app.py

import os
import requests
import streamlit as st
from langchain_huggingface import HuggingFaceEndpoint
from langchain_core.prompts import PromptTemplate
from langchain_core.output_parsers import StrOutputParser
from transformers import pipeline

# Use environment variables for keys
HF_TOKEN = os.getenv("HF_TOKEN")
if HF_TOKEN is None:
    raise ValueError("HF_TOKEN environment variable not set. Please set it in your Hugging Face Space settings.")

NASA_API_KEY = os.getenv("NASA_API_KEY")
if NASA_API_KEY is None:
    raise ValueError("NASA_API_KEY environment variable not set. Please set it in your Hugging Face Space settings.")

# Set up Streamlit UI
st.set_page_config(page_title="HAL - NASA ChatBot", page_icon="🚀")

# --- Initialize Session State Variables ---
if "chat_history" not in st.session_state:
    # Initial greeting stored in chat history
    st.session_state.chat_history = [{"role": "assistant", "content": "Hello! How can I assist you today?"}]

if "response_ready" not in st.session_state:
    st.session_state.response_ready = False  # Tracks whether HAL has responded

if "follow_up" not in st.session_state:
    st.session_state.follow_up = ""  # Stores follow-up question

# --- Set Up Model & API Functions ---
model_id = "mistralai/Mistral-7B-Instruct-v0.3"

# Initialize sentiment analysis pipeline with explicit model specification
sentiment_analyzer = pipeline(
    "sentiment-analysis",
    model="distilbert/distilbert-base-uncased-finetuned-sst-2-english",
    revision="714eb0f"
)

def get_llm_hf_inference(model_id=model_id, max_new_tokens=128, temperature=0.7):
    # Specify task="text-generation" so that the endpoint uses the right model function.
    return HuggingFaceEndpoint(
        repo_id=model_id,
        max_new_tokens=max_new_tokens,
        temperature=temperature,
        token=HF_TOKEN,
        task="text-generation"
    )

def get_nasa_apod():
    url = f"https://api.nasa.gov/planetary/apod?api_key={NASA_API_KEY}"
    response = requests.get(url)
    if response.status_code == 200:
        data = response.json()
        return data.get("url", ""), data.get("title", ""), data.get("explanation", "")
    else:
        return "", "NASA Data Unavailable", "I couldn't fetch data from NASA right now. Please try again later."

def analyze_sentiment(user_text):
    result = sentiment_analyzer(user_text)[0]
    return result['label']

def predict_action(user_text):
    if "NASA" in user_text or "space" in user_text:
        return "nasa_info"
    return "general_query"

def generate_follow_up(user_text):
    """
    Generates a concise and conversational follow-up question related to the user's input.
    """
    prompt_text = (
        f"Given the user's question: '{user_text}', generate a SHORT and SIMPLE follow-up question. "
        "Make it conversational and friendly. Example: 'Would you like to learn more about the six types of quarks?' "
        "Do NOT provide long explanations—just ask a friendly follow-up question."
    )
    hf = get_llm_hf_inference(max_new_tokens=32, temperature=0.7)
    return hf.invoke(input=prompt_text).strip()

def get_response(system_message, chat_history, user_text, max_new_tokens=256):
    """
    Generates HAL's response in a friendly, conversational manner.
    The prompt instructs the model to ignore previous greetings and focus on the new user question.
    """
    sentiment = analyze_sentiment(user_text)
    action = predict_action(user_text)

    if action == "nasa_info":
        nasa_url, nasa_title, nasa_explanation = get_nasa_apod()
        response = f"**{nasa_title}**\n\n{nasa_explanation}"
        chat_history.append({'role': 'user', 'content': user_text})
        chat_history.append({'role': 'assistant', 'content': response})
        
        follow_up = generate_follow_up(user_text)
        chat_history.append({'role': 'assistant', 'content': follow_up})
        return response, follow_up, chat_history, nasa_url

    hf = get_llm_hf_inference(max_new_tokens=max_new_tokens, temperature=0.9)

    # Updated prompt: Instruct the model not to repeat previous greetings.
    prompt = PromptTemplate.from_template(
        (
            "[INST] {system_message}\n\nCurrent Conversation:\n{chat_history}\n\n"
            "User: {user_text}.\n [/INST]\n"
            "AI: Please answer the user's question without repeating any previous greetings. "
            "Keep your response friendly and conversational, starting with a phrase like "
            "'Certainly!', 'Of course!', or 'Great question!'.\nHAL:"
        )
    )
    chat = prompt | hf.bind(skip_prompt=True) | StrOutputParser(output_key='content')
    response = chat.invoke(input=dict(system_message=system_message, user_text=user_text, chat_history=chat_history))
    response = response.split("HAL:")[-1].strip()

    chat_history.append({'role': 'user', 'content': user_text})
    chat_history.append({'role': 'assistant', 'content': response})

    if sentiment == "NEGATIVE":
        response = "I'm here to help. Let me know what I can do for you. 😊"

    follow_up = generate_follow_up(user_text)
    chat_history.append({'role': 'assistant', 'content': follow_up})

    return response, follow_up, chat_history, None

# --- Chat UI ---
st.title("🚀 HAL - Your NASA AI Assistant")
st.markdown("🌌 *Ask me about space, NASA, and beyond!*")

# Sidebar: Reset Chat
if st.sidebar.button("Reset Chat"):
    st.session_state.chat_history = [{"role": "assistant", "content": "Hello! How can I assist you today?"}]
    st.session_state.response_ready = False
    st.session_state.follow_up = ""
    st.experimental_rerun()

# Custom Chat Styling
st.markdown("""
    <style>
    .user-msg {
        background-color: #0078D7;
        color: white;
        padding: 10px;
        border-radius: 10px;
        margin-bottom: 5px;
        width: fit-content;
        max-width: 80%;
    }
    .assistant-msg {
        background-color: #333333;
        color: white;
        padding: 10px;
        border-radius: 10px;
        margin-bottom: 5px;
        width: fit-content;
        max-width: 80%;
    }
    .container {
        display: flex;
        flex-direction: column;
        align-items: flex-start;
    }
    @media (max-width: 600px) {
        .user-msg, .assistant-msg { font-size: 16px; max-width: 100%; }
    }
    </style>
""", unsafe_allow_html=True)

# Chat History Display
st.markdown("<div class='container'>", unsafe_allow_html=True)
for message in st.session_state.chat_history:
    if message["role"] == "user":
        st.markdown(f"<div class='user-msg'><strong>You:</strong> {message['content']}</div>", unsafe_allow_html=True)
    else:
        st.markdown(f"<div class='assistant-msg'><strong>HAL:</strong> {message['content']}</div>", unsafe_allow_html=True)
st.markdown("</div>", unsafe_allow_html=True)

# --- Single Input Box for Both Initial and Follow-Up Messages ---
user_input = st.chat_input("Type your message here...")  # Only ONE chat_input()

if user_input:
    response, follow_up, st.session_state.chat_history, image_url = get_response(
        system_message="You are a helpful AI assistant.",
        user_text=user_input,
        chat_history=st.session_state.chat_history
    )

    st.markdown(f"<div class='assistant-msg'><strong>HAL:</strong> {response}</div>", unsafe_allow_html=True)

    if image_url:
        st.image(image_url, caption="NASA Image of the Day")

    st.session_state.follow_up = follow_up
    st.session_state.response_ready = True

if st.session_state.response_ready and st.session_state.follow_up:
    st.markdown(f"<div class='assistant-msg'><strong>HAL:</strong> {st.session_state.follow_up}</div>", unsafe_allow_html=True)
    st.session_state.response_ready = False