app.py

import os
import tempfile
import time

import streamlit as st
from dotenv import load_dotenv
from langchain.callbacks.streaming_stdout import StreamingStdOutCallbackHandler
from langchain.chat_models import ChatOpenAI
from langchain.prompts import PromptTemplate
from langchain.schema import StrOutputParser
from langchain.vectorstores import Vectara

# Load environment variables from .env file
load_dotenv()

# Sidebar for PDF upload and API keys
with st.sidebar:
    st.header("Configuration")
    uploaded_file = st.file_uploader("Choose a PDF file", type=["pdf"])
    customer_id = st.text_input("Vectara Customer ID", value=os.getenv("CUSTOMER_ID", ""))
    api_key = st.text_input("Vectara API Key", value=os.getenv("API_KEY", ""))
    corpus_id = st.text_input("Vectara Corpus ID", value=str(os.getenv("CORPUS_ID", "")))
    openai_api_key = st.text_input("OpenAI API Key", value=os.getenv("OPENAI_API_KEY", ""))
    submit_button = st.button("Submit")

keys_provided = all([customer_id, api_key, corpus_id, openai_api_key])

if keys_provided:
    CUSTOMER_ID = customer_id
    API_KEY = api_key
    CORPUS_ID = int(corpus_id)
    OPENAI_API_KEY = openai_api_key

    vectara_client = Vectara(
        vectara_customer_id=CUSTOMER_ID,
        vectara_corpus_id=CORPUS_ID,
        vectara_api_key=API_KEY
    )

    # Function to get knowledge content from Vectara
    def get_knowledge_content(vectara, query, threshold=0.5):
        found_docs = vectara.similarity_search_with_score(
            query,
            score_threshold=threshold,
        )
        knowledge_content = ""
        for number, (score, doc) in enumerate(found_docs):
            knowledge_content += f"Document {number}: {found_docs[number][0].page_content}\n"
        return knowledge_content

    # Prompt and response setup
    prompt = PromptTemplate.from_template(
        """You are a professional and friendly Legal Consultant and you are helping a client with a legal issue. The client is asking you for advice on a legal issue. Just explain him in detail the answer and nothing else. This is the issue: {issue} 
        To assist him with his issue, you need to know the following information: {knowledge} 
        """
    )
    runnable = prompt | ChatOpenAI(streaming=True, callbacks=[StreamingStdOutCallbackHandler()], openai_api_key=OPENAI_API_KEY) | StrOutputParser()

    # Main Streamlit App
    st.title("Legal Consultation Chat")

    # Initialize chat history
    if "messages" not in st.session_state:
        st.session_state.messages = []

    # Display chat messages from history on app rerun
    for message in st.session_state.messages:
        with st.chat_message(message["role"]):
            st.markdown(message["content"])

    # Accept user input and run the main chat interaction
    if user_input := st.chat_input("Enter your issue:"):
        st.session_state.messages.append({"role": "user", "content": user_input})
        with st.chat_message("user"):
            st.markdown(user_input)

        knowledge_content = get_knowledge_content(vectara_client, user_input)
        response = runnable.invoke({"knowledge": knowledge_content, "issue": user_input})

        response_words = response.split()
        with st.chat_message("assistant"):
            message_placeholder = st.empty()
            full_response = ""
            for word in response_words:
                full_response += word + " "
                time.sleep(0.05)
                message_placeholder.markdown(full_response + "▌")
            message_placeholder.markdown(full_response)

        st.session_state.messages.append({"role": "assistant", "content": full_response})

    # Run when the submit button is pressed
    if submit_button and uploaded_file:
        with tempfile.NamedTemporaryFile(delete=False, suffix=".pdf") as tmpfile:
            tmpfile.write(uploaded_file.getvalue())
            tmp_filename = tmpfile.name

        try:
            vectara_client.add_files([tmp_filename])
            st.sidebar.success("PDF file successfully uploaded to Vectara!")
        except Exception as e:
            st.sidebar.error(f"An error occurred: {str(e)}")
        finally:
            os.remove(tmp_filename)  # Clean up temporary file
else:
    # Not all keys are provided, instruct the user to input them
    st.warning("Please input all required API keys in the sidebar to proceed.")