<?php
/**
 * POST /api/telemetry
 * Akzeptiert Heartbeat / Milestone / Stuck / Accessibility-Blocker.
 */

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

v2_validate_method('POST');
$auth = v2_auth_require('student');
$studentId = (int) ($auth['sub'] ?? 0);
$classId = (int) ($auth['class_id'] ?? 0);

$body = v2_request_body_json_required();
v2_validate_required($body, ['type', 'moduleSlug', 'moduleVersion']);

$type = (string) $body['type'];
v2_validate_enum($type, ['heartbeat', 'milestone', 'stuck', 'accessibility-blocker'], 'type');

// Payload-Größe-Check (Spec: max 4 KB pro Event)
if (strlen(json_encode($body)) > 4096) {
    v2_response_error(413, 'payload_too_large', 'Event darf max 4 KB sein.');
}

// Rate-Limit: max 1 Event/Sekunde pro Schüler*in
$lastTs = v2_db_one("
    SELECT UNIX_TIMESTAMP(MAX(ts)) AS last_unix
    FROM telemetry_events_v2
    WHERE student_id = :sid
", [':sid' => $studentId]);
if ($lastTs && $lastTs['last_unix'] && (time() - (int) $lastTs['last_unix']) < 1) {
    v2_response_error(429, 'rate_limited', 'Max 1 Event pro Sekunde.');
}

// Pro Sitzung max 2000 Events — dann Heartbeats droppen, Milestones noch akzeptieren
$count = v2_db_one("
    SELECT COUNT(*) AS c
    FROM telemetry_events_v2
    WHERE student_id = :sid
      AND module_slug = :slug
      AND ts > NOW() - INTERVAL 8 HOUR
", [':sid' => $studentId, ':slug' => $body['moduleSlug']]);
if ($count && (int) $count['c'] > 2000 && $type === 'heartbeat') {
    v2_response_ok(['ok' => true, 'dropped' => 'rate-cap-heartbeat']);
}

v2_db_exec("
    INSERT INTO telemetry_events_v2
        (student_id, class_id, module_slug, module_version, event_type,
         phase, phase_label, step, current_score, score_max,
         time_in_phase_s, total_time_s,
         milestone_id, milestone_label, score_delta,
         idle_s, last_action_label, hint, blocker_type, ts)
    VALUES
        (:sid, :cid, :slug, :mv, :et,
         :ph, :phl, :step, :cs, :csmax,
         :tip, :tt,
         :mid, :ml, :sd,
         :idle, :lal, :hint, :bt, :ts)
", [
    ':sid' => $studentId,
    ':cid' => $classId,
    ':slug' => $body['moduleSlug'],
    ':mv' => $body['moduleVersion'],
    ':et' => $type,
    ':ph' => $body['phase'] ?? null,
    ':phl' => $body['phaseLabel'] ?? null,
    ':step' => $body['step'] ?? null,
    ':cs' => isset($body['currentScore']) ? (int) $body['currentScore'] : null,
    ':csmax' => isset($body['scoreMax']) ? (int) $body['scoreMax'] : null,
    ':tip' => isset($body['timeInPhaseS']) ? (int) $body['timeInPhaseS'] : null,
    ':tt' => isset($body['totalTimeS']) ? (int) $body['totalTimeS'] : null,
    ':mid' => $body['milestoneId'] ?? null,
    ':ml' => $body['milestoneLabel'] ?? null,
    ':sd' => isset($body['scoreDelta']) ? (int) $body['scoreDelta'] : null,
    ':idle' => isset($body['idleS']) ? (int) $body['idleS'] : null,
    ':lal' => $body['lastActionLabel'] ?? null,
    ':hint' => $body['hint'] ?? null,
    ':bt' => $body['blockerType'] ?? null,
    ':ts' => date('Y-m-d H:i:s', strtotime($body['ts'] ?? 'now') ?: time()),
]);

v2_response_ok(['ok' => true]);