app.py

import os
import chainlit as cl
from dotenv import load_dotenv
from operator import itemgetter
from langchain_community.vectorstores import Qdrant
from qdrant_client import QdrantClient
from langchain_openai.chat_models import ChatOpenAI
from langchain_text_splitters import RecursiveCharacterTextSplitter
from langchain.prompts import ChatPromptTemplate
from langchain.schema.output_parser import StrOutputParser
from langchain_openai import OpenAIEmbeddings
from helpers import process_file, add_to_qdrant


load_dotenv()

embeddings = OpenAIEmbeddings(model="text-embedding-3-small")
llm = ChatOpenAI(model="gpt-4")
qdrant_client = QdrantClient(url=constants.QDRANT_ENDPOINT, api_key=constants.QDRANT_API_KEY) # TO DO: Add constants, info from Mark
collection_name = "marketing_data"

RAG_PROMPT_TEMPLATE = """\
<|start_header_id|>system<|end_header_id|>
You are a helpful assistant. You answer user questions based on provided context. If you can't answer the question with the provided context, say you don't know.<|eot_id|>
<|start_header_id|>user<|end_header_id|>
User Query:
{query}
Context:
{context}<|eot_id|>
<|start_header_id|>assistant<|end_header_id|>
"""

rag_prompt = ChatPromptTemplate.from_template(RAG_PROMPT_TEMPLATE)

### On Chat Start (Session Start) ###
@cl.on_chat_start
async def on_chat_start():
    files = None

    # Wait for the user to upload a file
    while files == None:
        files = await cl.AskFileMessage(
            content="Please ask a question or upload a Text or PDF File file to begin!",
            accept=["text/plain", "application/pdf"],
            max_size_mb=2,
            timeout=180,
        ).send()

    file = files[0]
    
    msg = cl.Message(
        content=f"Processing `{file.name}`...", disable_human_feedback=True
    )
    await msg.send()

    # load the file
    docs = process_file(file)
    for i, doc in enumerate(docs):
        doc.metadata["source"] = f"source_{i}" # TO DO: Add metadata
        add_to_qdrant(doc, embeddings, qdrant_client, collection_name)
    print(f"Processing {len(docs)} text chunks")

    # Create the vectorstore
    text_splitter = RecursiveCharacterTextSplitter(chunk_size=1000, chunk_overlap=200)
    splits = text_splitter.split_documents(docs)
    
    vectorstore = Qdrant.from_documents(
        documents=splits,
        embedding=embeddings,
        location=":memory:"  # TO DO: Add Qdrant server URL
    )
    retriever = vectorstore.as_retriever()
    
    # Create a chain
    rag_chain = (
        {"context": itemgetter("question") | retriever, "question": itemgetter("question")}
        | rag_prompt | llm | StrOutputParser()
    )
    
    # Let the user know that the system is ready
    msg.content = f"Processing `{file.name}` done. You can now ask questions!"
    await msg.update()
    cl.user_session.set("chain", rag_chain)

@cl.on_message  
async def main(message: cl.Message):
    chain = cl.user_session.get("chain")
    result = chain.invoke({"question":message.content})
    msg = cl.Message(content=result)

    await msg.send()