From 757cd18af8928734569db18f92fedb47827dc5d0 Mon Sep 17 00:00:00 2001
From: zoelee <31149915+zoeleesss@users.noreply.github.com>
Date: Sat, 17 Mar 2018 15:23:46 +0800
Subject: [PATCH] fix issue during mining

The bug was caused when
`timeTaken > timeExpected * 2`  at first round.
Originally, It would be -1, which is absolutely wrong.
So in order to avoid this bug, test if `prevAdjustmentBlock.difficulty > 0`.
if yes, then return prevAdjustmentBlock.difficulty - 1;
if not , then return prevAdjustmentBlock.difficulty;
---
 src/blockchain.ts | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/blockchain.ts b/src/blockchain.ts
index 85aedc3..c81e1d2 100644
--- a/src/blockchain.ts
+++ b/src/blockchain.ts
@@ -82,7 +82,11 @@ const getAdjustedDifficulty = (latestBlock: Block, aBlockchain: Block[]) => {
     if (timeTaken < timeExpected / 2) {
         return prevAdjustmentBlock.difficulty + 1;
     } else if (timeTaken > timeExpected * 2) {
-        return prevAdjustmentBlock.difficulty - 1;
+        if (prevAdjustmentBlock.difficulty > 0) {
+            return prevAdjustmentBlock.difficulty - 1;
+        } else {
+            return 0;
+        }
     } else {
         return prevAdjustmentBlock.difficulty;
     }