/** users.last_seen_at kolonunu tembel ekler */
function users_last_seen_sema(): void {
    static $ok = false;
    if ($ok) return;
    try {
        db()->exec('ALTER TABLE users ADD COLUMN last_seen_at DATETIME NULL DEFAULT NULL');
    } catch (Throwable $e) {
        // kolon zaten var
    }
    $ok = true;
}

/** Misafir + üye presence tablosu (sitedeki herkes). */
function online_presence_sema(): void {
    static $ok = false;
    if ($ok) {
        return;
    }
    try {
        db()->exec(
            "CREATE TABLE IF NOT EXISTS online_presence (
               session_id VARCHAR(128) NOT NULL PRIMARY KEY,
               user_id INT UNSIGNED NULL,
               nickname VARCHAR(100) NULL,
               ip VARCHAR(45) NULL,
               ip_hash CHAR(64) NULL,
               path VARCHAR(255) NULL,
               last_seen_at DATETIME NOT NULL,
               KEY idx_online_presence_seen (last_seen_at),
               KEY idx_online_presence_user (user_id)
             ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4"
        );
    } catch (Throwable $e) {
        // yok say
    }
    try {
        db()->exec('ALTER TABLE online_presence ADD COLUMN ip VARCHAR(45) NULL AFTER nickname');
    } catch (Throwable $e) {
        // kolon zaten var
    }
    $ok = true;
}

/**
 * Online eşiği (saniye). Bu süre içinde görülen ziyaretçi online sayılır.
 */
function online_esik_saniye(): int {
    return 900; // 15 dk
}

function online_bot_istegi_mi(): bool {
    $ua = (string)($_SERVER['HTTP_USER_AGENT'] ?? '');
    if ($ua === '') {
        return true;
    }
    return (bool)preg_match(
        '/bot|crawl|spider|slurp|wget|curl\/|python-requests|facebookexternalhit|preview|monitoring|uptimerobot|pingdom|headless/i',
        $ua
    );
}

/** Girişli kullanıcının last_seen_at değerini en fazla ~60 sn'de bir günceller */
function touch_user_last_seen(int $userId): void {
    if ($userId <= 0) return;
    $now = time();
    $prev = (int)($_SESSION['last_seen_touch'] ?? 0);
    if ($prev > 0 && ($now - $prev) < 60) {
        return;
    }
    $_SESSION['last_seen_touch'] = $now;
    try {
        users_last_seen_sema();
        db()->prepare('UPDATE users SET last_seen_at = NOW() WHERE id = :id')
            ->execute([':id' => $userId]);
    } catch (Throwable $e) {
        // sessiz
    }
}

/**
 * Sitedeki herkes (üye + misafir) için presence kaydı.
 * header.php üzerinden her HTML sayfada çağrılır.
 */
function touch_online_presence(): void {
    if (PHP_SAPI === 'cli') {
        return;
    }
    if (defined('SS_SKIP_SESSION') && SS_SKIP_SESSION) {
        return;
    }
    if (session_status() !== PHP_SESSION_ACTIVE) {
        return;
    }
    if (online_bot_istegi_mi()) {
        return;
    }
    $sid = session_id();
    if ($sid === '') {
        return;
    }
    $now = time();
    $prev = (int)($_SESSION['presence_touch'] ?? 0);
    if ($prev > 0 && ($now - $prev) < 45) {
        return;
    }
    $_SESSION['presence_touch'] = $now;

    $uid = !empty($_SESSION['user_id']) ? (int)$_SESSION['user_id'] : null;
    $nick = null;
    if ($uid) {
        $nick = nick_norm((string)($_SESSION['nickname'] ?? ''));
        if ($nick === '') {
            $nick = null;
        }
    }
    $path = (string)(strtok($_SERVER['REQUEST_URI'] ?? '/', '?') ?: '/');
    if (strlen($path) > 240) {
        $path = substr($path, 0, 240);
    }
    // Admin/cron gibi panelleri de say (gerçek ziyaretçi)
    $ip = (string)($_SERVER['REMOTE_ADDR'] ?? '');
    if (strlen($ip) > 45) {
        $ip = substr($ip, 0, 45);
    }
    $salt = defined('DB_NAME') ? (string)DB_NAME : 'sporsozluk';
    $ipHash = $ip !== '' ? hash('sha256', $ip . '|' . $salt) : null;

    try {
        online_presence_sema();
        db()->prepare(
            'INSERT INTO online_presence (session_id, user_id, nickname, ip, ip_hash, path, last_seen_at)
             VALUES (:s, :u, :n, :ip, :ih, :p, NOW())
             ON DUPLICATE KEY UPDATE
               user_id = VALUES(user_id),
               nickname = VALUES(nickname),
               ip = VALUES(ip),
               ip_hash = VALUES(ip_hash),
               path = VALUES(path),
               last_seen_at = NOW()'
        )->execute([
            ':s' => $sid,
            ':u' => $uid,
            ':n' => $nick,
            ':ip' => $ip !== '' ? $ip : null,
            ':ih' => $ipHash,
            ':p' => $path,
        ]);
        // Eski kayıtları seyrek temizle
        if (mt_rand(1, 40) === 1) {
            db()->exec('DELETE FROM online_presence WHERE last_seen_at < DATE_SUB(NOW(), INTERVAL 1 DAY)');
        }
    } catch (Throwable $e) {
        // sessiz
    }
}

/**
 * Online ziyaretçi listesi (üye + misafir).
 * @return list<array<string,mixed>>
 */
function online_kullanicilar(?int $esikSaniye = null): array {
    online_presence_sema();
    $esik = (int)($esikSaniye ?? online_esik_saniye());
    if ($esik < 60) {
        $esik = 60;
    }
    try {
        $st = db()->query(
            "SELECT p.session_id, p.user_id, p.nickname, p.path, p.last_seen_at, p.ip, p.ip_hash,
                    u.is_admin, u.is_mod, u.is_banned, u.nickname AS user_nickname
             FROM online_presence p
             LEFT JOIN users u ON u.id = p.user_id
             WHERE p.last_seen_at >= DATE_SUB(NOW(), INTERVAL {$esik} SECOND)
             ORDER BY p.last_seen_at DESC
             LIMIT 300"
        );
        $rows = $st ? ($st->fetchAll(PDO::FETCH_ASSOC) ?: []) : [];
    } catch (Throwable $e) {
        $rows = [];
    }

    // Presence henüz boşsa (ilk deploy) eski üye last_seen'e düş
    if (!$rows) {
        users_last_seen_sema();
        $st = db()->query(
            "SELECT id AS user_id, nickname, email, is_admin, is_mod, is_banned, last_seen_at, last_login_at,
                    NULL AS session_id, NULL AS path, NULL AS ip, NULL AS ip_hash, nickname AS user_nickname
             FROM users
             WHERE last_seen_at IS NOT NULL
               AND last_seen_at >= DATE_SUB(NOW(), INTERVAL {$esik} SECOND)
             ORDER BY last_seen_at DESC
             LIMIT 200"
        );
        $rows = $st ? ($st->fetchAll(PDO::FETCH_ASSOC) ?: []) : [];
    }

    $out = [];
    foreach ($rows as $r) {
        $uid = isset($r['user_id']) ? (int)$r['user_id'] : 0;
        $nick = trim((string)($r['user_nickname'] ?? $r['nickname'] ?? ''));
        if ($uid > 0 && $nick === '') {
            $nick = 'üye #' . $uid;
        }
        $ip = trim((string)($r['ip'] ?? ''));
        $out[] = [
            'session_id' => $r['session_id'] ?? null,
            'user_id' => $uid > 0 ? $uid : null,
            'id' => $uid > 0 ? $uid : null, // geriye uyum
            'nickname' => $uid > 0 ? $nick : null,
            'is_guest' => $uid < 1,
            'is_admin' => !empty($r['is_admin']),
            'is_mod' => !empty($r['is_mod']),
            'is_banned' => !empty($r['is_banned']),
            'path' => $r['path'] ?? null,
            'last_seen_at' => $r['last_seen_at'] ?? null,
            'ip' => $ip !== '' ? $ip : null,
            'ip_hash' => $r['ip_hash'] ?? null,
        ];
    }
    return $out;
}

function online_kullanici_sayisi(?int $esikSaniye = null): int {
    online_presence_sema();
    $esik = (int)($esikSaniye ?? online_esik_saniye());
    if ($esik < 60) {
        $esik = 60;
    }
    try {
        $st = db()->query(
            "SELECT COUNT(*) FROM online_presence
             WHERE last_seen_at >= DATE_SUB(NOW(), INTERVAL {$esik} SECOND)"
        );
        $n = $st ? (int)$st->fetchColumn() : 0;
        if ($n > 0) {
            return $n;
        }
    } catch (Throwable $e) {
        // fallback
    }
    users_last_seen_sema();
    $st = db()->query(
        "SELECT COUNT(*) FROM users
         WHERE last_seen_at IS NOT NULL
           AND last_seen_at >= DATE_SUB(NOW(), INTERVAL {$esik} SECOND)"
    );
    return $st ? (int)$st->fetchColumn() : 0;
}

/** last_seen_at için kısa göreli metin */
function online_gorulme_metni(?string $lastSeenAt): string {
    if ($lastSeenAt === null || $lastSeenAt === '') return '—';
    $ts = strtotime($lastSeenAt);
    if ($ts === false) return '—';
    $fark = max(0, time() - $ts);
    if ($fark < 45) return 'şimdi';
    if ($fark < 3600) return (int)floor($fark / 60) . ' dk önce';
    if ($fark < 86400) return (int)floor($fark / 3600) . ' saat önce';
    return date('d.m.Y H:i', $ts);
}