crypto dummy

main.py

import hashlib
import time
import json


class Block:
    def __init__(self, index, transactions, timestamp, previous_hash, nonce=0):
        self.index = index
        self.transactions = transactions
        self.timestamp = timestamp
        self.previous_hash = previous_hash
        self.nonce = nonce
        self.hash = self.calculate_hash()

    def calculate_hash(self):
        block_string = json.dumps(self.__dict__, sort_keys=True)
        return hashlib.sha256(block_string.encode()).hexdigest()

    def mine_block(self, difficulty):
        target = '0' * difficulty
        while not self.hash.startswith(target):
            self.nonce += 1
            self.hash = self.calculate_hash()


class Blockchain:
    def __init__(self):
        self.chain = [self.create_genesis_block()]
        self.difficulty = 4
        self.pending_transactions = []
        self.mining_reward = 10

    def create_genesis_block(self):
        return Block(0, [], time.time(), "0")

    def get_latest_block(self):
        return self.chain[-1]

    def add_transaction(self, transaction):
        if not transaction['sender'] or not transaction['recipient'] or not transaction['amount']:
            raise ValueError("Invalid transaction data")
        self.pending_transactions.append(transaction)

    def mine_pending_transactions(self, mining_reward_address):
        block = Block(
            len(self.chain),
            self.pending_transactions,
            time.time(),
            self.get_latest_block().hash
        )
        block.mine_block(self.difficulty)
        print(f"Block mined! Hash: {block.hash}")
        self.chain.append(block)
        self.pending_transactions = [{"sender": None, "recipient": mining_reward_address, "amount": self.mining_reward}]

    def is_chain_valid(self):
        for i in range(1, len(self.chain)):
            current_block = self.chain[i]
            previous_block = self.chain[i - 1]
            if current_block.hash != current_block.calculate_hash():
                return False
            if current_block.previous_hash != previous_block.hash:
                return False
        return True


# Test the cryptocurrency
if __name__ == "__main__":
    my_coin = Blockchain()

    # Adding transactions
    my_coin.add_transaction({"sender": "Alice", "recipient": "Bob", "amount": 50})
    my_coin.add_transaction({"sender": "Bob", "recipient": "Alice", "amount": 20})

    # Mining transactions
    print("Starting mining...")
    my_coin.mine_pending_transactions("Miner1")

    print("Starting mining again...")
    my_coin.mine_pending_transactions("Miner2")

    # Display the blockchain
    for block in my_coin.chain:
        print(f"Block {block.index}:\n{json.dumps(block.__dict__, indent=4)}")

    # Validate the chain
    print("Blockchain valid:", my_coin.is_chain_valid())