app.py

import os
import gradio as gr
from openai import OpenAI

# ---- Configuration ----

HF_API_KEY = os.getenv("HF_TOKEN")

client = OpenAI(
    base_url="https://router.huggingface.co/v1",
    api_key=HF_API_KEY
)

# ---- Chat function ----
def chat_with_model(user_message, history):
    if history is None:
        history = []

    messages = [{"role": "system", "content": "You are a helpful assistant."}]
    for human, bot in history:
        messages.append({"role": "user", "content": human})
        messages.append({"role": "assistant", "content": bot})

    messages.append({"role": "user", "content": user_message})

    try:
        completion = client.chat.completions.create(
            model="openai/gpt-oss-20b:nebius",
            messages=messages
        )

        assistant_reply = completion.choices[0].message["content"]
        history.append((user_message, assistant_reply))
        return assistant_reply, history

    except Exception as e:
        return f"Error: {str(e)}", history


# ---- Gradio UI ----
with gr.Blocks() as demo:
    gr.Markdown("# 🤖 Chatbot using HuggingFace Router (OpenAI API Compatible)")
    chatbot = gr.Chatbot(height=450)
    text_input = gr.Textbox(label="Your message")

    text_input.submit(chat_with_model, [text_input, chatbot], [chatbot])
    text_input.submit(lambda: "", None, text_input)  # clear input

demo.launch()