Create app.py

app.py

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+import streamlit as st
+import os
+import uuid
+from streamlit_chat import message
+
+# HuggingFace integration
+from langchain_huggingface import HuggingFaceEndpoint, ChatHuggingFace 
+
+# Core LangChain schema
+from langchain_core.messages import (
+    AIMessage,
+    HumanMessage,
+    SystemMessage,
+    BaseMessage
+)
+
+# --- 1. Load Environment Variables ---
+HF_API_TOKEN = os.environ.get("HUGGINGFACEHUB_API_TOKEN")
+MODEL_REPO_ID = "Mistralai/Mistral-7B-Instruct-v0.2"
+
+# --- 2. Global System Prompt (Chef Personality) ---
+SYSTEM_PROMPT = SystemMessage(
+    content=(
+        "You are Kitchen Buddy 👨‍🍳, a warm and friendly culinary assistant. "
+        "Your job is to help people with anything related to food, cooking, or cuisine.\n\n"
+        "You can:\n"
+        "- Explain what ingredients are, their uses, and their cultural background\n"
+        "- Suggest recipes and meal ideas\n"
+        "- Offer ingredient substitutions\n"
+        "- Teach cooking techniques and science\n"
+        "- Provide healthy diet adaptations\n"
+        "- Explore global cuisines & traditions\n\n"
+        "Keep your tone helpful and approachable. "
+        "If a user asks about a food item (e.g., 'what are apples'), explain what it is and how it’s commonly used. "
+        "If they ask what to cook with it, suggest a few recipes. "
+        "If something is unrelated to food or cooking, politely redirect back to culinary topics."
+    )
+)
+
+# --- 3. Streamlit UI Setup ---
+st.set_page_config(page_title="Kitchen Buddy 👨‍🍳", layout="centered")
+st.title("👨‍🍳 Kitchen Buddy")
+st.markdown(f"""
+Your friendly culinary assistant — ask about recipes, ingredients, and cooking techniques.  
+**🤖 Model in use:** `{MODEL_REPO_ID}`
+""")
+# --- 4. Initialise LLM ---
+@st.cache_resource
+def initialize_llm():
+    if not HF_API_TOKEN:
+        st.error("🚨 Please set the secret **HUGGINGFACEHUB_API_TOKEN** in your HF Space.")
+        return None
+
+    os.environ['HUGGINGFACEHUB_API_TOKEN'] = HF_API_TOKEN
+    try:
+        llm = HuggingFaceEndpoint(
+            repo_id=MODEL_REPO_ID,
+            task="text-generation",
+            max_new_tokens=512,
+            temperature=0.7,
+            do_sample=True,
+            repetition_penalty=1.03
+        )
+        chat_model = ChatHuggingFace(llm=llm)
+        return chat_model
+    except Exception as e:
+        st.error("❌ Failed to initialize LLM. Check API key and model availability.")
+        print(f"Detailed LLM init error: {e}")
+        return None
+
+CHAT_MODEL = initialize_llm()
+
+# --- 5. Session State for Multiple Chats ---
+def new_chat():
+    new_id = str(uuid.uuid4())
+    st.session_state.chats[new_id] = [SYSTEM_PROMPT]
+    st.session_state.chat_titles[new_id] = "New Chat"
+    st.session_state.current_chat_id = new_id
+
+if 'chats' not in st.session_state:
+    st.session_state.chats = {}
+    st.session_state.chat_titles = {}
+    new_chat()
+if 'current_chat_id' not in st.session_state:
+    new_chat()
+if 'generate_next' not in st.session_state:
+    st.session_state.generate_next = False
+
+
+def get_current_messages() -> list[BaseMessage]:
+    return st.session_state.chats.get(st.session_state.current_chat_id, [SYSTEM_PROMPT])
+
+def set_current_chat(chat_id):
+    st.session_state.current_chat_id = chat_id
+
+def convert_to_streamlit_message(msg: BaseMessage):
+    if isinstance(msg, SystemMessage):
+        return None, None
+    role = "user" if isinstance(msg, HumanMessage) else "assistant"
+    return msg.content, role
+
+
+# --- 6. Sidebar Chat History ---
+with st.sidebar:
+    # Check if any chat has more than just the system prompt
+    has_real_chats = any(
+        len(history) > 1 for history in st.session_state.chats.values()
+    )
+
+    if not has_real_chats:
+        # Show disabled red box instead of New Chat
+        st.button("📭 No saved conversations yet", use_container_width=True, disabled=True)
+
+        st.markdown("""
+        ### 👨‍🍳 Welcome!
+        Ask me anything about cooking:
+        -  Recipes and ideas  
+        -  Ingredient substitutions  
+        -  Cooking techniques  
+
+        *Try asking:*  
+        • "What can I make with apples?"  
+        • "How do I cook pasta al dente?"  
+        """)
+    else:
+        # Always show New Chat button if chats exist
+        if st.button("🟥 New Chat", use_container_width=True):
+            new_chat()
+            st.rerun()
+            
+        st.markdown("---")
+        st.subheader("📜 Chat History")
+
+        # List past chats
+        for chat_id, title in list(st.session_state.chat_titles.items()):
+            if len(st.session_state.chats.get(chat_id, [SYSTEM_PROMPT])) > 1:
+                display_title = title
+                is_current = chat_id == st.session_state.current_chat_id
+
+                if st.button(
+                    display_title,
+                    key=f"chat_switch_{chat_id}",
+                    type="primary" if is_current else "secondary",
+                    use_container_width=True
+                ):
+                    set_current_chat(chat_id)
+                    st.rerun()
+
+# --- Main App Execution ---
+
+# Step 1: Capture user prompt
+# --- Conversation Logic: Show user message immediately and stream bot response ---
+if prompt := st.chat_input("Ask about a recipe, technique, or substitution..."):
+    if CHAT_MODEL is None:
+        st.session_state.chats[st.session_state.current_chat_id].append(HumanMessage(content=prompt))
+        st.session_state.chats[st.session_state.current_chat_id].append(
+            AIMessage(content="Error: Model is not initialized. Check API key setup.")
+        )
+        st.rerun()
+
+    # 1. Append user message to the current chat history
+    st.session_state.chats[st.session_state.current_chat_id].append(HumanMessage(content=prompt))
+    
+    
+    # --- DOMAIN FILTER: Only allow culinary-related queries ---
+    culinary_keywords = [
+        # General
+        "cook", "cooking", "kitchen", "chef", "meal", "food", "dish", "recipe", "cuisine", "menu", "flavor", "taste",
+        # Ingredients
+        "ingredient", "spice", "herb", "oil", "salt", "pepper", "garlic", "onion", "tomato", "butter", "cheese",
+        "meat", "beef", "pork", "chicken", "lamb", "fish", "seafood", "shrimp", "crab", "lobster", 
+        "vegetable", "fruit", "grain", "rice", "pasta", "bread", "noodles", "beans", "tofu", "egg",
+        # Techniques
+        "bake", "roast", "grill", "barbecue", "bbq", "fry", "deep fry", "saute", "sauté", "boil", "steam", "poach",
+        "simmer", "stew", "braise", "marinate", "blend", "chop", "slice", "dice", "whisk", "knead", "ferment",
+        # Dishes
+        "soup", "salad", "sandwich", "burger", "pizza", "pasta", "stew", "curry", "sauce", "stir fry", "omelette",
+        "dessert", "cake", "cookie", "pie", "pastry", "bread", "tart", "pudding", "ice cream",
+        # Cuisines
+        "italian", "french", "spanish", "greek", "mediterranean", "japanese", "chinese", "korean", "thai", 
+        "vietnamese", "indian", "mexican", "latin", "filipino", "turkish", "middle eastern", "moroccan",
+        # Diets & health
+        "vegan", "vegetarian", "gluten-free", "keto", "paleo", "halal", "kosher", "low-carb", "low-fat",
+        # Beverages
+        "coffee", "tea", "smoothie", "wine", "cocktail", "beer", "drink", "juice",
+        # Seasonal & Events
+        "thanksgiving", "christmas", "new year", "ramadan", "eid", "hanukkah", "valentine", "birthday", "party",
+        # Advanced Techniques
+        "sous vide", "confit", "smoking", "curing", "pickling", "plating", "molecular gastronomy",
+        # Professional Culinary Terms
+        "mise en place", "umami", "maillard reaction", "deglaçage", "roux", "stock", "broth",
+        # Specialty Ingredients
+        "truffle", "saffron", "caviar", "foie gras", "kimchi", "kombu", "nori", "tamarind", "matcha", "miso",
+        # Dietary Preferences
+        "diabetic-friendly", "heart-healthy", "organic", "sustainable", "farm-to-table",
+        # Equipment
+        "blender", "mixer", "pressure cooker", "air fryer", "cast iron", "oven", "microwave", "thermometer"
+    ]
+
+
+    # Common cooking question patterns
+    culinary_phrases = [
+        "what can i make with",
+        "how do i cook",
+        "how to cook",
+        "how to make",
+        "substitute for",
+        "what is",
+        "uses of"
+    ]
+    
+    prompt_lower = prompt.lower()
+    
+    # Check both keywords and phrases
+    is_culinary = (
+        any(word in prompt_lower for word in culinary_keywords) or
+        any(phrase in prompt_lower for phrase in culinary_phrases)
+    )
+    
+    if not is_culinary:
+        restriction_msg = AIMessage(content="⚠️ I can only answer questions about cooking, recipes, ingredients, or culinary techniques. Please ask something food-related.")
+        st.session_state.chats[st.session_state.current_chat_id].append(restriction_msg)
+        st.rerun()
+    else:
+        st.session_state.generate_next = True
+        st.rerun()
+
+
+
+# Step 2: Generate model response
+messages = get_current_messages()
+
+# --- Render chat history first ---
+if len(messages) == 1 and isinstance(messages[0], SystemMessage):
+    message("Start the conversation by typing your first culinary question below!", key="welcome_bubble")
+
+for i in range(1, len(messages)):
+    content, role = convert_to_streamlit_message(messages[i])
+    if not content:
+        continue
+    
+    if role == "assistant":
+        if "recipe" in content.lower():
+            message(f"👨‍🍳 **Chef’s Recipe:**\n\n{content}", key=f"chat_ai_{i}")
+        else:
+            message(f"👨‍🍳 {content}", key=f"chat_ai_{i}")
+    elif role == "user":
+        message(content, is_user=True, key=f"chat_user_{i}")
+
+
+# --- Now show spinner / generate new response ---
+if st.session_state.generate_next:
+    st.session_state.generate_next = False 
+
+    full_history = get_current_messages()
+
+    # Spinner will show at the bottom of the chat
+    with st.spinner("👨‍🍳 Our culinary expert is crafting your response..."):
+        try:
+            ai_message: AIMessage = CHAT_MODEL.invoke(full_history)
+            st.session_state.chats[st.session_state.current_chat_id].append(ai_message)
+
+            # Rename untitled chat with first user message
+            if st.session_state.chat_titles[st.session_state.current_chat_id] == "New Chat":
+                st.session_state.chat_titles[st.session_state.current_chat_id] = full_history[-1].content[:30] + "..."
+        except Exception as e:
+            error_message = "I'm sorry, I encountered a brief issue while preparing the answer. Please try again."
+            st.session_state.chats[st.session_state.current_chat_id].append(AIMessage(content=error_message))
+            print(f"Full LLM invocation error: {e}")
+
+    st.rerun()