Enhance hex memo decoding

package.yaml

@@ -48,6 +48,7 @@ library:
   - vector
   - wai-cors
   - warp-tls
+  - hexstring
 
 executables:
   zgo-backend-exe:

src/ZGoBackend.hs

@@ -17,6 +17,8 @@ import qualified Data.HashMap.Strict as HM
 import Data.Maybe
 import Data.SecureMem
 import qualified Data.Text as T
+import qualified Data.Text.Encoding as E
+import Data.Text.Encoding.Error (lenientDecode)
 import qualified Data.Text.Lazy as L
 import Data.Time.Clock
 import Data.Time.Clock.POSIX
@@ -122,15 +124,7 @@ instance FromJSON ZcashTx where
       conf <- obj .: "confirmations"
       m <- obj .: "memo"
       pure $
-        ZcashTx
+        ZcashTx t a aZ bh bt c conf (T.filter (/= '\NUL') $ decodeHexText m)
-          t
-          a
-          aZ
-          bh
-          bt
-          c
-          conf
-          (T.pack (filter (/= '\NUL') $ decodeHexText m))
 
 instance ToJSON ZcashTx where
   toJSON (ZcashTx t a aZ bh bt c conf m) =
@@ -157,13 +151,15 @@ instance Arbitrary ZcashTx where
     ZcashTx a aZ t bh bt c cm <$> arbitrary
 
 -- | Helper function to turn a hex-encoded memo strings to readable text
-decodeHexText :: String -> String
+decodeHexText :: String -> T.Text
-decodeHexText hexText
+decodeHexText h = E.decodeUtf8With lenientDecode $ BS.pack $ hexRead h
-  -- | chunk == "00" = decodeHexText (drop 2 hexText)
-  | null chunk = ""
-  | otherwise = chr (read ("0x" <> chunk)) : decodeHexText (drop 2 hexText)
   where
-    chunk = take 2 hexText
+    hexRead hexText
+      | null chunk = []
+      | otherwise =
+        fromIntegral (read ("0x" <> chunk)) : hexRead (drop 2 hexText)
+      where
+        chunk = take 2 hexText
 
 -- | Helper function to turn a string into a hex-encoded string
 encodeHexText :: String -> String

stack.yaml

@@ -41,7 +41,9 @@ packages:
 #   commit: e7b331f14bcffb8367cd58fbfc8b40ec7642100a
 #
 # extra-deps: []
-
+extra-deps:
+  - git: https://github.com/reach-sh/haskell-hexstring.git
+    commit: 085c16fb21b9f856a435a3faab980e7e0b319341
 # Override default flag values for local packages and extra-deps
 # flags: {}
 

stack.yaml.lock

@@ -3,7 +3,18 @@
 # For more information, please see the documentation at:
 #   https://docs.haskellstack.org/en/stable/lock_files
 
-packages: []
+packages:
+- completed:
+    name: hexstring
+    version: 0.11.1
+    git: https://github.com/reach-sh/haskell-hexstring.git
+    pantry-tree:
+      size: 687
+      sha256: 9ecf67856f59dfb382b283eceb42e4fc1865935d1a7e59111556ed381c6a2ffd
+    commit: 085c16fb21b9f856a435a3faab980e7e0b319341
+  original:
+    git: https://github.com/reach-sh/haskell-hexstring.git
+    commit: 085c16fb21b9f856a435a3faab980e7e0b319341
 snapshots:
 - completed:
     size: 618683

zgo-backend.cabal

@@ -5,7 +5,7 @@ cabal-version: 1.12
 -- see: https://github.com/sol/hpack
 
 name:           zgo-backend
-version:        0.1.0.1
+version:        0.1.0.2
 synopsis:       Haskell Back-end for the ZGo point-of-sale application
 description:    Please see the README on GitLab at <https://gitlab.com/pitmutt/zgo-backend#readme>
 category:       Web
@@ -17,7 +17,7 @@ license-file:   LICENSE
 build-type:     Simple
 extra-source-files:
     README.md
-    ChangeLog.md
+    CHANGELOG.md
     zgo.cfg
 
 source-repository head
@@ -44,6 +44,7 @@ library
     , base >=4.7 && <5
     , bson
     , bytestring
+    , hexstring
     , http-conduit
     , http-types
     , mongoDB