|
| 1 | +# A built in module that provides functions from python standard library |
| 2 | +import functools |
| 3 | +import collections |
| 4 | +import json |
| 5 | + |
| 6 | +from utils import hash_block, hash_string_256 |
| 7 | + |
| 8 | +MINING_REWARD = 10 |
| 9 | +genesis_block = { |
| 10 | + 'previous_hash': '', |
| 11 | + 'index': 0, |
| 12 | + 'transactions': [], |
| 13 | + 'proof': 100 |
| 14 | +} |
| 15 | +my_blockchain = [genesis_block] |
| 16 | +open_transactions = [] |
| 17 | +waiting_for_input = True |
| 18 | +owner = 'Nicolas' |
| 19 | +participants = set([owner]) |
| 20 | + |
| 21 | +def add__line(): |
| 22 | + print('------------------------------') |
| 23 | + |
| 24 | +def generate_options_menu(): |
| 25 | + add__line() |
| 26 | + print('Please choose an option:') |
| 27 | + print('1: Add a new transaction') |
| 28 | + print('2: Mine a new block') |
| 29 | + print('3: Output all blockchain blocks') |
| 30 | + print('4: Output all participants') |
| 31 | + print('h: Manipulate blockchain') |
| 32 | + print('q: Quit') |
| 33 | + add__line() |
| 34 | + |
| 35 | +def get_user_input(): |
| 36 | + user_input = input('Please enter your selection: ') |
| 37 | + add__line() |
| 38 | + return user_input |
| 39 | + |
| 40 | +def valid_proof(transactions, last_hash, proof): |
| 41 | + guess = (str(transactions) + str(last_hash) + str(proof)).encode() |
| 42 | + guess_hash = hash_string_256(guess) |
| 43 | + # If the hash starts with 2 leading zeros, we consider it a valid proof |
| 44 | + return guess_hash[0:2] == '00' |
| 45 | + |
| 46 | +def proof_of_work(): |
| 47 | + last_block = my_blockchain[-1] |
| 48 | + hash_last_block = hash_block(last_block) |
| 49 | + proof = 0 |
| 50 | + while not valid_proof(open_transactions, hash_last_block, proof): |
| 51 | + proof += 1 |
| 52 | + return proof |
| 53 | + |
| 54 | + |
| 55 | + |
| 56 | +def mine_block(): |
| 57 | + last_block = my_blockchain[-1] |
| 58 | + hashed_block = hash_block(last_block) |
| 59 | + proof_of_work_value = proof_of_work() |
| 60 | + |
| 61 | + # Old way to create a mining reward transaction, it will be replaced by an OrderedDict to keep the order of the elements |
| 62 | + # reward_transaction = { |
| 63 | + # 'sender': 'MINING', |
| 64 | + # 'recipient': owner, |
| 65 | + # 'amount': MINING_REWARD |
| 66 | + # } |
| 67 | + reward_transaction = collections.OrderedDict([('sender', 'MINING'), ('recipient', owner), ('amount', MINING_REWARD)]) |
| 68 | + |
| 69 | + block = { |
| 70 | + 'previous_hash': hashed_block, |
| 71 | + 'index': len(my_blockchain), |
| 72 | + 'transactions': [open_transactions, reward_transaction], |
| 73 | + 'proof': proof_of_work_value |
| 74 | + } |
| 75 | + |
| 76 | + my_blockchain.append(block) |
| 77 | + print('Block added!') |
| 78 | + add__line() |
| 79 | + return True |
| 80 | + |
| 81 | +def get_transaction_value(): |
| 82 | + """ Returns the input of the user (a new transaction amount and its recipient) as a tuple """ |
| 83 | + tx_recipient_input = input('Please enter the recipient of the transaction: ') |
| 84 | + tx_amount_input = float(input('Please enter your transaction input: ')) |
| 85 | + add__line() |
| 86 | + |
| 87 | + return tx_recipient_input, tx_amount_input |
| 88 | + |
| 89 | +def take_last_blockchain_value(): |
| 90 | + if len(my_blockchain) < 1: |
| 91 | + return None |
| 92 | + |
| 93 | + return my_blockchain[-1] |
| 94 | + |
| 95 | +def verify_transaction(transaction): |
| 96 | + sender_balance = get_balance(transaction['sender']) |
| 97 | + |
| 98 | + if sender_balance >= transaction['amount']: |
| 99 | + return True |
| 100 | + return False |
| 101 | + |
| 102 | +def add_transaction(sender, recipient, amount=1): |
| 103 | + """ |
| 104 | + Add a new transaction to the list of open transactions (which will be added to the next mined block) |
| 105 | +
|
| 106 | + Arguments: |
| 107 | + :sender: The sender of the coins. |
| 108 | + :recipient: The recipient of the coins. |
| 109 | + :amount: The amount of the transaction. |
| 110 | + """ |
| 111 | + |
| 112 | + # An old way to create a transaction, it will be replaced by an OrderedDict to keep the order of the elements |
| 113 | + # new_transaction = { |
| 114 | + # 'sender': sender, |
| 115 | + # 'recipient': recipient, |
| 116 | + # 'amount': amount |
| 117 | + # } |
| 118 | + new_transaction = collections.OrderedDict([('sender', sender), ('recipient', recipient), ('amount', amount)]) |
| 119 | + |
| 120 | + if verify_transaction(new_transaction): |
| 121 | + open_transactions.append(new_transaction) |
| 122 | + participants.add(sender) |
| 123 | + participants.add(recipient) |
| 124 | + save_data() |
| 125 | + else: |
| 126 | + print('Transaction failed! Not enough balance!') |
| 127 | + add__line() |
| 128 | + |
| 129 | +def return_all_blocks(): |
| 130 | + print('---Outputting all blocks---') |
| 131 | + |
| 132 | + for block in my_blockchain: |
| 133 | + print(f'Outputting block: {block}') |
| 134 | + add__line() |
| 135 | + |
| 136 | +def get_balance(participant): |
| 137 | + sent_transactions = [[tx['amount'] for tx in block['transactions'] if tx['sender'] == participant] for block in my_blockchain] |
| 138 | + recieved_transactions = [[tx['amount'] for tx in block['transactions'] if tx['recipient'] == participant] for block in my_blockchain] |
| 139 | + open_sent_transactions = [tx['amount'] for tx in open_transactions if tx['sender'] == participant] |
| 140 | + |
| 141 | + sent_transactions.append(open_sent_transactions) |
| 142 | + sent_amounts = functools.reduce(lambda tx_sum, tx_amt: tx_sum + sum(tx_amt) if len(tx_amt) > 0 else tx_amt + 0, sent_transactions, 0) |
| 143 | + |
| 144 | + recieved_amounts = functools.reduce(lambda tx_sum, tx_amt: tx_sum + sum(tx_amt) if len(tx_amt) > 0 else tx_amt + 0, recieved_transactions, 0) |
| 145 | + |
| 146 | + return recieved_amounts - sent_amounts |
| 147 | + |
| 148 | +def verify_chain(): |
| 149 | + """ The function helps to verify the integrity of the blockchain by checking if each block's previous hash matches the hash of the previous block. """ |
| 150 | + for (index, block) in enumerate(my_blockchain): |
| 151 | + if index == 0: |
| 152 | + continue |
| 153 | + if block['previous_hash'] != hash_block(my_blockchain[index - 1]): |
| 154 | + return False |
| 155 | + # You are cheking all the transactions except the last one because the last one is the mining reward transaction |
| 156 | + if not valid_proof(block['transactions'][:-1], block['previous_hash'], block['proof']): |
| 157 | + print('Proof of work is invalid') |
| 158 | + return False |
| 159 | + return True |
| 160 | + |
| 161 | +def verify_transactions(): |
| 162 | + """ The function verifies all open transactions to ensure they are valid. """ |
| 163 | + return all([tx for tx in open_transactions if not verify_transaction(tx)]) |
| 164 | + |
| 165 | +def load_data(): |
| 166 | + with open('blockchain.txt', mode='r') as f: |
| 167 | + file_content = f.readlines() |
| 168 | + # This adds a reference of the mentioned varables to be handled |
| 169 | + global my_blockchain |
| 170 | + global open_transactions |
| 171 | + # Have in mind that the data you are returning is in string format, does not care if is a list or dictionary |
| 172 | + # my_blockchain = file_content[0] |
| 173 | + # To convert the string data into a list or dictionary you can use the json module |
| 174 | + my_blockchain = json.loads(file_content[0]) |
| 175 | + updated_blockchain = [] |
| 176 | + updated_transactions = [] |
| 177 | + |
| 178 | + for block in my_blockchain: |
| 179 | + updated_block = { |
| 180 | + 'previous_hash': block['previous_hash'], |
| 181 | + 'proof': block['proof'], |
| 182 | + 'index': block['index'], |
| 183 | + 'transactions': [collections.OrderedDict( |
| 184 | + [('sender', tx['sender']), ('recipient', tx['recipient']), ('amount', tx['amount'])]) for tx in block['transactions']], |
| 185 | + } |
| 186 | + updated_blockchain.append(updated_block) |
| 187 | + |
| 188 | + for tx in block['transactions']: |
| 189 | + updated_transaction = collections.OrderedDict( |
| 190 | + [('sender', tx['sender']), ('recipient', tx['recipient']), ('amount', tx['amount'])]) |
| 191 | + updated_transactions.append(updated_transaction) |
| 192 | + |
| 193 | + my_blockchain = updated_blockchain |
| 194 | + open_transactions = updated_transactions |
| 195 | + |
| 196 | +def save_data(): |
| 197 | + with open('blockchain.txt', mode='w') as f: |
| 198 | + # To save the data in another format rather than string, you can use the json module to convert it |
| 199 | + f.write(json.dumps(my_blockchain)) |
| 200 | + f.write('\n') |
| 201 | + f.write(json.dumps(open_transactions)) |
| 202 | + |
| 203 | +while waiting_for_input: |
| 204 | + generate_options_menu() |
| 205 | + |
| 206 | + user_choice = get_user_input() |
| 207 | + |
| 208 | + if user_choice == '1': |
| 209 | + tx_input_data = get_transaction_value() |
| 210 | + recipient, amount = tx_input_data |
| 211 | + add_transaction(owner, recipient, amount) |
| 212 | + elif user_choice == '2': |
| 213 | + if mine_block(): |
| 214 | + open_transactions = [] |
| 215 | + save_data() |
| 216 | + elif user_choice == '3': |
| 217 | + return_all_blocks() |
| 218 | + elif user_choice == '4': |
| 219 | + print(participants) |
| 220 | + elif user_choice == 'q': |
| 221 | + waiting_for_input = False |
| 222 | + elif user_choice == 'h': |
| 223 | + if len(my_blockchain) >= 1: |
| 224 | + my_blockchain[0] = [2.0] |
| 225 | + else: |
| 226 | + print('Invalid input, please choose a valid option') |
| 227 | + if not verify_chain(): |
| 228 | + print('Invalid blockchain!') |
| 229 | + waiting_for_input = False |
| 230 | + print(f"Balance of {owner}: {get_balance(owner)}") |
| 231 | +else: |
| 232 | + print('User left!') |
| 233 | + |
| 234 | +add__line() |
| 235 | +print('Done!') |
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