Code Editor for app.py

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

# Database setup
class Base(DeclarativeBase):
    pass

class FoodEntry(Base):
    __tablename__ = 'food_entries'
    
    id = Column(Integer, primary_key=True)
    user = Column(String)
    food_item = Column(String)
    timestamp = Column(DateTime, default=datetime.utcnow)

engine = create_engine('sqlite:///food_tracker.db')
Base.metadata.create_all(bind=engine)

# Session state initialization
if 'logged_in' not in st.session_state:
    st.session_state.logged_in = False
if 'username' not in st.session_state:
    st.session_state.username = ''
if 'food_items' not in st.session_state:
    st.session_state.food_items = []

# App title
st.title('Mat Tracker')

# Login/Logout section
col1, col2 = st.columns(2)

with col1:
    if not st.session_state.logged_in:
        username = st.text_input('Username')
        if st.button('Log in'):
            st.session_state.logged_in = True
            st.session_state.username = username
            st.rerun()

with col2:
    if st.session_state.logged_in:
        if st.button('Log out'):
            # Save food items to database before logging out
            with Session(engine) as session:
                for food_item in st.session_state.food_items:
                    entry = FoodEntry(
                        user=st.session_state.username,
                        food_item=food_item
                    )
                    session.add(entry)
                session.commit()
            
            # Clear session state
            st.session_state.logged_in = False
            st.session_state.username = ''
            st.session_state.food_items = []
            st.rerun()

# Main app content
if st.session_state.logged_in:
    st.write(f'Logged in as: {st.session_state.username}')
    
    # Add new food item
    new_food = st.text_input('Enter food item')
    if st.button('Add food'):
        if new_food:
            st.session_state.food_items.append(new_food)
            st.success('Food item added!')
    
    # Display current food items
    if st.session_state.food_items:
        st.write('Your food items:')
        for idx, item in enumerate(st.session_state.food_items, 1):
            st.write(f'{idx}. {item}')
    else:
        st.write('No food items added yet.')

    # Display previous entries from database
    with Session(engine) as session:
        previous_entries = session.query(FoodEntry).filter_by(user=st.session_state.username).all()
        if previous_entries:
            st.write('Previous entries:')
            for entry in previous_entries:
                st.write(f'{entry.timestamp}: {entry.food_item}')