Code Editor for app.py

import streamlit as st
from streamlit_extras.switch_page_button import switch_page
import pandas as pd
from pathlib import Path
import os
import sqlite3
from sqlalchemy import create_engine, Column, Integer, String, Boolean
from sqlalchemy.orm import Session, declarative_base
import hashlib

# Set page config
st.set_page_config(page_title="Role-Based Access Control Demo", layout="wide")

# Database setup
Base = declarative_base()

class User(Base):
    __tablename__ = "users"
    
    id = Column(Integer, primary_key=True)
    username = Column(String, unique=True, nullable=False)
    password_hash = Column(String, nullable=False)
    is_oga = Column(Boolean, default=False)  # True for "oga", False for "former"

# Create database engine
engine = create_engine("sqlite:///users.db")

# Create tables
Base.metadata.create_all(bind=engine)

# Helper functions
def hash_password(password):
    return hashlib.sha256(password.encode()).hexdigest()

def create_default_users():
    with Session(engine) as session:
        # Check if users already exist
        if session.query(User).count() == 0:
            # Create default users
            users = [
                User(username="former1", password_hash=hash_password("password"), is_oga=False),
                User(username="former2", password_hash=hash_password("password"), is_oga=False),
                User(username="oga1", password_hash=hash_password("password"), is_oga=True),
                User(username="oga2", password_hash=hash_password("password"), is_oga=True)
            ]
            for user in users:
                session.add(user)
            session.commit()

# Create default users when the app starts
create_default_users()

# Initialize session state variables
if "authenticated" not in st.session_state:
    st.session_state.authenticated = False
if "username" not in st.session_state:
    st.session_state.username = None
if "is_oga" not in st.session_state:
    st.session_state.is_oga = False
if "current_page" not in st.session_state:
    st.session_state.current_page = "home"

# Create pages directory if it doesn't exist
pages_dir = Path("pages")
if not pages_dir.exists():
    pages_dir.mkdir()

# Function to authenticate user
def authenticate(username, password):
    with Session(engine) as session:
        user = session.query(User).filter_by(username=username).first()
        if user and user.password_hash == hash_password(password):
            st.session_state.authenticated = True
            st.session_state.username = username
            st.session_state.is_oga = user.is_oga
            return True
    return False

# Function to logout
def logout():
    st.session_state.authenticated = False
    st.session_state.username = None
    st.session_state.is_oga = False
    st.session_state.current_page = "home"
    st.rerun()

# Login form
def show_login_form():
    st.title("Login")
    
    col1, col2, col3 = st.columns([1, 2, 1])
    
    with col2:
        with st.form("login_form"):
            username = st.text_input("Username")
            password = st.text_input("Password", type="password")
            submit = st.form_submit_button("Login")
            
            if submit:
                if authenticate(username, password):
                    st.success(f"Welcome, {username}!")
                    st.rerun()
                else:
                    st.error("Invalid username or password")
        
        # Display demo credentials
        with st.expander("Demo Credentials"):
            st.markdown("""
            **Former Users (Limited Access):**
            - Username: former1
            - Password: password
            
            **Oga Users (Full Access):**
            - Username: oga1
            - Password: password
            """)

# Navbar for navigation
def show_navbar():
    col1, col2, col3, col4, col5 = st.columns([1, 1, 1, 1, 1])
    
    with col1:
        if st.button("Home", use_container_width=True):
            st.session_state.current_page = "home"
            st.rerun()
    
    with col2:
        if st.button("Submission", use_container_width=True):
            st.session_state.current_page = "submission"
            st.rerun()
    
    with col3:
        if st.button("Statistics", use_container_width=True):
            # Check if user has access to statistics page
            if st.session_state.is_oga:
                st.session_state.current_page = "statistics"
                st.rerun()
            else:
                st.warning("You don't have access to this page")
    
    with col4:
        if st.button("Settings", use_container_width=True):
            # Check if user has access to settings page
            if st.session_state.is_oga:
                st.session_state.current_page = "settings"
                st.rerun()
            else:
                st.warning("You don't have access to this page")
    
    with col5:
        if st.button("Logout", use_container_width=True):
            logout()

# Home page
def show_home_page():
    st.title("Home Page")
    st.write("Welcome to the home page of our application.")
    
    st.info("This is the home page accessible to all authenticated users.")
    
    st.markdown("""
    ### Role-Based Access Control
    
    In this application, we have two types of users:
    
    1. **Formers** - Limited access (only submission page)
    2. **Ogas** - Full access to all pages
    
    Navigate using the buttons above to explore the application.
    """)

# Submission page
def show_submission_page():
    st.title("Submission Page")
    st.write("This is the submission page where users can submit their forms.")
    
    st.info("This page is accessible to both 'Former' and 'Oga' users.")
    
    with st.form("submission_form"):
        st.text_input("Full Name")
        st.text_area("Comments")
        st.file_uploader("Upload Document", type=["pdf", "docx", "doc"])
        st.date_input("Submission Date")
        
        submitted = st.form_submit_button("Submit")
        if submitted:
            st.success("Form submitted successfully!")

# Statistics page
def show_statistics_page():
    st.title("Statistics Page")
    st.write("This page shows statistics and analytics.")
    
    st.warning("This page is only accessible to 'Oga' users.")
    
    # Sample data for demonstration
    data = {
        'Category': ['Form A', 'Form B', 'Form C', 'Form D'],
        'Submissions': [42, 28, 63, 17],
        'Approval Rate': [75, 82, 45, 93]
    }
    
    df = pd.DataFrame(data)
    
    col1, col2 = st.columns(2)
    
    with col1:
        st.subheader("Submission Statistics")
        st.bar_chart(df.set_index('Category')['Submissions'])
    
    with col2:
        st.subheader("Approval Rate (%)")
        st.line_chart(df.set_index('Category')['Approval Rate'])
    
    st.dataframe(df, use_container_width=True)

# Settings page
def show_settings_page():
    st.title("Settings Page")
    st.write("Manage application settings and user permissions.")
    
    st.warning("This page is only accessible to 'Oga' users.")
    
    with Session(engine) as session:
        users = session.query(User).all()
        
        user_data = {
            'Username': [user.username for user in users],
            'Role': ['Oga' if user.is_oga else 'Former' for user in users],
        }
        
        df = pd.DataFrame(user_data)
        st.subheader("User List")
        st.dataframe(df, use_container_width=True)
        
        st.subheader("Add New User")
        with st.form("add_user_form"):
            new_username = st.text_input("Username")
            new_password = st.text_input("Password", type="password")
            is_oga = st.checkbox("Is Oga (Admin)")
            
            submitted = st.form_submit_button("Add User")
            if submitted:
                if not new_username or not new_password:
                    st.error("Username and password are required.")
                else:
                    # Check if username already exists
                    existing_user = session.query(User).filter_by(username=new_username).first()
                    if existing_user:
                        st.error(f"Username '{new_username}' already exists.")
                    else:
                        new_user = User(
                            username=new_username,
                            password_hash=hash_password(new_password),
                            is_oga=is_oga
                        )
                        session.add(new_user)
                        session.commit()
                        st.success(f"User '{new_username}' added successfully.")
                        st.rerun()

# Main app logic
def main():
    # Show login form if not authenticated
    if not st.session_state.authenticated:
        show_login_form()
    else:
        # Show navbar and appropriate page
        show_navbar()
        
        # Display user info and role
        role = "Oga (Admin)" if st.session_state.is_oga else "Former (Limited)"
        st.sidebar.success(f"Logged in as: {st.session_state.username} ({role})")
        
        # Automatic redirection for formers trying to access restricted pages
        if not st.session_state.is_oga and st.session_state.current_page not in ["home", "submission"]:
            st.session_state.current_page = "submission"
            st.warning("You've been redirected to an accessible page.")
        
        # Show the appropriate page based on navigation
        if st.session_state.current_page == "home":
            show_home_page()
        elif st.session_state.current_page == "submission":
            show_submission_page()
        elif st.session_state.current_page == "statistics":
            show_statistics_page()
        elif st.session_state.current_page == "settings":
            show_settings_page()

if __name__ == "__main__":
    main()