app.py

import re
from langchain_openai import OpenAIEmbeddings
from langchain_openai import ChatOpenAI
from langchain_openai.embeddings import OpenAIEmbeddings

from langchain.prompts import ChatPromptTemplate
from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain.schema import StrOutputParser

from langchain_community.document_loaders import PyMuPDFLoader
from langchain_community.vectorstores import Qdrant

from langchain_core.runnables import RunnablePassthrough, RunnableParallel
from langchain_core.documents import Document

from operator import itemgetter
import os
from dotenv import load_dotenv
import chainlit as cl
from langchain.embeddings.base import Embeddings
from sentence_transformers import SentenceTransformer

# Load environment variables
load_dotenv()

# Custom wrapper for SentenceTransformer to work with Langchain
class LangchainSentenceTransformerEmbeddings(Embeddings):
    def __init__(self, model_name: str):
        self.model = SentenceTransformer(model_name)

    def embed_documents(self, texts: list[str]) -> list[list[float]]:
        # Encode the documents using SentenceTransformer's encode method
        return self.model.encode(texts)

    def embed_query(self, text: str) -> list[float]:
        # Encode a single query using SentenceTransformer's encode method
        return self.model.encode([text])[0]

# Initialize the custom embedding model
embedding_model = LangchainSentenceTransformerEmbeddings("Cheselle/finetuned-arctic-sentence")

# Load the documents using PyMuPDFLoader
ai_framework_document = PyMuPDFLoader(file_path="https://nvlpubs.nist.gov/nistpubs/ai/NIST.AI.600-1.pdf").load()
ai_blueprint_document = PyMuPDFLoader(file_path="https://www.whitehouse.gov/wp-content/uploads/2022/10/Blueprint-for-an-AI-Bill-of-Rights.pdf").load()

# Metadata generator function to add metadata to documents
def metadata_generator(document, name):
    fixed_text_splitter = RecursiveCharacterTextSplitter(
        chunk_size=500,
        chunk_overlap=100,
        separators=["\n\n", "\n", ".", "!", "?"]
    )
    collection = fixed_text_splitter.split_documents(document)
    for doc in collection:
        doc.metadata["source"] = name
    return collection

# Generate metadata for the loaded documents
recursive_framework_document = metadata_generator(ai_framework_document, "AI Framework")
recursive_blueprint_document = metadata_generator(ai_blueprint_document, "AI Blueprint")
combined_documents = recursive_framework_document + recursive_blueprint_document

# Combine the content of the documents
ai_framework_text = "".join([doc.page_content for doc in ai_framework_document])
ai_blueprint_text = "".join([doc.page_content for doc in ai_blueprint_document])

# Pass the custom embedding model to Qdrant to create a vectorstore
vectorstore = Qdrant.from_documents(
    documents=combined_documents,  # List of documents
    embedding=embedding_model,     # Custom Langchain wrapper for SentenceTransformer
    location=":memory:",
    collection_name="ai_policy"
)

# Set up the retriever
retriever = vectorstore.as_retriever()

# LLM configuration
llm = ChatOpenAI(model="gpt-4o-mini")

# Define the RAG (Retrieval-Augmented Generation) prompt template
RAG_PROMPT = """\
You are an AI Policy Expert. 
Given a provided context and question, you must answer the question based only on context. 
Think through your answer carefully and step by step. 
Context: {context}
Question: {question}
"""

rag_prompt = ChatPromptTemplate.from_template(RAG_PROMPT)

# Define the retrieval-augmented QA chain
retrieval_augmented_qa_chain = (
    {"context": itemgetter("question") | retriever, "question": itemgetter("question")}
    | RunnablePassthrough.assign(context=itemgetter("context"))
    | {"response": rag_prompt | llm, "context": itemgetter("context")}
)

# Chainlit event handler for receiving messages
@cl.on_message
async def handle_message(message):
    try:
        # Process the incoming question using the RAG chain
        result = retrieval_augmented_qa_chain.invoke({"question": message.content})

        # Create a new message for the response
        response_message = cl.Message(content=result["response"].content)

        # Send the response back to the user
        await response_message.send()
    
    except Exception as e:
        # Handle any exception and log it or send a response back to the user
        error_message = cl.Message(content=f"An error occurred: {str(e)}")
        await error_message.send()
        print(f"Error occurred: {e}")

# Run the Chainlit server
if __name__ == "__main__":
    try:
        cl.run()
    except Exception as e:
        print(f"Server error occurred: {e}")