app.py

# app.py
import gradio as gr
import os
import torch
from langchain_community.document_loaders import PyPDFLoader
from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain_community.embeddings import HuggingFaceEmbeddings
from langchain_community.vectorstores import FAISS
from transformers import AutoModelForCausalLM, AutoTokenizer, BitsAndBytesConfig

# Configuration
DOCS_DIR = "business_docs"
EMBEDDING_MODEL = "sentence-transformers/all-MiniLM-L6-v2"
MODEL_NAME = "microsoft/phi-2"

# Quantization config
quant_config = BitsAndBytesConfig(
    load_in_4bit=True,
    bnb_4bit_quant_type="nf4",
    bnb_4bit_compute_dtype=torch.float16,
    bnb_4bit_use_double_quant=False
)

def initialize_system():
    # Document processing
    if not os.path.exists(DOCS_DIR):
        raise FileNotFoundError(f"Missing {DOCS_DIR} folder")
    
    pdf_files = [os.path.join(DOCS_DIR, f) 
                for f in os.listdir(DOCS_DIR) 
                if f.endswith(".pdf")]
    
    text_splitter = RecursiveCharacterTextSplitter(
        chunk_size=800,
        chunk_overlap=100
    )
    
    texts = []
    for pdf in pdf_files:
        loader = PyPDFLoader(pdf)
        pages = loader.load_and_split(text_splitter)
        texts.extend(pages)

    # Create embeddings
    embeddings = HuggingFaceEmbeddings(
        model_name=EMBEDDING_MODEL,
        model_kwargs={'device': 'cpu'}
    )
    
    # Vector store
    vector_store = FAISS.from_documents(texts, embeddings)

    # Model loading
    tokenizer = AutoTokenizer.from_pretrained(
        MODEL_NAME,
        trust_remote_code=True,
        padding_side="left"
    )
    
    model = AutoModelForCausalLM.from_pretrained(
        MODEL_NAME,
        trust_remote_code=True,
        device_map="auto",
        quantization_config=quant_config,
        torch_dtype=torch.float16
    )

    return vector_store, model, tokenizer

try:
    vector_store, model, tokenizer = initialize_system()
    print("✅ System initialized successfully")
except Exception as e:
    print(f"❌ Initialization failed: {str(e)}")
    raise

def generate_response(query):
    try:
        docs = vector_store.similarity_search(query, k=2)
        context = "\n".join([d.page_content for d in docs])
        
        prompt = f"""<|system|>
        Answer using only this context: {context}
        - Max 2 sentences
        - If unsure: "I'll check with the team"</s>
        <|user|>{query}</s>
        <|assistant|>"""
        
        inputs = tokenizer(prompt, return_tensors="pt").to(model.device)
        outputs = model.generate(
            **inputs,
            max_new_tokens=150,
            temperature=0.1,
            pad_token_id=tokenizer.eos_token_id
        )
        
        return tokenizer.decode(outputs[0], skip_special_tokens=True).split("<|assistant|>")[-1].strip()
    
    except Exception as e:
        return "Please try again later."

# Gradio interface
with gr.Blocks() as demo:
    gr.Markdown("# Customer Service Chatbot")
    chatbot = gr.Chatbot()
    msg = gr.Textbox(label="Your question")
    clear = gr.ClearButton([msg, chatbot])
    
    def respond(message, history):
        response = generate_response(message)
        history.append((message, response))
        return "", history
    
    msg.submit(respond, [msg, chatbot], [msg, chatbot])

demo.launch()