app.py

import torch
from transformers import (
    AutoModelForCausalLM,
    AutoTokenizer,
    BitsAndBytesConfig,
    pipeline
)
from peft import LoraConfig
import gradio as gr

# Load pre-trained model
llama_model = AutoModelForCausalLM.from_pretrained(
    pretrained_model_name_or_path="aboonaji/llama2finetune-v2",
    quantization_config=BitsAndBytesConfig(
        load_in_4bit=True,
        bnb_4bit_compute_dtype=getattr(torch, "float16"),
        bnb_4bit_quant_type="nf4"
    ),
    device_map="auto"
)
llama_model.config.use_cache = False
llama_model.config.pretraining_tp = 1

llama_tokenizer = AutoTokenizer.from_pretrained(
    pretrained_model_name_or_path="aboonaji/llama2finetune-v2",
    trust_remote_code=True
)
llama_tokenizer.pad_token = llama_tokenizer.eos_token
llama_tokenizer.padding_side = "right"

# Pipeline for inference
generator = pipeline(
    "text-generation",
    model=llama_model,
    tokenizer=llama_tokenizer,
    max_length=500
)

# In-memory user database
user_db = {}

def generate_response(prompt):
    response = generator(f"<s>[INST] {prompt} [/INST]")[0]["generated_text"]
    return response

def signup_user(new_username, new_password):
    if not new_username or not new_password:
        return "❌ No input. Please provide both username and password."
    if new_username in user_db:
        return "❌ Username already exists."
    user_db[new_username] = new_password
    return "✅ Account created! Please log in."

def login_user(username, password):
    if username in user_db and user_db[username] == password:
        return (
            gr.update(visible=True),
            gr.update(visible=False),
            "",
            gr.update(selected=3)
        )
    return (
        gr.update(visible=False),
        gr.update(visible=True),
        "❌ Invalid credentials",
        gr.update(selected=2)
    )

def logout_user():
    return (
        gr.update(visible=False),
        gr.update(visible=True),
        gr.update(selected=0)
    )

with gr.Blocks(theme="soft", css="""
#create-btn button,
#login-btn button,
#submit-btn button,
#logout-btn button {
    font-size: 12px !important;
    padding: 4px 8px !important;
    height: 30px !important;
    width: auto !important;
    min-width: 80px !important;
}
""") as demo:
    with gr.Tabs(selected=0, elem_id="tabs") as tabs:
        with gr.Tab("Home"):
            with gr.Column(elem_id="landing-container") as landing_ui:
                gr.Markdown("# 🏠 Welcome to MEDChat AI")
                gr.Markdown("---")
                gr.Markdown("#### 🔧 Features:")
                gr.Markdown("- Medical Q&A support\n- Easy-to-use chatbot interface\n- Privacy-focused with local data")
                gr.Markdown("---")
                gr.Markdown("© 2025 MEDChat AI | Finetuned by LLaMA 2 | Created for educational purposes")

        with gr.Tab("Sign Up"):
            with gr.Column() as signup_ui:
                gr.Markdown("### 📝 Sign Up")
                new_username = gr.Textbox(label="New Username")
                new_password = gr.Textbox(label="New Password", type="password")
                create_account_btn = gr.Button("Create Account", elem_id="create-btn")
                signup_msg = gr.Markdown()

        with gr.Tab("Login"):
            with gr.Column(visible=True) as login_ui:
                gr.Markdown("### 🔐 Login")
                username = gr.Textbox(label="Username")
                password = gr.Textbox(label="Password", type="password")
                login_btn = gr.Button("Login", elem_id="login-btn")
                login_msg = gr.Markdown()

        with gr.Tab("Chat"):
            with gr.Column(visible=False) as chat_ui:
                gr.Markdown("## 💬 MEDChat AI")
                gr.Markdown("What can I help with today?")
                logout_btn = gr.Button("🚪 Logout", elem_id="logout-btn")
                prompt = gr.Textbox(lines=5, placeholder="Enter your prompt...")
                submit_btn = gr.Button("Submit", elem_id="submit-btn")
                response = gr.Textbox(label="Response")

                gr.Markdown("### Try one of these:")
                examples = gr.Examples(
                    examples=[
                        ["What does the immune system do?"],
                        ["What is Epistaxis?"],
                        ["Do our intestines contain germs?"],
                        ["What are allergies?"],
                        ["Should I start taking creatine?"],
                        ["What are antibiotics?"],
                        ["Why do I get sick?"],
                        ["What's the difference between bacteria and viruses?"],
                        ["Where are some places that germs hide?"],
                    ],
                    inputs=prompt
                )

                logout_btn.click(fn=logout_user, outputs=[chat_ui, login_ui, tabs])

    # Navigation and interaction logic
    to_signup = gr.Button(visible=False)
    to_login = gr.Button(visible=False)

    to_signup.click(lambda: gr.update(selected=1), outputs=tabs)
    to_login.click(lambda: gr.update(selected=2), outputs=tabs)
    create_account_btn.click(fn=signup_user, inputs=[new_username, new_password], outputs=signup_msg)
    login_btn.click(fn=login_user, inputs=[username, password], outputs=[chat_ui, login_ui, login_msg, tabs])
    submit_btn.click(fn=generate_response, inputs=prompt, outputs=response)

demo.launch()