dsp-blockchain/lib/block.py

import hashlib
import json
import time

from lib.transaction import Transaction


class Block:
    def __init__(self, previous=None):
        self.proof = None
        self.previous_hash = previous.hash_value if previous is not None else None
        self.transactions = []
        self.hash_value = None
        self.locked = False
        self.timestamp = 0

    def add_transaction(self, trans: Transaction):
        if not self.locked:
            trans.lock_hash_finish()
            self.transactions.append(trans)
            self.log(f'Transaction added: {trans.id}')
            return True
        return False

    def lock_hash_finish(self):
        if not self.locked:
            self.timestamp = int(time.time())
            self.hash()
            self.locked = True
            self.log('Locked')
            return True
        return False

    def serialize(self):
        trans_serialize = []

        for transaction in self.transactions:
            trans_serialize.append(transaction.serialize())

        obj = {
            'timestamp': self.timestamp,
            'previous': self.previous_hash,
            'transactions': trans_serialize
        }
        self.log(f'Serialized: {len(trans_serialize)} transactions')
        return obj

    def hash(self):
        string_object = json.dumps(self.serialize(), sort_keys=True)
        block_string = string_object.encode()

        raw_hash = hashlib.sha256(block_string)
        hex_hash = raw_hash.hexdigest()

        self.hash_value = hex_hash
        self.log(f'Hashed: {self.hash_value}')

        return hex_hash

    def log(self, text):
        print(f'[ BLOCK ] {text}')