def get_hash_last_block(self):
""" Return the hash of the last block of the
blockchain. If there are not blocks, return
None.
"""
if len(blocks) > 0:
return hash_sha256(blocks[-1])
else:
return None
def check_blockchain(self):
""" Check the blockchain to find inconsistencies """
blocks = self.blocks
# The list must have at least one block (the genesis block)
if len(blocks) == 0:
return False
for ind in range(len(blocks) - 1, 0, -1):
if blocks[ind].hash_previous_block != hash_sha256(blocks[ind - 1]):
return False
return True
def add_block(self, block):
""" Add a block to the blockchain.
Return the hash of the block.
"""
if len(self.blocks) > 0:
block.hash_previous_block = hash_sha256(str(self.blocks[-1]).encode('utf-8'))
else:
block.hash_previous_block = None
block.transaction.id = len(self.blocks)
coin_num = 0
for coin in block.transaction.created_coins:
coin.id = CoinId(coin_num, block.transaction.id)
coin_num += 1
self.blocks.append(block)
return block