bchain2.py

import hashlib
import json

reward = 10.0

genesis_block = {
    'previous_hash': '',
    'index': 0,
    'transaction': [],
    'nonce': 23
}
blockchain = [genesis_block]
open_transactions = []
owner = 'LOLA'


def hash_block(block):
    print(hashlib.sha256(json.dumps(block).encode()).hexdigest())
    return hashlib.sha256(json.dumps(block).encode()).hexdigest()


def valid_proof(transactions, last_hash, nonce):
    guess = (str(transactions) + str(last_hash) + str(nonce)).encode()
    guess_hash = hashlib.sha256(guess).hexdigest()
    print(guess_hash)
    return guess_hash[0:2] == '00'


def proof_of_work():
    last_block = blockchain[-1]
    last_hash = hash_block(last_block)
    nonce = 0
    while not valid_proof(open_transactions, last_hash, nonce):
        nonce += 1
    return nonce


def get_last_value():
    """ extracting the last element of the blockchain list """
    return (blockchain[-1])


def add_value(recipient, sender=owner, amount=1.0):
    transaction = {'sender': sender,
                   'recipient': recipient,
                   'amount': amount}
    open_transactions.append(transaction)


def mine_block():
    last_block = blockchain[-1]
    hashed_block = hash_block(last_block)
    nonce = proof_of_work()
    reward_transaction = {
        'sender': 'MINING',
        'recipient': owner,
        'amount': reward
    }

    open_transactions.append(reward_transaction)
    block = {
        'previous_hash': hashed_block,
        'index': len(blockchain),
        'transaction': open_transactions,
        'nonce': nonce
    }

    blockchain.append(block)


def get_transaction_value():
    tx_recipient = input('Enter the recipient of the transaction: ')
    tx_amount = float(input('Enter your transaction amount '))
    return tx_recipient, tx_amount


def get_user_choice():
    user_input = input("Please give your choice here: ")
    return user_input


def print_block():
    print(blockchain)
    # for block in blockchain:
    #     print("Here is your block")
    #     print(block)


if __name__ == '__main__':
    while True:
        print("Choose an option")
        print('Choose 1 for adding a new transaction')
        print('Choose 2 for mining a new block')
        print('Choose 3 for printing the blockchain')
        print('Choose anything else if you want to quit')
        user_choice = get_user_choice()
        if user_choice == 1:
            tx_data = get_transaction_value()
            recipient, amount = tx_data
            add_value(recipient, amount=amount)
            print(open_transactions)
        elif user_choice == 2:
            mine_block()
        elif user_choice == 3:
            print_block()
        else:
            break