#!/usr/bin/env python3.6
# -*- encoding: utf-8 -*-
from blockchain import BlockChain
# Create the blockchain and add the genesis block
blockchain = BlockChain()
# How many blocks should we add to the chain
# after the genesis block
num_of_blocks_to_add = 20
# Add blocks to the chain
for i in range(0, num_of_blocks_to_add):
new_block = blockchain.create_block("Hey! I'm block " + str(i + 1))
last_block = blockchain.append_block(new_block)
# Tell everyone about it!
print("Block #{} has been added to the blockchain!".format(
last_block.get_index()))
print("Hash: {}".format(last_block.get_hash()))
print("Data: {}\n".format(last_block.get_data()))
blockchain = BlockChain(difficulty)
wallet_one = Wallet(utxos)
wallet_two = Wallet(utxos)
wallet_coinbase = Wallet(utxos)
# create genesis transaction, which sends 100 coins to wallet_one
genesis_transaction = get_genesis_transaction(wallet_coinbase, wallet_one,
100, utxos)
print("Creating and mining genesis block")
genesis = Block("0")
genesis.add_transaction(genesis_transaction, utxos, minimum_transaction)
blockchain.append_block(genesis)
# testing
print("Wallet one balance: %d" % wallet_one.get_balance())
print()
print("Attemping to send funds (40) to Wallet two")
block1 = Block(genesis.hash)
block1.add_transaction(
wallet_one.send_funds(wallet_two.public_key_as_str(), 40), utxos,
minimum_transaction)
blockchain.append_block(block1)
print("Wallet one balance: %d" % wallet_one.get_balance())
print("Wallet two balance: %d" % wallet_two.get_balance())
print()
class BlockchainHandler:
BLOCKCHAIN_PATH = 'resources/blockchain.json'
def __init__(self):
self.blockchain = None
self.central_bank = None
self.current_block = None
self.all_utxos = {}
def import_json(self, path):
if os.path.exists(self.BLOCKCHAIN_PATH):
raise Exception("blockchain file imported previously, if you want to reload it first reset blockchain")
copyfile(path, self.BLOCKCHAIN_PATH)
self.load_blockchain()
def reset_blockchain(self):
os.remove(self.BLOCKCHAIN_PATH)
self.load_blockchain()
def load_blockchain(self):
from models import CentralBank
try:
with open(self.BLOCKCHAIN_PATH) as f:
blocks_data = json.loads(f.read())
if not (isinstance(blocks_data, dict) or isinstance(blocks_data, list)):
raise Exception("blockchain.json file is not valid")
if isinstance(blocks_data, dict):
blocks_data = [blocks_data]
self.blockchain = 'pending'
self.central_bank = CentralBank.get_central_bank()
if not self.central_bank.has_valid_configuration():
raise Exception('central bank configuration is not properly set')
self.blockchain = BlockChain(self.central_bank.difficulty)
self.all_utxos = {}
for block_data in blocks_data:
block = Block.deserialize(block_data)
self.blockchain.append_block(block, mine_block=False)
for transaction in block.transactions:
for inp in transaction.inputs:
del self.all_utxos[inp.transaction_output_id]
for output in transaction.outputs:
self.all_utxos[output.id] = output
except Exception as exp:
print("Error occurred while loading blockchain")
print(exp)
self.blockchain = None
return
self.blockchain.print()
def is_blockchain_imported(self):
return bool(self.blockchain)
def new_transaction(self, sender_wallet: Wallet, receiver_wallet: Wallet, amount):
if not self.current_block:
self.current_block = Block(self.blockchain.last_block_hash())
transaction = sender_wallet.send_funds(self.all_utxos, receiver_wallet.public_key_str, amount)
self.current_block.add_transaction(transaction, self.all_utxos, 0.001)
if len(self.current_block.transactions) == self.central_bank.number_of_transactions_in_block:
self.blockchain.append_block(self.current_block, True)
self.current_block = None
