Add unsignedChange field to UnsignedTx.

This allows change outputs to be distinguished from ordinary outputs
within an `UnsignedTx`, which makes it easy to construct an
`ApiCoinSelection` where change outputs are distinguished from ordinary
outputs.

lib/core/src/Cardano/Wallet.hs

@@ -1619,7 +1619,7 @@ signPayment ctx wid argGenChange mkRewardAccount pwd md cs = db & \DBLayer{..} -
 
 -- | Very much like 'signPayment', but doesn't not generate change addresses.
 signTx
-    :: forall ctx s t k.
+    :: forall ctx s t k input output change.
         ( HasTransactionLayer t k ctx
         , HasDBLayer s k ctx
         , HasNetworkLayer t ctx
@@ -1628,14 +1628,16 @@ signTx
         , HardDerivation k
         , Bounded (Index (AddressIndexDerivationType k) 'AddressK)
         , WalletKey k
+        , input ~ (TxIn, TxOut)
+        , output ~ TxOut
         )
     => ctx
     -> WalletId
     -> Passphrase "raw"
     -> Maybe TxMetadata
-    -> UnsignedTx (TxIn, TxOut)
+    -> UnsignedTx input output change
     -> ExceptT ErrSignPayment IO (Tx, TxMeta, UTCTime, SealedTx)
-signTx ctx wid pwd md (UnsignedTx inpsNE outs) = db & \DBLayer{..} -> do
+signTx ctx wid pwd md (UnsignedTx inpsNE outs _change) = db & \DBLayer{..} ->
     withRootKey @_ @s ctx wid pwd ErrSignPaymentWithRootKey $ \xprv scheme -> do
         let pwdP = preparePassphrase scheme pwd
         nodeTip <- withExceptT ErrSignPaymentNetwork $ currentNodeTip nl
@@ -1664,32 +1666,32 @@ signTx ctx wid pwd md (UnsignedTx inpsNE outs) = db & \DBLayer{..} -> do
 
 -- | Makes a fully-resolved coin selection for the given set of payments.
 selectCoinsExternal
-    :: forall ctx s k e resolvedInput.
+    :: forall ctx s k e input output change.
         ( GenChange s
         , HasDBLayer s k ctx
         , IsOurs s Address
-        , resolvedInput ~ (TxIn, TxOut, NonEmpty DerivationIndex)
+        , input ~ (TxIn, TxOut, NonEmpty DerivationIndex)
+        , output ~ TxOut
         )
     => ctx
     -> WalletId
     -> ArgGenChange s
     -> ExceptT (ErrSelectCoinsExternal e) IO CoinSelection
-    -> ExceptT (ErrSelectCoinsExternal e) IO (UnsignedTx resolvedInput)
+    -> ExceptT (ErrSelectCoinsExternal e) IO (UnsignedTx input output change)
 selectCoinsExternal ctx wid argGenChange selectCoins = do
     cs <- selectCoins
-
     (cs', s') <- db & \DBLayer{..} ->
         withExceptT ErrSelectCoinsExternalNoSuchWallet $
             mapExceptT atomically $ do
                 cp <- withNoSuchWallet wid $ readCheckpoint $ PrimaryKey wid
                 (cs', s') <- assignChangeAddresses argGenChange cs (getState cp)
                 putCheckpoint (PrimaryKey wid) (updateState s' cp)
                 pure (cs', s')
-
     UnsignedTx
         <$> (fullyQualifiedInputs s' cs'
                 (ErrSelectCoinsExternalUnableToAssignInputs cs'))
         <*> pure (outputs cs')
+        <*> pure []
   where
     db = ctx ^. dbLayer @s @k
 

lib/core/src/Cardano/Wallet/Api/Server.hs

@@ -1685,22 +1685,27 @@ migrateWallet ctx (ApiT wid) migrateData = do
 -- the number of addresses in the specified address list, addresses will be
 -- recycled in order of their appearance in the original list.
 assignMigrationAddresses
-    :: [Address]
+    :: forall input output change .
+        ( input ~ (TxIn, TxOut)
+        , output ~ TxOut
+        )
+    => [Address]
     -- ^ Target addresses
     -> [CoinSelection]
     -- ^ Migration data for the source wallet.
-    -> [UnsignedTx (TxIn, TxOut)]
+    -> [UnsignedTx input output change]
 assignMigrationAddresses addrs selections =
     fst $ foldr accumulate ([], cycle addrs) selections
   where
     accumulate sel (txs, addrsAvailable) = first
         (\addrsSelected -> makeTx sel addrsSelected : txs)
         (splitAt (length $ view #change sel) addrsAvailable)
 
-    makeTx :: CoinSelection -> [Address] -> UnsignedTx (TxIn, TxOut)
+    makeTx :: CoinSelection -> [Address] -> UnsignedTx input output change
     makeTx sel addrsSelected = UnsignedTx
         (NE.fromList (sel ^. #inputs))
         (zipWith TxOut addrsSelected (sel ^. #change))
+        []
 
 {-------------------------------------------------------------------------------
                                     Network
@@ -1887,11 +1892,14 @@ rndStateChange ctx (ApiT wid) pwd =
 
 -- | Makes an 'ApiCoinSelection' from the given 'UnsignedTx'.
 mkApiCoinSelection
-    :: forall n. ()
+    :: forall n input output change.
+        ( input ~ (TxIn, TxOut, NonEmpty DerivationIndex)
+        , output ~ TxOut
+        )
     => Maybe (DelegationAction, NonEmpty DerivationIndex)
-    -> UnsignedTx (TxIn, TxOut, NonEmpty DerivationIndex)
+    -> UnsignedTx input output change
     -> ApiCoinSelection n
-mkApiCoinSelection mcerts (UnsignedTx inputs outputs) =
+mkApiCoinSelection mcerts (UnsignedTx inputs outputs _) =
     ApiCoinSelection
         (mkApiCoinSelectionInput <$> inputs)
         (mkAddressAmount <$> outputs)
@@ -1919,13 +1927,11 @@ mkApiCoinSelection mcerts (UnsignedTx inputs outputs) =
       where
         apiStakePath = ApiT <$> xs
 
-    mkAddressAmount :: TxOut -> AddressAmount (ApiT Address, Proxy n)
+    mkAddressAmount :: output -> AddressAmount (ApiT Address, Proxy n)
     mkAddressAmount (TxOut addr (Coin c)) =
         AddressAmount (ApiT addr, Proxy @n) (Quantity $ fromIntegral c)
 
-    mkApiCoinSelectionInput
-        :: (TxIn, TxOut, NonEmpty DerivationIndex)
-        -> ApiCoinSelectionInput n
+    mkApiCoinSelectionInput :: input -> ApiCoinSelectionInput n
     mkApiCoinSelectionInput (TxIn txid index, TxOut addr (Coin c), path) =
         ApiCoinSelectionInput
             { id = ApiT txid

lib/core/src/Cardano/Wallet/DB/Sqlite.hs

@@ -132,7 +132,7 @@ import Data.Coerce
 import Data.Either
     ( isRight )
 import Data.Generics.Internal.VL.Lens
-    ( (^.) )
+    ( view, (^.) )
 import Data.IORef
     ( modifyIORef', newIORef, readIORef )
 import Data.List
@@ -1176,7 +1176,7 @@ mkTxInputsOutputs tx =
     mkTxOut tid (ix, txOut) = TxOut
         { txOutputTxId = TxId tid
         , txOutputIndex = ix
-        , txOutputAddress = W.address txOut
+        , txOutputAddress = view #address txOut
         , txOutputAmount = W.coin txOut
         }
     ordered f = fmap (zip [0..] . f)

lib/core/src/Cardano/Wallet/Primitive/Types.hs

@@ -41,6 +41,7 @@ module Cardano.Wallet.Primitive.Types
 
     -- * Tx
     , Tx (..)
+    , TxChange (..)
     , TxIn(..)
     , TxOut(..)
     , TxMeta(..)
@@ -911,6 +912,15 @@ data TxOut = TxOut
         :: !Coin
     } deriving (Show, Generic, Eq, Ord)
 
+data TxChange derivationPath = TxChange
+    { address
+        :: !Address
+    , amount
+        :: !Coin
+    , derivationPath
+        :: derivationPath
+    } deriving (Show, Generic, Eq, Ord)
+
 instance NFData TxOut
 
 instance Buildable TxOut where
@@ -921,7 +931,7 @@ instance Buildable TxOut where
         <> "..."
         <> suffixF 8 addrF
       where
-        addrF = build $ address txout
+        addrF = build $ view #address txout
 
 instance Buildable (TxIn, TxOut) where
     build (txin, txout) = build txin <> " ==> " <> build txout
@@ -966,7 +976,7 @@ instance ToText TxStatus where
 --
 -- See 'Tx' for a signed transaction.
 --
-data UnsignedTx input = UnsignedTx
+data UnsignedTx input output change = UnsignedTx
     { unsignedInputs
         :: NonEmpty input
         -- Inputs are *necessarily* non-empty because Cardano requires at least
@@ -983,6 +993,8 @@ data UnsignedTx input = UnsignedTx
         -- depending on which input(s) get selected to fuel the transaction, it
         -- may or may not include a change output should its value be less than
         -- the minimal UTxO value set by the network.
+    , unsignedChange
+        :: [change]
     }
     deriving (Eq, Show)
 

lib/core/test/unit/Cardano/Wallet/Primitive/CoinSelectionSpec.hs

@@ -144,7 +144,7 @@ prop_coinValuesPreserved (CoinSelectionsSetup cs addrs) = do
             sum . map (\(_, TxOut _ (Coin c)) -> c)
     let selsCoinValue =
             sum $ getCoinValueFromInp . inputs . getCS <$> cs
-    let getCoinValueFromTxOut (UnsignedTx _ txouts) =
+    let getCoinValueFromTxOut (UnsignedTx _ txouts _) =
             sum $ map (\(TxOut _ (Coin c)) -> c) txouts
     let txsCoinValue =
             sum . map getCoinValueFromTxOut
@@ -163,7 +163,7 @@ prop_coinValuesPreservedPerTx f (CoinSelectionsSetup cs addrs) = do
     let getCoinValueFromInp =
             f . map (\(_, TxOut _ (Coin c)) -> c)
     let selsCoinValue = getCoinValueFromInp . inputs . getCS <$> cs
-    let getCoinValueFromTxOut (UnsignedTx _ txouts) =
+    let getCoinValueFromTxOut (UnsignedTx _ txouts _) =
             f $ map (\(TxOut _ (Coin c)) -> c) txouts
     let txsCoinValue = map getCoinValueFromTxOut
     txsCoinValue (assignMigrationAddresses addrs sels) === selsCoinValue
@@ -176,7 +176,7 @@ prop_allInputsAreUsed
 prop_allInputsAreUsed (CoinSelectionsSetup cs addrs) = do
     let sels = getCS <$> cs
     let csInps = Set.fromList $ concatMap inputs sels
-    let getInpsFromTx (UnsignedTx inp _) = NE.toList inp
+    let getInpsFromTx (UnsignedTx inp _ _) = NE.toList inp
     let txsCoinValue = Set.fromList . concatMap getInpsFromTx
     txsCoinValue (assignMigrationAddresses addrs sels) === csInps
 
@@ -189,7 +189,7 @@ prop_allInputsAreUsedPerTx
 prop_allInputsAreUsedPerTx (CoinSelectionsSetup cs addrs) = do
     let sels = getCS <$> cs
     let csInps = Set.fromList . inputs <$> sels
-    let getInpsFromTx (UnsignedTx inp _) = NE.toList inp
+    let getInpsFromTx (UnsignedTx inp _ _) = NE.toList inp
     let txsCoinValue = map (Set.fromList . getInpsFromTx)
     txsCoinValue (assignMigrationAddresses addrs sels) === csInps
 
@@ -201,7 +201,7 @@ prop_fairAddressesRecycled
     -> Property
 prop_fairAddressesRecycled (CoinSelectionsSetup cs addrs) = do
     let sels = getCS <$> cs
-    let getAllAddrPerTx (UnsignedTx _ txouts) =
+    let getAllAddrPerTx (UnsignedTx _ txouts _) =
             map (\(TxOut addr _) -> addr) txouts
     let getAllAddrCounts =
             Map.elems .