From e6d16267ee2000c4ef70087fd19db746e8e0ae95 Mon Sep 17 00:00:00 2001
From: "Rene V. Vergara" <rvergara59@protonmail.com>
Date: Wed, 17 Apr 2024 20:36:04 -0400
Subject: [PATCH] rvv040 - Functions to create and decode  an ExchangeAddress
 added

New DataType ExchangeAddress added.
---
 src/ZcashHaskell/Sapling.hs     | 19 ---------
 src/ZcashHaskell/Transparent.hs | 70 ++++++++++++++++++++++++++-------
 src/ZcashHaskell/Types.hs       |  6 +++
 test/Spec.hs                    | 16 ++++++++
 4 files changed, 78 insertions(+), 33 deletions(-)

diff --git a/src/ZcashHaskell/Sapling.hs b/src/ZcashHaskell/Sapling.hs
index fb62a7a..6e3c7b0 100644
--- a/src/ZcashHaskell/Sapling.hs
+++ b/src/ZcashHaskell/Sapling.hs
@@ -43,25 +43,6 @@ import Foreign.Rust.Marshall.Variable
   , withPureBorshVarBuffer
   )
 import ZcashHaskell.Types  
---import ZcashHaskell.Types
---  ( AccountId
---  , CoinType
---  , DecodedNote(..)
---  , RawData(..)
---  , RawTxResponse(..)
---  , SaplingAddress(..)
---  , SaplingCommitmentTree(..)
---  , SaplingReceiver(..)
---  , SaplingSpendingKey(..)
---  , SaplingWitness(..)
---  , Scope(..)
---  , Seed(..)
---  , ShieldedOutput(..)
---  , ToBytes(..)
---  , ZcashNet(..)
---  , decodeHexText
---  , getValue
---  )
 import ZcashHaskell.Utils (decodeBech32, encodeBech32, encodeBech32m)
 
 -- | Check if given bytesting is a valid encoded shielded address
diff --git a/src/ZcashHaskell/Transparent.hs b/src/ZcashHaskell/Transparent.hs
index 366dfe4..a76be58 100644
--- a/src/ZcashHaskell/Transparent.hs
+++ b/src/ZcashHaskell/Transparent.hs
@@ -22,7 +22,8 @@ import qualified Data.ByteArray as BA
 import qualified Data.ByteString as BS
 import Data.ByteString.Base58 (bitcoinAlphabet, decodeBase58, encodeBase58)
 import Data.Char (chr)
-import Data.HexString
+import qualified Data.ByteString.Char8 as BC
+import Data.HexString 
 import qualified Data.Text as T
 import qualified Data.Text.Encoding as E
 import Data.Word
@@ -30,19 +31,20 @@ import Haskoin.Address (Address(..))
 import qualified Haskoin.Crypto.Hash as H
 import Haskoin.Crypto.Keys.Extended
 import ZcashHaskell.Types
-  ( AccountId
-  , CoinType(..)
-  , Scope(..)
-  , Seed(..)
-  , ToBytes(..)
-  , TransparentAddress(..)
-  , TransparentReceiver(..)
-  , TransparentSpendingKey(..)
-  , TransparentType(..)
-  , ZcashNet(..)
-  , getTransparentPrefix
-  , getValue
-  )
+--  ( AccountId
+--  , CoinType(..)
+--  , Scope(..)
+--  , Seed(..)
+--  , ToBytes(..)
+--  , TransparentAddress(..)
+--  , TransparentReceiver(..)
+--  , TransparentSpendingKey(..)
+--  , TransparentType(..)
+--  , ZcashNet(..)
+--  , getTransparentPrefix
+--  , getValue
+--  )
+import ZcashHaskell.Utils( encodeBech32m, decodeBech32 )
 
 -- | Required for `TransparentReceiver` encoding and decoding 
 sha256 :: BS.ByteString -> BS.ByteString
@@ -142,3 +144,43 @@ decodeTransparentAddress taddress = do
                          TransparentReceiver P2PKH (fromRawBytes transparentReceiver)
                     else Nothing
                 _ -> Nothing
+
+-- | Encode an Exchange Addresss into HRF from TransparentReceiver
+encodeExchangeAddress:: ZcashNet -> TransparentReceiver -> Maybe T.Text
+encodeExchangeAddress net tr = do 
+  case (tr_type tr) of
+    P2PKH -> do 
+      case net of
+        MainNet -> do
+          let vhash = encodeBech32m (BC.pack "tex") (toBytes (tr_bytes tr))
+          Just vhash
+        TestNet -> do  
+          let vhash = encodeBech32m (BC.pack "textest") (toBytes (tr_bytes tr))
+          Just vhash
+    _ -> Nothing          
+
+-- | Decode an Exchange Address into a TransparentAddress
+decodeExchangeAddress:: T.Text-> Maybe TransparentAddress
+decodeExchangeAddress ex = do  
+  if (T.length ex ) > 1
+    then do  
+      let rawd =  decodeBech32 (E.encodeUtf8 ex)
+      let tMain =  BS.unpack (BC.pack "tex")
+      let tTest =  BS.unpack (BC.pack "textest")
+      let tFail =  BS.unpack (BC.pack "fail")
+      let hr = BS.unpack (hrp rawd) 
+      if hr /= tFail
+        then do
+          let transparentReceiver = bytes rawd
+          if hr == tMain 
+            then Just $
+                 TransparentAddress MainNet $
+                 TransparentReceiver P2PKH (fromRawBytes transparentReceiver)
+            else do  
+              if hr == tTest  
+                then Just $
+                     TransparentAddress TestNet $
+                     TransparentReceiver P2PKH (fromRawBytes transparentReceiver)
+                else Nothing                  
+        else Nothing
+    else Nothing  
\ No newline at end of file
diff --git a/src/ZcashHaskell/Types.hs b/src/ZcashHaskell/Types.hs
index c6d9c34..54da7aa 100644
--- a/src/ZcashHaskell/Types.hs
+++ b/src/ZcashHaskell/Types.hs
@@ -434,6 +434,12 @@ data TransparentAddress = TransparentAddress
   , ta_receiver :: !TransparentReceiver
   } deriving (Eq, Prelude.Show, Read)
 
+-- | Type to represent a TEX Zcash addresses
+data ExchangeAddress = ExchangeAddress
+  { ex_network :: !ZcashNet
+  , ex_address :: !TransparentReceiver
+  } deriving (Eq, Prelude.Show, Read)
+
 -- | Wrapper types for transparent elements
 data RawTxIn = RawTxIn
   { rti_outpoint :: !RawOutPoint
diff --git a/test/Spec.hs b/test/Spec.hs
index 5931df8..245b824 100644
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -1068,6 +1068,22 @@ main = do
                                 p
                         dn `shouldNotBe` Nothing
 
+      describe "Generate an ExchangeAddress (MainNet) from transparent address" $ do
+        let ta = decodeTransparentAddress "t1dMjvesbzdG41xgKaGU3HgwYJwSgbCK54e"
+        it "Try to generate valid ExchangeAddress from Transparent Address" $ do
+          case ta of 
+            Nothing -> assertFailure "Failed to decode transparent address" 
+            Just t  -> do  
+              case  (tr_type (ta_receiver t) ) of
+                P2SH -> assertFailure "P2SH not supported for ExchengeAddress generation" 
+                P2PKH -> do
+                  let exch = encodeExchangeAddress (ta_network t) (ta_receiver t)
+                  case exch of
+                    Nothing -> assertFailure "Failed to encode Exchange address" 
+                    Just addr -> do  
+                      let tadr = decodeExchangeAddress addr
+                      tadr `shouldNotBe` Nothing 
+
 -- | Properties
 prop_PhraseLength :: Property
 prop_PhraseLength =