From 344aceb4850f6fe175b38040ee8a42cb764f168a Mon Sep 17 00:00:00 2001
From: Nithish Karthik <nithishkarthik01@gmail.com>
Date: Thu, 11 Apr 2024 01:02:45 +0530
Subject: [PATCH] fix: Add coinbase transaction for merkle root calculation

---
 src/main.go          | 40 +++++++++++++++++++++++++++++++++++++++-
 src/mining/block.go  |  2 ++
 src/mining/mining.go | 15 +++++++--------
 3 files changed, 48 insertions(+), 9 deletions(-)

diff --git a/src/main.go b/src/main.go
index 8495424..968d0ca 100644
--- a/src/main.go
+++ b/src/main.go
@@ -67,9 +67,47 @@ func UpdateValidTxns() {
     }
 }
 
+var TemporaryValidTxns =  []string{
+    "000cb561188c762c81f76976f816829424e2af9e0e491c617b7bf41038df3d35.json",
+    "001035505afbf143e51bd667099190943a38eee20092bb691e72eaa44992b2f7.json",
+    "0018c221bca3da35128baabe412a14c95b6864b2e6f7f7a8ffdd8eb0923dec49.json",
+    "001e296ba3feddda174e62df57506861823b0831af983364d2c1808779b443f7.json", 
+    "0022a52ad27796a1a2d9eddd6f4b055c097b51ad7cb8f000fe0d78b26cb71639.json",
+    "002f5ff2f870154b109d823bbad6fd349582d5b85ead5ce0f9f7a4a0270ce37a.json",
+    "0030b203ff93ff7f4c6fdabda1026a8167038dfb94985669721086df9ad4337a.json",
+    "00359dc6a7cf0d808eb5cf6450cf8243408395c6fa5be649f4f6c3b5a394d1b7.json",
+    "003d95255dacb65b0896ab1fc7d3f88d347c762d5164de45a5bea75da95c3830.json",
+    "004c2dec582638c26fed3d55b2fee8bbf1c2d4b70449b0a3f03faa105ad03f15.json",
+    "00550d2c315129f77a97d1b5f8483d1efc9e9edebbb229dcf4a87e0c988f6840.json",
+    "005747a8401a6ef30f3d55172fea54a4c4e940d0dcde372087aea286661e04c5.json",
+    "00703f54c52da70ce7a94f2f59b73c2435476eb531362adb20e78ecc159dd376.json",
+    "007b0fd78cdb709f83823b79fd9824bc39873632c6472f4e4d7c766f9a7e0e82.json",
+    "00b6d3b2d204a97a8877e34c1f3ce454cba5d299aab705e263b49328cbc683f1.json",
+    "00b8ffa99b973547fb665bdee70d3123f345c12664046e767777a822284fea3f.json",
+    "00c4387b3de5d0376b3df4db81a6016b584aad10c5aff619d15627e43ca4d697.json",
+    "00cd2a7549860949e9b7b1c182060ace476f5127f3ee561d72633ffaaea2b2ec.json",
+    "00d12b523d8b7ad90e2269767478764c243625539dc59bcd457d14ca1aa4e38c.json",
+    "00d7c8ddc2e75f6ba97520623390f01a910dc66a9e6a2052ee31f1b99aabdea5.json",
+    "00d9c01fd8722f63cc327c93e59de64395d1e6ca5861ae6b9b149b364d082352.json",
+}
+
+
+func SelectTransactionsFromPaths(validTxnPaths []string) []*txn.Transaction {
+    txnSlice := make([]*txn.Transaction, 0)
+
+    for _, fileName := range validTxnPaths {
+        var transaction txn.Transaction
+        txnPath := fmt.Sprintf("%s/%s", MempoolDirPath, fileName)
+        byteResult, _ := os.ReadFile(txnPath)
+        json.Unmarshal(byteResult, &transaction)
+        txnSlice = append(txnSlice, &transaction)
+    }
+    return txnSlice
+}
+
 func main() {
     UpdateValidTxns()
-    txns := mining.SelectTransactionsFromFolder(ValidTxnsDirPath)
+    txns := SelectTransactionsFromPaths(TemporaryValidTxns)
     candidateBlock := mining.GetCandidateBlock(txns, true)
     mining.MineBlock(candidateBlock, OutputFilePath)
 }
diff --git a/src/mining/block.go b/src/mining/block.go
index adc42f3..7fcb433 100644
--- a/src/mining/block.go
+++ b/src/mining/block.go
@@ -100,6 +100,8 @@ func (b *Block) WriteToFile(filePath string) error {
 
     // Txid of rest of the transactions
     for _, txn := range b.Transactions {
+        // because the txid of coinbase is already added
+        if(txn.Vin[0].IsCoinbase){continue}
         txid := txn.TxHash()
         w.WriteString(hex.EncodeToString(txid)+"\n")
     }
diff --git a/src/mining/mining.go b/src/mining/mining.go
index 0a2d2a0..4a442a6 100644
--- a/src/mining/mining.go
+++ b/src/mining/mining.go
@@ -18,19 +18,21 @@ var targetDifficultyHexString = "0000ffff000000000000000000000000000000000000000
 func GetCandidateBlock(txns []*txn.Transaction, hasWitness bool) Block {
 	tarDif := new(big.Int)
 	tarDif.SetString(targetDifficultyHexString, 16)
+    fmt.Printf("TargetDifficulty: %064x\n", tarDif)
     candidateBlock := Block{}
 
-    // header
-    header := NewBlockHeader(BlockVersion, utils.RandomSha256(), CalcMerkleRoot(txns, false), time.Now().Unix(),TargetToNbits(tarDif), 0)
-    candidateBlock.BlockHeader = header
-
     // coinbase transaction
     cb := NewCoinbaseTransaction(calculateFees(txns))
+    txns = append(txns, &cb)
     if(hasWitness){
         AddWitnessCommitment(&cb, txns)
     }
     candidateBlock.Coinbase = cb
 
+    // header
+    header := NewBlockHeader(BlockVersion, utils.RandomSha256(), CalcMerkleRoot(txns, false), time.Now().Unix(),TargetToNbits(tarDif), 0)
+    candidateBlock.BlockHeader = header
+
     // transactions
     for _, t := range txns {
         candidateBlock.AddTransaction(*t)
@@ -53,13 +55,10 @@ func MineBlock(candidateBlock Block, outputFilePath string) error {
 func findNonce(candidateBlock Block) uint32 {
     // serialized block will be of 80 byte
     w := bytes.NewBuffer(make([]byte, 0, 80))
-
-     
     for {
-        nonce := GetRandomNonce()
-
         header := candidateBlock.BlockHeader
         nBits := candidateBlock.BlockHeader.Bits
+        nonce := GetRandomNonce()
 
         // hash the block header
         // TODO: Properly calculate the capacity