Implement Server-Side AI Question Bank Generator, Adaptive Weakness Sampling 60/40, and Curriculum Studio One-Click Generation

backend/app/Controllers/CurriculumController.php

@@ -298,4 +298,32 @@ class CurriculumController
             ]);
         }
     }
+
+    /**
+     * Generate & Refresh AI Question Bank for any Unit or Lesson (Triggered from Curriculum Studio)
+     * POST /api/curriculum/generate-questions
+     */
+    public function generateQuestionBank(Request $request, Response $response): void
+    {
+        $body = $request->getBody();
+        $unitPath = $body['unit_path'] ?? 'grade_10/math_10/semester_1/unit_01';
+        $courseId = (int)($body['course_id'] ?? 1);
+        $count = (int)($body['count'] ?? 50);
+
+        try {
+            require_once __DIR__ . '/../Services/AiQuestionBankGeneratorService.php';
+            $result = \App\Services\AiQuestionBankGeneratorService::generateUnitQuestionBank($unitPath, $courseId, $count);
+
+            $response->json([
+                'status'  => 'success',
+                'message' => "تم توليد وتحديث بنك الأسئلة بالذكاء الاصطناعي بنجاح ({$result['total_in_bank']} سؤالاً معيارياً في قاعدة البيانات)!",
+                'data'    => $result
+            ]);
+        } catch (\Throwable $e) {
+            $response->status(500)->json([
+                'status'  => 'error',
+                'message' => 'تعذر توليد بنك الأسئلة: ' . $e->getMessage()
+            ]);
+        }
+    }
 }

backend/app/Controllers/ExamController.php

@@ -70,7 +70,61 @@ class ExamController
             return;
         }
 
-        $questions = Database::select("SELECT * FROM questions WHERE exam_id = ? ORDER BY id ASC", [$examId]);
+        $allQuestions = Database::select("SELECT * FROM questions WHERE exam_id = ? ORDER BY id ASC", [$examId]);
+        
+        $questions = [];
+        if (count($allQuestions) > 15) {
+            // Adaptive Sampling Engine based on Student Weakness History
+            $studentId = $request->user_id ?? 0;
+            $weakTopics = [];
+
+            if ($studentId > 0) {
+                // Fetch failed topics from student's answers
+                $fails = Database::select(
+                    "SELECT q.topic_tag, COUNT(*) as cnt 
+                     FROM student_question_answers sqa 
+                     JOIN questions q ON sqa.question_id = q.id 
+                     WHERE sqa.student_id = ? AND sqa.is_correct = 0 AND q.topic_tag IS NOT NULL
+                     GROUP BY q.topic_tag ORDER BY cnt DESC LIMIT 5",
+                    [$studentId]
+                );
+                foreach ($fails as $f) {
+                    $weakTopics[] = $f['topic_tag'];
+                }
+            }
+
+            // Split questions into weak vs other topics
+            $weakPool = [];
+            $otherPool = [];
+
+            foreach ($allQuestions as $q) {
+                if (!empty($weakTopics) && in_array($q['topic_tag'], $weakTopics)) {
+                    $weakPool[] = $q;
+                } else {
+                    $otherPool[] = $q;
+                }
+            }
+
+            shuffle($weakPool);
+            shuffle($otherPool);
+
+            if (!empty($weakPool)) {
+                // 60% focused on weak concepts for adaptive remediation
+                $targetWeakCount = min(count($weakPool), 9);
+                $questions = array_slice($weakPool, 0, $targetWeakCount);
+                
+                // 40% from rest of unit concepts
+                $needed = 15 - count($questions);
+                $questions = array_merge($questions, array_slice($otherPool, 0, $needed));
+            } else {
+                // Stratified random sampling from the comprehensive bank
+                $questions = array_slice($otherPool, 0, 15);
+            }
+            
+            shuffle($questions);
+        } else {
+            $questions = $allQuestions;
+        }
 
         foreach ($questions as &$q) {
             $options = Database::select("SELECT id, option_text, feedback_text" . ($isTeacher ? ", is_correct" : "") . " FROM question_options WHERE question_id = ? ORDER BY id ASC", [$q['id']]);
@@ -78,6 +132,7 @@ class ExamController
         }
 
         $exam['questions'] = $questions;
+        $exam['questions_count'] = count($questions);
 
         $response->json([
             'status' => 'success',
@@ -394,27 +449,17 @@ class ExamController
             }
         }
 
-        if (count($existingQuestions) < 15 || $hasCalculus) {
+        if (count($existingQuestions) < 45 || $hasCalculus) {
             // Wipe legacy corrupt questions
             foreach ($existingQuestions as $oq) {
                 Database::query("DELETE FROM question_options WHERE question_id = ?", [$oq['id']]);
             }
             Database::query("DELETE FROM questions WHERE exam_id = ?", [$examId]);
 
-            $bank = self::getUnit1QuestionBank();
-            foreach ($bank as $qData) {
-                $qId = (int)Database::insert(
-                    "INSERT INTO questions (uuid, exam_id, question_text, question_type, bloom_taxonomy, topic_tag, explanation_text, points)
-                     VALUES (UUID(), ?, ?, 'multiple_choice', ?, ?, ?, ?)",
-                    [$examId, $qData['question_text'], $qData['bloom'], $qData['topic'], $qData['explanation'], $qData['points']]
-                );
-                foreach ($qData['options'] as $idx => $optText) {
-                    Database::insert(
-                        "INSERT INTO question_options (question_id, option_text, is_correct) VALUES (?, ?, ?)",
-                        [$qId, $optText, ($idx === $qData['correct_index']) ? 1 : 0]
-                    );
-                }
-            }
+            require_once __DIR__ . '/../Services/AiQuestionBankGeneratorService.php';
+            $unitPath = 'grade_10/math_10/semester_1/unit_01';
+            $res = \App\Services\AiQuestionBankGeneratorService::generateUnitQuestionBank($unitPath, 1, 50);
+            return (int)$res['exam_id'];
         }
 
         return $examId;