From 19b0a6836b180f136bf03425e463efbe475e11e3 Mon Sep 17 00:00:00 2001
From: Nithish Karthik <nithishkarthik01@gmail.com>
Date: Thu, 11 Apr 2024 23:43:15 +0530
Subject: [PATCH] use simple merkle tree calculator

---
 src/mining/merkle_tree.go | 33 +++++++++++++++++++++++++++++++++
 src/mining/mining.go      |  6 +++++-
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/src/mining/merkle_tree.go b/src/mining/merkle_tree.go
index da1eb4e..b17e174 100644
--- a/src/mining/merkle_tree.go
+++ b/src/mining/merkle_tree.go
@@ -68,6 +68,39 @@ func (s *rollingMerkleTreeStore) add(add [32]byte) {
 	s.numLeaves++
 }
 
+func GenerateMerkleTreeRoot(txids [][32]byte) [32]byte{
+  // reverse the txids
+    level := make([][32]byte, 0)
+    for _, t := range txids {
+        level = append(level, [32]byte(utils.ReverseBytes(t[:])))
+    }
+
+    for len(level) > 1 {
+    nextLevel := make([][32]byte, 0)
+
+    for i := 0; i < len(level); i += 2 {
+      var pairHash [32]byte
+      if (i + 1 == len(level)) {
+        // In case of an odd number of elements, duplicate the last one
+        var x [64]byte
+        copy(x[:32], level[i][:])
+        copy(x[32:], level[i][:])
+        pairHash = utils.DoubleHashRaw(x[:])
+      } else {
+        var x [64]byte
+        copy(x[:32], level[i][:])
+        copy(x[32:], level[i+1][:])
+        pairHash = utils.DoubleHashRaw(x[:])
+      }
+            nextLevel = append(nextLevel, pairHash)
+    }
+
+    level = nextLevel
+  }
+
+  return level[0]
+}
+
 
 func CalcMerkleRoot(transactions []*transaction.Transaction, witness bool) [32]byte {
 	s := newRollingMerkleTreeStore(uint64(len(transactions)))
diff --git a/src/mining/mining.go b/src/mining/mining.go
index c73b606..6f135b5 100644
--- a/src/mining/mining.go
+++ b/src/mining/mining.go
@@ -49,7 +49,11 @@ func GetCandidateBlock(txns []*txn.Transaction, hasWitness bool) Block {
     // header
     nBits := TargetToNbits(tarDif)
     prevBH,_ := hex.DecodeString(prevBlockHash)
-    header := NewBlockHeader(BlockVersion, *utils.NewHash(prevBH), CalcMerkleRoot(blockTxns, false), time.Now().Unix(),nBits, 0)
+    txids := make([][32]byte, 0)
+    for _, t := range blockTxns {
+        txids = append(txids, [32]byte(utils.ReverseBytes(t.TxHash())))
+    }
+    header := NewBlockHeader(BlockVersion, *utils.NewHash(prevBH), GenerateMerkleTreeRoot(txids), time.Now().Unix(),nBits, 0)
     candidateBlock.BlockHeader = header
 
     // transactions