From 68758140a8b59b97fbefca495d9d2a778c36efe0 Mon Sep 17 00:00:00 2001
From: James Zuccon <zuccon@gmail.com>
Date: Thu, 12 Sep 2024 21:44:02 +1000
Subject: [PATCH] Fix isCoinbase

Signed-off-by: James Zuccon <zuccon@gmail.com>
---
 packages/primitives/src/transaction.ts        | 24 +++++++++----------
 .../wallet/src/blockchain/blockchain-local.ts |  9 -------
 2 files changed, 11 insertions(+), 22 deletions(-)

diff --git a/packages/primitives/src/transaction.ts b/packages/primitives/src/transaction.ts
index 399e9ff..7734233 100644
--- a/packages/primitives/src/transaction.ts
+++ b/packages/primitives/src/transaction.ts
@@ -108,24 +108,22 @@ export class Transaction {
   }
 
   public isCoinbase(): boolean {
-    // TODO: This definitely needs checking.
-    // TODO: You're a moron Jim. outpointTransactionHash is 0x00 x 32 for Coinbase.
-
-    // A coinbase transaction MUST only have one input.
-    if (this.getInputs().length > 1) {
+    // A coinbase transaction MUST only have one input
+    if (this.getInputs().length !== 1) {
       return false;
     }
 
-    // Get the input's unlocking bytecode.
-    const unlockingBytecode = this.getInputs()[0].unlockingBytecode;
+    const input = this.getInputs()[0];
 
-    // Get the firt byte.
-    const firstByte = unlockingBytecode[0];
+    // Check if the outpoint transaction hash is all zeros (32 bytes of 0x00)
+    const isOutpointZero = input.outpointTransactionHash.every(
+      (byte) => byte === 0x00
+    );
 
-    if (firstByte >= 0x01 && firstByte <= 0x4b) {
-      return true;
-    }
+    // Check if the outpoint index is 0xFFFFFFFF (or -1 in signed 32-bit integer representation)
+    const isOutpointIndexMax = input.outpointIndex === 0xffffffff;
 
-    return false;
+    // Both conditions must be true for a coinbase transaction
+    return isOutpointZero && isOutpointIndexMax;
   }
 }
diff --git a/packages/wallet/src/blockchain/blockchain-local.ts b/packages/wallet/src/blockchain/blockchain-local.ts
index 65d71aa..e0a980f 100644
--- a/packages/wallet/src/blockchain/blockchain-local.ts
+++ b/packages/wallet/src/blockchain/blockchain-local.ts
@@ -81,21 +81,15 @@ export class BlockchainLocal implements IBlockchain {
     const utxoSet = this.deriveUtxoSet();
 
     if (!opts.skipValidation) {
-      console.log('utxoSet', utxoSet);
-
       // Find the source outputs from our UTXO set so that we can make sure the transaction is valid.
       const sourceOutputs = tx.getInputs().map((input) => {
         const utxoId = `${binToHex(input.outpointTransactionHash)}:${
           input.outpointIndex
         }`;
 
-        console.log(utxoId);
-
         return utxoSet[utxoId];
       });
 
-      console.log('sourceOutputs', sourceOutputs);
-
       // Validate the transaction.
       BlockchainLocal.validateTransaction(tx, sourceOutputs);
     }
@@ -333,9 +327,6 @@ export class BlockchainLocal implements IBlockchain {
    * @todo Consider moving this to Transaction Primitive. Trade-off is that it's probably big. Maybe standalone util?
    */
   static validateTransaction(tx: Transaction, sourceOutputs: Array<Output>) {
-    console.log(tx);
-    console.log(sourceOutputs);
-
     const virtualMachine = createVirtualMachineBCH();
     const virtualMachineResult = virtualMachine.verify({
       transaction: {