src/streamlit_app.py

import streamlit as st
from chain import GlossaryChain

MODEL_AVATAR_URL= "./mistral.jpeg"
EXAMPLE_PROMPTS = [
    "How is a data lake used at Vanderbilt University Medical Center?",
    "In a table, what are some of the greatest hurdles to healthcare in the United States?",
    "What does EDW stand for?",
    "Give me a Python code snippet that reads a dataframe from a Databricks Unity Catalog table.",
    "Write a short story about a country concert in Nashville, Tennessee.",
    "Tell me about maximum out-of-pocket costs for healthcare in the United States.",
]
TITLE = "Mistral AI🇫🇷 + LangChain🦜 + FAISS📘: VUMC Glossary Chatbot"
DESCRIPTION= """Welcome to the Mistral AI🇫🇷 + LangChain🦜 + FAISS📘: VUMC Glossary Chatbot! \n

**Overview and Usage**: This Hugging Face 🤗 Space demos a retrieval-augmented chat model built with Mistral AI. 

This AI assistant is built atop two Mistral AI🇫🇷 models: the **mistral-embed** model for the embedding and retrieval of information from the VUMC Glossary 
and the open-weights **open-mistral-7b** model for the generation of the response. The external information is embedded to and retrieved from a FAISS📘 vector store. LangChain🦜 is used to chain the models together into a working chatbot.

The model has been augmented with a glossary of terms specific to Vanderbilt University Medical Center.
The chat model has knowledge of terms like **EDW**, **HCERA**, **NRHA** and **thousands more**. (Ask the assistant if you don't know what any of these terms mean!) 

On the left is a sidebar of **Examples**; click any of these examples to issue the corresponding query to the chat model.

**Disclaimer**: The model has **no access to PHI**. \n

Please provide any additional, larger feedback, ideas, or issues to the email: **johngrahamreynolds@gmail.com**. Happy chatting!"""


st.set_page_config(layout="wide")

st.title(TITLE)
st.image("mistral.jpeg", caption="Mistral AI for Retrieval Augmented Generation", width=400)
st.markdown(DESCRIPTION)
st.markdown("\n")

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

if "messages" not in st.session_state:
    st.session_state["messages"] = []

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

def clear_chat_history():
    st.session_state["messages"] = []

st.button('Clear Chat', on_click=clear_chat_history)

# construct the chain
chain = GlossaryChain()

def last_role_is_user():
    return len(st.session_state["messages"]) > 0 and st.session_state["messages"][-1]["role"] == "user"

def get_last_question():
    return st.session_state["messages"][-1]["content"]

# If the assistant is the last message, we need to prompt the user
# If user is the last message, we need to retry the assistant.
def handle_user_input(user_input):
    with history:
        response_content = ""
        if last_role_is_user():
            # retry the assistant if the user tries to send a new message
            with st.chat_message("assistant", avatar=MODEL_AVATAR_URL):
                response_stream = chain.stream(user_input) # NOTE chaining does not currently process chat history for context
                response_content = st.write_stream(response_stream)
        
        else:
            st.session_state["messages"].append({"role": "user", "content": user_input})
            with st.chat_message("user", avatar="🧑‍💻"):
                st.markdown(user_input)
            with st.chat_message("assistant", avatar=MODEL_AVATAR_URL):
                response_stream = chain.stream(user_input) # NOTE chaining does not currently process chat history for context
                response_content = st.write_stream(response_stream)
        
        st.session_state["messages"].append({"role": "assistant", "content": response_content})


main = st.container()
with main:
    history = st.container(height=400)
    with history:
        for message in st.session_state["messages"]:
            avatar = "🧑‍💻"
            if message["role"] == "assistant":
                avatar = MODEL_AVATAR_URL
            with st.chat_message(message["role"], avatar=avatar):
                if message["content"] is not None:
                    st.markdown(message["content"])

    if prompt := st.chat_input("Type a message!", max_chars=5000):
        handle_user_input(prompt)
    st.markdown("\n") #add some space for iphone users


with st.sidebar:
    with st.container():
        st.title("Examples")
        for prompt in EXAMPLE_PROMPTS:
            st.button(prompt, args=(prompt,), on_click=handle_user_input)