app.py

import streamlit as st

# BankAccount class using OOP
class BankAccount:
    def __init__(self, account_id, name):
        self.account_id = account_id
        self.name = name
        self.balance = 0

    def deposit(self, amount):
        if amount > 0:
            self.balance += amount
            return True
        return False

    def withdraw(self, amount):
        if 0 < amount <= self.balance:
            self.balance -= amount
            return True
        return False

# Store accounts in session state
if 'accounts' not in st.session_state:
    st.session_state.accounts = {}

st.set_page_config(page_title="🏦 Bank App", layout="centered")
st.title("🏦 Bank Account Management System")

# Section 1: Create New Account
st.header("➕ Create New Account")
with st.form("create_account"):
    new_id = st.text_input("Enter Account ID")
    new_name = st.text_input("Enter Account Holder Name")
    create_btn = st.form_submit_button("Create Account")
    if create_btn:
        if new_id in st.session_state.accounts:
            st.warning("⚠️ Account ID already exists.")
        elif not new_id or not new_name:
            st.warning("⚠️ Please enter both ID and Name.")
        else:
            st.session_state.accounts[new_id] = BankAccount(new_id, new_name)
            st.success(f"✅ Account for {new_name} created with ID {new_id}.")

# Section 2: Deposit / Withdraw
st.header("💸 Deposit / Withdraw Money")
with st.form("transaction"):
    trans_id = st.text_input("Enter Account ID")
    trans_type = st.radio("Choose Transaction Type", ["Deposit", "Withdraw"], horizontal=True)
    trans_amount = st.number_input("Enter Amount (Rs.)", min_value=0, step=100)
    trans_btn = st.form_submit_button("Submit Transaction")

    if trans_btn:
        account = st.session_state.accounts.get(trans_id)
        if account:
            if trans_type == "Deposit":
                if account.deposit(trans_amount):
                    st.success(f"✅ Deposited Rs. {trans_amount} to {account.name}'s account.")
                else:
                    st.error("❌ Invalid deposit amount.")
            elif trans_type == "Withdraw":
                if account.withdraw(trans_amount):
                    st.success(f"✅ Withdrew Rs. {trans_amount} from {account.name}'s account.")
                else:
                    st.error("❌ Insufficient balance or invalid amount.")
        else:
            st.warning("⚠️ Account ID not found.")

# Section 3: Show All Accounts
st.header("📄 All Accounts")
if st.session_state.accounts:
    account_data = {
        "Account ID": [],
        "Name": [],
        "Balance (Rs.)": []
    }
    for acc in st.session_state.accounts.values():
        account_data["Account ID"].append(acc.account_id)
        account_data["Name"].append(acc.name)
        account_data["Balance (Rs.)"].append(acc.balance)
    
    st.table(account_data)
else:
    st.info("ℹ️ No accounts created yet.")