<?php
/**
 * GET  /api/module/state?slug=<slug>     → Resume-State holen
 * PUT  /api/module/state                 → Resume-State speichern
 */

declare(strict_types=1);
require_once __DIR__ . '/../../bootstrap.php';

$method = v2_validate_method_in(['GET', 'PUT']);
$auth = v2_auth_require('student');
$studentId = (int) ($auth['sub'] ?? 0);

if ($method === 'GET') {
    $slug = $_GET['slug'] ?? '';
    if (!$slug) {
        v2_response_error(400, 'missing_slug', 'Parameter "slug" fehlt.');
    }

    $row = v2_db_one("
        SELECT state_json, summary, updated_at
        FROM module_state_v2
        WHERE student_id = :sid AND module_slug = :slug
    ", [':sid' => $studentId, ':slug' => $slug]);

    if (!$row) {
        v2_response_ok(['exists' => false]);
    }

    v2_response_ok([
        'exists' => true,
        'lastUpdated' => $row['updated_at'],
        'state' => json_decode($row['state_json'], true),
        'summary' => $row['summary'] ?? '',
    ]);
}

// PUT — State speichern
$body = v2_request_body_json_required();
v2_validate_required($body, ['moduleSlug', 'state']);

$slug = (string) $body['moduleSlug'];
$stateJson = json_encode($body['state'], JSON_UNESCAPED_UNICODE);
$summary = (string) ($body['summary'] ?? '');

if (strlen($stateJson) > 1024 * 1024) {  // 1 MB Limit
    v2_response_error(413, 'state_too_large', 'State darf max 1 MB sein.');
}

v2_db_exec("
    INSERT INTO module_state_v2 (student_id, module_slug, state_json, summary)
    VALUES (:sid, :slug, :st, :sum)
    ON DUPLICATE KEY UPDATE
        state_json = VALUES(state_json),
        summary = VALUES(summary),
        updated_at = CURRENT_TIMESTAMP
", [':sid' => $studentId, ':slug' => $slug, ':st' => $stateJson, ':sum' => $summary]);

v2_response_ok(['ok' => true, 'savedAt' => date('c')]);