interim/app.py

# to-do: Enable downloading multiple patent PDFs via corresponding links 
import sys
import os
import re
import shutil
import time
import fitz 
import streamlit as st
import nltk
import tempfile
import subprocess

# Pin NLTK to version 3.9.1
REQUIRED_NLTK_VERSION = "3.9.1"
subprocess.run([sys.executable, "-m", "pip", "install", f"nltk=={REQUIRED_NLTK_VERSION}"])

# Set up temporary directory for NLTK resources
nltk_data_path = os.path.join(tempfile.gettempdir(), "nltk_data")
os.makedirs(nltk_data_path, exist_ok=True)
nltk.data.path.append(nltk_data_path)

# Download 'punkt_tab' for compatibility
try:
    print("Ensuring NLTK 'punkt_tab' resource is downloaded...")
    nltk.download("punkt_tab", download_dir=nltk_data_path)
except Exception as e:
    print(f"Error downloading NLTK 'punkt_tab': {e}")
    raise e

sys.path.append(os.path.abspath("."))
from langchain.chains import ConversationalRetrievalChain
from langchain.memory import ConversationBufferMemory
from langchain.llms import OpenAI
from langchain.document_loaders import UnstructuredPDFLoader
from langchain.vectorstores import Chroma
from langchain.embeddings import HuggingFaceEmbeddings
from langchain.text_splitter import NLTKTextSplitter
from patent_downloader import PatentDownloader
from langchain.document_loaders import PyMuPDFLoader
from langchain.text_splitter import RecursiveCharacterTextSplitter

PERSISTED_DIRECTORY = tempfile.mkdtemp()

# Fetch API key securely from the environment
OPENAI_API_KEY = os.getenv("OPENAI_API_KEY")
if not OPENAI_API_KEY:
    st.error("Critical Error: OpenAI API key not found in the environment variables. Please configure it.")
    st.stop()

def check_poppler_installed():
    if not shutil.which("pdfinfo"):
        raise EnvironmentError(
            "Poppler is not installed or not in PATH. Install 'poppler-utils' for PDF processing."
        )

check_poppler_installed()

def load_docs(document_path):
    """
    Load and clean the PDF content, then split into chunks.
    """
    try:
        import fitz  # PyMuPDF for text extraction

        # Step 1: Extract plain text from PDF
        doc = fitz.open(document_path)
        extracted_text = []

        for page_num, page in enumerate(doc):
            page_text = page.get_text("text")  # Extract text
            clean_page_text = clean_extracted_text(page_text)
            if clean_page_text:  # Keep only non-empty cleaned text
                extracted_text.append(clean_page_text)

        doc.close()

        # Combine all pages into one text
        full_text = "\n".join(extracted_text)
        st.write(f"📄 Total Cleaned Text Length: {len(full_text)} characters")

        # Step 2: Chunk the cleaned text
        text_splitter = RecursiveCharacterTextSplitter(
            chunk_size=1000,
            chunk_overlap=100,
            separators=["\n\n", "\n", " ", ""]
        )
        split_docs = text_splitter.create_documents([full_text])

        # Debug: Show total chunks count and first 3 chunks for verification
        st.write(f"🔍 Total Chunks After Splitting: {len(split_docs)}")
        for i, doc in enumerate(split_docs[:3]):  # Show first 3 chunks only
            st.write(f"Chunk {i + 1}: {doc.page_content[:300]}...")

        return split_docs
    except Exception as e:
        st.error(f"Failed to load and process PDF: {e}")
        st.stop()


def clean_extracted_text(text):
    """
    Cleans extracted text to remove metadata, headers, and irrelevant content.
    """
    lines = text.split("\n")
    cleaned_lines = []

    for line in lines:
        line = line.strip()

        # Filter out lines with metadata patterns
        if (
            re.match(r"^(U\.S\.|United States|Sheet|Figure|References|Patent No|Date of Patent)", line)
            or re.match(r"^\(?\d+\)?$", line)  # Matches single numbers (page numbers)
            or "Examiner" in line
            or "Attorney" in line
            or len(line) < 30  # Skip very short lines
        ):
            continue

        cleaned_lines.append(line)

    return "\n".join(cleaned_lines)


def already_indexed(vectordb, file_name):
    indexed_sources = set(
        x["source"] for x in vectordb.get(include=["metadatas"])["metadatas"]
    )
    return file_name in indexed_sources

def load_chain(file_name=None):
    """
    Load cleaned PDF text, split into chunks, and update the vectorstore.
    """
    loaded_patent = st.session_state.get("LOADED_PATENT")

    # Debug: Show persist directory
    st.write(f"🗂 Using Persisted Directory: {PERSISTED_DIRECTORY}")

    vectordb = Chroma(
        persist_directory=PERSISTED_DIRECTORY,
        embedding_function=HuggingFaceEmbeddings(),
    )

    if loaded_patent == file_name or already_indexed(vectordb, file_name):
        st.write("✅ Already indexed.")
    else:
        st.write("🔄 Starting document processing and vectorstore update...")

        # Remove existing collection and load new docs
        vectordb.delete_collection()
        docs = load_docs(file_name)

        # Update vectorstore
        vectordb = Chroma.from_documents(
            docs, HuggingFaceEmbeddings(), persist_directory=PERSISTED_DIRECTORY
        )
        vectordb.persist()
        st.write("✅ Vectorstore successfully updated and persisted.")

        # Save loaded patent in session state
        st.session_state["LOADED_PATENT"] = file_name

    # Debug: Check vectorstore indexing summary
    indexed_docs = vectordb.get(include=["documents"])
    st.write(f"✅ Total Indexed Documents: {len(indexed_docs['documents'])}")

    # Test retrieval with a simple query
    retriever = vectordb.as_retriever(search_kwargs={"k": 3})
    test_query = "What is this document about?"
    results = retriever.get_relevant_documents(test_query)

    st.write("🔍 Test Retrieval Results for Query:")
    if results:
        for i, res in enumerate(results):
            st.write(f"Retrieved Doc {i + 1}: {res.page_content[:200]}...")
    else:
        st.warning("No documents retrieved for test query.")

    # Configure memory for conversation
    memory = ConversationBufferMemory(
        memory_key="chat_history",
        return_messages=True
    )

    return ConversationalRetrievalChain.from_llm(
        OpenAI(temperature=0, openai_api_key=OPENAI_API_KEY),
        retriever,
        memory=memory
    )


def extract_patent_number(url):
    pattern = r"/patent/([A-Z]{2}\d+)"
    match = re.search(pattern, url)
    return match.group(1) if match else None

def download_pdf(patent_number):
    try:
        patent_downloader = PatentDownloader(verbose=True)
        output_path = patent_downloader.download(patents=patent_number, output_path=tempfile.gettempdir())
        return output_path[0]
    except Exception as e:
        st.error(f"Failed to download patent PDF: {e}")
        st.stop()

def preview_pdf(pdf_path, scale_factor=0.5):
    """
    Generate and display a resized preview of the first page of the PDF.
    Args:
        pdf_path (str): Path to the PDF file.
        scale_factor (float): Factor to reduce the image size (default is 0.5).
    Returns:
        str: Path to the resized image preview.
    """
    try:
        # Open the PDF and extract the first page
        doc = fitz.open(pdf_path)
        first_page = doc[0]
        
        # Apply scaling using a transformation matrix
        matrix = fitz.Matrix(scale_factor, scale_factor)  # Scale down the image
        pix = first_page.get_pixmap(matrix=matrix)  # Generate scaled image
        
        # Save the preview image
        temp_image_path = os.path.join(tempfile.gettempdir(), "pdf_preview.png")
        pix.save(temp_image_path)
        
        doc.close()
        return temp_image_path
    
    except Exception as e:
        st.error(f"Error generating PDF preview: {e}")
        return None


if __name__ == "__main__":
    st.set_page_config(
        page_title="Patent Chat: Google Patents Chat Demo",
        page_icon="📖",
        layout="wide",
        initial_sidebar_state="expanded",
    )
    st.header("📖 Patent Chat: Google Patents Chat Demo")

    # Input for Google Patent Link
    patent_link = st.text_area(
        "Enter Google Patent Link:", 
        value="https://patents.google.com/patent/US8676427B1/en", 
        height=90
    )

    # Initialize session state
    for key in ["LOADED_PATENT", "pdf_preview", "loaded_pdf_path", "chain", "messages"]:
        if key not in st.session_state:
            st.session_state[key] = None

    # Button to load and process patent
    if st.button("Load and Process Patent"):
        if not patent_link:
            st.warning("Please enter a valid Google patent link.")
            st.stop()

        # Extract patent number
        patent_number = extract_patent_number(patent_link)
        if not patent_number:
            st.error("Invalid patent link format.")
            st.stop()

        st.write(f"Patent number: **{patent_number}**")

        # File handling
        pdf_path = os.path.join(tempfile.gettempdir(), f"{patent_number}.pdf")
        if not os.path.isfile(pdf_path):
            with st.spinner("📥 Downloading patent file..."):
                try:
                    pdf_path = download_pdf(patent_number)
                    st.write(f"✅ File downloaded: {pdf_path}")
                except Exception as e:
                    st.error(f"Failed to download patent: {e}")
                    st.stop()
        else:
            st.write("✅ File already downloaded.")

        # Generate PDF preview only if not already displayed
        if not st.session_state.get("pdf_preview_displayed", False):
            with st.spinner("🖼️ Generating PDF preview..."):
                preview_image_path = preview_pdf(pdf_path, scale_factor=0.5)
                if preview_image_path:
                    st.session_state.pdf_preview = preview_image_path
                    st.image(preview_image_path, caption="First Page Preview", use_container_width=False)
                    st.session_state["pdf_preview_displayed"] = True
                else:
                    st.warning("Failed to generate PDF preview.")
                    st.session_state.pdf_preview = None

        # Load the document into the system
        with st.spinner("🔄 Loading document into the system..."):
            try:
                st.session_state.chain = load_chain(pdf_path)
                st.session_state.LOADED_PATENT = patent_number
                st.session_state.loaded_pdf_path = pdf_path
                st.session_state.messages = [{"role": "assistant", "content": "Hello! How can I assist you with this patent?"}]
                st.success("🚀 Document successfully loaded! You can now start asking questions.")
            except Exception as e:
                st.error(f"Failed to load the document: {e}")
                st.stop()

    # Display previous chat messages
    if st.session_state.messages:
        for message in st.session_state.messages:
            with st.chat_message(message["role"]):
                st.markdown(message["content"])

    # User input for questions
    if st.session_state.chain:
        if user_input := st.chat_input("What is your question?"):
            # User message
            st.session_state.messages.append({"role": "user", "content": user_input})
            with st.chat_message("user"):
                st.markdown(user_input)

            # Assistant response
            with st.chat_message("assistant"):
                message_placeholder = st.empty()
                full_response = ""

                with st.spinner("Generating response..."):
                    try:
                        # Generate response using the chain
                        assistant_response = st.session_state.chain({"question": user_input})
                        full_response = assistant_response.get("answer", "I'm sorry, I couldn't process that question.")
                    except Exception as e:
                        full_response = f"An error occurred: {e}"

                message_placeholder.markdown(full_response)
                st.session_state.messages.append({"role": "assistant", "content": full_response})
    else:
        st.info("Press the 'Load and Process Patent' button to start processing.")