midterm.py

import os
from dotenv import load_dotenv
import openai
import chainlit as cl
from langchain_community.document_loaders import PyMuPDFLoader
from operator import itemgetter
from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain.schema.output_parser import StrOutputParser
from langchain.schema.runnable import RunnablePassthrough
from langchain.schema.runnable.config import RunnableConfig
from langchain import hub
from langchain_community.vectorstores import Qdrant
from langchain.prompts import ChatPromptTemplate
from langchain_openai import OpenAIEmbeddings
from langchain_openai import ChatOpenAI
import json

load_dotenv()

OPENAI_API_KEY = os.environ["OPENAI_API_KEY"]
openai.api_key = OPENAI_API_KEY

# Load PDF
loader = PyMuPDFLoader("AirBnB10Q.pdf")
documents = loader.load()

# Split Document
text_splitter = RecursiveCharacterTextSplitter(
    chunk_size=300,
    chunk_overlap=50
)
documents = text_splitter.split_documents(documents)

# Load OpenAI Embeddings
embeddings = OpenAIEmbeddings(model="text-embedding-ada-002")

# Load Qdrant Vector Store
qdrant_vector_store = Qdrant.from_documents(
    documents,
    embeddings,
    location=":memory:",
    collection_name="AirBnB10Q"
)
retriever = qdrant_vector_store.as_retriever()

# Pull LangChain QA Prompt Template
retrieval_qa_prompt = hub.pull("langchain-ai/retrieval-qa-chat")

template = """Answer the question based only on the following context. If you cannot answer the question with the context, please respond with 'I don't know':

Context:
{context}

Question:
{query}
"""

rag_prompt = ChatPromptTemplate.from_template(template)
qa_llm = ChatOpenAI(model_name="gpt-4o", temperature=0)

@cl.on_chat_start
async def start_chat():
    """
    This function will be called at the start of every user session. 

    We will build our LCEL RAG chain here, and store it in the user session. 

    The user session is a dictionary that is unique to each user session, and is stored in the memory of the server.
    """

    ### BUILD LCEL RAG CHAIN THAT ONLY RETURNS TEXT
    lcel_rag_chain = (
        {"context": itemgetter("query") | retriever, "query": itemgetter("query")}
        | rag_prompt | qa_llm
    )

    cl.user_session.set("lcel_rag_chain", lcel_rag_chain)

@cl.on_message  
async def main(message: cl.Message):
    """
    This function will be called every time a message is recieved from a session.

    We will use the LCEL RAG chain to generate a response to the user query.

    The LCEL RAG chain is stored in the user session, and is unique to each user session - this is why we can access it here.
    """
    lcel_rag_chain = cl.user_session.get("lcel_rag_chain")

    msg = cl.Message(content="")

    async for chunk in lcel_rag_chain.astream(
        {"query": message.content},
        config=RunnableConfig(callbacks=[cl.LangchainCallbackHandler()]),
    ):
        if isinstance(chunk, dict) and 'content' in chunk:
            await msg.stream_token(chunk['content'])
        elif hasattr(chunk, 'content'):
            await msg.stream_token(chunk.content)
        elif isinstance(chunk, str):
            await msg.stream_token(chunk)

    await msg.send()