app.py

import streamlit as st
import os
import json
import requests
import pdfplumber
import chromadb
import re
from langchain.document_loaders import PDFPlumberLoader
from langchain_huggingface import HuggingFaceEmbeddings
from langchain_experimental.text_splitter import SemanticChunker
from langchain_chroma import Chroma
from langchain.chains import LLMChain
from langchain.prompts import PromptTemplate
from langchain_groq import ChatGroq
from prompts import rag_prompt, relevancy_prompt, relevant_context_picker_prompt, response_synth

# ----------------- Streamlit UI Setup -----------------
st.set_page_config(page_title="Blah-1", layout="centered")

# ----------------- API Keys -----------------
os.environ["GROQ_API_KEY"] = st.secrets.get("GROQ_API_KEY", "")

# Load LLM models
llm_judge = ChatGroq(model="deepseek-r1-distill-llama-70b")
rag_llm = ChatGroq(model="mixtral-8x7b-32768")

llm_judge.verbose = True
rag_llm.verbose = True

# Clear ChromaDB cache to fix tenant issue
chromadb.api.client.SharedSystemClient.clear_system_cache()


# ----------------- ChromaDB Persistent Directory -----------------
CHROMA_DB_DIR = "/mnt/data/chroma_db" 
os.makedirs(CHROMA_DB_DIR, exist_ok=True)

# ----------------- Initialize Session State -----------------
if "pdf_loaded" not in st.session_state:
    st.session_state.pdf_loaded = False
if "chunked" not in st.session_state:
    st.session_state.chunked = False
if "vector_created" not in st.session_state:
    st.session_state.vector_created = False
if "processed_chunks" not in st.session_state:
    st.session_state.processed_chunks = None
if "vector_store" not in st.session_state:
    st.session_state.vector_store = None


# ----------------- Text Cleaning Functions -----------------
def clean_extracted_text(text):
    """
    Cleans extracted PDF text by removing excessive line breaks, fixing spacing issues, and resolving OCR artifacts.
    """
    text = re.sub(r'\n+', '\n', text)  # Remove excessive newlines
    text = re.sub(r'\s{2,}', ' ', text)  # Remove extra spaces
    text = re.sub(r'(\w)-\n(\w)', r'\1\2', text)  # Fix hyphenated words split by a newline
    return text.strip()

def extract_title_manually(text):
    """
    Attempts to find the title by checking the first few lines.
    - Titles are usually long enough (more than 5 words).
    - Ignores common header text like "Abstract", "Introduction".
    """
    lines = text.split("\n")
    ignore_keywords = ["abstract", "introduction", "keywords", "contents", "table", "figure"]
    
    for line in lines[:5]:  # Check only the first 5 lines
        clean_line = line.strip()
        if len(clean_line.split()) > 5 and not any(word.lower() in clean_line.lower() for word in ignore_keywords):
            return clean_line  # Return first valid title
    return "Unknown"

# ----------------- Metadata Extraction -----------------
def extract_metadata(pdf_path):
    """Extracts metadata (title, authors, emails, affiliations) from the first page of a PDF."""
    
    with pdfplumber.open(pdf_path) as pdf:
        if not pdf.pages:
            return {
                "Title": "Unknown",
                "Author": "Unknown",
                "Emails": "No emails found",
                "Affiliations": "No affiliations found"
            }

        # Extract text from the first page
        first_page_text = pdf.pages[0].extract_text() or "No text found."
        cleaned_text = clean_extracted_text(first_page_text)
        lines = cleaned_text.split("\n")

        # ---- Extract Title ----
        title = "Unknown"
        for line in lines[:5]:  # First few lines usually contain the title
            clean_line = line.strip()
            if len(clean_line.split()) > 5 and not clean_line.lower().startswith(("abstract", "introduction", "keywords")):
                title = clean_line
                break

        # ---- Extract Authors ----
        author_pattern = re.compile(r"([\w\-\s]+,\s?)+[\w\-\s]+")  # Names are comma-separated
        authors = "Unknown"
        for line in lines:
            if "@" in line:  # Authors appear before emails
                break
            match = author_pattern.search(line)
            if match:
                authors = match.group(0)
                break

        # ---- Extract Emails ----
        email_pattern = re.compile(r"[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}")
        emails = ", ".join(email_pattern.findall(cleaned_text)) or "No emails found"

        # ---- Extract Affiliations ----
        affiliations = "Unknown"
        for i, line in enumerate(lines):
            if "@" in line:  # Affiliations are usually after emails
                if i + 1 < len(lines):
                    affiliations = lines[i + 1].strip()
                break

        return {
            "Title": title,
            "Author": authors,
            "Emails": emails,
            "Affiliations": affiliations
        }


# ----------------- Step 1: Choose PDF Source -----------------
pdf_source = st.radio("Upload or provide a link to a PDF:", ["Upload a PDF file", "Enter a PDF URL"], index=0, horizontal=True)

if pdf_source == "Upload a PDF file":
    uploaded_file = st.file_uploader("Upload your PDF file", type=["pdf"])
    if uploaded_file:
        st.session_state.pdf_path = "/mnt/data/temp.pdf"
        with open(st.session_state.pdf_path, "wb") as f:
            f.write(uploaded_file.getbuffer())
        st.session_state.pdf_loaded = False
        st.session_state.chunked = False
        st.session_state.vector_created = False

elif pdf_source == "Enter a PDF URL":
    pdf_url = st.text_input("Enter PDF URL:")
    if pdf_url and not st.session_state.pdf_loaded:
        with st.spinner("🔄 Downloading PDF..."):
            try:
                response = requests.get(pdf_url)
                if response.status_code == 200:
                    st.session_state.pdf_path = "/mnt/data/temp.pdf"
                    with open(st.session_state.pdf_path, "wb") as f:
                        f.write(response.content)
                    st.session_state.pdf_loaded = False
                    st.session_state.chunked = False
                    st.session_state.vector_created = False
                    st.success("✅ PDF Downloaded Successfully!")
                else:
                    st.error("❌ Failed to download PDF. Check the URL.")
            except Exception as e:
                st.error(f"Error downloading PDF: {e}")


# ----------------- Process PDF -----------------
if not st.session_state.pdf_loaded and "pdf_path" in st.session_state:
    with st.spinner("🔄 Processing document... Please wait."):
        loader = PDFPlumberLoader(st.session_state.pdf_path)
        docs = loader.load()
        st.json(docs[0].metadata)

        # Extract metadata
        metadata = extract_metadata(st.session_state.pdf_path)

        # Display extracted-metadata
        if isinstance(metadata, dict):
            st.subheader("📄 Extracted Document Metadata")
            st.write(f"**Title:** {metadata.get('Title', 'Unknown')}")
            st.write(f"**Author:** {metadata.get('Author', 'Unknown')}")
            st.write(f"**Emails:** {metadata.get('Emails', 'No emails found')}")
            st.write(f"**Affiliations:** {metadata.get('Affiliations', 'No affiliations found')}")
        else:
            st.error("Metadata extraction failed.")

        # Embedding Model
        model_name = "nomic-ai/modernbert-embed-base"
        embedding_model = HuggingFaceEmbeddings(model_name=model_name, model_kwargs={"device": "cpu"}, encode_kwargs={'normalize_embeddings': False})

        # Convert metadata into a retrievable chunk
        metadata_doc = {"page_content": metadata, "metadata": {"source": "metadata"}}


        # Prevent unnecessary re-chunking
        if not st.session_state.chunked:
            text_splitter = SemanticChunker(embedding_model)
            document_chunks = text_splitter.split_documents(docs)
            document_chunks.insert(0, metadata_doc)  # Insert metadata as a retrievable document
            st.session_state.processed_chunks = document_chunks
            st.session_state.chunked = True

        st.session_state.pdf_loaded = True
        st.success("✅ Document processed and chunked successfully!")

# ----------------- Setup Vector Store -----------------
if not st.session_state.vector_created and st.session_state.processed_chunks:
    with st.spinner("🔄 Initializing Vector Store..."):
        st.session_state.vector_store = Chroma(
            persist_directory=CHROMA_DB_DIR,  # <-- Ensures persistence
            collection_name="deepseek_collection",
            collection_metadata={"hnsw:space": "cosine"},
            embedding_function=embedding_model
        )
        st.session_state.vector_store.add_documents(st.session_state.processed_chunks)
        st.session_state.vector_created = True
        st.success("✅ Vector store initialized successfully!")


# ----------------- Query Input -----------------
query = st.text_input("🔍 Ask a question about the document:")

if query:
    with st.spinner("🔄 Retrieving relevant context..."):
        retriever = st.session_state.vector_store.as_retriever(search_type="similarity", search_kwargs={"k": 5})
        retrieved_docs = retriever.invoke(query)
        context = [d.page_content for d in retrieved_docs]
        st.success("✅ Context retrieved successfully!")

    # ----------------- Run Individual Chains Explicitly -----------------
    context_relevancy_chain = LLMChain(llm=llm_judge, prompt=PromptTemplate(input_variables=["retriever_query", "context"], template=relevancy_prompt), output_key="relevancy_response")
    relevant_context_chain = LLMChain(llm=llm_judge, prompt=PromptTemplate(input_variables=["relevancy_response"], template=relevant_context_picker_prompt), output_key="context_number")
    relevant_contexts_chain = LLMChain(llm=llm_judge, prompt=PromptTemplate(input_variables=["context_number", "context"], template=response_synth), output_key="relevant_contexts")
    response_chain = LLMChain(llm=rag_llm, prompt=PromptTemplate(input_variables=["query", "context"], template=rag_prompt), output_key="final_response")

    response_crisis = context_relevancy_chain.invoke({"context": context, "retriever_query": query})
    relevant_response = relevant_context_chain.invoke({"relevancy_response": response_crisis["relevancy_response"]})
    contexts = relevant_contexts_chain.invoke({"context_number": relevant_response["context_number"], "context": context})
    final_response = response_chain.invoke({"query": query, "context": contexts["relevant_contexts"]})

    # ----------------- Display All Outputs -----------------
    st.markdown("### Context Relevancy Evaluation")
    st.json(response_crisis["relevancy_response"])

    st.markdown("### Picked Relevant Contexts")
    st.json(relevant_response["context_number"])

    st.markdown("### Extracted Relevant Contexts")
    st.json(contexts["relevant_contexts"])

    st.subheader("context_relevancy_evaluation_chain Statement")
    st.json(final_response["relevancy_response"])

    st.subheader("pick_relevant_context_chain Statement")
    st.json(final_response["context_number"])

    st.subheader("relevant_contexts_chain Statement")
    st.json(final_response["relevant_contexts"])

    st.subheader("RAG Response Statement")
    st.json(final_response["final_response"])