fix: optimize FFI for large results

src/ZcashHaskell/Utils.hs

@@ -132,9 +132,10 @@ createTransaction ::
   -> ZcashNet -- ^ the network to be used
   -> Int -- ^ target block height
   -> Bool -- ^ True to build, False to estimate fee
-  -> HexString
+  -> IO (Either TxError HexString)
-createTransaction sapAnchor orchAnchor tSpend sSpend oSpend outgoing znet bh build =
+createTransaction sapAnchor orchAnchor tSpend sSpend oSpend outgoing znet bh build = do
-  withPureBorshVarBuffer $
+  txResult <-
+    withBorshBufferOfInitSize 5120 $
     rustWrapperCreateTx
       (case sapAnchor of
          Nothing -> "0"
@@ -149,3 +150,18 @@ createTransaction sapAnchor orchAnchor tSpend sSpend oSpend outgoing znet bh bui
       (znet == MainNet)
       (fromIntegral bh)
       build
+  if BS.length (hexBytes txResult) > 1
+    then pure $ Right txResult
+    else case head (BS.unpack $ hexBytes txResult) of
+           0 -> pure $ Left InsufficientFunds
+           1 -> pure $ Left ChangeRequired
+           2 -> pure $ Left Fee
+           3 -> pure $ Left Balance
+           4 -> pure $ Left TransparentBuild
+           5 -> pure $ Left SaplingBuild
+           6 -> pure $ Left OrchardBuild
+           7 -> pure $ Left OrchardSpend
+           8 -> pure $ Left OrchardRecipient
+           9 -> pure $ Left SaplingBuilderNotAvailable
+           10 -> pure $ Left OrchardBuilderNotAvailable
+           _ -> pure $ Left ZHError