correção de bugs, creação propria para turmas, e preparação para criar quizzes

lib/features/auth/presentation/pages/signup_page.dart

@@ -1,3 +1,4 @@
+import 'package:cloud_firestore/cloud_firestore.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_animate/flutter_animate.dart';
 import 'package:go_router/go_router.dart';
@@ -22,12 +23,39 @@ class _SignupPageState extends State<SignupPage> {
   bool _isLoading = false;
   bool _obscurePassword = true;
   late String _selectedRole;
+  String? _selectedSchoolClassId;
+  List<Map<String, String>> _availableClasses = [];
+  bool _isLoadingClasses = false;
 
   @override
   void initState() {
     super.initState();
     // Usar role passado da tela anterior ou default 'student'
     _selectedRole = widget.selectedRole ?? 'student';
+    if (_selectedRole == 'student') {
+      _loadAvailableClasses();
+    }
+  }
+
+  Future<void> _loadAvailableClasses() async {
+    setState(() => _isLoadingClasses = true);
+    try {
+      final snapshot = await FirebaseFirestore.instance
+          .collection('school_classes')
+          .where('active', isEqualTo: true)
+          .orderBy('year')
+          .orderBy('section')
+          .get();
+      setState(() {
+        _availableClasses = snapshot.docs.map((doc) {
+          final data = doc.data();
+          return {'id': doc.id, 'name': (data['name'] as String? ?? doc.id)};
+        }).toList();
+        _isLoadingClasses = false;
+      });
+    } catch (e) {
+      setState(() => _isLoadingClasses = false);
+    }
   }
 
   @override
@@ -38,6 +66,99 @@ class _SignupPageState extends State<SignupPage> {
     super.dispose();
   }
 
+  Widget _buildClassSelector(BuildContext context) {
+    if (_isLoadingClasses) {
+      return Padding(
+        padding: const EdgeInsets.symmetric(vertical: 8.0),
+        child: Row(
+          children: [
+            SizedBox(
+              width: 18,
+              height: 18,
+              child: CircularProgressIndicator(
+                strokeWidth: 2,
+                color: Theme.of(context).colorScheme.primary,
+              ),
+            ),
+            const SizedBox(width: 12),
+            Text(
+              'A carregar turmas...',
+              style: TextStyle(
+                color: Theme.of(context).colorScheme.onSurfaceVariant,
+                fontSize: 14,
+              ),
+            ),
+          ],
+        ),
+      );
+    }
+
+    if (_availableClasses.isEmpty) {
+      return Padding(
+        padding: const EdgeInsets.symmetric(vertical: 8.0),
+        child: Text(
+          'Nenhuma turma disponível. Contacta o teu professor.',
+          style: TextStyle(
+            color: Theme.of(context).colorScheme.error,
+            fontSize: 13,
+          ),
+        ),
+      );
+    }
+
+    return DropdownButtonFormField<String>(
+      value: _selectedSchoolClassId,
+      isExpanded: true,
+      decoration: InputDecoration(
+        labelText: 'Turma',
+        labelStyle: TextStyle(color: Theme.of(context).colorScheme.onSurface),
+        enabledBorder: OutlineInputBorder(
+          borderRadius: BorderRadius.circular(8.0),
+          borderSide: BorderSide(
+            color: Theme.of(context).colorScheme.outline.withOpacity(0.3),
+          ),
+        ),
+        focusedBorder: OutlineInputBorder(
+          borderRadius: BorderRadius.circular(8.0),
+          borderSide: BorderSide(color: Theme.of(context).colorScheme.primary),
+        ),
+        errorBorder: OutlineInputBorder(
+          borderRadius: BorderRadius.circular(8.0),
+          borderSide: BorderSide(color: Theme.of(context).colorScheme.error),
+        ),
+        focusedErrorBorder: OutlineInputBorder(
+          borderRadius: BorderRadius.circular(8.0),
+          borderSide: BorderSide(color: Theme.of(context).colorScheme.error),
+        ),
+        filled: true,
+        fillColor: Theme.of(context).brightness == Brightness.dark
+            ? Theme.of(context).colorScheme.surfaceContainerHighest
+            : Theme.of(context).colorScheme.surface,
+      ),
+      style: TextStyle(color: Theme.of(context).colorScheme.onSurface),
+      dropdownColor: Theme.of(context).colorScheme.surface,
+      hint: Text(
+        'Seleciona a tua turma',
+        style: TextStyle(color: Theme.of(context).colorScheme.onSurfaceVariant),
+      ),
+      items: _availableClasses
+          .map(
+            (c) => DropdownMenuItem<String>(
+              value: c['id'],
+              child: Text(c['name']!),
+            ),
+          )
+          .toList(),
+      onChanged: (value) => setState(() => _selectedSchoolClassId = value),
+      validator: (value) {
+        if (value == null || value.isEmpty) {
+          return 'Seleciona a tua turma';
+        }
+        return null;
+      },
+    );
+  }
+
   Future<void> _handleSignup() async {
     if (!_formKey.currentState!.validate()) return;
 
@@ -60,6 +181,9 @@ class _SignupPageState extends State<SignupPage> {
         password: password,
         displayName: name,
         role: _selectedRole,
+        schoolClassId: _selectedRole == 'student'
+            ? _selectedSchoolClassId
+            : null,
       );
 
       print('DEBUG: Signup Firebase bem-sucedido, navegando para dashboard');
@@ -295,6 +419,12 @@ class _SignupPageState extends State<SignupPage> {
                                 ),
                                 const SizedBox(height: 16),
 
+                                // Seletor de turma (apenas para alunos)
+                                if (_selectedRole == 'student') ...[
+                                  _buildClassSelector(context),
+                                  const SizedBox(height: 16),
+                                ],
+
                                 // Email field
                                 TextFormField(
                                   controller: _emailController,