app.py

""" app.py

Question / answer over a collection of PDF documents using late interaction
ColBERT model for retrieval and DSPy+Mistral for answer generation.

:author: Didier Guillevic
:date: 2024-12-22
"""

import gradio as gr

import logging
logger = logging.getLogger(__name__)
logging.basicConfig(level=logging.INFO)

import os
import pdf_utils # utilities for pdf processing
import colbert_utils # utilities for to build a ColBERT retrieval model
import dspy_utils # utilities for building a DSPy based retrieval generation model

from tqdm.notebook import tqdm
import warnings
warnings.filterwarnings('ignore')


dspy_rag_model = None

def build_rag_model(files: list[str]) -> str:
    """Build a retrieval augmented model using given files to index.
    
    """
    global dspy_rag_model

    # Get the text from the pdf files
    documents = []
    metadatas = []
    for pdf_file in files:
        logger.info(f"Processing {pdf_file}")
        metadata = pdf_utils.get_metadata_info(pdf_file)
        text = pdf_utils.get_text_from_pdf(pdf_file)
        if text:
            documents.append(text)
            metadatas.append(metadata)
    
    # Build the ColBERT retrieval model
    colbert_base_model = 'antoinelouis/colbert-xm' # multilingual model
    colbert_index_name = 'OECD_HNW' # for web app, generate unique name with uuid.uuid4()
    retrieval_model = colbert_utils.build_colbert_model(
        documents,
        metadatas,
        pretrained_model=colbert_base_model, 
        index_name=colbert_index_name
    )

    # Instanatiate the DSPy based RAG model
    dspy_rag_model = dspy_utils.DSPyRagModel(retrieval_model)

    return "Done building RAG model."


def generate_response(question: str) -> list[str, str, str]:
    """Generate a response to a given question using the RAG model.
    
    """
    global dspy_rag_model

    if dspy_rag_model is None:
        return "RAG model not built. Please build the model first.", [], []

    # Generate response
    responses, references, snippets = dspy_rag_model.generate_response(
        question=question, k=5, method='chain_of_thought')
    
    return responses, references, snippets


with gr.Blocks() as demo:
    gr.Markdown("""
        # Retrieval (ColBERT) + Generation (DSPy & Mistral)
        - Note:
            - building the retrieval model will be slow on **free CPU** (expect 5+ minutes).
            - first question & answer will be slow (2 minutes for model loading). Subsequent question approx. 10 seconds.
        - Usage: upload a few PDF files to index. Build the model. Ask questions.
    """)

    # Input files and build status
    with gr.Row():
        upload_files = gr.File(
            label="Upload PDF files to index", file_count="multiple",
            value=["OECD_Dividend_tax_fraud_2023-en.pdf",],
            scale=5)
        build_status = gr.Textbox(label="Build status", placeholder="", scale=2)
    
    # button
    build_button = gr.Button("Build retrieval generation model", variant='primary')
    
    # Question to answer
    question = gr.Textbox(
        label="Question",
        placeholder="What is dividend stripping?"
    )
    response = gr.Textbox(
        label="Response",
        placeholder=""
    )
    with gr.Accordion("References & snippets", open=False):
        references = gr.HTML(label="References")
        snippets = gr.HTML(label="Snippets")
    
    # button
    response_button = gr.Button("Submit", variant='primary')
    
    # Example questions given default provided PDF file
    with gr.Accordion("Sample questions", open=False):
        gr.Examples(
            [
                ["What is dividend stripping?",],
                ["What are the most common types of dividend stripping schemes?",],
                ["How do authorities detect dividend stripping?",],
                ["What are some indicators of potential dividend stripping?",],
                ["What are the consequences of dividend stripping?",],
                ["How can countries combat dividend stripping?",],
                ["What is the role of professional enablers in dividend stripping?",],
                ["How can countries address the role of professional enablers in dividend stripping?",],
            ],
            inputs=[question,],
            outputs=[response, references, snippets],
            fn=generate_response,
            cache_examples=False,
            label="Sample questions"
        )
    
    # Documentation
    with gr.Accordion("Documentation", open=False):
        gr.Markdown("""
            - What
                - Retrieval augmented generation (RAG) model based on ColBERT and DSPy.
                - Retrieval base model:  'antoinelouis/colbert-xm' (multilingual model)
                - Generation framework: DSPy and Mistral.
            - How
                - Upload PDF files to index.
                - Build the retrieval generation model (might take a few minutes)
                - Ask a question about the content of those uploaded documents.
        """)

    # Click actions
    build_button.click(
        fn=build_rag_model,
        inputs=[upload_files],
        outputs=[build_status]
    )
    response_button.click(
        fn=generate_response,
        inputs=[question],
        outputs=[response, references, snippets]
    )


demo.launch(show_api=False)