Update app.py

app.py

@@ -1,131 +1,168 @@
 import streamlit as st
 import google.generativeai as genai
+from google.generativeai import types
+
+# --- CONFIGURATION ---
+# Task 3: Use Case Adaptation (Academic Tutor)
+APP_TITLE = "🧠 Academic Tutor Assistant powered by Gemini"
+DEFAULT_SYSTEM_PROMPT = (
+    "You are an expert **Academic Tutor**. Your goal is to help the user understand complex "
+    "concepts, review essays, solve problems, and provide study guidance. "
+    "Respond with clear, structured, and encouraging explanations. "
+    "Always ask a follow-up question to encourage deeper learning."
+)
 
-# -------------------
-# API Key Setup
-# -------------------
-gemini_api_key = st.secrets.get("GEN_API_KEY", "")
-
-# -------------------
-# Page Configuration
-# -------------------
-st.set_page_config(page_title="Your AI Buddy", layout="wide")
-st.title("💡 Need answers? Just type below!")
-
-# -------------------
-# Gemini Setup
-# -------------------
-if not gemini_api_key:
-    st.error("⚠️ Please set your 'GEN_API_KEY' in Streamlit secrets.")
-    st.stop()
-
-genai.configure(api_key=gemini_api_key)
+# --- HELPER FUNCTIONS ---
 
-# Fetch available Gemini models
-available_models = [
-    m.name for m in genai.list_models()
-    if "generateContent" in m.supported_generation_methods
-]
+@st.cache_resource(show_spinner="Connecting to Gemini...")
+def setup_gemini_client(api_key):
+    """Initializes and configures the Gemini client."""
+    if not api_key:
+        st.error("⚠️ Please set your 'GEN_API_KEY' in Streamlit secrets.")
+        st.stop()
+    try:
+        genai.configure(api_key=api_key)
+        return genai
+    except Exception as e:
+        st.error(f"⚠️ Error configuring Gemini client: {e}")
+        st.stop()
 
-if not available_models:
-    st.error("⚠️ No Gemini models available for your API key.")
-    st.stop()
 
-# Reset session if old model is invalid
-if "model" in st.session_state and st.session_state["model"] not in available_models:
-    del st.session_state["model"]
+def get_available_models():
+    """Fetches and filters available chat-capable models."""
+    try:
+        available_models = [
+            m.name for m in genai.list_models()
+            if "generateContent" in m.supported_generation_methods
+            and ("gemini-2.5" in m.name or "gemini-1.5" in m.name) # Filter for high-quality models
+        ]
+        if not available_models:
+            st.error("⚠️ No suitable Gemini models available for your API key.")
+            st.stop()
+        return available_models
+    except Exception as e:
+        st.error(f"⚠️ Error fetching models: {e}")
+        st.stop()
 
-model = st.sidebar.selectbox("Model", available_models, index=0)
 
-# Initialize Gemini chat if needed
-if "gemini_chat" not in st.session_state or st.session_state.get("model") != model:
-    st.session_state.model = model
+def init_chat_session(model_name, system_prompt):
+    """Initializes a new Gemini chat session with a system instruction."""
     try:
-        gemini_model = genai.GenerativeModel(model)
-        st.session_state.gemini_chat = gemini_model.start_chat(history=[])
+        # Task 2: Proper System Prompt Injection via config
+        config = types.GenerateContentConfig(
+            system_instruction=system_prompt
+        )
+        gemini_model = genai.GenerativeModel(model_name)
+        st.session_state.gemini_chat = gemini_model.start_chat(
+            history=[],
+            config=config  # Apply the system instruction here
+        )
     except Exception as e:
-        st.error(f"⚠️ Could not initialize Gemini model: {e}")
+        st.error(f"⚠️ Could not initialize Gemini model '{model_name}': {e}")
         st.stop()
 
-# -------------------
-# Sidebar Options
-# -------------------
-system_prompt = st.sidebar.text_area(
-    "System Prompt",
-    "You are a helpful AI assistant. Provide concise and accurate answers."
+# --- STREAMLIT PAGE SETUP ---
+
+# 1. Page Configuration (Task 4: UI Improvement)
+st.set_page_config(page_title=APP_TITLE, layout="wide", initial_sidebar_state="expanded")
+st.title(APP_TITLE)
+st.markdown(
+    "Ask any academic question, paste your homework problem, or submit a paragraph for review. Let's learn together!"
 )
 
-if "messages" not in st.session_state:
+# 2. API Key and Client Setup
+gemini_api_key = st.secrets.get("GEN_API_KEY", "")
+gemini_client = setup_gemini_client(gemini_api_key)
+
+
+# 3. Sidebar Controls (Task 4: Usability Enhancement)
+with st.sidebar:
+    st.header("⚙️ Settings")
+    
+    # Model Selection
+    available_models = get_available_models()
+    default_index = 0
+    if "gemini-2.5-flash" in available_models:
+        default_index = available_models.index("gemini-2.5-flash")
+
+    new_model = st.selectbox(
+        "Select Model", 
+        available_models, 
+        index=default_index,
+        key="_selected_model_name"
+    )
+    
+    # System Prompt (Task 3: Use Case Adaptation)
+    system_prompt_key = "_system_prompt_area"
+    system_prompt = st.text_area(
+        "Tutor Persona / System Instruction",
+        DEFAULT_SYSTEM_PROMPT,
+        height=180,
+        key=system_prompt_key
+    )
+
+    # Check for configuration change and re-initialize chat
+    if (st.session_state.get("model") != new_model) or \
+       (st.session_state.get("system_prompt") != system_prompt):
+        
+        # Save new values and re-initialize chat
+        st.session_state.model = new_model
+        st.session_state.system_prompt = system_prompt
+        st.session_state.messages = []
+        init_chat_session(new_model, system_prompt)
+        st.info("Tutor persona updated. Conversation restarted.")
+        
+    # Reset Conversation Button (Task 4: Usability Enhancement)
+    if st.button("🔄 Reset Conversation"):
+        st.session_state.messages = []
+        init_chat_session(st.session_state.model, st.session_state.system_prompt)
+        # Note: No st.rerun() needed due to Streamlit's natural flow
+
+# 4. Chat Initialization (First run check)
+if "gemini_chat" not in st.session_state:
+    st.session_state.model = new_model
+    st.session_state.system_prompt = system_prompt
     st.session_state.messages = []
+    init_chat_session(new_model, system_prompt)
 
-# Reset conversation button
-if st.sidebar.button("Reset Conversation"):
-    st.session_state.messages = []
-    gemini_model = genai.GenerativeModel(model)
-    st.session_state.gemini_chat = gemini_model.start_chat(history=[])
-    st.rerun()
-
-# -------------------
-# Custom Chat Bubble Styling
-# -------------------
-st.markdown("""
-<style>
-/* General chat bubble styling */
-.stChatMessage > div {
-    border-radius: 15px;
-    padding: 10px 14px;
-    margin: 6px 0;
-    max-width: 80%;
-    font-size: 15px;
-}
-
-/* User messages (right side) */
-.stChatMessage[data-testid="stChatMessage-user"] > div {
-    background-color: #d1e9ff;
-    color: #0a2f5c;
-    border: 1px solid #a3cfff;
-    margin-left: auto;
-    text-align: right;
-}
-
-/* Assistant messages (left side) */
-.stChatMessage[data-testid="stChatMessage-assistant"] > div {
-    background-color: #f1f1f1;
-    color: #1a1a1a;
-    border: 1px solid #ddd;
-    margin-right: auto;
-    text-align: left;
-}
-
-/* Avatars */
-.stChatMessage [data-testid="stChatAvatar"] {
-    border-radius: 50%;
-    width: 32px;
-    height: 32px;
-    font-size: 18px;
-    background-color: #ffffff;
-    display: flex;
-    align-items: center;
-    justify-content: center;
-    box-shadow: 0 1px 3px rgba(0,0,0,0.2);
-}
-</style>
-""", unsafe_allow_html=True)
-
-# -------------------
-# Display Chat Messages
-# -------------------
+# --- CHAT INTERACTION ---
+
+# 5. Display Chat Messages (Task 4: Visualization)
 for msg in st.session_state.messages:
     with st.chat_message(msg["role"]):
         st.markdown(msg["content"])
 
-# -------------------
-# User Input
-# -------------------
-if user_input := st.chat_input("Type your message..."):
-    # Show user message
-    st.chat_message("user").markdown(user_input)
+
+# 6. User Input (Task 4: Placeholder)
+if user_input := st.chat_input("Ask about history, math, or review your essay draft..."):
+    # 6a. Add and display user message
     st.session_state.messages.append({"role": "user", "content": user_input})
+    with st.chat_message("user"):
+        st.markdown(user_input)
 
+    # 6b. Send message to Gemini
     try:
-        with st.spinner("Gemini is thinking..."):
+        with st.spinner("💡 Tutor is thinking..."):
+            # The system prompt is in the config, so we only send the user's message.
+            response = st.session_state.gemini_chat.send_message(user_input, stream=True)
+            
+            # Display response chunks as they arrive (Streaming for better UX)
+            full_response = ""
+            with st.chat_message("assistant"):
+                message_placeholder = st.empty()
+                for chunk in response:
+                    full_response += chunk.text
+                    message_placeholder.markdown(full_response + "▌") 
+                message_placeholder.markdown(full_response) # Final rendering
+
+        bot_text = full_response
+
+    except Exception as e:
+        bot_text = f"⚠️ The tutor could not respond right now. Please try again. Error: {e}"
+        with st.chat_message("assistant"):
+            st.markdown(bot_text)
+
+    # 6c. Save assistant message
+    st.session_state.messages.append({"role": "assistant", "content": bot_text})
+    
+    # Task 4: Removed st.rerun() for better stability.