app.py

import os
import openai
import gradio as gr
import pdfplumber
import boto3
from llama_index.core import Document, VectorStoreIndex, Settings
from llama_index.llms.openai import OpenAI
from llama_index.embeddings.openai import OpenAIEmbedding
from llama_index.core.postprocessor import MetadataReplacementPostProcessor
from llama_index.core.node_parser import SentenceWindowNodeParser
from dotenv import load_dotenv

# Load environment variables
load_dotenv("config.env")

# Set your OpenAI API key here
OPENAI_API_KEY = os.getenv("OPENAI_API_KEY")
openai.api_key = OPENAI_API_KEY

# AWS S3 setup
s3_bucket_name = "sagemaker-studio-gm4vm5dimae"
s3_client = boto3.client('s3')

# Directory to store downloaded PDFs
resume_path = 'resumes'
os.makedirs(resume_path, exist_ok=True)

# Function to download PDFs from S3
def download_pdfs_from_s3(bucket_name, local_path):
    objects = s3_client.list_objects_v2(Bucket=bucket_name)
    for obj in objects.get('Contents', []):
        file_name = obj['Key']
        local_file_path = os.path.join(local_path, file_name)
        s3_client.download_file(bucket_name, file_name, local_file_path)
        print(f"Downloaded {file_name} to {local_file_path}")

# Download PDFs
download_pdfs_from_s3(s3_bucket_name, resume_path)

# Function to load PDFs using pdfplumber
def load_pdfs_with_pdfplumber(directory):
    documents = []
    for filename in os.listdir(directory):
        if filename.endswith(".pdf"):
            try:
                with pdfplumber.open(os.path.join(directory, filename)) as pdf:
                    text = ""
                    for page in pdf.pages:
                        text += page.extract_text() or ""
                    documents.append(Document(text=text))
            except Exception as e:
                print(f"Error processing {filename}: {e}")
    return documents

# Load documents from the resume directory using pdfplumber
documents = load_pdfs_with_pdfplumber(resume_path)
print(f"Number of documents: {len(documents)}")

# Set up the LLM (GPT-4o)
llm = OpenAI(model="gpt-4o", temperature=0.9)

# Set up the embedding model
embed_model = OpenAIEmbedding(model="text-embedding-3-large")

# Create sentence window node parser with default settings
sentence_node_parser = SentenceWindowNodeParser.from_defaults(
    window_size=3,
    window_metadata_key="window",
    original_text_metadata_key="original_text"
)

# Configure global settings
Settings.llm = llm
Settings.embed_model = embed_model
Settings.node_parser = sentence_node_parser

# Create index
index = VectorStoreIndex.from_documents(documents)

# Custom reranking function
def custom_rerank(nodes, query):
    rerank_prompt = (
        "Given the following query and text chunks, rate each chunk's relevance "
        "to the query on a scale of 1-10, where 10 is most relevant.\n\n"
        f"Query: {query}\n\n"
    )
    for i, node in enumerate(nodes):
        rerank_prompt += f"Chunk {i+1}:\n{node.get_content()}\n\n"
    
    rerank_prompt += "Provide your ratings as a comma-separated list of numbers, e.g., '7,4,9,2,6'"
    
    response = llm.complete(rerank_prompt)
    try:
        ratings = [int(r.strip()) for r in response.text.split(',')]
        if len(ratings) != len(nodes):
            raise ValueError("Number of ratings does not match number of nodes")
        sorted_nodes = [node for _, node in sorted(zip(ratings, nodes), key=lambda x: x[0], reverse=True)]
        return sorted_nodes[:5]  # Return top 5 reranked nodes
    except Exception as e:
        print(f"Error in reranking: {e}, returning original order")
        return nodes[:5]

# Create query engine
query_engine = index.as_query_engine(
    similarity_top_k=20,
    node_postprocessors=[
        MetadataReplacementPostProcessor("window")
    ],
)

# Chatbot function
def chatbot(message, history):
    history_text = "\n".join([f"Human: {h[0]}\nAI: {h[1]}" for h in history])
    full_query = f"Given the following chat history:\n{history_text}\n\nHuman: {message}\nAI:"
    
    # Retrieve nodes
    retrieved_nodes = query_engine.retrieve(full_query)
    
    # Apply custom reranking
    reranked_nodes = custom_rerank(retrieved_nodes, full_query)
    
    # Synthesize answer from reranked nodes
    context = "\n".join([node.get_content() for node in reranked_nodes])
    response = llm.complete(
        f"Using the following context, answer the query:\n\nContext: {context}\n\nQuery: {full_query}"
    )
    
    return response.text

# Create Gradio interface
iface = gr.ChatInterface(
    chatbot,
    title="Resume Chatbot",
    description="Ask questions about resumes in the database.",
    theme="soft",
    examples=[
        "Out of all the resumes tell me three of them who have experience in SQL?",
        "Give me key summary takeaways of the resumes who have experience in Project Management?",
        "Give me the names of 10 candidates who have more than two years of experience in general?",
    ],
    retry_btn=None,
    undo_btn="Delete Previous",
    clear_btn="Clear",
    chatbot=gr.Chatbot(height=400),
    textbox=gr.Textbox(scale=5)
)

# Launch the interface
iface.launch(share=True)