import streamlit as st
import random
import os
import smtplib
from email.message import EmailMessage
import json

# ---------- UTILITY FUNCTIONS ----------

def load_data():
    try:
        with open('accounts.json', 'r') as f:
            return json.load(f)
    except:
        return {}

def save_data(data):
    with open('accounts.json', 'w') as f:
        json.dump(data, f, indent=4)

def send_otp(email):
    otp = str(random.randint(1000, 9999))
    st.session_state['otp'] = otp

    sender_email = os.environ['EMAIL_USER']
    sender_password = os.environ['EMAIL_PASS']

    msg = EmailMessage()
    msg['Subject'] = "Your Baryashah Bank OTP"
    msg['From'] = sender_email
    msg['To'] = email
    msg.set_content(f"Your OTP for Baryashah Bank is: {otp}")

    with smtplib.SMTP_SSL('smtp.gmail.com', 465) as smtp:
        smtp.login(sender_email, sender_password)
        smtp.send_message(msg)

    st.info(f"✅ OTP sent to {email}")
    return otp

def verify_otp(user_input):
    return user_input == st.session_state.get('otp')

# ---------- APP UI ----------

st.title("🌟 Baryashah Bank Pro Dashboard 🌟")
st.write("Professional banking simulation. Login, withdraw, deposit & reset password securely.")

data = load_data()

menu = ["Create Account", "Login", "Reset Password"]
choice = st.sidebar.selectbox("Menu", menu)

# ---------- CREATE ACCOUNT ----------
if choice == "Create Account":
    st.header("📝 Create New Account")
    name = st.text_input("Full Name")
    email = st.text_input("Email")
    age = st.number_input("Age", min_value=1, max_value=120)
    password = st.text_input("Create Password", type="password")

    if st.button("Create Account"):
        if age < 18:
            st.error("❌ Must be 18 or older to create an account.")
        elif email in data:
            st.error("❌ Account with this email already exists.")
        else:
            data[email] = {
                "name": name,
                "age": age,
                "password": password,
                "balance": 0,
                "transactions": []
            }
            save_data(data)
            st.success(f"✅ Account created for {name}!")

# ---------- LOGIN ----------
elif choice == "Login":
    st.header("🔑 Login")
    email = st.text_input("Email")
    password = st.text_input("Password", type="password")

    if st.button("Send OTP"):
        if email not in data:
            st.error("❌ Email not registered!")
        elif data[email]["password"] != password:
            st.error("❌ Wrong password!")
        else:
            send_otp(email)

    otp_input = st.text_input("Enter OTP")
    if st.button("Verify OTP"):
        if verify_otp(otp_input):
            st.success(f"✅ Welcome {data[email]['name']}!")
            # Dashboard
            st.subheader("💰 Account Dashboard")
            st.metric("Balance", f"${data[email]['balance']}")
            col1, col2 = st.columns(2)
            with col1:
                deposit_amount = st.number_input("Deposit Amount", min_value=1)
                if st.button("Deposit"):
                    data[email]['balance'] += deposit_amount
                    data[email]['transactions'].append(f"Deposit: +${deposit_amount}")
                    save_data(data)
                    st.success(f"✅ Deposited ${deposit_amount} successfully!")
            with col2:
                withdraw_amount = st.number_input("Withdraw Amount", min_value=1)
                if st.button("Withdraw"):
                    # Send OTP before withdrawal
                    send_otp(email)
                    otp_withdraw = st.text_input("Enter OTP to withdraw")
                    if st.button("Confirm Withdrawal"):
                        if verify_otp(otp_withdraw):
                            if withdraw_amount <= data[email]['balance']:
                                data[email]['balance'] -= withdraw_amount
                                data[email]['transactions'].append(f"Withdraw: -${withdraw_amount}")
                                save_data(data)
                                st.success(f"✅ Withdrawn ${withdraw_amount} successfully!")
                            else:
                                st.error("❌ Insufficient Balance!")
                        else:
                            st.error("❌ Wrong OTP!")
            # Show transactions
            st.subheader("📜 Transaction History")
            for t in data[email]['transactions']:
                st.write(t)
        else:
            st.error("❌ OTP incorrect!")

# ---------- PASSWORD RESET ----------
elif choice == "Reset Password":
    st.header("🔄 Reset Password")
    email = st.text_input("Registered Email")
    if st.button("Send OTP for Reset"):
        if email not in data:
            st.error("❌ Email not registered!")
        else:
            send_otp(email)
    otp_input = st.text_input("Enter OTP received")
    new_pass = st.text_input("Enter New Password", type="password")
    if st.button("Reset Password"):
        if verify_otp(otp_input):
            data[email]['password'] = new_pass
            save_data(data)
            st.success("✅ Password reset successfully!")
        else:
            st.error("❌ OTP incorrect!")