From 694ab8fd172ba0328f94c5f73d6ca0a9e3167585 Mon Sep 17 00:00:00 2001
From: Rene Vergara <rene@vergara.network>
Date: Tue, 5 Mar 2024 14:44:00 -0600
Subject: [PATCH] Add new Orchard spending key generation

---
 src/C/Zcash.chs             | 9 +++++++++
 src/ZcashHaskell/Orchard.hs | 9 ++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/C/Zcash.chs b/src/C/Zcash.chs
index 0013f83..84a641b 100644
--- a/src/C/Zcash.chs
+++ b/src/C/Zcash.chs
@@ -133,3 +133,12 @@ import ZcashHaskell.Types
      }
   -> `()'
 #}
+
+{# fun unsafe rust_wrapper_derive_orchard_spending_key as rustWrapperGenOrchardSpendKey
+     { toBorshVar* `BS.ByteString'&
+     , `Word32'
+     , `Word32'
+     , getVarBuffer `Buffer (BS.ByteString)'&
+     }
+  -> `()'
+#}
diff --git a/src/ZcashHaskell/Orchard.hs b/src/ZcashHaskell/Orchard.hs
index f0dba87..ffe5248 100644
--- a/src/ZcashHaskell/Orchard.hs
+++ b/src/ZcashHaskell/Orchard.hs
@@ -18,7 +18,8 @@
 module ZcashHaskell.Orchard where
 
 import C.Zcash
-  ( rustWrapperOrchardCheck
+  ( rustWrapperGenOrchardSpendKey
+  , rustWrapperOrchardCheck
   , rustWrapperOrchardNoteDecode
   , rustWrapperUADecode
   , rustWrapperUfvkDecode
@@ -32,6 +33,12 @@ import Foreign.Rust.Marshall.Variable
 import ZcashHaskell.Types
 import ZcashHaskell.Utils (encodeBech32m, f4Jumble)
 
+-- | Derives an Orchard spending key for the given seed and account ID
+genOrchardSpendingKey :: Seed -> CoinType -> AccountId -> BS.ByteString
+genOrchardSpendingKey s coinType accountId =
+  withPureBorshVarBuffer $
+  rustWrapperGenOrchardSpendKey s (getValue coinType) (fromIntegral accountId)
+
 -- | Checks if given bytestring is a valid encoded unified address
 isValidUnifiedAddress :: BS.ByteString -> Maybe UnifiedAddress
 isValidUnifiedAddress str =