def valid_chain(self, chain: []) -> bool:
"""
Determine if a given blockchain is valid
:param chain: <list> A blockchain
:return: <bool> True if valid, False if not
"""
last_block = Block()
last_block.from_dict(chain[0])
current_index = 1
while current_index < len(chain):
# block_dict = chain[current_index]
block = Block()
block.from_dict(chain[current_index])
# print(f'{last_block.__dict__}')
# print(f'{block.__dict__}')
# print("\n-----------\n")
# Check that the hash of the block is correct
if block.previous_hash != last_block.hash:
return False
# Check that the Proof of Work is correct
if not self.valid_proof(last_block.proof, block.proof):
return False
last_block = block
current_index += 1
return True
def total_amount(self, node_id) -> int:
self.resolve_conflicts()
current_index = 1
total_amount = 0
while current_index < len(self.chain):
block = Block()
block.from_dict(self.chain[current_index])
for transaction in block.transactions:
if transaction['recipient'] == node_id:
total_amount += transaction['amount'];
elif transaction['sender'] == node_id:
total_amount -= transaction['amount']
current_index += 1
return total_amount
def last_block(self) -> Block:
# last_block_dict = self.chain[-1]
last_block = Block()
last_block.from_dict(self.chain[-1])
return last_block