From Zero to Blockchain in Python - Part 1 - Replace Blockchain

replace_blockchain.py

def validate_chain(self, chain_to_validate):
    """
    Verifies if a given chain is valid

    :param chain_to_validate: <[Block]>
    :return: <bool> True if the chain is valid
    """
    # First validate both genesis blocks
    if chain_to_validate[0].hash_block() != self.__chain[0].hash_block():
        return False

    # Then we compare each block with its previous one
    for x in range(1, len(chain_to_validate)):
        if not self.validate_block(chain_to_validate[x], chain_to_validate[x - 1]):
            return False

    return True

def replace_chain(self, new_chain):
    """
    Attempts to replace the chain for a new one

    :param new_chain:
    :return: <bool> True if the chain was replace, False if not.
    """
    # We only replace if the new chain is bigger than the current one
    if len(new_chain) <= len(self.__chain):
        return False

    # Validate the new chain
    if not self.validate_chain(new_chain):
        return False

    new_blocks = new_chain[len(self.__chain):]
    for block in new_blocks:
        self.add_block(block)