app.py

import os
import sys
import zipfile

# --- 1. SQLITE FIX ---
try:
    __import__('pysqlite3')
    sys.modules['sqlite3'] = sys.modules.pop('pysqlite3')
except ImportError:
    pass

import torch
import gradio as gr
from transformers import AutoTokenizer, AutoModelForCausalLM, pipeline
from langchain_huggingface import HuggingFacePipeline, HuggingFaceEmbeddings
from langchain_chroma import Chroma
from typing import Dict, Any, List

# --- 2. UNZIP & AUTO-DETECT PATH ---
print("⏳ Checking for Database...")

# Unzip if the zip exists
if os.path.exists("./chroma_db.zip"):
    print("📦 Found zip file! Unzipping...")
    with zipfile.ZipFile("./chroma_db.zip", 'r') as zip_ref:
        zip_ref.extractall(".")
    print("✅ Unzip complete.")

# SMART DETECTION: Find where the database went
db_path = ""

if os.path.exists("./chroma_db/chroma.sqlite3"):
    # Case A: It's inside the folder (Perfect)
    db_path = "./chroma_db"
    print(f"📂 Found database in folder: {db_path}")

elif os.path.exists("./chroma.sqlite3"):
    # Case B: It spilled into the root directory
    db_path = "."
    print(f"📂 Found database in root directory: {db_path}")

elif os.path.exists("./content/chroma_db/chroma.sqlite3"):
    # Case C: It's inside a 'content' folder (Common Colab issue)
    db_path = "./content/chroma_db"
    print(f"📂 Found database in content folder: {db_path}")

else:
    # Case D: Panic
    # Let's list the files to debug
    print("❌ ERROR: Cannot find chroma.sqlite3. Current files in folder:")
    print(os.listdir("."))
    raise ValueError("Could not find the database file after unzipping!")

# --- 3. MODEL SETUP ---
print("⏳ Loading Embeddings...")
embedding_function = HuggingFaceEmbeddings(
    model_name="nomic-ai/nomic-embed-text-v1.5",
    model_kwargs={"trust_remote_code": True, "device": "cpu"}
)

print(f"⏳ Loading Database from {db_path}...")
vector_db = Chroma(
    persist_directory=db_path, 
    embedding_function=embedding_function
)

print("⏳ Loading TinyLlama Model...")
model_id = "TinyLlama/TinyLlama-1.1B-Chat-v1.0"
tokenizer = AutoTokenizer.from_pretrained(model_id)
model = AutoModelForCausalLM.from_pretrained(model_id)

pipe = pipeline(
    "text-generation",
    model=model,
    tokenizer=tokenizer,
    max_new_tokens=256,
    repetition_penalty=1.15,
    temperature=0.1,
    do_sample=True
)

llm = HuggingFacePipeline(pipeline=pipe)

# --- 4. RAG CHAIN ---
class ManualQAChain:
    def __init__(self, vector_store: Chroma, llm_pipeline: HuggingFacePipeline):
        self.retriever = vector_store.as_retriever(search_kwargs={"k": 2})
        self.llm = llm_pipeline

    def invoke(self, inputs: Dict[str, str]) -> Dict[str, Any]:
        query = inputs.get("query", "")
        
        # Retrieval
        docs = self.retriever.invoke(query)
        context = "\n\n".join([d.page_content for d in docs]) if docs else "No context found."

        # Prompt
        prompt = f"""<|system|>
You are a helpful medical assistant. Use ONLY the context below.
If the answer is not in the context, say "I cannot find the answer."

Context:
{context[:2000]}
</s>
<|user|>
{query}
</s>
<|assistant|>
"""
        # Generation
        response = self.llm.invoke(prompt)
        text = response[0]['generated_text'] if isinstance(response, list) else str(response)
        
        if "<|assistant|>" in text:
            final_answer = text.split("<|assistant|>")[-1].strip()
        else:
            final_answer = text.strip()

        return {"result": final_answer, "source_documents": docs}

# Initialize
qa_chain = ManualQAChain(vector_db, llm)

# --- 5. UI ---
def medical_rag_chat(message, history):
    if not message: return "Please ask a question."
    try:
        response = qa_chain.invoke({"query": message})
        sources = "\n\n---\n**Retrieved Context:**\n"
        
        if response.get('source_documents'):
            for i, doc in enumerate(response['source_documents']):
                topic = doc.metadata.get('focus_area', 'Protocol')
                sources += f"**{i+1}. [{topic}]** {doc.page_content[:300]}...\n"
        else:
            sources += "(No context found)"
            
        return response['result'] + sources
    except Exception as e:
        return f"Error: {str(e)}"

demo = gr.ChatInterface(
    fn=medical_rag_chat,
    title="Cardio-Oncology RAG Assistant",
    description="TinyLlama-1.1B + MedQuAD RAG",
    examples=["What are the symptoms of Lung Cancer?", "Who is at risk for Heart Failure?"]
)

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