Code Editor for app.py

import streamlit as st
from sqlalchemy import create_engine, Column, Integer, String
from sqlalchemy.orm import Session, DeclarativeBase
import hashlib

# Database setup
class Base(DeclarativeBase):
    pass

class User(Base):
    __tablename__ = 'users'
    
    id = Column(Integer, primary_key=True)
    username = Column(String(50), unique=True, nullable=False)
    password = Column(String(256), nullable=False)
    email = Column(String(120), unique=True, nullable=False)

# Create database and tables
engine = create_engine('sqlite:///users.sqlite')
Base.metadata.create_all(bind=engine)

def hash_password(password):
    """Hash a password using SHA-256"""
    return hashlib.sha256(password.encode()).hexdigest()

def create_user(username, password, email):
    """Create a new user in the database"""
    with Session(engine) as session:
        # Check if username already exists
        existing_user = session.query(User).filter_by(username=username).first()
        if existing_user:
            return False, "Username already exists"
        
        # Check if email already exists
        existing_email = session.query(User).filter_by(email=email).first()
        if existing_email:
            return False, "Email already exists"
        
        # Create new user
        hashed_password = hash_password(password)
        new_user = User(username=username, password=hashed_password, email=email)
        session.add(new_user)
        try:
            session.commit()
            return True, "User created successfully"
        except Exception as e:
            session.rollback()
            return False, str(e)

# Streamlit UI
st.title("Create User Account")

with st.form("user_form"):
    username = st.text_input("Username")
    email = st.text_input("Email")
    password = st.text_input("Password", type="password")
    confirm_password = st.text_input("Confirm Password", type="password")
    
    submit_button = st.form_submit_button("Create Account")
    
    if submit_button:
        if not username or not email or not password or not confirm_password:
            st.error("Please fill in all fields")
        elif password != confirm_password:
            st.error("Passwords do not match")
        else:
            success, message = create_user(username, password, email)
            if success:
                st.success(message)
            else:
                st.error(message)

# Display existing users (for demonstration purposes)
with Session(engine) as session:
    users = session.query(User).all()
    if users:
        st.subheader("Registered Users")
        user_data = [[user.username, user.email] for user in users]
        st.table({"Username": [u[0] for u in user_data], 
                 "Email": [u[1] for u in user_data]})