From f4ecfe9d11c67b8517ccabc7b6bb18b55c99dab4 Mon Sep 17 00:00:00 2001
From: Rene Vergara <rene@vergara.network>
Date: Wed, 30 Oct 2024 10:23:23 -0500
Subject: [PATCH] fix: optimize FFI for large results

---
 src/ZcashHaskell/Utils.hs | 50 ++++++++++++++++++++++++++-------------
 1 file changed, 33 insertions(+), 17 deletions(-)

diff --git a/src/ZcashHaskell/Utils.hs b/src/ZcashHaskell/Utils.hs
index bc3566b..62fb89c 100644
--- a/src/ZcashHaskell/Utils.hs
+++ b/src/ZcashHaskell/Utils.hs
@@ -132,20 +132,36 @@ createTransaction ::
   -> ZcashNet -- ^ the network to be used
   -> Int -- ^ target block height
   -> Bool -- ^ True to build, False to estimate fee
-  -> HexString
-createTransaction sapAnchor orchAnchor tSpend sSpend oSpend outgoing znet bh build =
-  withPureBorshVarBuffer $
-  rustWrapperCreateTx
-    (case sapAnchor of
-       Nothing -> "0"
-       Just sA -> toBytes $ sapTree sA)
-    (case orchAnchor of
-       Nothing -> "0"
-       Just oA -> toBytes $ orchTree oA)
-    tSpend
-    sSpend
-    oSpend
-    outgoing
-    (znet == MainNet)
-    (fromIntegral bh)
-    build
+  -> IO (Either TxError HexString)
+createTransaction sapAnchor orchAnchor tSpend sSpend oSpend outgoing znet bh build = do
+  txResult <-
+    withBorshBufferOfInitSize 5120 $
+    rustWrapperCreateTx
+      (case sapAnchor of
+         Nothing -> "0"
+         Just sA -> toBytes $ sapTree sA)
+      (case orchAnchor of
+         Nothing -> "0"
+         Just oA -> toBytes $ orchTree oA)
+      tSpend
+      sSpend
+      oSpend
+      outgoing
+      (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