<?php

namespace App\Controllers;

use App\Core\Database;
use App\Core\Request;
use App\Core\Response;
use App\Services\RemediationAttemptGrader;

class ErrorNotebookController
{
    public function getErrorNotebook(Request $request, Response $response): void
    {
        $studentId = (int)$request->user_id;
        $sql = "SELECT *, (retention_due_at IS NOT NULL AND retention_due_at <= NOW()) AS retention_is_due FROM student_error_notebook WHERE student_id = ?";
        $params = [$studentId];
        $subject = trim((string)$request->getQuery('subject', ''));
        $status = trim((string)$request->getQuery('status', ''));
        if ($subject !== '') { $sql .= ' AND subject_id = ?'; $params[] = $subject; }
        if ($status !== '') { $sql .= ' AND status = ?'; $params[] = $status; }
        $items = Database::select($sql . ' ORDER BY created_at DESC', $params);

        $mastered = count(array_filter($items, fn($item) => ($item['status'] ?? '') === 'mastered'));
        $inRemediation = count(array_filter($items, fn($item) => ($item['status'] ?? '') === 'in_remediation'));
        $pending = count(array_filter($items, fn($item) => ($item['status'] ?? '') === 'pending_remediation'));
        $bySubject = [];
        foreach ($items as $item) {
            $name = (string)($item['subject_name'] ?? '');
            if ($name !== '') $bySubject[$name] = ($bySubject[$name] ?? 0) + 1;
        }
        $total = count($items);
        $response->json(['status' => 'success', 'data' => [
            'summary' => [
                'total_errors' => $total,
                'mastered_count' => $mastered,
                'in_remediation_count' => $inRemediation,
                'pending_count' => $pending,
                'mastery_percentage' => $total ? round(($mastered / $total) * 100, 1) : 0.0,
                'by_subject' => $bySubject,
            ],
            'items' => $items,
        ]]);
    }

    public function logError(Request $request, Response $response): void
    {
        $body = $request->getBody();
        foreach (['subject_id', 'subject_name', 'topic_name', 'source_type', 'question_text', 'student_wrong_answer', 'correct_answer'] as $field) {
            if (trim((string)($body[$field] ?? '')) === '') {
                $response->status(422)->json(['status' => 'error', 'message' => "الحقل {$field} مطلوب"]);
                return;
            }
        }
        $uuid = $this->uuid();
        Database::insert(
            "INSERT INTO student_error_notebook
             (uuid, student_id, subject_id, subject_name, topic_name, lesson_id, source_type, question_text, options_json,
              student_wrong_answer, correct_answer, socratic_hint, error_category, status, created_at)
             VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 'pending_remediation', NOW())",
            [
                $uuid, (int)$request->user_id, $body['subject_id'], $body['subject_name'], $body['topic_name'],
                !empty($body['lesson_id']) ? (int)$body['lesson_id'] : null, $body['source_type'], $body['question_text'],
                isset($body['options']) ? json_encode($body['options'], JSON_UNESCAPED_UNICODE) : null,
                $body['student_wrong_answer'], $body['correct_answer'], (string)($body['socratic_hint'] ?? ''),
                (string)($body['error_category'] ?? 'conceptual'),
            ]
        );
        $response->status(201)->json(['status' => 'success', 'uuid' => $uuid]);
    }

    public function getRemediationQuiz(Request $request, Response $response): void
    {
        $body = $request->getBody();
        $uuid = trim((string)($body['error_uuid'] ?? ''));
        $error = Database::selectOne(
            "SELECT *, (retention_due_at IS NOT NULL AND retention_due_at <= NOW()) AS retention_is_due
             FROM student_error_notebook WHERE uuid = ? AND student_id = ? LIMIT 1",
            [$uuid, (int)$request->user_id]
        );
        if (!$error) {
            $response->status(404)->json(['status' => 'error', 'message' => 'الفجوة التعليمية غير موجودة']);
            return;
        }

        if ($error['status'] === 'mastered') {
            $response->status(409)->json(['status' => 'error', 'message' => 'هذه الفجوة متقنة بالفعل']);
            return;
        }
        if ($error['status'] === 'in_remediation' && (int)$error['retention_is_due'] !== 1) {
            $response->status(409)->json(['status' => 'not_due', 'message' => 'اختبار الاسترجاع متاح بعد موعده المحدد']);
            return;
        }
        if (empty($error['lesson_id'])) {
            $response->status(422)->json(['status' => 'unavailable', 'message' => 'لا يوجد درس محدد لهذه الفجوة لتكوين اختبار موثوق']);
            return;
        }
        $dbQuestions = Database::select(
            "SELECT q.id, q.question_text FROM questions q
             JOIN exams e ON e.id = q.exam_id
             WHERE e.lesson_id = ? AND e.is_published = 1 AND q.topic_tag = ?
               AND q.question_type = 'multiple_choice'
               AND q.remediation_review_status = 'approved'
               AND q.remediation_reviewed_by IS NOT NULL
               AND q.remediation_reviewed_at IS NOT NULL
               AND q.remediation_source_reference IS NOT NULL
             ORDER BY q.id ASC LIMIT 20",
            [(int)$error['lesson_id'], $error['topic_name']]
        );
        $questions = [];
        $answerKey = [];
        foreach ($dbQuestions as $question) {
            $options = Database::select(
                'SELECT id, option_text, is_correct FROM question_options WHERE question_id = ? ORDER BY id ASC',
                [(int)$question['id']]
            );
            if (count($options) < 2 || count(array_filter($options, fn($o) => (int)$o['is_correct'] === 1)) !== 1) continue;
            $questions[] = [
                'id' => (int)$question['id'], 'question' => $question['question_text'],
                'options' => array_map(fn($o) => ['id' => (int)$o['id'], 'text' => $o['option_text']], $options),
            ];
            $answerKey[] = [
                'question_id' => (int)$question['id'],
                'option_ids' => array_map(fn($o) => (int)$o['id'], $options),
                'correct_option_id' => (int)array_values(array_filter($options, fn($o) => (int)$o['is_correct'] === 1))[0]['id'],
            ];
            if (count($questions) === 3) break;
        }
        if (count($questions) !== 3) {
            $response->status(422)->json(['status' => 'unavailable', 'message' => 'لا توجد ثلاثة أسئلة منشورة ومراجعة لهذا الدرس والمفهوم']);
            return;
        }

        $attemptUuid = $this->uuid();
        Database::insert(
            "INSERT INTO error_notebook_quiz_attempts (uuid,error_id,student_id,phase,question_ids_json,answer_key_json,expires_at)
             VALUES (?,?,?,?,?,?,DATE_ADD(NOW(), INTERVAL 30 MINUTE))",
            [$attemptUuid, (int)$error['id'], (int)$request->user_id,
             $error['status'] === 'in_remediation' ? 'retention' : 'initial',
             json_encode(array_column($questions, 'id')), json_encode($answerKey)]
        );

        $response->json([
            'status' => 'success',
            'data' => [
                'error_uuid' => $uuid,
                'topic_name' => $error['topic_name'],
                'subject_name' => $error['subject_name'],
                'attempt_uuid' => $attemptUuid,
                'questions' => $questions,
            ],
        ]);
    }

    public function resolveError(Request $request, Response $response): void
    {
        $body = $request->getBody();
        $uuid = trim((string)($body['error_uuid'] ?? ''));
        $attemptUuid = trim((string)($body['attempt_uuid'] ?? ''));
        $studentId = (int)$request->user_id;
        $answers = $body['answers'] ?? null;
        if (!is_array($answers) || count($answers) !== 3) {
            $response->status(422)->json(['status' => 'error', 'message' => 'يجب إرسال إجابات الأسئلة الثلاثة']);
            return;
        }
        $answersHash = hash('sha256', json_encode($answers));
        $pdo = Database::getConnection();
        $pdo->beginTransaction();
        try {
            $error = Database::selectOne(
                'SELECT *, (retention_due_at IS NOT NULL AND retention_due_at <= NOW()) AS retention_is_due FROM student_error_notebook WHERE uuid = ? AND student_id = ? FOR UPDATE',
                [$uuid, $studentId]
            );
            $attempt = $error ? Database::selectOne(
                'SELECT *, (expires_at > NOW()) AS is_fresh FROM error_notebook_quiz_attempts WHERE uuid = ? AND error_id = ? AND student_id = ? FOR UPDATE',
                [$attemptUuid, (int)$error['id'], $studentId]
            ) : null;
            if ($attempt && $attempt['status'] !== 'open' && hash_equals((string)($attempt['answers_sha256'] ?? ''), $answersHash)) {
                $pdo->commit();
                $response->json(['status' => 'success', 'passed' => $attempt['status'] === 'passed',
                    'correct_count' => (int)$attempt['correct_count'],
                    'new_status' => $attempt['status'] === 'passed' ? ($attempt['phase'] === 'retention' ? 'mastered' : 'in_remediation') : $error['status']]);
                return;
            }
            if (!$attempt || $attempt['status'] !== 'open' || (int)$attempt['is_fresh'] !== 1) {
                $pdo->rollBack();
                $response->status(409)->json(['status' => 'error', 'message' => 'المحاولة غير متاحة أو انتهت صلاحيتها']);
                return;
            }
            $phase = $error['status'] === 'in_remediation' ? 'retention' : 'initial';
            if ($error['status'] === 'mastered' || $attempt['phase'] !== $phase ||
                ($phase === 'retention' && (int)$error['retention_is_due'] !== 1)) {
                $pdo->rollBack();
                $response->status(409)->json(['status' => 'error', 'message' => 'حالة الفجوة تغيرت؛ ابدأ محاولة جديدة']);
                return;
            }
            $ids = json_decode($attempt['question_ids_json'], true);
            $answerKey = json_decode($attempt['answer_key_json'], true);
            if (!is_array($ids) || !is_array($answerKey)) {
                $pdo->rollBack();
                $response->status(422)->json(['status' => 'error', 'message' => 'إجابات المحاولة غير صالحة']);
                return;
            }
            foreach ($ids as $index => $questionId) {
                $published = Database::selectOne(
                    "SELECT q.id FROM questions q JOIN exams e ON e.id = q.exam_id
                     WHERE q.id = ? AND e.lesson_id = ? AND e.is_published = 1 AND q.topic_tag = ?
                       AND q.remediation_review_status = 'approved' AND q.remediation_reviewed_by IS NOT NULL
                       AND q.remediation_reviewed_at IS NOT NULL AND q.remediation_source_reference IS NOT NULL FOR UPDATE",
                    [(int)$questionId, (int)$error['lesson_id'], $error['topic_name']]
                );
                if (!$published) {
                    $pdo->rollBack();
                    $response->status(409)->json(['status' => 'error', 'message' => 'سُحب سؤال من هذه المحاولة؛ ابدأ محاولة جديدة']);
                    return;
                }
            }
            try {
                $correct = RemediationAttemptGrader::grade($ids, $answerKey, $answers);
            } catch (\InvalidArgumentException $invalidAnswer) {
                $pdo->rollBack();
                $response->status(422)->json(['status' => 'error', 'message' => 'إجابات المحاولة غير صالحة']);
                return;
            }
            $passed = $correct >= 2;
            Database::query(
                "UPDATE error_notebook_quiz_attempts SET status = ?, correct_count = ?, answers_sha256 = ?, submitted_at = NOW() WHERE id = ?",
                [$passed ? 'passed' : 'failed', $correct, $answersHash, (int)$attempt['id']]
            );
            if ($passed) {
                Database::query(
                    "UPDATE student_error_notebook SET status = ?, remediation_attempts_count = remediation_attempts_count + 1,
                     retention_due_at = IF(? = 'initial', DATE_ADD(NOW(), INTERVAL 7 DAY), retention_due_at),
                     mastered_at = IF(? = 'retention', NOW(), mastered_at) WHERE id = ?",
                    [$phase === 'retention' ? 'mastered' : 'in_remediation', $phase, $phase, (int)$error['id']]
                );
            } else {
                Database::query('UPDATE student_error_notebook SET remediation_attempts_count = remediation_attempts_count + 1 WHERE id = ?', [(int)$error['id']]);
            }
            $pdo->commit();
            $response->json(['status' => 'success', 'passed' => $passed, 'correct_count' => $correct,
                'new_status' => $passed ? ($phase === 'retention' ? 'mastered' : 'in_remediation') : $error['status']]);
        } catch (\Throwable $e) {
            if ($pdo->inTransaction()) $pdo->rollBack();
            throw $e;
        }
    }

    private function uuid(): string
    {
        $data = random_bytes(16);
        $data[6] = chr((ord($data[6]) & 0x0f) | 0x40);
        $data[8] = chr((ord($data[8]) & 0x3f) | 0x80);
        return vsprintf('%s%s-%s-%s-%s-%s%s%s', str_split(bin2hex($data), 4));
    }
}