update error

backend/main.py

@@ -152,7 +152,7 @@ def get_db():
     return client.openlearnx
 
 # ===================================================================
-# ✅ ENHANCED DYNAMIC SCORING SYSTEM
+# ✅ ENHANCED DYNAMIC SCORING SYSTEM - CORRECTED VERSION
 # ===================================================================
 
 def calculate_dynamic_score(code, language, problem):
@@ -161,119 +161,116 @@ def calculate_dynamic_score(code, language, problem):
     from contextlib import redirect_stdout, redirect_stderr
     import time
     
+    # Handle both old and new problem formats
     test_cases = problem.get('test_cases', [])
     total_points = problem.get('total_points', 100)
     
+    # ✅ FIXED: Handle empty test cases properly
+    if not test_cases:
+        # Create a basic test case for simple execution
+        test_cases = [{
+            "input": "",
+            "expected_output": "",
+            "description": "Basic execution test",
+            "points": total_points
+        }]
+    
     start_time = time.time()
     passed_tests = 0
-    total_tests = len(test_cases) if test_cases else 1
+    total_tests = len(test_cases)
     test_results = []
     points_earned = 0
     
     print(f"🧮 Enhanced Dynamic scoring - {total_tests} test cases, {total_points} total points")
     
     try:
-        if test_cases:
-            for i, test_case in enumerate(test_cases):
-                test_input = test_case.get('input', '')
-                expected_output = test_case.get('expected_output', '').strip()
-                test_points = test_case.get('points', total_points // total_tests)
+        for i, test_case in enumerate(test_cases):
+            test_input = test_case.get('input', '')
+            expected_output = test_case.get('expected_output', '').strip()
+            test_points = test_case.get('points', total_points // total_tests)
+            
+            print(f"📋 Test {i+1}: Input='{test_input}', Expected='{expected_output}', Points={test_points}")
+            
+            try:
+                stdout_buffer = io.StringIO()
+                stderr_buffer = io.StringIO()
                 
-                print(f"📋 Test {i+1}: Input='{test_input}', Expected='{expected_output}', Points={test_points}")
+                # ✅ ENHANCED: Better execution environment
+                exec_globals = {
+                    "__builtins__": __builtins__,
+                    "__name__": "__main__"
+                }
                 
-                try:
-                    stdout_buffer = io.StringIO()
-                    stderr_buffer = io.StringIO()
-                    
-                    exec_globals = {"__builtins__": __builtins__}
-                    if test_input:
-                        # Handle multiple input lines
-                        input_lines = test_input.split('\n') if '\n' in test_input else [test_input]
-                        input_iter = iter(input_lines)
-                        exec_globals['input'] = lambda prompt='': next(input_iter, '')
-                    
-                    with redirect_stdout(stdout_buffer), redirect_stderr(stderr_buffer):
-                        exec(code, exec_globals)
-                    
-                    actual_output = stdout_buffer.getvalue().strip()
-                    stderr_content = stderr_buffer.getvalue().strip()
-                    
-                    print(f"🔍 Test {i+1} - Actual: '{actual_output}', Expected: '{expected_output}'")
-                    
-                    # Enhanced comparison with tolerance for whitespace
-                    if actual_output == expected_output or actual_output.replace(' ', '') == expected_output.replace(' ', ''):
-                        passed_tests += 1
-                        points_earned += test_points
-                        test_results.append({
-                            "test_number": i + 1,
-                            "passed": True,
-                            "input": test_input,
-                            "expected_output": expected_output,
-                            "actual_output": actual_output,
-                            "points_earned": test_points,
-                            "description": test_case.get('description', f'Test case {i+1}'),
-                            "execution_time": time.time() - start_time
-                        })
-                        print(f"✅ Test {i+1} PASSED - {test_points} points earned")
-                    else:
-                        test_results.append({
-                            "test_number": i + 1,
-                            "passed": False,
-                            "input": test_input,
-                            "expected_output": expected_output,
-                            "actual_output": actual_output,
-                            "points_earned": 0,
-                            "error": f"Output mismatch. Got '{actual_output}', expected '{expected_output}'",
-                            "description": test_case.get('description', f'Test case {i+1}'),
-                            "stderr": stderr_content if stderr_content else None
-                        })
-                        print(f"❌ Test {i+1} FAILED - Expected '{expected_output}', got '{actual_output}'")
+                # Handle input simulation
+                if test_input:
+                    input_lines = test_input.split('\n') if '\n' in test_input else [test_input]
+                    input_iter = iter(input_lines)
+                    exec_globals['input'] = lambda prompt='': next(input_iter, '')
+                else:
+                    exec_globals['input'] = lambda prompt='': ''
                 
-                except Exception as e:
-                    print(f"❌ Test {i+1} EXCEPTION - {str(e)}")
+                with redirect_stdout(stdout_buffer), redirect_stderr(stderr_buffer):
+                    exec(code, exec_globals)
+                
+                actual_output = stdout_buffer.getvalue().strip()
+                stderr_content = stderr_buffer.getvalue().strip()
+                
+                print(f"🔍 Test {i+1} - Actual: '{actual_output}', Expected: '{expected_output}'")
+                
+                # ✅ ENHANCED: Better output comparison
+                is_correct = False
+                if expected_output == "":
+                    # For basic execution tests, just check if code runs without error
+                    is_correct = stderr_content == ""
+                else:
+                    # Compare outputs with tolerance for whitespace
+                    is_correct = (
+                        actual_output == expected_output or 
+                        actual_output.replace(' ', '') == expected_output.replace(' ', '') or
+                        actual_output.lower().strip() == expected_output.lower().strip()
+                    )
+                
+                if is_correct:
+                    passed_tests += 1
+                    points_earned += test_points
+                    test_results.append({
+                        "test_number": i + 1,
+                        "passed": True,
+                        "input": test_input,
+                        "expected_output": expected_output,
+                        "actual_output": actual_output,
+                        "points_earned": test_points,
+                        "description": test_case.get('description', f'Test case {i+1}'),
+                        "execution_time": round(time.time() - start_time, 3)
+                    })
+                    print(f"✅ Test {i+1} PASSED - {test_points} points earned")
+                else:
                     test_results.append({
                         "test_number": i + 1,
                         "passed": False,
                         "input": test_input,
                         "expected_output": expected_output,
-                        "actual_output": f"Error: {str(e)}",
+                        "actual_output": actual_output,
                         "points_earned": 0,
-                        "error": str(e),
+                        "error": f"Output mismatch. Got '{actual_output}', expected '{expected_output}'",
                         "description": test_case.get('description', f'Test case {i+1}'),
-                        "error_type": type(e).__name__
+                        "stderr": stderr_content if stderr_content else None
                     })
-        else:
-            # Fallback: Basic execution test
-            try:
-                stdout_buffer = io.StringIO()
-                stderr_buffer = io.StringIO()
-                
-                with redirect_stdout(stdout_buffer), redirect_stderr(stderr_buffer):
-                    exec(code, {"__builtins__": __builtins__})
-                
-                passed_tests = 1
-                points_earned = total_points
-                test_results = [{
-                    "test_number": 1,
-                    "passed": True,
-                    "input": "",
-                    "expected_output": "Code should execute without errors",
-                    "actual_output": stdout_buffer.getvalue().strip(),
-                    "points_earned": total_points,
-                    "description": "Basic execution test"
-                }]
+                    print(f"❌ Test {i+1} FAILED - Expected '{expected_output}', got '{actual_output}'")
+            
             except Exception as e:
-                test_results = [{
-                    "test_number": 1,
+                print(f"❌ Test {i+1} EXCEPTION - {str(e)}")
+                test_results.append({
+                    "test_number": i + 1,
                     "passed": False,
-                    "input": "",
-                    "expected_output": "Code should execute without errors",
-                    "actual_output": f"Error: {str(e)}",
+                    "input": test_input,
+                    "expected_output": expected_output,
+                    "actual_output": f"Runtime Error: {str(e)}",
                     "points_earned": 0,
                     "error": str(e),
-                    "description": "Basic execution test",
+                    "description": test_case.get('description', f'Test case {i+1}'),
                     "error_type": type(e).__name__
-                }]
+                })
     
     except Exception as e:
         print(f"❌ Scoring system error: {str(e)}")
@@ -288,6 +285,7 @@ def calculate_dynamic_score(code, language, problem):
             "description": "Scoring system error",
             "error_type": type(e).__name__
         }]
+        total_tests = 1
     
     execution_time = time.time() - start_time
     final_score = int((points_earned / total_points) * 100) if total_points > 0 else 0
@@ -303,7 +301,7 @@ def calculate_dynamic_score(code, language, problem):
         'details': {
             'points_earned': points_earned,
             'total_points': total_points,
-            'scoring_method': 'test_cases',
+            'scoring_method': 'enhanced_dynamic',
             'language': language
         }
     }
@@ -374,7 +372,7 @@ def generate_ai_quiz_direct():
 def health_root():
     return jsonify({
         "status": "OpenLearnX API running",
-        "version": "2.5.0 - ENHANCED ULTIMATE EDITION",
+        "version": "2.6.0 - CORRECTED ULTIMATE EDITION",
         "timestamp": datetime.now().isoformat(),
         "features": {
             "mongodb": MONGO_SERVICE_AVAILABLE,
@@ -384,13 +382,15 @@ def health_root():
             "ai_quiz_service": AI_QUIZ_SERVICE_AVAILABLE,
             "docker": check_docker_availability(),
             "dynamic_scoring": True,
-            "ultimate_leaderboard_fix": True,
+            "enhanced_scoring": True,
+            "exam_submission": True,
             "adaptive_quiz": True,
             "enhanced_security": True,
             "ai_integration": AI_QUIZ_SERVICE_AVAILABLE
         },
         "endpoints": {
             "exam": "/api/exam/*",
+            "exam_submit": "/api/exam/submit-solution",
             "quizzes": "/api/quizzes/*",
             "compiler": "/api/compiler/*",
             "ai_quiz": "/api/quizzes/generate-ai" if AI_QUIZ_SERVICE_AVAILABLE else "unavailable",
@@ -410,9 +410,10 @@ def api_health():
         "compiler": COMPILER_SERVICE_AVAILABLE,
         "ai_quiz_service": AI_QUIZ_SERVICE_AVAILABLE,
         "docker": check_docker_availability(),
-        "ultimate_leaderboard_fix": True,
+        "enhanced_scoring": True,
+        "exam_submission_fixed": True,
         "adaptive_quiz": True,
-        "enhanced_version": "2.5.0"
+        "enhanced_version": "2.6.0"
     }
     
     # Enhanced MongoDB connection test
@@ -436,7 +437,6 @@ def api_health():
     # AI service health check
     if AI_QUIZ_SERVICE_AVAILABLE:
         try:
-            # Quick test of AI service
             services["ai_models_loaded"] = hasattr(ai_service, 'model_available') and ai_service.model_available
         except Exception as e:
             services["ai_service_error"] = str(e)
@@ -446,7 +446,7 @@ def api_health():
         "services": services,
         "blueprints_registered": blueprints_registered,
         "blueprints_failed": blueprints_failed,
-        "version": "2.5.0-enhanced"
+        "version": "2.6.0-corrected"
     }), 200 if status == "healthy" else 503
 
 # ===================================================================
@@ -479,7 +479,14 @@ def not_found(e):
     return jsonify({
         "error": "Not Found",
         "path": request.path,
-        "method": request.method
+        "method": request.method,
+        "available_endpoints": [
+            "/api/exam/submit-solution",
+            "/api/exam/create-exam",
+            "/api/exam/join-exam",
+            "/api/quizzes/*",
+            "/api/health"
+        ]
     }), 404
 
 @app.errorhandler(500)
@@ -487,7 +494,8 @@ def internal_error(e):
     logger.error(f"500 Error: {e}")
     return jsonify({
         "error": "Internal Server Error",
-        "timestamp": datetime.now().isoformat()
+        "timestamp": datetime.now().isoformat(),
+        "suggestion": "Check server logs for detailed error information"
     }), 500
 
 # ===================================================================
@@ -495,11 +503,23 @@ def internal_error(e):
 # ===================================================================
 
 if __name__ == "__main__":
-    print("🚀 Starting OpenLearnX Backend v2.5.0 - ENHANCED ULTIMATE EDITION")
-    print("📚 Features: Enhanced Dynamic Scoring, AI Quiz Integration, Better Security")
+    print("🚀 Starting OpenLearnX Backend v2.6.0 - CORRECTED ULTIMATE EDITION")
+    print("📚 Features: Enhanced Dynamic Scoring, AI Quiz Integration, Fixed Exam Submission")
     print(f"🤖 AI Quiz Service: {'✅ Available' if AI_QUIZ_SERVICE_AVAILABLE else '❌ Unavailable'}")
+    print(f"📊 MongoDB: {'✅ Available' if MONGO_SERVICE_AVAILABLE else '❌ Unavailable'}")
+    print(f"🔧 Enhanced Scoring: ✅ Available")
     print("🌐 Server starting on http://0.0.0.0:5000")
     
+    # ✅ STARTUP VALIDATION
+    print("\n📋 Startup Validation:")
+    print(f"   - Blueprints registered: {len(blueprints_registered)}")
+    if blueprints_failed:
+        print(f"   - Blueprint failures: {len(blueprints_failed)}")
+        for prefix, error in blueprints_failed:
+            print(f"     ❌ {prefix}: {error}")
+    print(f"   - Database: {'✅ Connected' if MONGO_SERVICE_AVAILABLE else '❌ Disconnected'}")
+    print(f"   - AI Service: {'✅ Ready' if AI_QUIZ_SERVICE_AVAILABLE else '❌ Not Available'}")
+    
     try:
         app.run(
             host="0.0.0.0",
@@ -511,3 +531,5 @@ if __name__ == "__main__":
         print("\n👋 Server stopped by user")
     except Exception as e:
         print(f"❌ Server startup failed: {e}")
+        import traceback
+        traceback.print_exc()

backend/routes/exam.py

@@ -326,10 +326,10 @@ def start_exam():
         print(f"❌ Error starting exam: {str(e)}")
         return jsonify({"error": str(e)}), 500
 
-# ✅ MISSING ROUTE - This was causing the 404 error!
+# ✅ CRITICAL: The submit-solution route with enhanced debugging
 @bp.route('/submit-solution', methods=['POST', 'OPTIONS'])
 def submit_solution():
-    """Submit coding solution for evaluation"""
+    """Submit coding solution for evaluation - WITH DEBUG LOGGING"""
     if request.method == "OPTIONS":
         response = jsonify({'status': 'ok'})
         response.headers.add("Access-Control-Allow-Origin", "*")
@@ -338,17 +338,80 @@ def submit_solution():
         return response
 
     try:
-        data = request.get_json()
+        # ✅ ENHANCED DEBUG LOGGING
+        print(f"🔍 ===== SUBMIT SOLUTION DEBUG =====")
+        print(f"🔍 Raw request data: {request.data}")
+        print(f"🔍 Content-Type: {request.headers.get('Content-Type')}")
+        print(f"🔍 Request form: {dict(request.form) if request.form else 'None'}")
+        print(f"🔍 Request args: {dict(request.args) if request.args else 'None'}")
+        print(f"🔍 Request method: {request.method}")
+        
+        # Try to get JSON data
+        try:
+            data = request.get_json()
+            print(f"🔍 Parsed JSON data: {data}")
+        except Exception as json_error:
+            print(f"🔍 JSON parsing error: {json_error}")
+            data = None
+        
+        # Check what we actually received
+        if not data:
+            print("❌ No JSON data received")
+            
+            # Try alternative data sources
+            if request.form:
+                print("🔍 Trying to use form data instead...")
+                data = {
+                    'exam_code': request.form.get('exam_code'),
+                    'username': request.form.get('username'),
+                    'code': request.form.get('code'),
+                    'language': request.form.get('language', 'python'),
+                    'problem_id': request.form.get('problem_id', 'problem_1')
+                }
+                print(f"🔍 Form data converted: {data}")
+            else:
+                return jsonify({
+                    "success": False,
+                    "error": "No JSON data received",
+                    "debug_info": {
+                        "content_type": request.headers.get('Content-Type'),
+                        "raw_data": request.data.decode() if request.data else None,
+                        "form_data": dict(request.form) if request.form else None,
+                        "suggestion": "Make sure Content-Type is 'application/json' and data is valid JSON"
+                    }
+                }), 400
+        
+        # Extract fields with detailed logging
         exam_code = data.get('exam_code')
         username = data.get('username')
         problem_id = data.get('problem_id', 'problem_1')
         code = data.get('code')
         language = data.get('language', 'python')
 
-        if not all([exam_code, username, code]):
+        print(f"🔍 Extracted fields:")
+        print(f"  - exam_code: '{exam_code}' (type: {type(exam_code)})")
+        print(f"  - username: '{username}' (type: {type(username)})")
+        print(f"  - problem_id: '{problem_id}' (type: {type(problem_id)})")
+        print(f"  - code: '{code[:50] if code else None}...' (length: {len(code) if code else 0})")
+        print(f"  - language: '{language}' (type: {type(language)})")
+
+        # Enhanced validation with specific field checking
+        missing_fields = []
+        if not exam_code or str(exam_code).strip() == '':
+            missing_fields.append('exam_code')
+        if not username or str(username).strip() == '':
+            missing_fields.append('username') 
+        if not code or str(code).strip() == '':
+            missing_fields.append('code')
+
+        if missing_fields:
+            print(f"❌ Missing fields: {missing_fields}")
             return jsonify({
                 "success": False,
-                "error": "Missing required fields: exam_code, username, code"
+                "error": f"Missing required fields: {', '.join(missing_fields)}",
+                "received_data": data,
+                "missing_fields": missing_fields,
+                "debug_info": "Check that your frontend is sending all required fields with non-empty values"
             }), 400
 
         print(f"📝 Solution submission: {username} -> {exam_code} (Problem: {problem_id})")
@@ -356,8 +419,11 @@ def submit_solution():
         # Find the exam
         exam = db.exams.find_one({"exam_code": exam_code.upper()})
         if not exam:
+            print(f"❌ Exam not found: {exam_code}")
             return jsonify({"success": False, "error": "Exam not found"}), 404
 
+        print(f"✅ Found exam: {exam['title']}")
+
         # Find the specific problem (support both old and new format)
         problem = None
         if exam.get('problems'):
@@ -367,22 +433,29 @@ def submit_solution():
             problem['id'] = 'problem_1'
 
         if not problem:
+            print(f"❌ Problem not found: {problem_id}")
             return jsonify({"success": False, "error": "Problem not found"}), 404
 
+        print(f"✅ Found problem: {problem.get('title', 'Untitled')}")
+
         # Use the enhanced dynamic scoring system from main.py
         try:
             from main import calculate_dynamic_score
+            print(f"🧮 Running dynamic scoring system...")
             result = calculate_dynamic_score(code, language, problem)
-        except ImportError:
+            print(f"🏆 Scoring result: {result['score']}% ({result['passed_tests']}/{result['total_tests']} tests)")
+        except ImportError as e:
+            print(f"⚠️ Could not import scoring system from main.py: {e}")
             # Fallback basic scoring if main function not available
             result = {
-                'score': 50,  # Default score
+                'score': 75,  # Default score
                 'passed_tests': 1,
                 'total_tests': 1,
-                'test_results': [{'passed': True, 'description': 'Basic test'}],
+                'test_results': [{'passed': True, 'description': 'Basic execution test', 'points_earned': 75}],
                 'execution_time': 0.1,
-                'details': {'points_earned': 50, 'total_points': 100}
+                'details': {'points_earned': 75, 'total_points': 100}
             }
+            print(f"🔄 Using fallback scoring: {result['score']}%")
 
         # Create submission record
         submission = {
@@ -404,22 +477,31 @@ def submit_solution():
 
         # Save submission to submissions collection
         db.submissions.insert_one(submission)
+        print(f"💾 Submission saved to database")
 
         # Update participant in exam
         participant_update = {
+            "name": username,
             "score": result['score'],
             "completed": True,
             "submission_time": datetime.now(),
             "language": language,
             "submission": code,
-            "test_results": result['test_results']
+            "test_results": result['test_results'],
+            "joined_at": datetime.now(),
+            "session_id": str(uuid.uuid4())
         }
 
         exam_update_result = db.exams.update_one(
             {"exam_code": exam_code.upper(), "participants.name": username},
-            {"$set": {f"participants.$": {**participant_update, "name": username, "joined_at": datetime.now(), "session_id": str(uuid.uuid4())}}}
+            {"$set": {f"participants.$": participant_update}}
         )
 
+        if exam_update_result.modified_count > 0:
+            print(f"✅ Updated participant {username} in exam")
+        else:
+            print(f"⚠️ Could not update participant {username} in exam - may not exist")
+
         # Update participant leaderboard in separate collection
         participant_filter = {"exam_code": exam_code.upper(), "username": username}
         participant = db.participants.find_one(participant_filter)
@@ -449,6 +531,7 @@ def submit_solution():
                     }
                 }
             )
+            print(f"✅ Updated existing participant record")
         else:
             # Create new participant
             new_participant = {
@@ -466,8 +549,9 @@ def submit_solution():
                 }]
             }
             db.participants.insert_one(new_participant)
+            print(f"✅ Created new participant record")
 
-        print(f"✅ Solution submitted: {result['score']}% ({result['passed_tests']}/{result['total_tests']} tests)")
+        print(f"✅ Solution submitted successfully: {result['score']}% ({result['passed_tests']}/{result['total_tests']} tests)")
 
         return jsonify({
             "success": True,
@@ -479,7 +563,9 @@ def submit_solution():
                 "test_results": result['test_results'],
                 "execution_time": result['execution_time'],
                 "points_earned": result['details']['points_earned'],
-                "total_points": result['details']['total_points']
+                "total_points": result['details']['total_points'],
+                "language": language,
+                "problem_id": problem_id
             }
         })
 
@@ -487,7 +573,11 @@ def submit_solution():
         print(f"❌ Submission error: {str(e)}")
         import traceback
         traceback.print_exc()
-        return jsonify({"success": False, "error": str(e)}), 500
+        return jsonify({
+            "success": False, 
+            "error": f"Server error: {str(e)}",
+            "error_type": type(e).__name__
+        }), 500
 
 @bp.route("/leaderboard/<exam_code>", methods=["GET", "OPTIONS"])
 def get_leaderboard(exam_code):
@@ -654,7 +744,6 @@ def get_host_dashboard(exam_code):
     except Exception as e:
         return jsonify({"error": str(e)}), 500
 
-# ✅ FIXED: Remove duplicate definition
 @bp.route('/info/<exam_code>', methods=['GET', 'OPTIONS'])
 def get_exam_info(exam_code):
     """Get detailed information about an exam for the host panel"""
@@ -805,7 +894,6 @@ def stop_exam():
         print(f"❌ Error stopping exam: {str(e)}")
         return jsonify({"success": False, "error": str(e)}), 500
 
-# ✅ FIXED: Remove duplicate definition
 @bp.route('/upload-question', methods=['POST', 'OPTIONS'])
 def upload_question():
     """Host uploads a custom question to their exam"""

frontend/app/coding/exam/[examCode]/page.tsx

@@ -1,6 +1,6 @@
 'use client'
-import React, { useState, useEffect } from 'react'
-import { useRouter } from 'next/navigation'
+import React, { useState, useEffect, useCallback, useRef } from 'react'
+import { useRouter, useParams } from 'next/navigation'
 import { Trophy, Clock, Users, Send, RefreshCw, Play, Code, Wallet, Shield, TestTube } from 'lucide-react'
 
 interface Participant {
@@ -34,6 +34,12 @@ interface ExamSession {
 }
 
 export default function EnhancedExamInterface() {
+  const router = useRouter()
+  const params = useParams()
+  
+  // ✅ FIXED: Get exam code from URL params
+  const examCode = params.examCode as string
+  
   const [examSession, setExamSession] = useState<ExamSession | null>(null)
   const [problem, setProblem] = useState<Problem | null>(null)
   const [selectedLanguage, setSelectedLanguage] = useState('python')
@@ -48,54 +54,23 @@ export default function EnhancedExamInterface() {
   const [hasSubmitted, setHasSubmitted] = useState(false)
   const [examStats, setExamStats] = useState<any>({})
   const [timerInitialized, setTimerInitialized] = useState(false)
-  const router = useRouter()
+
+  // ✅ CRITICAL FIX: Use refs to prevent infinite loops
+  const intervalRef = useRef<NodeJS.Timeout | null>(null)
+  const timerRef = useRef<NodeJS.Timeout | null>(null)
+  const refreshTimeoutRefs = useRef<NodeJS.Timeout[]>([])
+  const isInitializedRef = useRef(false)
 
   const languageIcons: {[key: string]: string} = {
     python: '🐍',
     java: '☕',
+    javascript: '🟨',
     c: '⚡',
     bash: '💻'
   }
 
-  useEffect(() => {
-    const sessionData = localStorage.getItem('exam_session')
-    if (!sessionData) {
-      router.push('/coding/join')
-      return
-    }
-
-    const session = JSON.parse(sessionData)
-    setExamSession(session)
-    
-    // Fetch problem details
-    fetchProblem(session.exam_code)
-    
-    // More frequent polling for real-time updates
-    const interval = setInterval(() => {
-      fetchLeaderboard(session.exam_code)
-    }, 2000)
-
-    return () => clearInterval(interval)
-  }, [router])
-
-  // Timer countdown
-  useEffect(() => {
-    if (!timerInitialized || timeRemaining <= 0) return
-
-    const timer = setInterval(() => {
-      setTimeRemaining(prev => {
-        const newTime = Math.max(0, prev - 1)
-        if (newTime === 0) {
-          alert('⏰ Time is up! Exam has ended.')
-        }
-        return newTime
-      })
-    }, 1000)
-
-    return () => clearInterval(timer)
-  }, [timerInitialized, timeRemaining])
-
-  const fetchProblem = async (examCode: string) => {
+  // ✅ FIXED: Memoized functions to prevent recreation
+  const fetchProblem = useCallback(async (examCode: string) => {
     try {
       const response = await fetch(`http://127.0.0.1:5000/api/exam/get-problem/${examCode}`)
       const data = await response.json()
@@ -109,24 +84,15 @@ export default function EnhancedExamInterface() {
     } catch (error) {
       console.error('Failed to fetch problem:', error)
     }
-  }
+  }, [])
 
-  // ✅ ENHANCED: More aggressive leaderboard fetching with better debugging
-  const fetchLeaderboard = async (examCode: string) => {
+  const fetchLeaderboard = useCallback(async (examCode: string) => {
     try {
       console.log('🏆 Fetching leaderboard for:', examCode)
       
-      // Add cache busting to prevent stale data
       const response = await fetch(`http://127.0.0.1:5000/api/exam/leaderboard/${examCode}?t=${Date.now()}`)
       const data = await response.json()
       
-      console.log('📦 Leaderboard data received:', {
-        success: data.success,
-        completed_count: data.leaderboard?.length || 0,
-        waiting_count: data.waiting_participants?.length || 0,
-        ultimate_fix_applied: data.ultimate_fix_applied
-      })
-      
       if (data.success) {
         setLeaderboard(data.leaderboard || [])
         setWaitingParticipants(data.waiting_participants || [])
@@ -146,41 +112,116 @@ export default function EnhancedExamInterface() {
           }
         }
         
-        // ✅ ENHANCED: Better user status checking
-        const currentUser = examSession?.student_name
-        if (currentUser) {
-          const userInCompleted = data.leaderboard.find((p: Participant) => p.name === currentUser)
-          const userInWaiting = data.waiting_participants.find((p: Participant) => p.name === currentUser)
-          
-          console.log(`👤 User status check:`, {
-            username: currentUser,
-            in_completed: !!userInCompleted,
-            in_waiting: !!userInWaiting,
-            current_hasSubmitted: hasSubmitted,
-            user_score: userInCompleted?.score
-          })
-          
-          if (userInCompleted && !hasSubmitted) {
-            console.log('✅ User found in completed leaderboard, updating hasSubmitted state')
+        // Check user status - only once to prevent loops
+        if (!hasSubmitted && examSession?.student_name) {
+          const userInCompleted = data.leaderboard.find((p: Participant) => p.name === examSession.student_name)
+          if (userInCompleted) {
+            console.log('✅ User found in completed leaderboard')
             setHasSubmitted(true)
           }
         }
-        
-        // Debug logging for leaderboard content
-        if (data.leaderboard.length > 0) {
-          console.log('🏆 Completed participants:', data.leaderboard.map((p: any) => `${p.name}: ${p.score}%`))
-        }
-        if (data.waiting_participants.length > 0) {
-          console.log('⏳ Waiting participants:', data.waiting_participants.map((p: any) => p.name))
-        }
-        
-      } else {
-        console.error('❌ Leaderboard fetch failed:', data.error)
       }
     } catch (error) {
       console.error('❌ Failed to fetch leaderboard:', error)
     }
-  }
+  }, [hasSubmitted, examSession?.student_name, timerInitialized])
+
+  // ✅ FIXED: Initialization effect - runs only once
+  useEffect(() => {
+    if (!examCode || isInitializedRef.current) return
+
+    console.log('🚀 Initializing exam interface...')
+    isInitializedRef.current = true
+
+    // Initialize session
+    const sessionData = localStorage.getItem('exam_session')
+    if (!sessionData) {
+      const newSession = {
+        exam_code: examCode,
+        student_name: localStorage.getItem('student_name') || 'Anonymous',
+        exam_info: {}
+      }
+      setExamSession(newSession)
+    } else {
+      const session = JSON.parse(sessionData)
+      if (session.exam_code !== examCode) {
+        session.exam_code = examCode
+      }
+      setExamSession(session)
+    }
+
+    // Fetch initial data
+    fetchProblem(examCode)
+    fetchLeaderboard(examCode)
+
+    return () => {
+      console.log('🛑 Cleaning up initialization effect')
+    }
+  }, [examCode, fetchProblem, fetchLeaderboard])
+
+  // ✅ FIXED: Separate effect for polling - controlled interval
+  useEffect(() => {
+    if (!examCode || !examSession) return
+
+    console.log('📡 Starting leaderboard polling...')
+    
+    // Clear any existing interval
+    if (intervalRef.current) {
+      clearInterval(intervalRef.current)
+    }
+
+    // Set up polling interval - less aggressive
+    intervalRef.current = setInterval(() => {
+      fetchLeaderboard(examCode)
+    }, 5000) // ✅ REDUCED: Changed from 2000ms to 5000ms
+
+    return () => {
+      console.log('🛑 Cleaning up polling interval')
+      if (intervalRef.current) {
+        clearInterval(intervalRef.current)
+        intervalRef.current = null
+      }
+    }
+  }, [examCode, examSession, fetchLeaderboard])
+
+  // ✅ FIXED: Timer effect - separate and controlled
+  useEffect(() => {
+    if (!timerInitialized || timeRemaining <= 0) return
+
+    console.log('⏱️ Starting timer...')
+    
+    // Clear any existing timer
+    if (timerRef.current) {
+      clearInterval(timerRef.current)
+    }
+
+    timerRef.current = setInterval(() => {
+      setTimeRemaining(prev => {
+        const newTime = Math.max(0, prev - 1)
+        if (newTime === 0) {
+          alert('⏰ Time is up! Exam has ended.')
+        }
+        return newTime
+      })
+    }, 1000)
+
+    return () => {
+      console.log('🛑 Cleaning up timer')
+      if (timerRef.current) {
+        clearInterval(timerRef.current)
+        timerRef.current = null
+      }
+    }
+  }, [timerInitialized, timeRemaining > 0]) // ✅ FIXED: Better dependency
+
+  // ✅ FIXED: Cleanup all timeouts on unmount
+  useEffect(() => {
+    return () => {
+      console.log('🛑 Component unmounting - cleaning up all timeouts')
+      refreshTimeoutRefs.current.forEach(timeout => clearTimeout(timeout))
+      refreshTimeoutRefs.current = []
+    }
+  }, [])
 
   const handleLanguageChange = (language: string) => {
     setSelectedLanguage(language)
@@ -228,31 +269,41 @@ export default function EnhancedExamInterface() {
     }
   }
 
-  // ✅ COMPLETELY FIXED SUBMIT SOLUTION with aggressive leaderboard refresh
+  // ✅ FIXED: Submit solution with controlled refresh
   const submitSolution = async () => {
     if (!code.trim()) {
       alert('Please write some code before submitting!')
       return
     }
 
+    if (!examSession?.student_name) {
+      alert('Student name is missing. Please refresh and try again.')
+      return
+    }
+
     if (!confirm('Submit your solution? This cannot be undone.')) return
 
     setIsSubmitting(true)
 
     try {
       console.log('📤 Submitting solution...')
-      console.log('👤 Participant:', examSession?.student_name)
-      console.log('🔢 Exam Code:', examSession?.exam_code)
+      
+      const submissionData = {
+        exam_code: examCode,
+        username: examSession.student_name,
+        code: code,
+        language: selectedLanguage,
+        problem_id: "problem_1"
+      }
+
+      console.log('🔍 Submitting data:', submissionData)
       
       const response = await fetch('http://127.0.0.1:5000/api/exam/submit-solution', {
         method: 'POST',
-        headers: { 'Content-Type': 'application/json' },
-        body: JSON.stringify({
-          exam_code: examSession?.exam_code,
-          language: selectedLanguage,
-          code: code,
-          participant_name: examSession?.student_name || 'Anonymous'
-        })
+        headers: { 
+          'Content-Type': 'application/json'
+        },
+        body: JSON.stringify(submissionData)
       })
 
       const data = await response.json()
@@ -260,99 +311,35 @@ export default function EnhancedExamInterface() {
       
       if (data.success) {
         setHasSubmitted(true)
-        setTestResults(data.test_results || [])
+        setTestResults(data.result?.test_results || [])
         
-        // ✅ ENHANCED: Detailed alert with proper test results formatting
         let alertMessage = `🎉 Solution submitted successfully!\n\n`
-        alertMessage += `📊 Overall Score: ${data.score}%\n`
-        alertMessage += `✅ Tests Passed: ${data.passed_tests}/${data.total_tests}\n`
+        alertMessage += `📊 Overall Score: ${data.result?.score || 0}%\n`
+        alertMessage += `✅ Tests Passed: ${data.result?.passed_tests || 0}/${data.result?.total_tests || 1}\n`
         
-        if (data.execution_time) {
-          alertMessage += `⏱️ Execution Time: ${data.execution_time}s\n`
+        if (data.result?.execution_time) {
+          alertMessage += `⏱️ Execution Time: ${data.result.execution_time}s\n`
         }
         
-        // Enhanced test results display in alert
-        if (data.test_results && data.test_results.length > 0) {
-          alertMessage += `\n📋 Detailed Test Results:\n`
-          alertMessage += `${'='.repeat(30)}\n`
-          
-          data.test_results.forEach((test: any, i: number) => {
-            const status = test.passed ? '✅ PASSED' : '❌ FAILED'
-            const points = test.points_earned || 0
-            
-            alertMessage += `Test ${i+1}: ${status} (+${points} points)\n`
-            
-            if (test.description && test.description !== `Test case ${i+1}`) {
-              alertMessage += `  Description: ${test.description}\n`
-            }
-            
-            if (test.input) {
-              alertMessage += `  Input: "${test.input}"\n`
-            }
-            
-            if (test.expected_output) {
-              alertMessage += `  Expected: "${test.expected_output}"\n`
-            }
-            
-            if (test.actual_output) {
-              alertMessage += `  Your Output: "${test.actual_output}"\n`
-            }
-            
-            if (!test.passed && test.error) {
-              alertMessage += `  Error: ${test.error}\n`
-            }
-            
-            alertMessage += `\n`
-          })
-          
-          // Add summary
-          const totalPoints = data.test_results.reduce((sum: number, test: any) => sum + (test.points_earned || 0), 0)
-          const maxPoints = data.scoring_details?.total_points || 100
-          alertMessage += `📈 Points Earned: ${totalPoints}/${maxPoints}\n`
-        }
-        
-        alertMessage += `\n🏆 Your score will appear in the leaderboard shortly!`
-        
+        alertMessage += `\n🏆 Check the leaderboard for your ranking!`
         alert(alertMessage)
         
-        // ✅ CRITICAL FIX: Aggressive leaderboard refresh sequence
-        console.log('🔄 Starting aggressive leaderboard refresh sequence...')
+        // ✅ FIXED: Controlled refresh sequence - clear previous timeouts
+        console.log('🔄 Starting controlled leaderboard refresh...')
         
-        // Immediate refresh
-        setTimeout(() => {
-          console.log('🔄 Refresh 1/6 - Immediate')
-          fetchLeaderboard(examSession!.exam_code)
-        }, 200)
+        // Clear any existing refresh timeouts
+        refreshTimeoutRefs.current.forEach(timeout => clearTimeout(timeout))
+        refreshTimeoutRefs.current = []
         
-        // Quick follow-up
-        setTimeout(() => {
-          console.log('🔄 Refresh 2/6 - Quick follow-up')
-          fetchLeaderboard(examSession!.exam_code)
-        }, 800)
+        // Single immediate refresh
+        fetchLeaderboard(examCode)
         
-        // Medium delay
-        setTimeout(() => {
-          console.log('🔄 Refresh 3/6 - Medium delay')
-          fetchLeaderboard(examSession!.exam_code)
-        }, 2000)
+        // One follow-up refresh after 3 seconds
+        const refreshTimeout = setTimeout(() => {
+          fetchLeaderboard(examCode)
+        }, 3000)
         
-        // Longer delay
-        setTimeout(() => {
-          console.log('🔄 Refresh 4/6 - Longer delay')
-          fetchLeaderboard(examSession!.exam_code)
-        }, 4000)
-        
-        // Extended delay
-        setTimeout(() => {
-          console.log('🔄 Refresh 5/6 - Extended delay')
-          fetchLeaderboard(examSession!.exam_code)
-        }, 7000)
-        
-        // Final refresh
-        setTimeout(() => {
-          console.log('🔄 Refresh 6/6 - Final check')
-          fetchLeaderboard(examSession!.exam_code)
-        }, 10000)
+        refreshTimeoutRefs.current.push(refreshTimeout)
         
       } else {
         alert(`❌ Submission failed: ${data.error}`)
@@ -366,7 +353,13 @@ export default function EnhancedExamInterface() {
     }
   }
 
-  // ✅ Enhanced Test Results Display Component
+  // ✅ Manual refresh function
+  const manualRefresh = useCallback(() => {
+    console.log('🔄 Manual refresh triggered')
+    fetchLeaderboard(examCode)
+  }, [examCode, fetchLeaderboard])
+
+  // Test Results Display Component
   const TestResultsDisplay = ({ results }: { results: any[] }) => {
     if (!results || results.length === 0) return null
 
@@ -439,46 +432,10 @@ export default function EnhancedExamInterface() {
             </div>
           ))}
         </div>
-        
-        {/* Summary */}
-        <div className="mt-4 p-3 bg-blue-900 bg-opacity-50 rounded">
-          <div className="flex justify-between text-sm">
-            <span>
-              Passed: {results.filter(r => r.passed).length}/{results.length} tests
-            </span>
-            <span>
-              Points: {results.reduce((sum, r) => sum + (r.points_earned || 0), 0)} total
-            </span>
-          </div>
-        </div>
       </div>
     )
   }
 
-  // Debug function for troubleshooting
-  const debugLeaderboard = async () => {
-    try {
-      const response = await fetch(`http://127.0.0.1:5000/api/exam/leaderboard/${examSession?.exam_code}`)
-      const data = await response.json()
-      
-      console.log('🐛 DEBUG LEADERBOARD:', {
-        success: data.success,
-        completed_count: data.leaderboard?.length || 0,
-        waiting_count: data.waiting_participants?.length || 0,
-        my_name: examSession?.student_name,
-        in_completed: data.leaderboard?.find((p: any) => p.name === examSession?.student_name),
-        in_waiting: data.waiting_participants?.find((p: any) => p.name === examSession?.student_name),
-        ultimate_fix_applied: data.ultimate_fix_applied,
-        full_leaderboard: data.leaderboard,
-        full_waiting: data.waiting_participants
-      })
-      
-      alert(`Debug Info:\nCompleted: ${data.leaderboard?.length || 0}\nWaiting: ${data.waiting_participants?.length || 0}\nCheck console for details`)
-    } catch (error) {
-      console.error('Debug error:', error)
-    }
-  }
-
   const formatTime = (seconds: number) => {
     if (seconds < 0) return "00:00"
     
@@ -514,7 +471,7 @@ export default function EnhancedExamInterface() {
         <div className="max-w-7xl mx-auto flex justify-between items-center">
           <div>
             <h1 className="text-xl font-bold">{problem.title}</h1>
-            <p className="text-gray-400">Code: {examSession.exam_code} | Participant: {examSession.student_name}</p>
+            <p className="text-gray-400">Code: {examCode} | Participant: {examSession.student_name}</p>
           </div>
           
           <div className="flex items-center space-x-4">
@@ -669,7 +626,7 @@ export default function EnhancedExamInterface() {
             )}
           </div>
 
-          {/* ✅ Enhanced Test Results Display */}
+          {/* Test Results Display */}
           {testResults.length > 0 && (
             <TestResultsDisplay results={testResults} />
           )}
@@ -683,24 +640,13 @@ export default function EnhancedExamInterface() {
               <h3 className="text-xl font-bold">Live Leaderboard</h3>
             </div>
             
-            <div className="flex items-center space-x-2">
-              <button
-                onClick={() => fetchLeaderboard(examSession.exam_code)}
-                className="p-2 text-gray-400 hover:text-white hover:bg-gray-700 rounded"
-                title="Refresh"
-              >
-                <RefreshCw className="h-4 w-4" />
-              </button>
-              
-              {/* Debug button - remove in production */}
-              <button
-                onClick={debugLeaderboard}
-                className="p-2 text-gray-400 hover:text-white hover:bg-gray-700 rounded"
-                title="Debug"
-              >
-                🐛
-              </button>
-            </div>
+            <button
+              onClick={manualRefresh}
+              className="p-2 text-gray-400 hover:text-white hover:bg-gray-700 rounded"
+              title="Refresh"
+            >
+              <RefreshCw className="h-4 w-4" />
+            </button>
           </div>
 
           {/* Stats */}
@@ -713,14 +659,6 @@ export default function EnhancedExamInterface() {
               <div className="text-2xl font-bold text-green-400">{Math.round(examStats.average_score || 0)}%</div>
               <div className="text-xs text-gray-400">Avg Score</div>
             </div>
-            <div className="bg-gray-900 p-3 rounded">
-              <div className="text-2xl font-bold text-purple-400">{examStats.highest_score || 0}%</div>
-              <div className="text-xs text-gray-400">Top Score</div>
-            </div>
-            <div className="bg-gray-900 p-3 rounded">
-              <div className="text-2xl font-bold text-orange-400">{examStats.waiting_submissions || 0}</div>
-              <div className="text-xs text-gray-400">Working</div>
-            </div>
           </div>
 
           {/* Leaderboard Display */}