public function orderSimpan(): void
{
    if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
        redirect();
    }

    // ===============================
    // Ambil input
    // ===============================
    $produkId = (int) ($_POST['produk_id'] ?? 0);
    $namaPemesan = trim($_POST['nama_pemesan'] ?? '');
    $noHp = trim($_POST['no_hp_pemesan'] ?? '');
    $ucapan = trim($_POST['ucapan'] ?? '');
    $namaPengirim = trim($_POST['nama_pengirim'] ?? '');
    $tanggalKirim = $_POST['tanggal_kirim'] ?? null;
    $jamKirim = $_POST['jam_kirim'] ?? null;
    $alamatKirim = trim($_POST['alamat_kirim'] ?? '');
    $catatan = trim($_POST['catatan'] ?? '');

    // ===============================
    // Validasi sederhana
    // ===============================
    if (
        !$produkId ||
        !$namaPemesan ||
        !$noHp ||
        !$ucapan ||
        !$tanggalKirim ||
        !$alamatKirim
    ) {
        die('Data tidak lengkap.');
    }

    // ===============================
    // Ambil produk
    // ===============================
    require_once APP_PATH . '/models/Produk.php';
    $produk = Produk::findById($produkId);

    if (!$produk) {
        die('Produk tidak ditemukan.');
    }

    // ===============================
    // Generate kode order
    // ===============================
    $kodeOrder = 'ORD-' . date('YmdHis') . '-' . rand(100, 999);

    // ===============================
    // Simpan customer (simple)
    // ===============================
    $stmt = db()->prepare("
        INSERT INTO customer (nama, no_hp, created_at)
        VALUES (:nama, :no_hp, NOW())
    ");
    $stmt->execute([
        ':nama' => $namaPemesan,
        ':no_hp' => $noHp,
    ]);

    $customerId = db()->lastInsertId();

    // ===============================
    // Hitung total
    // ===============================
    $harga = (float) $produk['harga'];
    $subtotal = $harga;
    $total = $subtotal; // nanti bisa tambah ongkir/diskon

    // ===============================
    // Simpan order
    // ===============================
    $stmt = db()->prepare("
        INSERT INTO orders (
            kode_order,
            customer_id,
            tanggal_order,
            tanggal_kirim,
            jam_kirim,
            nama_pemesan,
            no_hp_pemesan,
            nama_pengirim,
            ucapan,
            alamat_kirim,
            catatan,
            subtotal,
            total_harga,
            status_order,
            status_pembayaran,
            token_tracking,
            created_at
        ) VALUES (
            :kode_order,
            :customer_id,
            NOW(),
            :tanggal_kirim,
            :jam_kirim,
            :nama_pemesan,
            :no_hp_pemesan,
            :nama_pengirim,
            :ucapan,
            :alamat_kirim,
            :catatan,
            :subtotal,
            :total_harga,
            'pending',
            'belum_bayar',
            :token_tracking,
            NOW()
        )
    ");

    $tokenTracking = bin2hex(random_bytes(8));

    $stmt->execute([
        ':kode_order' => $kodeOrder,
        ':customer_id' => $customerId,
        ':tanggal_kirim' => $tanggalKirim,
        ':jam_kirim' => $jamKirim,
        ':nama_pemesan' => $namaPemesan,
        ':no_hp_pemesan' => $noHp,
        ':nama_pengirim' => $namaPengirim,
        ':ucapan' => $ucapan,
        ':alamat_kirim' => $alamatKirim,
        ':catatan' => $catatan,
        ':subtotal' => $subtotal,
        ':total_harga' => $total,
        ':token_tracking' => $tokenTracking,
    ]);

    $orderId = db()->lastInsertId();

    // ===============================
    // Simpan order item
    // ===============================
    $stmt = db()->prepare("
        INSERT INTO order_items (
            order_id,
            produk_id,
            kode_produk,
            nama_produk,
            harga,
            qty,
            subtotal,
            created_at
        ) VALUES (
            :order_id,
            :produk_id,
            :kode_produk,
            :nama_produk,
            :harga,
            1,
            :subtotal,
            NOW()
        )
    ");

    $stmt->execute([
        ':order_id' => $orderId,
        ':produk_id' => $produkId,
        ':kode_produk' => $produk['kode_produk'],
        ':nama_produk' => $produk['nama_produk'],
        ':harga' => $harga,
        ':subtotal' => $subtotal,
    ]);

    // ===============================
    // Redirect ke sukses
    // ===============================
    redirect('order/sukses?kode_order=' . urlencode($kodeOrder));
}500 - Class controller tidak ditemukan: FrontendController