<?php

namespace App\Controllers;

use App\Core\Request;
use App\Core\Response;
use App\Core\Database;
use App\Core\Validator;

class ExamController
{
    /**
     * List exams for a specific course/lesson/scope
     * GET /api/exams?course_id=1&lesson_id=2&scope=in_video_checkpoint
     */
    public function getExams(Request $request, Response $response): void
    {
        $queryParams = $request->getQueryParams();
        $courseId = !empty($queryParams['course_id']) ? (int)$queryParams['course_id'] : null;
        $lessonId = !empty($queryParams['lesson_id']) ? (int)$queryParams['lesson_id'] : null;
        $scope    = $queryParams['scope'] ?? null;

        $sql = "SELECT e.*, COUNT(q.id) as questions_count 
                FROM exams e 
                LEFT JOIN questions q ON q.exam_id = e.id 
                WHERE e.is_published = 1";
        $params = [];

        if ($courseId) {
            $sql .= " AND e.course_id = ?";
            $params[] = $courseId;
        }
        if ($lessonId) {
            $sql .= " AND e.lesson_id = ?";
            $params[] = $lessonId;
        }
        if ($scope) {
            $sql .= " AND e.scope = ?";
            $params[] = $scope;
        }

        $sql .= " GROUP BY e.id ORDER BY e.timestamp_seconds ASC, e.id ASC";

        $exams = Database::select($sql, $params);

        $response->json([
            'status' => 'success',
            'data'   => $exams
        ]);
    }

    /**
     * Get single exam with questions and sanitized options
     * GET /api/exams/{id}
     */
    public function getExamDetails(Request $request, Response $response): void
    {
        $examId = (int)$request->getParam('id');
        $isTeacher = ($request->role === 'teacher' || $request->role === 'super_admin');

        $exam = Database::selectOne("SELECT * FROM exams WHERE id = ? LIMIT 1", [$examId]);
        if (!$exam) {
            $response->status(404)->json(['status' => 'error', 'message' => 'الامتحان غير موجود']);
            return;
        }

        $questions = Database::select("SELECT * FROM questions WHERE exam_id = ? ORDER BY id ASC", [$examId]);

        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']]);
            $q['options'] = $options;
        }

        $exam['questions'] = $questions;

        $response->json([
            'status' => 'success',
            'data'   => $exam
        ]);
    }

    /**
     * Submit Exam Attempt & Calculate Instant AI Diagnostic Evaluation
     * POST /api/exams/{id}/submit
     */
    public function submitExam(Request $request, Response $response): void
    {
        $studentId = $request->user_id;
        $examId    = (int)$request->getParam('id');
        $body      = $request->getBody();

        $answers    = $body['answers'] ?? []; // Array of ['question_id' => X, 'selected_option_id' => Y]
        $timeSpent  = (int)($body['time_spent_seconds'] ?? 0);

        $exam = Database::selectOne("SELECT * FROM exams WHERE id = ? LIMIT 1", [$examId]);
        if (!$exam) {
            $response->status(404)->json(['status' => 'error', 'message' => 'الامتحان غير موجود']);
            return;
        }

        // Fetch all questions and correct options
        $questions = Database::select("SELECT id, points, topic_tag, explanation_text, ai_hint FROM questions WHERE exam_id = ?", [$examId]);
        $questionMap = [];
        $totalPoints = 0;
        foreach ($questions as $q) {
            $questionMap[$q['id']] = $q;
            $totalPoints += (int)$q['points'];
        }

        $options = Database::select("SELECT id, question_id, is_correct, feedback_text FROM question_options WHERE question_id IN (" . implode(',', array_keys($questionMap)) . ")");
        $correctOptions = [];
        foreach ($options as $opt) {
            if ($opt['is_correct']) {
                $correctOptions[$opt['question_id']] = (int)$opt['id'];
            }
        }

        // Score evaluation
        $earnedScore = 0;
        $weakTopics = [];
        $detailedAnswers = [];

        foreach ($answers as $ans) {
            $qId = (int)($ans['question_id'] ?? 0);
            $selectedOptId = (int)($ans['selected_option_id'] ?? 0);

            if (!isset($questionMap[$qId])) continue;

            $isCorrect = (isset($correctOptions[$qId]) && $correctOptions[$qId] === $selectedOptId);
            $qPoints = (int)$questionMap[$qId]['points'];
            $awarded = $isCorrect ? $qPoints : 0;
            $earnedScore += $awarded;

            if (!$isCorrect) {
                $topic = $questionMap[$qId]['topic_tag'] ?: 'المفاهيم العامة';
                $weakTopics[$topic] = ($weakTopics[$topic] ?? 0) + 1;
            }

            $detailedAnswers[] = [
                'question_id'        => $qId,
                'selected_option_id' => $selectedOptId,
                'is_correct'         => $isCorrect ? 1 : 0,
                'points_awarded'     => $awarded,
                'explanation'        => $questionMap[$qId]['explanation_text'] ?? null,
                'ai_hint'            => $questionMap[$qId]['ai_hint'] ?? null
            ];
        }

        $percentage = $totalPoints > 0 ? round(($earnedScore / $totalPoints) * 100, 2) : 0;
        $passed = ($percentage >= (float)$exam['passing_percentage']);
        $status = $passed ? 'passed' : 'needs_remediation';

        // AI Diagnostic Report
        $aiReport = $passed 
            ? "أداء ممتاز! استيعاب قوي للمفاهيم بنسبة {$percentage}%. أنت جاهز تماماً للانتقال للدرس التالي."
            : "تحتاج لمراجعة المفاهيم المتعلقة بـ: " . implode('، ', array_keys($weakTopics)) . ". يُنصح بمشاهدة مقطع الشرح الموصى به.";

        // Insert Attempt Record
        $uuid = sprintf('%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
            mt_rand(0, 0xffff), mt_rand(0, 0xffff),
            mt_rand(0, 0xffff),
            mt_rand(0, 0x0fff) | 0x4000,
            mt_rand(0, 0x3fff) | 0x8000,
            mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff)
        );

        $attemptId = Database::insert(
            "INSERT INTO exam_attempts (uuid, student_id, exam_id, score, total_score, percentage, status, time_spent_seconds, weak_topics_json, ai_diagnostic_report, completed_at)
             VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, NOW())",
            [$uuid, $studentId, $examId, $earnedScore, $totalPoints, $percentage, $status, $timeSpent, json_encode(array_keys($weakTopics), JSON_UNESCAPED_UNICODE), $aiReport]
        );

        // Save detailed question answers
        foreach ($detailedAnswers as $dAns) {
            Database::insert(
                "INSERT INTO student_question_answers (attempt_id, student_id, question_id, selected_option_id, is_correct, points_awarded, time_spent_seconds)
                 VALUES (?, ?, ?, ?, ?, ?, ?)",
                [$attemptId, $studentId, $dAns['question_id'], $dAns['selected_option_id'], $dAns['is_correct'], $dAns['points_awarded'], 0]
            );
        }

        // Update Student Cumulative Mastery & Tawjihi Readiness Score
        $courseId = (int)$exam['course_id'];
        $subjectId = (int)Database::selectOne("SELECT subject_id FROM courses WHERE id = ? LIMIT 1", [$courseId])['subject_id'];

        $allAttempts = Database::select(
            "SELECT ea.percentage, ea.status FROM exam_attempts ea 
             JOIN exams e ON e.id = ea.exam_id 
             WHERE ea.student_id = ? AND e.course_id = ?",
            [$studentId, $courseId]
        );

        $totalExams = count($allAttempts);
        $passedExams = 0;
        $sumPct = 0;
        foreach ($allAttempts as $att) {
            $sumPct += (float)$att['percentage'];
            if ($att['status'] === 'passed') $passedExams++;
        }

        $avgMastery = $totalExams > 0 ? round($sumPct / $totalExams, 2) : 0;
        $tawjihiIndex = round(($avgMastery * 0.7) + (($passedExams / max(1, $totalExams)) * 30), 1);

        Database::query("
            INSERT INTO student_mastery_analytics 
                (student_id, course_id, subject_id, mastery_percentage, tawjihi_readiness_score, exams_passed_count, exams_total_count, updated_at)
            VALUES (?, ?, ?, ?, ?, ?, ?, NOW())
            ON DUPLICATE KEY UPDATE 
                mastery_percentage = VALUES(mastery_percentage),
                tawjihi_readiness_score = VALUES(tawjihi_readiness_score),
                exams_passed_count = VALUES(exams_passed_count),
                exams_total_count = VALUES(exams_total_count),
                updated_at = NOW()
        ", [$studentId, $courseId, $subjectId, $avgMastery, $tawjihiIndex, $passedExams, $totalExams]);

        $response->json([
            'status' => 'success',
            'data'   => [
                'attempt_id'             => $attemptId,
                'score'                  => $earnedScore,
                'total_score'            => $totalPoints,
                'percentage'             => $percentage,
                'passed'                 => $passed,
                'rewind_seconds'         => $passed ? 0 : (int)$exam['rewind_on_fail_seconds'],
                'ai_diagnostic_report'   => $aiReport,
                'weak_topics'            => array_keys($weakTopics),
                'tawjihi_readiness_score'=> $tawjihiIndex,
                'detailed_answers'       => $detailedAnswers
            ]
        ]);
    }

    /**
     * Get Student Mastery & Tawjihi Readiness Analytics
     * GET /api/student/progress/mastery?course_id=1
     */
    public function getMastery(Request $request, Response $response): void
    {
        $studentId = $request->user_id;
        $courseId  = (int)$request->getParam('course_id');

        $analytics = Database::selectOne(
            "SELECT * FROM student_mastery_analytics WHERE student_id = ? AND course_id = ? LIMIT 1",
            [$studentId, $courseId]
        );

        $recentAttempts = Database::select(
            "SELECT ea.id, ea.score, ea.total_score, ea.percentage, ea.status, ea.ai_diagnostic_report, ea.completed_at, e.title as exam_title, e.scope
             FROM exam_attempts ea
             JOIN exams e ON e.id = ea.exam_id
             WHERE ea.student_id = ? AND e.course_id = ?
             ORDER BY ea.id DESC LIMIT 10",
            [$studentId, $courseId]
        );

        $response->json([
            'status' => 'success',
            'data'   => [
                'analytics'       => $analytics ?: [
                    'mastery_percentage'     => 0,
                    'tawjihi_readiness_score'=> 0,
                    'exams_passed_count'     => 0,
                    'exams_total_count'      => 0
                ],
                'recent_attempts' => $recentAttempts
            ]
        ]);
    }
}