def __init__(self, chain: list = None):
"""
Create a new Blockchain instance.
:param list chain: chain of blocks.
"""
self.chain = chain or [Block.genesis()]
def valid_chain(cls, value: list):
"""
Validate chain items values.
:param list value: provided chain value.
:return list: validated chain value.
:raise ValueError: on invalid block in chain.
"""
genesis = last_block = value[0]
if not isinstance(genesis, Block) or genesis != Block.genesis():
message = f'Invalid chain genesis block: {genesis}.'
logger.error(f'[BlockchainSchema] Validation error. {message}')
raise ValueError(message)
for block in value[1:]:
try:
assert isinstance(block, Block)
Block.is_valid(last_block, block)
except (AssertionError, BlockError) as err:
message = err.message if hasattr(err, 'message') else f'Invalid block: {block}.'
logger.error(f'[BlockchainSchema] Validation error. {message}')
raise ValueError(message)
last_block = block
return value
def _get_genesis_block(self):
return Block.genesis()