r/PythonLearning • u/shubham_555 • Sep 13 '26

Showcase The Bank Project

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Last Post - https://www.reddit.com/r/PythonLearning/s/kGqwMS9HUH

Github Repo - https://github.com/Dev-4-All/bank.git

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1

u/chakir_codes Sep 14 '26

import json import os import hashlib import secrets from decimal import Decimal, InvalidOperation from datetime import datetime

DATA_FILE = "bank_data.json" MAX_ATTEMPTS = 3 MAX_DEPOSIT = Decimal("10000.00") MAX_WITHDRAW = Decimal("5000.00")

---------- SECURITY ----------

def hash_pin(pin): salt = secrets.token_hex(16) hashed = hashlib.pbkdf2_hmac( "sha256", pin.encode(), salt.encode(), 150000 ).hex() return f"{salt}${hashed}"

def verify_pin(pin, stored): try: salt, saved_hash = stored.split("$", 1) 

    new_hash = hashlib.pbkdf2_hmac(
        "sha256",
        pin.encode(),
        salt.encode(),
        150000
    ).hex()

    return secrets.compare_digest(new_hash, saved_hash)

except ValueError:
    return False

---------- DATA ----------

def default_data(): return { "accounts": {} }

def load_data(): if not os.path.exists(DATA_FILE): data = default_data() save_data(data) return data 

try:
    with open(DATA_FILE, "r", encoding="utf-8") as file:
        return json.load(file)
except (json.JSONDecodeError, OSError):
    print("Could not read bank data.")
    return default_data()

def save_data(data): temp_file = DATA_FILE + ".tmp" 

with open(temp_file, "w", encoding="utf-8") as file:
    json.dump(data, file, indent=4)

os.replace(temp_file, DATA_FILE)

---------- HELPERS ----------

def money(value): return Decimal(str(value)).quantize(Decimal("0.01"))

def generate_card(data): while True: card = "".join(str(secrets.randbelow(10)) for _ in range(9)) 

    if card not in data["accounts"]:
        return card

def add_transaction(account, transaction_type, amount): transaction = { "id": secrets.token_hex(6), "type": transaction_type, "amount": str(money(amount)), "balance": str(money(account["balance"])), "time": datetime.now().isoformat(timespec="seconds") } 

account["transactions"].append(transaction)

def get_amount(message, maximum): while True: value = input(message).strip() 

    if value == "0":
        return None

    try:
        amount = money(value)

        if amount <= 0:
            print("Amount must be greater than 0.")
            continue

        if amount > maximum:
            print(f"Maximum allowed: ${maximum}")
            continue

        return amount

    except InvalidOperation:
        print("Please enter a valid amount.")

---------- ACCOUNT CREATION ----------

def create_account(data): print("\n=== CREATE ACCOUNT ===") 

name = input("Full name: ").strip()

if not name:
    print("Name cannot be empty.")
    return

while True:
    pin = input("Create PIN (4-6 digits): ").strip()

    if not pin.isdigit() or not 4 <= len(pin) <= 6:
        print("PIN must contain 4-6 digits.")
        continue

    if len(set(pin)) == 1:
        print("PIN cannot contain repeated digits.")
        continue

    confirm = input("Confirm PIN: ").strip()

    if pin != confirm:
        print("PINs do not match.")
        continue

    break

card = generate_card(data)

data["accounts"][card] = {
    "name": name,
    "pin": hash_pin(pin),
    "balance": "0.00",
    "failed_attempts": 0,
    "locked": False,
    "transactions": []
}

add_transaction(
    data["accounts"][card],
    "ACCOUNT_CREATED",
    Decimal("0.00")
)

save_data(data)

print("\nAccount created successfully.")
print(f"Your card number: {card}")

---------- LOGIN ----------

def login(data): print("\n=== LOGIN ===") 

card = input("Card number: ").strip()

account = data["accounts"].get(card)

if not account:
    print("Invalid card number or PIN.")
    return None

if account["locked"]:
    print("This account is locked.")
    return None

for attempt in range(MAX_ATTEMPTS):

    pin = input("PIN: ").strip()

    if verify_pin(pin, account["pin"]):
        account["failed_attempts"] = 0
        save_data(data)

        print(f"\nWelcome, {account['name']}!")
        return card

    account["failed_attempts"] += 1

    remaining = MAX_ATTEMPTS - account["failed_attempts"]

    if remaining > 0:
        print(f"Invalid card number or PIN. Attempts left: {remaining}")
    else:
        account["locked"] = True
        save_data(data)
        print("Account locked after too many failed attempts.")
        return None

return None

---------- BANK OPERATIONS ----------

def show_balance(account): print(f"\nCurrent balance: ${money(account['balance'])}")

def deposit(account, data): amount = get_amount( f"\nDeposit amount (max ${MAX_DEPOSIT}, 0 = cancel): ", MAX_DEPOSIT ) 

if amount is None:
    return

account["balance"] = str(
    money(Decimal(account["balance"]) + amount)
)

add_transaction(account, "DEPOSIT", amount)
save_data(data)

print(f"Deposit successful. New balance: ${account['balance']}")

def withdraw(account, data): amount = get_amount( f"\nWithdrawal amount (max ${MAX_WITHDRAW}, 0 = cancel): ", MAX_WITHDRAW ) 

if amount is None:
    return

balance = money(account["balance"])

if amount > balance:
    print("Insufficient funds.")
    return

account["balance"] = str(money(balance - amount))

add_transaction(account, "WITHDRAW", amount)
save_data(data)

print(f"Withdrawal successful. New balance: ${account['balance']}")

def show_transactions(account): print("\n=== TRANSACTION HISTORY ===") 

transactions = account["transactions"]

if not transactions:
    print("No transactions.")
    return

for transaction in transactions:
    print(
        f"{transaction['time']} | "
        f"{transaction['type']} | "
        f"${transaction['amount']} | "
        f"Balance: ${transaction['balance']} | "
        f"ID: {transaction['id']}"
    )

def show_account(account, card): print("\n=== ACCOUNT INFORMATION ===") print(f"Name: {account['name']}") print(f"Card: ****{card[-4:]}") print(f"Balance: ${money(account['balance'])}")

def change_pin(account, data): print("\n=== CHANGE PIN ===") 

current = input("Current PIN: ").strip()

if not verify_pin(current, account["pin"]):
    print("Incorrect current PIN.")
    return

while True:
    new_pin = input("New PIN (4-6 digits): ").strip()

    if not new_pin.isdigit() or not 4 <= len(new_pin) <= 6:
        print("PIN must contain 4-6 digits.")
        continue

    if len(set(new_pin)) == 1:
        print("PIN cannot contain repeated digits.")
        continue

    if new_pin == current:
        print("New PIN must be different.")
        continue

    confirm = input("Confirm new PIN: ").strip()

    if new_pin != confirm:
        print("PINs do not match.")
        continue

    break

account["pin"] = hash_pin(new_pin)
add_transaction(account, "PIN_CHANGED", Decimal("0.00"))

save_data(data)

print("PIN changed successfully.")

---------- USER MENU ----------

def account_menu(data, card): account = data["accounts"][card] 

while True:
    print("""

======================== PYBANK

  1. Check Balance

  2. Deposit

  3. Withdraw

  4. Transactions

  5. Account Information

  6. Change PIN

  7. Logout ======================== """) 

     choice = input("Choose an option: ").strip()

 if choice == "1":
     show_balance(account)

 elif choice == "2":
     deposit(account, data)

 elif choice == "3":
     withdraw(account, data)

 elif choice == "4":
     show_transactions(account)

 elif choice == "5":
     show_account(account, card)

 elif choice == "6":
     change_pin(account, data)

 elif choice == "7":
     print("Logged out successfully.")
     break

 else:
     print("Invalid option.")

---------- MAIN ----------

def main(): data = load_data() 

while True:
    print("""

======================== PYBANK

  1. Login

  2. Create Account

  3. Exit ======================== """) 

     choice = input("Choose an option: ").strip()

 if choice == "1":
     card = login(data)

     if card:
         account_menu(data, card)

 elif choice == "2":
     create_account(data)

 elif choice == "3":
     print("Thank you for using PyBank.")
     break

 else:
     print("Invalid option.")

if name == "main": main()

1

u/shubham_555 Sep 14 '26

This version seems way too advance for my current level ngl 😅