app.py

import gradio as gr
from huggingface_hub import InferenceClient
from langchain.chains import ConversationalRetrievalChain
from langchain.vectorstores import FAISS
from langchain.embeddings import HuggingFaceEmbeddings
from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain.document_loaders import PyPDFLoader
import tempfile

# Initialize global variables
vectorstore = None
retrieval_chain = None


def process_pdf(file):
    global vectorstore, retrieval_chain

    # `file` is a gradio.NamedString → use file.name to get the path
    tmp_path = file.name  

    # Load PDF
    loader = PyPDFLoader(tmp_path)
    documents = loader.load()

    # Split into chunks
    text_splitter = RecursiveCharacterTextSplitter(chunk_size=1000, chunk_overlap=200)
    docs = text_splitter.split_documents(documents)

    # Create embeddings and FAISS vectorstore
    embeddings = HuggingFaceEmbeddings()
    vectorstore = FAISS.from_documents(docs, embeddings)

    # Setup retrieval chain
    retriever = vectorstore.as_retriever()
    retriever.search_kwargs["k"] = 4

    client = InferenceClient(model="deepseek-ai/DeepSeek-R1-0528")

    retrieval_chain = ConversationalRetrievalChain.from_llm(
        llm=client,
        retriever=retriever,
        return_source_documents=True
    )

    return "PDF processed. You can now ask questions!"


def respond(
    message,
    history: list[dict[str, str]],
    system_message,
    max_tokens,
    temperature,
    top_p,
    hf_token: gr.OAuthToken,
):
    global retrieval_chain

    if retrieval_chain is None:
        return "Please upload a PDF first."

    # Reformat history for LangChain
    chat_history = [(h["content"], h.get("response", "")) for h in history if h["role"] == "user"]

    result = retrieval_chain({"question": message, "chat_history": chat_history})

    return result["answer"]


chatbot = gr.ChatInterface(
    respond,
    type="messages",
    additional_inputs=[
        gr.Textbox(value="You are a friendly Chatbot.", label="System message"),
        gr.Slider(minimum=1, maximum=2048, value=512, step=1, label="Max new tokens"),
        gr.Slider(minimum=0.1, maximum=4.0, value=0.7, step=0.1, label="Temperature"),
        gr.Slider(
            minimum=0.1,
            maximum=1.0,
            value=0.95,
            step=0.05,
            label="Top-p (nucleus sampling)",
        ),
    ],
)

with gr.Blocks() as demo:
    with gr.Sidebar():
        gr.LoginButton()
        pdf_upload = gr.File(label="Upload PDF", file_types=[".pdf"])
        pdf_upload.upload(process_pdf, inputs=pdf_upload, outputs=[])
    chatbot.render()


if __name__ == "__main__":
    demo.launch()