add verify command

blockchain/chain.py

@@ -179,3 +179,15 @@ class Blockchain:
             self.writeBlocks()
         return True
 
+    def isChainValid(self):
+        """
+            Method to verify integrity of blockchain
+        """
+        for i in range(1, len(self.chain)):
+            eachBlock = self.chain[i]
+            if eachBlock.hash != eachBlock.calculateHash():
+                return i
+            if eachBlock.previousHash != self.chain[i-1].hash:
+                return i
+        return 0
+

bscli.py

@@ -27,6 +27,7 @@ SUPPORTED_COMMANDS = [
     'getblock',
     'help',
     'modify',
+    'verify',
 ]
 
 def printLogo():
@@ -161,6 +162,16 @@ def modify(args):
     else:
         throwError("Block modification failed!")
 
+def verify(cmd):
+    """
+        Method to verify the validity of blockchain.
+    """
+    chain_valid = coin.isChainValid()
+    if chain_valid == 0:
+        printSuccess("Blockchain is valid!")
+    else:
+        throwError(f"Blockchain is not valid! Error on block {chain_valid}. Altered Chain!")
+
 def throwError(msg):
     """
         Method to throw an error from Blockshell.