app.py

import streamlit as st
from llama_index import VectorStoreIndex, ServiceContext, Document
from llama_index.llms import OpenAI
import openai
from llama_index import SimpleDirectoryReader
import pypdf

openai.api_key = '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'
st.header("Chat with the Streamlit docs 💬 📚")

if "messages" not in st.session_state.keys(): # Initialize the chat message history
    st.session_state.messages = [
        {"role": "assistant", "content": "Ask me a question about the decision by the UK Supreme Court in McDonald v Kensington"}
    ]

@st.cache_resource(show_spinner=False)
def load_data():
    with st.spinner(text="Loading and indexing the Streamlit docs – hang tight! This should take 1-2 minutes."):
        reader = SimpleDirectoryReader(input_dir="./data", recursive=True)
        docs = reader.load_data()
        service_context = ServiceContext.from_defaults(llm=OpenAI(model="gpt-3.5-turbo", temperature=0.5, system_prompt="Guide students in their exploration of topics by encouraging them to discover answers independently, rather than providing direct answers, to enhance their reasoning and analytical skills.\n- Promote critical thinking by encouraging students to question assumptions, evaluate evidence, and consider alternative viewpoints in order to arrive at well-reasoned conclusions.\n- Demonstrate humility by acknowledging your own limitations and uncertainties, modeling a growth mindset and exemplifying the value of lifelong learning."))
        index = VectorStoreIndex.from_documents(docs, service_context=service_context)
        return index

index = load_data()

chat_engine = index.as_chat_engine(chat_mode="condense_question", verbose=True)

if prompt := st.chat_input("Your question"): # Prompt for user input and save to chat history
    st.session_state.messages.append({"role": "user", "content": prompt})

for message in st.session_state.messages: # Display the prior chat messages
    with st.chat_message(message["role"]):
        st.write(message["content"])

# If last message is not from assistant, generate a new response
if st.session_state.messages[-1]["role"] != "assistant":
    with st.chat_message("assistant"):
        with st.spinner("Thinking..."):
            response = chat_engine.chat(prompt)
            st.write(response.response)
            message = {"role": "assistant", "content": response.response}
            st.session_state.messages.append(message) # Add response to message history