app.py

import logging
from typing import Optional

import openai
import streamlit as st
from langchain_core.messages import AIMessage, HumanMessage

from rag.runnable_and_memory import get_runnable_and_memory
from utils.error_message_template import ERROR_MESSAGE

logging.basicConfig(level=logging.ERROR)


# Streamlit page configuration
st.set_page_config(
    page_title="ELLA AI Assistant",
    page_icon="💬",
    layout="centered",
    initial_sidebar_state="collapsed",
)

# CSS
with open("styles/styles.css") as css:
    st.markdown(f"<style>{css.read()}</style>", unsafe_allow_html=True)


def initialize_session_state():
    # Initialize the runnable and memory
    if "runnable" not in st.session_state:
        try:
            st.session_state["runnable"], st.session_state["memory"] = (
                get_runnable_and_memory(model="gpt-4o", temperature=0)
            )
            # Clear the memory
            st.session_state["memory"].clear()
        except Exception:
            handle_errors()

    # Other session state variables
    if "chat_history" not in st.session_state:
        st.session_state["chat_history"] = []

    if "selected_location" not in st.session_state:
        st.session_state["selected_location"] = None

    if "disable_chat_input" not in st.session_state:
        st.session_state["disable_chat_input"] = True


@st.cache_resource
def load_avatars():
    return {
        "Human": "images/user.png",
        "AI": "images/tall-tree-logo.png",
    }


# Disable chat input if no location is selected
def on_change_location():
    st.session_state["disable_chat_input"] = (
        False if st.session_state["selected_location"] else True
    )


def app_layout():
    with st.container():
        # Welcome message
        st.markdown(
            "Hello there! 👋 Need help finding the right service or practitioner? Let our AI assistant give you a hand.\n\n"
            "To get started, please select your preferred location and share details about your symptoms or needs. "
        )

        # Selectbox for location preferences
        st.radio(
            "**Our Locations**:",
            (
                "Cordova Bay - Victoria",
                "James Bay - Victoria",
                "Commercial Drive - Vancouver",
            ),
            index=None,
            label_visibility="visible",
            key="selected_location",
            on_change=on_change_location,
        )
        st.markdown("<br>", unsafe_allow_html=True)


def handle_errors(error: Optional[Exception] = None):
    st.warning(error if error else ERROR_MESSAGE, icon="🙁")
    st.stop()


# Chat app logic
if __name__ == "__main__":
    initialize_session_state()
    app_layout()

    # Render conversation
    avatars = load_avatars()
    for message in st.session_state["chat_history"]:
        if isinstance(message, AIMessage):
            with st.chat_message("AI", avatar=avatars["AI"]):
                st.write(message.content)
        elif isinstance(message, HumanMessage):
            with st.chat_message("Human", avatar=avatars["Human"]):
                st.write(message.content)

    # Get user input only if a location is selected
    user_input = st.chat_input(
        "Ask ELLA...", disabled=st.session_state["disable_chat_input"]
    )

    # Chat interface
    if user_input and user_input.strip():
        st.session_state["chat_history"].append(HumanMessage(content=user_input))

        # Append the location to the user input (important!)
        user_query_location = (
            f"{user_input}\nLocation: {st.session_state.selected_location}."
        )

        # Render the user input
        with st.chat_message("Human", avatar=avatars["Human"]):
            st.write(user_input)

        # Render the AI response
        with st.chat_message("AI", avatar=avatars["AI"]):
            try:
                with st.spinner(" "):
                    response = st.write_stream(
                        st.session_state["runnable"].stream(
                            {"user_query": user_query_location}
                        )
                    )
            except openai.BadRequestError:
                handle_errors()
            except Exception:
                handle_errors()

        # Add AI response to the message history
        st.session_state["chat_history"].append(AIMessage(content=response))

        # Update runnable memory
        st.session_state["memory"].chat_memory.add_user_message(
            HumanMessage(content=user_query_location)
        )
        st.session_state["memory"].chat_memory.add_ai_message(
            AIMessage(content=response)
        )