Code Editor for app.py

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

# Database setup
class Base(DeclarativeBase):
    pass

class Conversation(Base):
    __tablename__ = 'conversations'
    
    id = Column(Integer, primary_key=True)
    title = Column(String(200))
    created_at = Column(DateTime, default=datetime.utcnow)
    messages = relationship("Message", back_populates="conversation", cascade="all, delete-orphan")

class Message(Base):
    __tablename__ = 'messages'
    
    id = Column(Integer, primary_key=True)
    conversation_id = Column(Integer, ForeignKey('conversations.id'))
    role = Column(String(50))
    content = Column(Text)
    created_at = Column(DateTime, default=datetime.utcnow)
    conversation = relationship("Conversation", back_populates="messages")

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

def get_or_create_conversation(session, conversation_id=None):
    if conversation_id:
        return session.query(Conversation).filter_by(id=conversation_id).first()
    new_conv = Conversation(title=f"New Chat {datetime.now().strftime('%Y-%m-%d %H:%M')}")
    session.add(new_conv)
    session.commit()
    return new_conv

# Initialize session states
if 'current_conversation_id' not in st.session_state:
    st.session_state.current_conversation_id = None

# Page layout
st.title("ChatBot with History")

# Sidebar with conversation history
with st.sidebar:
    st.title("Conversations")
    
    # New chat button
    if st.button("New Chat"):
        st.session_state.current_conversation_id = None
        st.rerun()
    
    # List existing conversations
    with Session(engine) as session:
        conversations = session.query(Conversation).order_by(Conversation.created_at.desc()).all()
        for conv in conversations:
            if st.button(f"📝 {conv.title}", key=f"conv_{conv.id}"):
                st.session_state.current_conversation_id = conv.id
                st.rerun()

# Main chat interface
with Session(engine) as session:
    # Get or create conversation
    current_conversation = get_or_create_conversation(session, st.session_state.current_conversation_id)
    st.session_state.current_conversation_id = current_conversation.id
    
    # Display existing messages
    messages = session.query(Message).filter_by(conversation_id=current_conversation.id).order_by(Message.created_at).all()
    for message in messages:
        with st.chat_message(message.role):
            st.write(message.content)

    # Chat input
    if prompt := st.chat_input("Type your message here..."):
        # Display user message
        with st.chat_message("user"):
            st.write(prompt)
        
        # Save user message
        user_message = Message(
            conversation_id=current_conversation.id,
            role="user",
            content=prompt
        )
        session.add(user_message)
        
        # Generate and display assistant response
        assistant_response = f"You said: {prompt}\n\nThis is a demo response. In a real application, you would integrate with an AI model here."
        with st.chat_message("assistant"):
            st.write(assistant_response)
        
        # Save assistant message
        assistant_message = Message(
            conversation_id=current_conversation.id,
            role="assistant",
            content=assistant_response
        )
        session.add(assistant_message)
        
        session.commit()