WIP

cardano-foundation · Jul 29, 2021 · ac1e615 · ac1e615
1 parent ae7a44c
commit ac1e615
Showing 1 changed file with 22 additions and 7 deletions.
diff --git a/lib/core/src/Cardano/Wallet/Primitive/CoinSelection/Collateral.hs b/lib/core/src/Cardano/Wallet/Primitive/CoinSelection/Collateral.hs
@@ -108,20 +108,28 @@ selectCollateralSmallest params =
         Nothing ->
             Left (SelectCollateralError mempty)
   where
+    coinsToConsider :: [(inputId, Coin)]
+    coinsToConsider = coinsAvailable
+        & Map.toList
+        & L.sortOn snd
+        & takeUntil ((>= minimumCollateralAmount) . snd)
+
+    numberOfCoinsToConsider :: Int
+    numberOfCoinsToConsider = length coinsToConsider
+
     smallestValidCombination :: Maybe (Map inputId Coin)
     smallestValidCombination =
         listToMaybe $ L.sortOn F.fold validCombinations
       where
         validCombinations :: [Map inputId Coin]
-        validCombinations = mapMaybe smallestValidCombinationOfSize
+        validCombinations =
+            mapMaybe smallestValidCombinationOfSize
             [1 .. maximumCollateralEntryCount]
 
     smallestValidCombinationOfSize :: Int -> Maybe (Map inputId Coin)
-    smallestValidCombinationOfSize size = guardSearchSpaceSize $
-        -- TODO: Pre-filter the list, removing anything above the smallest
-        -- single coin that satisfies the minimum.
-        coinsAvailable
-            & Map.toList
+    smallestValidCombinationOfSize size =
+        guardSearchSpaceSize
+            $ coinsToConsider
             & (`subsequencesOfSize` size)
             & fmap (\ics -> (ics, F.foldMap snd ics))
             & L.sortOn snd
@@ -138,7 +146,7 @@ selectCollateralSmallest params =
                 _ -> id
           where
             requiredSearchSpaceSize =
-                Map.size coinsAvailable `numberOfSubsequencesOfSize` size
+                numberOfCoinsToConsider `numberOfSubsequencesOfSize` size
 
     SelectCollateralParams
         { coinsAvailable
@@ -218,3 +226,10 @@ subsequencesOfSize xs k
             (next ++ [[]])
       where
         next = subsequencesBySize xs
+
+--------------------------------------------------------------------------------
+-- Utility functions
+--------------------------------------------------------------------------------
+
+takeUntil :: (a -> Bool) -> [a] -> [a]
+takeUntil p = foldr (\x ys -> x : if p x then [] else ys) []