feat/grading

- Create grading logic

Author: MikaTech-dev

api/services.py

@@ -0,0 +1,50 @@
+def grade_submission(submission):
+    """
+    Modular grading service to evaluate a submission.
+    Currently implements a Mock Grading Service using keyword matching.
+    """
+    # TODO: Implement AI integration to help grade a and provide feedback on SA (Short answer questions)
+    total_questions = submission.exam.questions.count()
+    correct_count = 0
+    feedback_notes = []
+
+    # Get all student answers for this submission
+    answers = submission.answers.all()
+
+    for ans in answers:
+        question = ans.question
+        # if question is Multiple Choice Question
+        if question.question_type == 'MCQ':
+            expected = question.correct_answers.get('answer')
+            actual = ans.student_answer.get('choice')
+
+            if expected == actual:
+                ans.is_correct = True
+                correct_count += 1
+            else:
+                ans.is_correct = False
+                feedback_notes.append(f"Q{question.order}: Expected {expected}, got {actual}.")
+
+        # if question is Short Answer (SA) - Keyword Matching
+        elif question.question_type == 'SA':
+            expected_keywords = question.correct_answers.get('keywords', [])
+            student_text = ans.student_answer.get('text', '').lower()
+
+            # Checks for how many keywords match
+            matches = [word for word in expected_keywords if word.lower() in student_text]
+            if len(matches) >= len(expected_keywords) * 0.666: # 66% match threshold (1 matching keyword at least...)
+                ans.is_correct = True
+                correct_count += 1
+            else:
+                ans.is_correct = False
+                feedback_notes.append(f"Q{question.order}: Missed key concepts.")
+
+        ans.save()
+
+    # Calculate final score
+    if total_questions > 0:
+        submission.total_score = (correct_count / total_questions) * 100
+
+    submission.status = 'graded' # Update status per requirement
+    submission.feedback = " ".join(feedback_notes) if feedback_notes else "Excellent work!"
+    submission.save()