM.HashMap D.District Integer
+-- | 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}
 
 {-|
 Normalize list of integers, i. e. proportionally decrease each list element
@@ -125,52 +137,29 @@ True
 
 -}
 manyToOne ::
-     DistrictFunds -- ^ Amounts of available funds per district.
+     D.DistrictFunds -- ^ Amounts of available funds per district.
   -> B.Bill -- ^ A bill requiring funding.
-  -> DistrictFunds -- ^ Contribution of each district.
-manyToOne funds bill = fundRaising (B.amount bill) funds
+  -> D.DistrictFunds -- ^ Contribution of each district.
+manyToOne df b = fundRaising (B.amount b) df
 
 {-|
 Districts funding multiple bills. No constraints.
-
->>> :set -XOverloadedStrings
->>> import Data.Maybe (fromJust)
->>> 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
-
->>> let billA = B.Bill { B.amount = 30, B.name = "Bill A", B.ministry = M.Science }
->>> let billB = B.Bill { B.amount = 10, B.name = "Bill B", B.ministry = M.Welfare }
->>> let equalAmountBills = take 3 (repeat billB)
->>> let nonEqualAmountBills = [billA, billB]
-
-
-If all bills requires the same amount, funds of a single district are
-allocated evenly:
-
->>> let funds = HM.fromList [(D.Palolene, 100)]
->>> let contribution = manyToMany funds equalAmountBills
->>> all (== B.amount (head equalAmountBills)) (fromJust . HM.lookup D.Palolene <$> contribution)
-True
-
 -}
 manyToMany ::
-     DistrictFunds -- ^ Amounts of available funds per district.
+     D.DistrictFunds -- ^ Amounts of available funds per district.
   -> [B.Bill] -- ^ Bills requiring funding.
-  -> [DistrictFunds] -- ^ Contribution of each district to each bill.
-manyToMany funds bills =
-  flip fundRaising funds <$> normalizeDown fundsTotal billAmounts
+  -> [BillBudget] -- ^ Contribution of each district to each bill.
+manyToMany df bills = zipBills bills allocated
   where
     billAmounts = B.amount <$> bills
-    fundsTotal = sum $ HM.elems funds
+    fundsTotal = sum $ HM.elems df
+    allocated = flip fundRaising df <$> normalizeDown fundsTotal billAmounts
 
 -- | Helper function to maintain DRY and backward compatibility.
 fundRaising ::
      Integer -- ^ Amount to be raised.
-  -> DistrictFunds -- ^ Amounts of available funds per district.
-  -> DistrictFunds -- ^ Contribution of each district.
-fundRaising needed df = HM.fromList $ zip districts funds'
+  -> D.DistrictFunds -- ^ Amounts of available funds per district.
+  -> D.DistrictFunds -- ^ Contribution of each district.
+fundRaising needed df = HM.fromList $ zip ds (normalizeDown needed fs)
   where
-    (districts, funds) = unzip $ HM.toList df
-    funds' = normalizeDown needed funds
+    (ds, fs) = unzip $ HM.toList df
diff --git a/lib/Malodivo/Types/District.hs b/lib/Malodivo/Types/District.hs
index 058377b..2e78634 100644
--- a/lib/Malodivo/Types/District.hs
+++ b/lib/Malodivo/Types/District.hs
@@ -18,11 +18,17 @@ Just [Lakos]
 
 module Malodivo.Types.District
   ( District(..)
+  , DistrictFunds
+  , DistrictInfo(..)
+  , di2df
+  , df2di
   ) where
 
+import Control.Arrow ((&&&))
 import GHC.Generics (Generic)
 
 import Data.Aeson (FromJSON, ToJSON)
+import qualified Data.HashMap.Strict as HM
 import Data.Hashable (Hashable)
 
 -- | District of the Kindom of Malodivo.
@@ -30,10 +36,24 @@ data District
   = Palolene
   | SouthernPalolene
   | Lakos
-  deriving ( Eq
-           , Hashable
-           , Show
-           , Generic
-           , FromJSON
-           , ToJSON
-           )
+  deriving (Eq, Hashable, Show, Generic, FromJSON, ToJSON)
+
+-- | Convenient type.
+type DistrictFunds = HM.HashMap District Integer
+
+{-|
+We use this data type instead of 'DistrictFunds' for JSON,
+because maps other than @HashMap Text _@ are hard to decode/encode see
+<https://github.com/bos/aeson/issues/79>.  Anyway, we still have type-checked
+typos-proof structure.
+-}
+data DistrictInfo = DistrictInfo
+  { name :: District
+  , amount :: Integer
+  } deriving (Generic, FromJSON, ToJSON)
+
+di2df :: [DistrictInfo] -> DistrictFunds
+di2df = HM.fromListWith (+) . map (name &&& amount)
+
+df2di :: DistrictFunds -> [DistrictInfo]
+df2di = map (\(n, a) -> DistrictInfo {name = n, amount = a}) . HM.toList
diff --git a/lib/Malodivo/Types/Ministry.hs b/lib/Malodivo/Types/Ministry.hs
index c3e315b..f3878d1 100644
--- a/lib/Malodivo/Types/Ministry.hs
+++ b/lib/Malodivo/Types/Ministry.hs
@@ -18,15 +18,38 @@ Just [Science]
 
 module Malodivo.Types.Ministry
   ( Ministry(..)
+  , MinistryInfo
+  , MinistryLimits
+  , mi2ml
   ) where
 
+import Control.Arrow ((&&&))
 import GHC.Generics (Generic)
 
 import Data.Aeson (FromJSON, ToJSON)
+import qualified Data.HashMap.Strict as HM
+import Data.Hashable (Hashable)
 
 -- | Ministry of the Kingdom of Malodivo.
 data Ministry
   = Defense
   | Science
   | Welfare
-  deriving (Show, Generic, FromJSON, ToJSON)
+  deriving (Eq, Hashable, Show, Generic, FromJSON, ToJSON)
+
+-- | Convenient type. Describes maximum money a ministry can get.
+type MinistryLimits = HM.HashMap Ministry Integer
+
+{-|
+We use this data type instead of 'MinistryLimits' for JSON,
+because maps other than @HashMap Text _@ are hard to decode/encode see
+<https://github.com/bos/aeson/issues/79>.  Anyway, we still have type-checked
+typos-proof structure.
+-}
+data MinistryInfo = MinistryInfo
+  { name :: Ministry
+  , amount :: Integer
+  } deriving (Generic, FromJSON)
+
+mi2ml :: [MinistryInfo] -> MinistryLimits
+mi2ml = HM.fromListWith (+) . map (name &&& amount)