Very tiny BlockChain implementation for learning purpose

tinyblock.py

"""
Very tiny blockchain implementation -- for learning purpose
"""

import hashlib
import datetime

__author__ = "ibrahim@sikilabs.com"
__reference__ = "https://medium.com/crypto-currently/lets-build-the-tiniest-blockchain-e70965a248b"


class TBlock:
    def __init__(self, idx=0, ts=datetime.datetime.now(), data="Genesis 313",
                 prev_hash="0"):
        """
        Block entity -- creates a genesis block if no parameter is supplied
        :param idx: block index
        :param ts: timestamp
        :param data: whatever data
        :param prev_hash: previous block hash -- 0 if genesis
        """

        self.index = idx
        self.ts = ts
        self.data = data
        self.previous_hash = prev_hash
        self.hash = hashlib.sha256()
        self.hash.update(str(self.index) +
                         str(self.ts) +
                         str(self.data) +
                         str(self.previous_hash))

    def __str__(self):
        return str({"index": self.index, "hash": self.hash.hexdigest()})

    def create_next(self, data):
        """
        Create next block in chain from previous block
        :param data: whatever data
        :return: block instance
        """
        return TBlock(self.index + 1, datetime.datetime.now(), data, self.hash)