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

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

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=1000,
        chunk_overlap=200
    )
    
    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)

    # Load model and tokenizer
    tokenizer = AutoTokenizer.from_pretrained(MODEL_NAME, trust_remote_code=True)
    tokenizer.pad_token = tokenizer.eos_token  # Fix padding issue
    
    model = AutoModelForCausalLM.from_pretrained(
        MODEL_NAME,
        trust_remote_code=True,
        torch_dtype=torch.float32 if not torch.cuda.is_available() else torch.float16,
        device_map="auto",
        low_cpu_mem_usage=True
    )

    return vector_store, model, tokenizer

try:
    vector_store, model, tokenizer = initialize_system()
    print("✅ System initialized successfully")
    if torch.cuda.is_available():
        print("🚀 Using CUDA")
        print(f"Memory usage: {torch.cuda.memory_allocated()/1024**3:.2f} GB")
    else:
        print("🧠 Using CPU")
except Exception as e:
    print(f"❌ Initialization failed: {str(e)}")
    raise

def generate_response(query):
    try:
        # Context retrieval
        docs = vector_store.similarity_search(query, k=3)
        context = "\n".join([d.page_content for d in docs])

        # Prompt template optimized for Phi-2
        prompt = f"""Context:
{context}

Question: {query}
Answer:"""
        
        inputs = tokenizer(prompt, return_tensors="pt").to(model.device)
        outputs = model.generate(
            inputs.input_ids,
            max_new_tokens=300,
            temperature=0.3,
            do_sample=True,
            pad_token_id=tokenizer.eos_token_id
        )
        
        response = tokenizer.decode(outputs[0], skip_special_tokens=True)
        return response.split("Answer:")[-1].strip()
    
    except Exception as e:
        return "Sorry, an error occurred while generating a response."

# Gradio UI
with gr.Blocks(theme=gr.themes.Soft()) as demo:
    gr.Markdown("# 🧠 Enterprise Customer Support Chatbot")
    
    chatbot = gr.Chatbot(height=500, label="Conversation")
    
    with gr.Row():
        msg = gr.Textbox(placeholder="Ask about our services...", scale=7)
        submit_btn = gr.Button("Send", variant="primary", scale=1)

    clear = gr.ClearButton([msg, chatbot])

    def respond(message, history):
        response = generate_response(message)
        history.append((message, response))
        return "", history

    submit_btn.click(respond, [msg, chatbot], [msg, chatbot])
    msg.submit(respond, [msg, chatbot], [msg, chatbot])

demo.launch(server_port=7860)