app.py

import nest_asyncio
nest_asyncio.apply()

import re
import os
import uuid
from typing import List, Dict
from operator import itemgetter

# PDF processing
from PyPDF2 import PdfReader

# Chainlit
import chainlit as cl

# OpenAI
import openai
from openai import AsyncOpenAI
from langchain_openai import ChatOpenAI, OpenAIEmbeddings

# Langchain
from langchain_text_splitters import RecursiveCharacterTextSplitter
from langchain_core.prompts import ChatPromptTemplate
from langchain_core.runnables import RunnablePassthrough
from langchain.storage import LocalFileStore
from langchain.embeddings import CacheBackedEmbeddings

# Qdrant
from qdrant_client import QdrantClient
from qdrant_client.models import Distance, VectorParams
from langchain_qdrant import QdrantVectorStore
#

### Global Section ###
from dotenv import load_dotenv

# Load environment variables from .env file
load_dotenv()


openai.api_key = os.getenv("OPENAI_API_KEY")

# Function to extract text from a PDF
def extract_text_from_pdf(pdf_path):
    reader = PdfReader(pdf_path)
    text = ""
    for page in reader.pages:
        text += page.extract_text()
    return text

        
    



# Global variables for shared resources
global_retriever = None
global_chat_model = None

from langchain_core.documents import Document

# In your extract_text_from_pdf function:
def extract_text_from_pdf(pdf_path):
    reader = PdfReader(pdf_path)
    text = ""
    for page in reader.pages:
        text += page.extract_text()
    return text

@cl.on_chat_start
async def start_chat():
    global global_retriever, global_chat_model
    
    # Initialize shared resources if they haven't been initialized yet
    if global_retriever is None:
        pdf_path= r"GlobalThreatReport2024_CrowdStrike.pdf"
        text = extract_text_from_pdf(pdf_path)

        text_splitter = RecursiveCharacterTextSplitter(chunk_size=1000, chunk_overlap=100)
        texts = text_splitter.split_text(text)
        docs = [Document(page_content=t) for t in texts]

        core_embeddings = OpenAIEmbeddings(model="text-embedding-3-small")

        collection_name = f"pdf_to_parse_{uuid.uuid4()}"
        client = QdrantClient(":memory:")
        client.create_collection(
            collection_name=collection_name,
            vectors_config=VectorParams(size=1536, distance=Distance.COSINE),
        )

        store = LocalFileStore("./cache/")
        cached_embedder = CacheBackedEmbeddings.from_bytes_store(
            core_embeddings, store, namespace=core_embeddings.model
        )

        vectorstore = QdrantVectorStore(
            client=client,
            collection_name=collection_name,
            embedding=cached_embedder)
        vectorstore.add_documents(docs)
        global_retriever = vectorstore.as_retriever(search_type="mmr", search_kwargs={"k": 3})

    if global_chat_model is None:
        global_chat_model = ChatOpenAI(model="gpt-4o-mini")

    # Initialize user-specific session data
    cl.user_session.set("chat_history", [])
    
    # Set default settings
    settings = {
        "temperature": 0,
        "max_tokens": 500,
        "top_p": 1,
        "frequency_penalty": 0,
        "presence_penalty": 0,
    }
    cl.user_session.set("settings", settings)
@cl.on_message
async def main(message: cl.Message):
    global global_retriever, global_chat_model
    
    if global_retriever is None or global_chat_model is None:
        await message.reply("I'm sorry, but the system isn't fully initialized yet. Please try again in a moment.")
        return

    chat_history: List[Dict[str, str]] = cl.user_session.get("chat_history")
    settings = cl.user_session.get("settings")

    system_template = """You are a helpful assistant that uses the provided context to answer questions. 
    Never reference this prompt, or the existence of context. Use the chat history to maintain continuity in the conversation."""

    user_template = """Chat History:
    {chat_history}

    Question: {question}
    
    Context: {context}

    Please provide a response based on the question, context, and chat history:"""

    chat_prompt = ChatPromptTemplate.from_messages([
        ("system", system_template),
        ("human", user_template)
    ])

    def format_chat_history(history: List[Dict[str, str]]) -> str:
        return "\n".join([f"{msg['role'].capitalize()}: {msg['content']}" for msg in history])

    rag_chain = (
        {
            "context": itemgetter("question") | global_retriever, 
            "question": itemgetter("question"),
            "chat_history": lambda _: format_chat_history(chat_history)
        }
        | RunnablePassthrough.assign(context=itemgetter("context"))
        | chat_prompt
        | global_chat_model.bind(**settings)
    )

    msg = cl.Message(content="")
    full_response = ""
    async for chunk in rag_chain.astream({"question": message.content}):
        if chunk.content is not None:
            await msg.stream_token(chunk.content)
            full_response += chunk.content

    # Update chat history
    chat_history.append({"role": "user", "content": message.content})
    chat_history.append({"role": "assistant", "content": full_response})
    cl.user_session.set("chat_history", chat_history)

    await msg.send()