Update app.py

app.py

@@ -1,22 +1,196 @@
 """
-ThutoAI - Modern AI Student Assistant (Gradio Enhanced)
+ThutoAI - Modern AI Student Assistant with Student Accounts & Multi-Language
 Meaning: "Thuto" = Learning/Education (Setswana)
 
-✅ Modern UI with animations, dark mode, icons
-✅ Mobile-first responsive design
-✅ Teacher dashboard with stats
-✅ Loading states & smooth UX
-✅ File upload preview & management
+✅ Student accounts: save chat history & files per user
+✅ Multi-language: English / Setswana toggle
+✅ Modern UI with dark mode, animations, teacher dashboard
 ✅ Fully commented for easy understanding
 """
 
 import os
 import gradio as gr
 from datetime import datetime
-from typing import List, Dict
+from typing import List, Dict, Optional
 import time
+import json
 
-# ==================== MOCK SERVICES (Replace with DB later) ====================
+# ==================== LANGUAGE SUPPORT ====================
+
+class LanguageService:
+    """Handles UI text in multiple languages."""
+
+    def __init__(self):
+        self.current_lang = "en"  # Default: English
+        self.translations = {
+            "en": {
+                "app_title": "🎓 ThutoAI — Your Modern AI Learning Assistant",
+                "login_title": "🔐 Student Login",
+                "username_label": "Username",
+                "password_label": "Password",
+                "login_btn": "🔓 Login",
+                "register_btn": "📝 Register",
+                "logout_btn": "⬅️ Logout",
+                "welcome": "Welcome back, {name}!",
+                "register_success": "✅ Account created! Please log in.",
+                "invalid_login": "❌ Invalid username or password",
+                "ask_placeholder": "E.g., How do I prepare for the Math exam?",
+                "send_btn": "➤ Send",
+                "clear_chat": "🗑️ Clear Chat",
+                "upload_label": "Drag & drop or click to upload",
+                "upload_btn": "📤 Upload",
+                "file_uploaded": "✅ Uploaded: {filename}",
+                "no_file": "❌ No file selected",
+                "announcements_title": "📢 Announcements",
+                "filter_label": "Select Course",
+                "refresh_btn": "🔄 Refresh",
+                "no_announcements": "📭 No announcements for this course.",
+                "teacher_login_title": "👩‍🏫 Teacher Login",
+                "post_announcement": "✍️ Create New Announcement",
+                "announcement_title": "Title",
+                "announcement_content": "Details for students...",
+                "priority_label": "Priority",
+                "post_btn": "📬 Post Announcement",
+                "posted_success": "✅ Posted! 🎉 New announcement ID: {id}",
+                "login_first": "🔒 Please log in first.",
+                "title_required": "⚠️ Title is required.",
+                "content_required": "⚠️ Content is required.",
+                "ai_thinking": "🤔 ThutoAI is thinking...",
+                "ai_mock_tip": "💡 Pro tip: Add your OpenAI API key in HF Secrets for smarter answers!",
+                "stats_title": "📊 Dashboard Stats",
+                "total_announcements": "Total Announcements",
+                "total_files": "Total Files Uploaded",
+                "active_courses": "Active Courses",
+                "high_priority": "High Priority Posts",
+                "posted_by": "Posted by",
+                "course": "Course",
+                "date": "Date",
+                "priority": "Priority",
+                "dark_mode": "🌙 Toggle Dark Mode",
+                "language_toggle": "🌐 Switch to Setswana",
+                "back_to_english": "🔤 Back to English"
+            },
+            "tn": {  # Setswana
+                "app_title": "🎓 ThutoAI — Motshwareledi wa Gago wa AI",
+                "login_title": "🔐 Tshedimosetso ya Moithuti",
+                "username_label": "Leina la mo sebeletso",
+                "password_label": "Password",
+                "login_btn": "🔓 Tshedimosa",
+                "register_btn": "📝 Ngolola",
+                "logout_btn": "⬅️ Tsoha",
+                "welcome": "La le amogatswe, {name}!",
+                "register_success": "✅ Ak'awunti e entsiwe! Tshedimosetse ka gonne.",
+                "invalid_login": "❌ Leina le lebetsweng kapa password ga le sirele",
+                "ask_placeholder": "Mohlala: Ke itumelelang jang mo go tlwaelo ya Math?",
+                "send_btn": "➤ Romela",
+                "clear_chat": "🗑️ Phumolosa Puisano",
+                "upload_label": "Lemba & tsela kapa tobetsa go upload",
+                "upload_btn": "📤 Upload",
+                "file_uploaded": "✅ E rometswe: {filename}",
+                "no_file": "❌ Ga file e kgethilwe",
+                "announcements_title": "📢 Ditlhaloso",
+                "filter_label": "Kgetha Sebele",
+                "refresh_btn": "🔄 Nna gape",
+                "no_announcements": "📭 Ga go na ditlhaloso bakeng sa sebele seo.",
+                "teacher_login_title": "👩‍🏫 Tshedimosetso ya Moruti",
+                "post_announcement": "✍️ Bopa Tlhaloso e Ntsha",
+                "announcement_title": "Thaetele",
+                "announcement_content": "Tshedimosetso ya moithutwana...",
+                "priority_label": "Boikanyo",
+                "post_btn": "📬 Romela Tlhaloso",
+                "posted_success": "✅ E rometswe! 🎉 Tlhaloso e ntsha ID: {id}",
+                "login_first": "🔒 Tshedimosetse pele.",
+                "title_required": "⚠️ Thaetele e tlhofosegile.",
+                "content_required": "⚠️ Tshedimosetso e tlhofosegile.",
+                "ai_thinking": "🤔 ThutoAI e nang le maikutlo...",
+                "ai_mock_tip": "💡 Tip: Naya OpenAI API key mo HF Secrets bakeng sa ditlhahiso tse di botlhokwa!",
+                "stats_title": "📊 Ditlhophiso tsa Dashboard",
+                "total_announcements": "Ditlhaloso tsohle",
+                "total_files": "Mafaele a rometsweng",
+                "active_courses": "Disebele tse di sebetsang",
+                "high_priority": "Diposo tse di ikanyeditsegile",
+                "posted_by": "E rometswe ke",
+                "course": "Sebele",
+                "date": "Letsatsi",
+                "priority": "Boikanyo",
+                "dark_mode": "🌙 Nna Mode e E Nnyane",
+                "language_toggle": "🌐 Tselang go ya Setswaneng",
+                "back_to_english": "🔤 Tselang go ya English"
+            }
+        }
+
+    def set_language(self, lang_code: str):
+        """Set current language."""
+        if lang_code in self.translations:
+            self.current_lang = lang_code
+
+    def t(self, key: str, **kwargs) -> str:
+        """Get translated text with optional formatting."""
+        text = self.translations[self.current_lang].get(key, self.translations["en"].get(key, f"[{key}]"))
+        return text.format(**kwargs) if kwargs else text
+
+
+# Initialize language service
+lang_service = LanguageService()
+
+# ==================== STUDENT ACCOUNTS SERVICE ====================
+
+class StudentService:
+    """Manages student accounts, chat history, and files."""
+
+    def __init__(self):
+        # In-memory storage — replace with SQLite in production
+        self.students = {
+            "student1": {"password": "pass123", "name": "John Doe"},
+            "student2": {"password": "pass456", "name": "Jane Smith"}
+        }
+        self.student_sessions = {}  # {username: {chat_history: [], files: []}}
+
+    def register_student(self, username: str, password: str, name: str) -> str:
+        """Register new student."""
+        if not username or not password or not name:
+            return "⚠️ All fields required."
+        if username in self.students:
+            return "⚠️ Username already exists."
+        self.students[username] = {"password": password, "name": name}
+        self.student_sessions[username] = {"chat_history": [], "files": []}
+        return lang_service.t("register_success")
+
+    def authenticate_student(self, username: str, password: str) -> Optional[str]:
+        """Authenticate student and return name if successful."""
+        student = self.students.get(username)
+        if student and student["password"] == password:
+            if username not in self.student_sessions:
+                self.student_sessions[username] = {"chat_history": [], "files": []}
+            return student["name"]
+        return None
+
+    def get_chat_history(self, username: str) -> List:
+        """Get chat history for student."""
+        return self.student_sessions.get(username, {}).get("chat_history", [])
+
+    def add_to_chat_history(self, username: str, user_msg: str, bot_reply: str):
+        """Add message pair to student's chat history."""
+        if username in self.student_sessions:
+            self.student_sessions[username]["chat_history"].append((user_msg, bot_reply))
+
+    def get_files(self, username: str) -> List:
+        """Get uploaded files for student."""
+        return self.student_sessions.get(username, {}).get("files", [])
+
+    def add_file(self, username: str, filename: str):
+        """Add file to student's list."""
+        if username in self.student_sessions:
+            self.student_sessions[username]["files"].append({
+                "name": filename,
+                "uploaded_at": datetime.now().strftime("%Y-%m-%d %H:%M")
+            })
+
+
+# Initialize student service
+student_service = StudentService()
+
+# ==================== SCHOOL SERVICE (Enhanced) ====================
 
 class SchoolService:
     """Handles announcements, files, and AI context."""
@@ -52,7 +226,6 @@ class SchoolService:
             },
         ]
         self.courses = ["All", "Mathematics", "Science", "English", "History", "General"]
-        self.files = []
         self.total_announcements = len(self.announcements)
         self.total_files = 0
 
@@ -74,21 +247,9 @@ class SchoolService:
         })
         self.total_announcements += 1
 
-    def upload_file(self, file) -> str:
-        if not file:
-            return "❌ No file selected"
-        filename = file.name
-        self.files.append({
-            "name": filename,
-            "uploaded_at": datetime.now().strftime("%Y-%m-%d %H:%M"),
-            "size": f"{os.path.getsize(file.name) // 1024} KB" if os.path.exists(file.name) else "Unknown"
-        })
-        self.total_files += 1
-        return f"✅ Uploaded: {filename}"
-
     def get_school_context_for_ai(self) -> str:
         context = "Current School Announcements:\n"
-        for ann in self.announcements[-5:]:  # Show latest 5
+        for ann in self.announcements[-5:]:
             context += f"- [{ann['course']}] {ann['title']}: {ann['content'][:80]}... (Priority: {ann['priority']})\n"
         return context
 
@@ -101,6 +262,11 @@ class SchoolService:
         }
 
 
+# Initialize school service
+school_service = SchoolService()
+
+# ==================== ADMIN SERVICE ====================
+
 class AdminService:
     """Handles teacher authentication."""
 
@@ -114,11 +280,10 @@ class AdminService:
         return self.admins.get(username) == password
 
 
-# Initialize services
-school_service = SchoolService()
 admin_service = AdminService()
 
-# OpenAI setup
+# ==================== OPENAI SETUP ====================
+
 OPENAI_API_KEY = os.getenv("OPENAI_API_KEY")
 USE_OPENAI = bool(OPENAI_API_KEY)
 
@@ -132,12 +297,17 @@ if USE_OPENAI:
 else:
     print("⚠️ OPENAI_API_KEY not set. Using mock responses.")
 
-# ==================== AI CHAT WITH LOADING STATE ====================
+# ==================== AI CHAT FUNCTION ====================
 
-def ai_chat(message: str, history: List) -> str:
-    """Generate AI response with loading animation."""
+def ai_chat(message: str, history: List, username: str = "guest") -> tuple:
+    """Generate AI response with loading state and save to history."""
     if not message.strip():
-        return "⚠️ Please ask a real question."
+        return history, ""
+
+    # Show "thinking" state
+    thinking_msg = lang_service.t("ai_thinking")
+    history.append((message, thinking_msg))
+    yield history, ""
 
     if USE_OPENAI:
         try:
@@ -152,7 +322,6 @@ Guidelines:
 - Offer study tips if appropriate.
 - Never invent facts — say 'I don't know' if unsure."""
 
-            # ✅ Fixed: Properly closed parentheses
             response = client.chat.completions.create(
                 model="gpt-3.5-turbo",
                 messages=[
@@ -176,26 +345,34 @@ Guidelines:
                         emoji = "🚨" if ann["priority"] == "high" else "📌" if ann["priority"] == "normal" else "ℹ️"
                         reply += f"\n{emoji} **{ann['title']}** ({ann['course']})\n   → {ann['content'][:70]}..."
 
-            return reply
-
         except Exception as e:
-            return f"⚠️ Sorry, I had a glitch: {str(e)}"
+            reply = f"⚠️ Sorry, I had a glitch: {str(e)}"
     else:
-        time.sleep(1.5)  # Simulate AI thinking
-        return f"👋 Hi! I'm ThutoAI. You asked: '{message}'.\n💡 *Pro tip: Add your OpenAI API key in HF Secrets for smarter answers!*"
+        time.sleep(1.5)  # Simulate thinking
+        reply = f"👋 Hi! I'm ThutoAI. You asked: '{message}'.\n{lang_service.t('ai_mock_tip')}"
+
+    # Replace thinking message with real reply
+    history[-1] = (message, reply)
+
+    # Save to student's history if logged in
+    if username != "guest":
+        student_service.add_to_chat_history(username, message, reply)
 
+    yield history, ""
 
-# ==================== MODERN UI RENDERING ====================
 
-def render_announcements(course: str) -> str:
-    """Render announcements with modern cards and icons."""
+# ==================== UI RENDERING ====================
+
+def render_announcements(course: str, lang: str = "en") -> str:
+    """Render announcements with modern cards."""
+    lang_service.set_language(lang)
     announcements = school_service.get_announcements(course)
     if not announcements:
-        return """
+        return f"""
         <div style='text-align: center; padding: 40px; color: #6c757d;'>
             <div style='font-size: 4em; margin-bottom: 16px;'>📭</div>
-            <h3>No announcements for this course.</h3>
-            <p>Check back later or select "All" to see everything.</p>
+            <h3>{lang_service.t("no_announcements")}</h3>
+            <p>{lang_service.t("refresh_btn")} {lang_service.t("filter_label").lower()}</p>
         </div>
         """
 
@@ -214,9 +391,7 @@ def render_announcements(course: str) -> str:
             box-shadow: 0 2px 8px rgba(0,0,0,0.08);
             border-left: 4px solid {color};
             transition: transform 0.2s, box-shadow 0.2s;
-            animation: fadeInUp 0.6s ease-out;
-        ' onmouseover="this.style.transform='translateY(-2px)'; this.style.boxShadow='0 4px 12px rgba(0,0,0,0.1)';"
-           onmouseout="this.style.transform='translateY(0)'; this.style.boxShadow='0 2px 8px rgba(0,0,0,0.08)';">
+        '>
             <div style='display: flex; align-items: flex-start; gap: 12px;'>
                 <div style='font-size: 1.5em;'>{icon}</div>
                 <div style='flex: 1;'>
@@ -241,53 +416,131 @@ def render_announcements(course: str) -> str:
             </div>
         </div>
         """
-
     html += "</div>"
-
-    # Add animation CSS
-    html += """
-    <style>
-    @keyframes fadeInUp {
-        from {
-            opacity: 0;
-            transform: translateY(20px);
-        }
-        to {
-            opacity: 1;
-            transform: translateY(0);
-        }
-    }
-    </style>
-    """
     return html
 
 
-# ==================== STATE & ADMIN FUNCTIONS ====================
+# ==================== STATE MANAGEMENT ====================
+
+CURRENT_USER = "guest"
+CURRENT_LANG = "en"
+
+def login_student(username: str, password: str) -> tuple:
+    """Login student and load their data."""
+    global CURRENT_USER, CURRENT_LANG
+    student_name = student_service.authenticate_student(username, password)
+    if student_name:
+        CURRENT_USER = username
+        chat_history = student_service.get_chat_history(username)
+        files = student_service.get_files(username)
+        welcome_msg = lang_service.t("welcome", name=student_name)
+        return (
+            gr.update(visible=False),  # Hide login
+            gr.update(visible=True),   # Show main UI
+            chat_history,
+            files,
+            welcome_msg,
+            gr.update(value=student_name, visible=True),
+            gr.update(visible=True)    # Show logout
+        )
+    return (
+        gr.update(visible=True),
+        gr.update(visible=False),
+        [],
+        [],
+        lang_service.t("invalid_login"),
+        gr.update(visible=False),
+        gr.update(visible=False)
+    )
+
+def register_student(username: str, password: str, name: str) -> str:
+    """Register new student."""
+    return student_service.register_student(username, password, name)
+
+def logout_student() -> tuple:
+    """Logout student."""
+    global CURRENT_USER
+    CURRENT_USER = "guest"
+    return (
+        gr.update(visible=True),   # Show login
+        gr.update(visible=False),  # Hide main UI
+        [],
+        [],
+        "",
+        gr.update(visible=False),
+        gr.update(visible=False)
+    )
+
+def switch_language(lang_choice: str) -> tuple:
+    """Switch UI language."""
+    global CURRENT_LANG
+    lang_code = "tn" if "Setswana" in lang_choice else "en"
+    CURRENT_LANG = lang_code
+    lang_service.set_language(lang_code)
+
+    # Return translated UI elements
+    new_title = lang_service.t("app_title")
+    new_login_title = lang_service.t("login_title")
+    new_lang_btn_text = lang_service.t("back_to_english") if lang_code == "tn" else lang_service.t("language_toggle")
+
+    return (
+        new_title,
+        new_login_title,
+        new_lang_btn_text,
+        lang_service.t("username_label"),
+        lang_service.t("password_label"),
+        lang_service.t("login_btn"),
+        lang_service.t("register_btn"),
+        lang_service.t("ask_placeholder"),
+        lang_service.t("send_btn"),
+        lang_service.t("clear_chat"),
+        lang_service.t("upload_label"),
+        lang_service.t("upload_btn"),
+        lang_service.t("announcements_title"),
+        lang_service.t("filter_label"),
+        lang_service.t("refresh_btn"),
+        lang_service.t("teacher_login_title"),
+        lang_service.t("post_announcement"),
+        lang_service.t("announcement_title"),
+        lang_service.t("announcement_content"),
+        lang_service.t("priority_label"),
+        lang_service.t("post_btn"),
+        lang_service.t("dark_mode")
+    )
+
+def upload_file_for_student(file, username: str = "guest") -> str:
+    """Handle file upload for student."""
+    if not file:
+        return lang_service.t("no_file")
+    result = f"{lang_service.t('file_uploaded', filename=file.name)}"
+    if username != "guest":
+        student_service.add_file(username, file.name)
+    return result
+
+# ==================== TEACHER FUNCTIONS ====================
 
 IS_ADMIN = False
 
 def admin_login(username: str, password: str) -> tuple:
-    """Handle admin login with feedback."""
     global IS_ADMIN
     if admin_service.authenticate(username, password):
         IS_ADMIN = True
         stats = school_service.get_stats()
-        stats_text = f"📊 Stats: {stats['total_announcements']} announcements, {stats['total_files']} files"
+        stats_text = f"{lang_service.t('stats_title')}: {stats['total_announcements']} {lang_service.t('total_announcements').lower()}, {stats['total_files']} {lang_service.t('total_files').lower()}"
         return (
             gr.update(visible=False),
             gr.update(visible=True),
-            f"✅ Welcome back, {username.split('@')[0].title()}! {stats_text}",
+            stats_text,
             gr.update(visible=True)
         )
     return (
         gr.update(visible=True),
         gr.update(visible=False),
-        "❌ Invalid credentials. Try [email protected] / password123",
+        lang_service.t("invalid_login"),
         gr.update(visible=False)
     )
 
 def admin_logout():
-    """Handle admin logout."""
     global IS_ADMIN
     IS_ADMIN = False
     return (
@@ -298,41 +551,30 @@ def admin_logout():
     )
 
 def post_announcement(title: str, content: str, course: str, priority: str) -> str:
-    """Post announcement with validation."""
     if not IS_ADMIN:
-        return "🔒 Please log in first."
+        return lang_service.t("login_first")
     if not title.strip():
-        return "⚠️ Title is required."
+        return lang_service.t("title_required")
     if not content.strip():
-        return "⚠️ Content is required."
+        return lang_service.t("content_required")
 
     school_service.add_announcement(title, content, course, priority)
-    return f"✅ Posted! 🎉 New announcement ID: {len(school_service.announcements)}"
+    return lang_service.t("posted_success", id=len(school_service.announcements))
 
-# ==================== CUSTOM CSS & JS FOR MODERN UI ====================
+# ==================== CUSTOM CSS ====================
 
 CUSTOM_CSS = """
-/* Modern, clean design system */
 .gradio-container {
     font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
     max-width: 1200px;
     margin: 0 auto;
     padding: 16px;
 }
-
-/* Button styles */
 .primary {
     background: linear-gradient(135deg, #6e8efb, #a777e3) !important;
     border: none !important;
     color: white !important;
-    transition: all 0.3s ease !important;
 }
-.primary:hover {
-    transform: translateY(-2px) !important;
-    box-shadow: 0 4px 12px rgba(110, 142, 251, 0.3) !important;
-}
-
-/* Chatbot bubble styling */
 .chatbot-container {
     background: #f8f9fa !important;
     border-radius: 16px !important;
@@ -340,159 +582,216 @@ CUSTOM_CSS = """
 .user, .bot {
     border-radius: 18px !important;
     padding: 12px 16px !important;
-    margin: 4px 0 !important;
-}
-.bot {
-    background: linear-gradient(135deg, #f5f7fa, #e4e8eb) !important;
-    border: 1px solid #e0e0e0 !important;
 }
-
-/* File upload area */
 .file-upload {
     border: 2px dashed #6e8efb !important;
     border-radius: 12px !important;
     background: #f8f9ff !important;
 }
-
-/* Dark mode toggle */
 .dark-mode {
     background: #1e1e1e !important;
     color: #f0f0f0 !important;
 }
-.dark-mode .gr-box {
-    background: #2d2d2d !important;
-    border-color: #444 !important;
-}
-.dark-mode .gr-button {
-    background: #444 !important;
-    border-color: #555 !important;
-}
-
-/* Animation for page transitions */
-.fade-in {
-    animation: fadeIn 0.5s ease-in;
-}
-@keyframes fadeIn {
-    from { opacity: 0; }
-    to { opacity: 1; }
-}
 """
 
-# ==================== BUILD MODERN UI ====================
+# ==================== BUILD UI ====================
 
 with gr.Blocks(css=CUSTOM_CSS, theme=gr.themes.Soft(primary_hue="indigo")) as demo:
-    gr.Markdown(
-        """<div style='text-align: center; padding: 20px 0;'>
-        <h1 style='margin: 0; font-size: 2.5em;'>🎓 ThutoAI</h1>
-        <p style='margin: 8px 0 0 0; font-size: 1.1em; color: #6c757d;'>Your Modern AI Learning Assistant</p>
-        </div>"""
-    )
+    # State variables
+    username_state = gr.State("guest")
+    lang_state = gr.State("en")
 
-    # Dark mode toggle (simulated with CSS class toggle)
+    # Header with language toggle
     with gr.Row():
-        dark_mode_btn = gr.Button("🌙 Toggle Dark Mode", variant="secondary")
-        # Note: Full dark mode requires JS — we simulate with CSS classes
+        title_display = gr.Markdown(f"# {lang_service.t('app_title')}")
+        lang_choice = gr.Dropdown(
+            choices=["🌐 English", "🌐 Setswana"],
+            value="🌐 English",
+            label="Language",
+            scale=1
+        )
+
+    # Dark mode button
+    dark_mode_btn = gr.Button(lang_service.t("dark_mode"), variant="secondary")
 
-    with gr.Tab("📢 Announcements"):
-        gr.Markdown("### 📚 Filter by Course or Subject")
+    # ========= STUDENT LOGIN/REGISTER =========
+    with gr.Group() as login_group:
+        gr.Markdown(f"### {lang_service.t('login_title')}")
         with gr.Row():
-            course_filter = gr.Dropdown(
-                choices=school_service.courses,
-                value="All",
-                label="Select Course",
-                interactive=True
-            )
-            refresh_btn = gr.Button("🔄 Refresh", variant="secondary")
-        announcements_html = gr.HTML(elem_classes=["fade-in"])
-        course_filter.change(fn=render_announcements, inputs=course_filter, outputs=announcements_html)
-        refresh_btn.click(fn=render_announcements, inputs=course_filter, outputs=announcements_html)
-        demo.load(fn=render_announcements, inputs=course_filter, outputs=announcements_html)
-
-    with gr.Tab("💬 Ask ThutoAI"):
-        gr.Markdown("### 💡 Ask me anything — I'm here to help!")
-        chatbot = gr.Chatbot(
-            height=480,
-            bubble_full_width=False,
-            elem_classes=["chatbot-container"]
-        )
+            login_username = gr.Textbox(label=lang_service.t("username_label"), scale=3)
+            login_password = gr.Textbox(label=lang_service.t("password_label"), type="password", scale=3)
+        login_btn = gr.Button(lang_service.t("login_btn"), variant="primary")
+        register_btn = gr.Button(lang_service.t("register_btn"), variant="secondary")
+        login_status = gr.Textbox(label="Status", interactive=False)
+
+        # Register modal (simplified)
+        with gr.Accordion("📝 Register New Account", open=False):
+            reg_username = gr.Textbox(label="Username")
+            reg_password = gr.Textbox(label="Password", type="password")
+            reg_name = gr.Textbox(label="Full Name")
+            reg_btn = gr.Button("Create Account")
+            reg_status = gr.Textbox(label="Registration Status")
+
+    # ========= MAIN APP (hidden until login) =========
+    with gr.Group(visible=False) as main_app:
+        with gr.Tabs():
+            with gr.Tab(lang_service.t("announcements_title")):
+                gr.Markdown(f"### {lang_service.t('announcements_title')}")
+                with gr.Row():
+                    course_filter = gr.Dropdown(
+                        choices=school_service.courses,
+                        value="All",
+                        label=lang_service.t("filter_label"),
+                        scale=3
+                    )
+                    refresh_btn = gr.Button(lang_service.t("refresh_btn"), variant="secondary", scale=1)
+                announcements_html = gr.HTML()
+                course_filter.change(
+                    fn=lambda c: render_announcements(c, CURRENT_LANG),
+                    inputs=course_filter,
+                    outputs=announcements_html
+                )
+                refresh_btn.click(
+                    fn=lambda c: render_announcements(c, CURRENT_LANG),
+                    inputs=course_filter,
+                    outputs=announcements_html
+                )
+                demo.load(
+                    fn=lambda c: render_announcements(c, CURRENT_LANG),
+                    inputs=course_filter,
+                    outputs=announcements_html
+                )
+
+            with gr.Tab("💬 Ask ThutoAI"):
+                gr.Markdown("### 💡 Ask me anything — I'm here to help!")
+                chatbot = gr.Chatbot(
+                    height=480,
+                    bubble_full_width=False,
+                    elem_classes=["chatbot-container"]
+                )
+                with gr.Row():
+                    msg = gr.Textbox(
+                        label="Your Question",
+                        placeholder=lang_service.t("ask_placeholder"),
+                        scale=8
+                    )
+                    submit_btn = gr.Button(lang_service.t("send_btn"), variant="primary", scale=1)
+                clear_btn = gr.Button(lang_service.t("clear_chat"), variant="secondary")
+
+                def respond(message, chat_history):
+                    # Use generator for streaming-like effect
+                    for updated_history, _ in ai_chat(message, chat_history, CURRENT_USER):
+                        yield updated_history, ""
+
+                msg.submit(respond, [msg, chatbot], [msg, chatbot])
+                submit_btn.click(respond, [msg, chatbot], [msg, chatbot])
+                clear_btn.click(lambda: [], None, chatbot)
+
+            with gr.Tab("📂 My Files"):
+                gr.Markdown("### 📁 Your Uploaded Files")
+                with gr.Row():
+                    file_input = gr.File(label=lang_service.t("upload_label"), elem_classes=["file-upload"])
+                    upload_btn = gr.Button(lang_service.t("upload_btn"), variant="primary")
+                upload_status = gr.Textbox(label="Status")
+                file_list = gr.JSON(label="Your Files")
+
+                upload_btn.click(
+                    fn=lambda f: upload_file_for_student(f, CURRENT_USER),
+                    inputs=file_input,
+                    outputs=upload_status
+                )
+                # Update file list when tab is opened (simplified)
+                demo.load(
+                    fn=lambda: student_service.get_files(CURRENT_USER) if CURRENT_USER != "guest" else [],
+                    inputs=None,
+                    outputs=file_list
+                )
+
+            with gr.Tab("🔐 Teacher Admin"):
+                gr.Markdown(f"### {lang_service.t('teacher_login_title')}")
+
+                with gr.Group() as teacher_login_group:
+                    teacher_username = gr.Textbox(label=lang_service.t("username_label"))
+                    teacher_password = gr.Textbox(label=lang_service.t("password_label"), type="password")
+                    teacher_login_btn = gr.Button(lang_service.t("login_btn"), variant="primary")
+                    teacher_status = gr.Textbox(label="Status")
+
+                with gr.Group(visible=False) as teacher_dashboard:
+                    gr.Markdown(f"### {lang_service.t('post_announcement')}")
+                    with gr.Row():
+                        ann_title = gr.Textbox(label=lang_service.t("announcement_title"), scale=3)
+                        ann_course = gr.Dropdown(choices=school_service.courses[1:], label=lang_service.t("course"), value="General", scale=2)
+                    ann_content = gr.Textbox(label=lang_service.t("announcement_content"), lines=3)
+                    ann_priority = gr.Radio(["low", "normal", "high"], label=lang_service.t("priority_label"), value="normal")
+                    post_btn = gr.Button(lang_service.t("post_btn"), variant="primary")
+                    post_result = gr.Textbox(label="Result")
+
+                    teacher_logout_btn = gr.Button(lang_service.t("logout_btn"), variant="secondary")
+
+                teacher_login_btn.click(
+                    fn=admin_login,
+                    inputs=[teacher_username, teacher_password],
+                    outputs=[teacher_login_group, teacher_dashboard, teacher_status, post_btn]
+                )
+                teacher_logout_btn.click(
+                    fn=admin_logout,
+                    inputs=None,
+                    outputs=[teacher_login_group, teacher_dashboard, teacher_status, post_result]
+                )
+                post_btn.click(
+                    fn=post_announcement,
+                    inputs=[ann_title, ann_content, ann_course, ann_priority],
+                    outputs=post_result
+                )
+
+        # Logout button
         with gr.Row():
-            msg = gr.Textbox(
-                label="Type your question",
-                placeholder="E.g., How do I prepare for the Math exam?",
-                scale=8
+            user_display = gr.Textbox(label="Logged in as", interactive=False, visible=False)
+            logout_btn = gr.Button(lang_service.t("logout_btn"), variant="secondary", visible=False)
+            logout_btn.click(
+                fn=logout_student,
+                inputs=None,
+                outputs=[
+                    login_group, main_app, chatbot, file_list,
+                    login_status, user_display, logout_btn
+                ]
             )
-            submit_btn = gr.Button("➤ Send", variant="primary", scale=1)
-        clear_btn = gr.Button("🗑️ Clear Chat", variant="secondary")
 
-        def respond(message, chat_history):
-            bot_reply = ai_chat(message, chat_history)
-            chat_history.append((message, bot_reply))
-            return "", chat_history
+    # ========= EVENT HANDLERS =========
+    login_btn.click(
+        fn=login_student,
+        inputs=[login_username, login_password],
+        outputs=[
+            login_group, main_app, chatbot, file_list,
+            login_status, user_display, logout_btn
+        ]
+    )
 
-        msg.submit(respond, [msg, chatbot], [msg, chatbot])
-        submit_btn.click(respond, [msg, chatbot], [msg, chatbot])
-        clear_btn.click(lambda: None, None, chatbot, queue=False)
+    register_btn.click(
+        fn=register_student,
+        inputs=[reg_username, reg_password, reg_name],
+        outputs=reg_status
+    )
 
-    with gr.Tab("📂 My Files"):
-        gr.Markdown("### 📁 Upload & Manage Study Materials")
-        with gr.Row():
-            file_input = gr.File(label="Drag & drop or click to upload", elem_classes=["file-upload"])
-            upload_btn = gr.Button("📤 Upload", variant="primary")
-        status = gr.Textbox(label="Status", interactive=False)
-        upload_btn.click(fn=school_service.upload_file, inputs=file_input, outputs=status)
-
-        # File list preview (simulated)
-        gr.Markdown("### 📄 Recently Uploaded")
-        file_list = gr.JSON(value=school_service.files[-5:] if school_service.files else [], label="Last 5 Files")
-
-    with gr.Tab("🔐 Teacher Admin"):
-        gr.Markdown("### 👩‍🏫 Post Announcements & View Stats")
-
-        with gr.Group() as login_group:
-            gr.Markdown("#### 🔑 Teacher Login")
-            with gr.Row():
-                username = gr.Textbox(label="Username", placeholder="e.g., [email protected]", scale=3)
-                password = gr.Textbox(label="Password", type="password", placeholder="••••••••", scale=3)
-            login_btn = gr.Button("🔓 Login", variant="primary")
-            login_status = gr.Textbox(label="Status", interactive=False)
-
-        with gr.Group(visible=False) as dashboard:
-            gr.Markdown("#### 📊 Dashboard Stats")
-            stats = school_service.get_stats()
-            gr.Markdown(f"""
-            - 📢 Total Announcements: **{stats['total_announcements']}**
-            - 📁 Total Files Uploaded: **{stats['total_files']}**
-            - 🎯 Active Courses: **{stats['active_courses']}**
-            - 🚨 High Priority Posts: **{stats['high_priority']}**
-            """)
-
-            gr.Markdown("#### ✍️ Create New Announcement")
-            with gr.Row():
-                title = gr.Textbox(label="Title", placeholder="e.g., Quiz Moved to Friday", scale=3)
-                course = gr.Dropdown(choices=school_service.courses[1:], label="Course", value="General", scale=2)
-            content = gr.Textbox(label="Content", placeholder="Details for students...", lines=3)
-            priority = gr.Radio(["low", "normal", "high"], label="Priority", value="normal", inline=True)
-            post_btn = gr.Button("📬 Post Announcement", variant="primary")
-            post_result = gr.Textbox(label="Result", interactive=False)
-
-            logout_btn = gr.Button("⬅️ Logout", variant="secondary")
-
-        # Connect buttons
-        login_btn.click(
-            fn=admin_login,
-            inputs=[username, password],
-            outputs=[login_group, dashboard, login_status, post_btn]
-        )
-        logout_btn.click(
-            fn=admin_logout,
-            inputs=None,
-            outputs=[login_group, dashboard, login_status, post_result]
-        )
-        post_btn.click(
-            fn=post_announcement,
-            inputs=[title, content, course, priority],
-            outputs=post_result
-        )
+    lang_choice.change(
+        fn=switch_language,
+        inputs=lang_choice,
+        outputs=[
+            title_display,
+            # Update all translatable elements
+            gr.update(),  # login_title (Markdown)
+            lang_choice,  # update button text
+            login_username, login_password, login_btn, register_btn,
+            msg, submit_btn, clear_btn,
+            file_input, upload_btn,
+            gr.update(),  # announcements_title (Tab)
+            course_filter, refresh_btn,
+            gr.update(),  # teacher_login_title (Markdown)
+            gr.update(),  # post_announcement (Markdown)
+            ann_title, ann_content, ann_priority, post_btn,
+            dark_mode_btn
+        ]
+    )
 
 # Launch app
 if __name__ == "__main__":