app.py

import gradio as gr
import os
import time
import re
import pandas as pd
from dotenv import load_dotenv
from pinecone import Pinecone, ServerlessSpec

# --- Langchain components for document processing and embedding ---
from langchain_openai import OpenAIEmbeddings
from langchain_core.documents import Document
from langchain_community.document_loaders import PyPDFLoader
from langchain_text_splitters import RecursiveCharacterTextSplitter


# Load environment variables from a .env file
load_dotenv()

# --- Backend Functions ---

def get_stored_files():
    """Retrieve a list of files currently stored in the Pinecone index using the pinecone library."""
    try:
        pc = Pinecone(api_key=os.environ.get("PINECONE_API_KEY"))
        index_name = os.environ.get("PINECONE_INDEX_NAME")

        # Check if the index exists. If not, there are no files.
        if index_name not in [index_info["name"] for index_info in pc.list_indexes()]:
            return []

        index = pc.Index(index_name)
        # A dummy query to fetch metadata from all vectors.
        # Increase top_k if you expect to have more than 1000 chunks.
        results = index.query(vector=[0.0] * 3072, top_k=10000, include_metadata=True)

        unique_files = set()
        if results.matches:
            for match in results.matches:
                if 'metadata' in match and 'source' in match.metadata:
                    unique_files.add(match.metadata['source'])

        return sorted(list(unique_files))
    except Exception as e:
        print(f"Error retrieving stored files: {str(e)}")
        return []

def delete_file_from_vectorstore(filename):
    """Deletes all vectors associated with a specific filename from Pinecone using the pinecone library."""
    if not filename:
        return "No file selected for deletion.", get_files_df()
    try:
        pc = Pinecone(api_key=os.environ.get("PINECONE_API_KEY"))
        index_name = os.environ.get("PINECONE_INDEX_NAME")
        index = pc.Index(index_name)

        # Use metadata filtering to delete all vectors associated with the file.
        index.delete(filter={"source": {"$eq": filename}})

        return f"Successfully deleted {filename}.", get_files_df()
    except Exception as e:
        return f"Error while deleting the file: {str(e)}", get_files_df()

def embedder(uploaded_file_path):
    """
    Handles the embedding of the uploaded PDF file using langchain for processing
    and the pinecone library for vector store operations.
    """
    if uploaded_file_path is None:
        return "No file uploaded. Please upload a PDF.", get_files_df()

    try:
        original_filename = os.path.basename(uploaded_file_path)

        pc = Pinecone(api_key=os.environ.get("PINECONE_API_KEY"))
        index_name = os.environ.get("PINECONE_INDEX_NAME")
        embedding_dimension = 3072 # As specified for text-embedding-3-large

        # Create the index if it doesn't exist
        if index_name not in [index_info["name"] for index_info in pc.list_indexes()]:
            pc.create_index(
                name=index_name,
                dimension=embedding_dimension,
                metric="cosine",
                spec=ServerlessSpec(cloud="aws", region="us-east-1"),
            )
            while not pc.describe_index(index_name).status["ready"]:
                time.sleep(1)

        index = pc.Index(index_name)

        # 1. Load and Split Document
        loader = PyPDFLoader(uploaded_file_path)
        raw_documents = loader.load()

        text_splitter = RecursiveCharacterTextSplitter(
            chunk_size=800,
            chunk_overlap=400,
            length_function=len,
        )
        documents = text_splitter.split_documents(raw_documents)

        # 2. Create Embeddings
        embeddings_model = OpenAIEmbeddings(model="text-embedding-3-large", api_key=os.environ.get("OPENAI_API_KEY"))
        texts_to_embed = [doc.page_content for doc in documents]
        embeddings = embeddings_model.embed_documents(texts_to_embed)

        # 3. Sanitize filename and prepare vectors for upsert
        sanitized_filename = re.sub(r'[^a-z0-9]', '-', original_filename.replace('.pdf', '').strip().lower())
        sanitized_filename = re.sub(r'-+', '-', sanitized_filename).strip('-')

        vectors_to_upsert = []
        for i, (doc, vec) in enumerate(zip(documents, embeddings)):
            vector_id = f"{sanitized_filename}-{i}"
            metadata = {
                "text": doc.page_content,
                "source": original_filename
            }
            vectors_to_upsert.append({"id": vector_id, "values": vec, "metadata": metadata})

        # 4. Upsert vectors to Pinecone in batches
        batch_size = 100
        for i in range(0, len(vectors_to_upsert), batch_size):
            batch = vectors_to_upsert[i:i+batch_size]
            index.upsert(vectors=batch)

        return f"File '{original_filename}' successfully embedded!", get_files_df()

    except Exception as e:
        return f"Unable to create embeddings: {str(e)}", get_files_df()


# --- Gradio Interface Functions ---
def get_files_df():
    """Creates a DataFrame from the list of stored files for Gradio display."""
    files = get_stored_files()
    if files:
        return pd.DataFrame({"Stored Files": files})
    else:
        return pd.DataFrame({"Stored Files": []})

def handle_file_selection(evt: gr.SelectData):
    """Handles the file selection event from the DataFrame."""
    if evt.value:
        return evt.value
    return ""

# --- Gradio UI ---
with gr.Blocks(theme=gr.themes.Soft(), title="PDF Uploader") as demo:
    gr.Markdown("# PDF File Uploader for Chatbot")
    gr.Markdown("Upload PDF files to add their content to the chatbot's knowledge base.")

    with gr.Row():
        with gr.Column(scale=1):
            gr.Markdown("## 📤 Upload New File")
            file_uploader = gr.File(
                label="Upload your PDF file",
                file_types=[".pdf"],
                type="filepath"
            )
            upload_button = gr.Button("Upload to Chatbot Memory", variant="primary")
            upload_status = gr.Markdown("")

        with gr.Column(scale=1):
            gr.Markdown("## 🗂️ Stored Files")
            refresh_button = gr.Button("Refresh File List")
            file_df = gr.DataFrame(
                value=get_files_df,
                headers=["Stored Files"],
                interactive=True
            )
            selected_file_text = gr.Textbox(
                label="Selected File",
                interactive=False,
                placeholder="Click on a file above to select it"
            )
            delete_button = gr.Button("🗑️ Delete Selected File", variant="stop")
            delete_status = gr.Markdown("")

    # --- Event Handlers ---
    upload_button.click(
        fn=embedder,
        inputs=[file_uploader],
        outputs=[upload_status, file_df]
    )

    refresh_button.click(
        fn=get_files_df,
        inputs=[],
        outputs=[file_df]
    )

    file_df.select(
        fn=handle_file_selection,
        outputs=[selected_file_text]
    )

    delete_button.click(
        fn=delete_file_from_vectorstore,
        inputs=[selected_file_text],
        outputs=[delete_status, file_df]
    )

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