# imports
from hashlib import sha256
from random import randint

# Constants
MAX_NONCE = 1000000     # Limit for the simulation
DIFFICULTY = 3          # How many lead zeros has the hash

def random_with_N_digits(n):
    """Generate a random string with n chars."""
    range_start = 10 ** (n - 1)
    range_end = (10 ** n) - 1
    return randint(range_start, range_end)

def generate_transactions(count=3):
    """Create the list of transactions"""
    transactions = []
    for _ in range(count):
        sender = random_with_N_digits(5)
        receiver = random_with_N_digits(5)
        bitcoins = random_with_N_digits(2)
        transactions.append(f"{sender}->{receiver}->{bitcoins}")
    return "; ".join(transactions)

def SHA256(text):
    """Creates a SHA256-Hash for the text."""
    return sha256(text.encode("ascii")).hexdigest()

def mine(block_number, transactions, previous_hash, prefix_zeros):
    """Simulates the mining of a block."""
    prefix_str = '0' * prefix_zeros
    for nonce in range(MAX_NONCE):
        text = f"{block_number}{transactions}{previous_hash}{nonce}"
        new_hash = SHA256(text)
        if new_hash.startswith(prefix_str):
            print(f"Block found! Nonce: {nonce}, Hash: {new_hash}")
            return new_hash
    raise RuntimeError(f"Mining not succesful after {MAX_NONCE} tries.")

if __name__ == '__main__':
    block_number = 1
    previous_hash = "0" * 64  # Star Value for the first block
    num_blocks_to_mine = 10

    for _ in range(num_blocks_to_mine):
        transactions = generate_transactions()
        print(f"Mining Block {block_number} with transactions: {transactions}")
        new_hash = mine(block_number, transactions, previous_hash, DIFFICULTY)
        previous_hash = new_hash  # Hash wird zum vorherigen Hash für den nächsten Block
        block_number += 1
        print(f"New Hash: {new_hash}\n")