[CO-347] Change computeUtxoStatistics API to take [Utxo]

This is more semantically correct and type-safe than taking a raw list of 'Word64'. This way, we also get documentation
for free simply by looking at the function signature and also makes calls for callers simpler (provided they have a list
of available utxos, but why would they call the function if they hadn't? :) )

Author: KtorZ

wallet-new/integration/TransactionSpecs.hs

@@ -8,13 +8,17 @@ import           Universum
 import           Cardano.Wallet.API.V1.Errors hiding (describe)
 import           Cardano.Wallet.Client.Http
 import           Control.Lens
-import qualified Pos.Core as Core
 import           Test.Hspec
 
 import           Control.Concurrent (threadDelay)
 import           Text.Show.Pretty (ppShow)
 import           Util
 
+import qualified Data.Map.Strict as Map
+import qualified Pos.Core as Core
+import qualified Pos.Core.Txp as Txp
+
+
 {-# ANN module ("HLint: ignore Reduce duplication" :: Text) #-}
 
 log :: MonadIO m => Text -> m ()
@@ -216,7 +220,14 @@ transactionSpecs wRef wc =
             void $ postTransaction wc (payment 1)
             threadDelay 120000000
 
+            let txIn  = Txp.TxInUnknown 0 "test"
+            let txOut = Txp.TxOutAux Txp.TxOut
+                    { Txp.txOutAddress = unV1 (addrId toAddr)
+                    , Txp.txOutValue = Core.mkCoin 1
+                    }
+            let utxos = [Map.fromList [(txIn, txOut)]]
+
             eresp <- getUtxoStatistics wc (walId wallet)
             utxoStatistics <- fmap wrData eresp `shouldPrism` _Right
-            let utxoStatisticsExpected = computeUtxoStatistics log10 [1]
+            let utxoStatisticsExpected = computeUtxoStatistics log10 utxos
             utxoStatistics `shouldBe` utxoStatisticsExpected

wallet-new/src/Cardano/Wallet/API/V1/Handlers/Wallets.hs

@@ -2,22 +2,18 @@ module Cardano.Wallet.API.V1.Handlers.Wallets where
 
 import           Universum
 
+import           Servant
+
 import           Cardano.Wallet.API.Request
 import           Cardano.Wallet.API.Response
 import           Cardano.Wallet.API.V1.Types as V1
-import qualified Cardano.Wallet.API.V1.Wallets as Wallets
-
 import           Cardano.Wallet.WalletLayer (PassiveWalletLayer (..))
-import qualified Cardano.Wallet.WalletLayer.Types as WalletLayer
 
+import qualified Cardano.Wallet.API.V1.Wallets as Wallets
 import qualified Cardano.Wallet.Kernel.DB.Util.IxSet as KernelIxSet
+import qualified Cardano.Wallet.WalletLayer.Types as WalletLayer
 import qualified Data.IxSet.Typed as IxSet
-import           Pos.Chain.Txp (Utxo)
-import           Pos.Core.Common (Coin (..))
-import           Pos.Core.Txp (TxOut (..), TxOutAux (..))
 
-import qualified Data.Map.Strict as M (elems)
-import           Servant
 
 -- | All the @Servant@ handlers for wallet-specific operations.
 handlers :: PassiveWalletLayer IO -> ServerT Wallets.API Handler
@@ -110,10 +106,5 @@ getUtxoStatistics pwl wid = do
     res <- liftIO $ WalletLayer.getUtxos pwl wid
     case res of
          Left e  -> throwM e
-         Right w -> do
-             let extractValue :: TxOutAux ->  Word64
-                 extractValue = getCoin . txOutValue . toaOut
-             let utxosCoinValuesForAllAccounts :: [(Account, Utxo)] -> [Word64]
-                 utxosCoinValuesForAllAccounts =
-                     concatMap (\pair -> map extractValue (M.elems $ snd pair) )
-             return $ single (V1.computeUtxoStatistics V1.log10 $ utxosCoinValuesForAllAccounts w)
+         Right w ->
+            return $ single $ V1.computeUtxoStatistics V1.log10 (map snd w)

wallet-new/src/Cardano/Wallet/Types/UtxoStatistics.hs

@@ -34,6 +34,9 @@ import           Test.QuickCheck (Arbitrary (..), arbitrary, choose, elements,
                      infiniteListOf, shuffle)
 
 import           Cardano.Wallet.API.V1.Swagger.Example (Example)
+import           Pos.Chain.Txp (Utxo)
+import           Pos.Core.Common (Coin (..))
+import           Pos.Core.Txp (TxOut (..), TxOutAux (..))
 import           Pos.Infra.Util.LogSafe (BuildableSafeGen (..),
                      deriveSafeBuildable)
 
@@ -184,11 +187,19 @@ log10 = Log10
 {-# INLINE log10 #-}
 
 -- | Compute UtxoStatistics from a bunch of UTXOs
-computeUtxoStatistics :: BoundType -> [Word64] -> UtxoStatistics
-computeUtxoStatistics btype = L.fold $ UtxoStatistics
-    <$> foldBuckets (generateBounds btype)
-    <*> L.sum
+computeUtxoStatistics :: BoundType -> [Utxo] -> UtxoStatistics
+computeUtxoStatistics btype =
+    L.fold foldStatistics . concatMap getCoins
   where
+    getCoins :: Utxo ->  [Word64]
+    getCoins =
+        map (getCoin . txOutValue . toaOut) . Map.elems
+
+    foldStatistics :: L.Fold Word64 UtxoStatistics
+    foldStatistics = UtxoStatistics
+        <$> foldBuckets (generateBounds btype)
+        <*> L.sum
+
     foldBuckets :: NonEmpty Word64 -> L.Fold Word64 [HistogramBar]
     foldBuckets bounds =
         let