keuangan/app/Domains/Billing/Actions/Invoicing/GenerateInvoiceCode.php

<?php

namespace App\Domains\Billing\Actions\Invoicing;

use App\Domains\Billing\Models\Invoice;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Str;
use Throwable;

class GenerateInvoiceCode
{
    /**
     * @throws Throwable
     */
    public function execute(int $clientId, ?string $prefix = null): string
    {
        $token = $prefix ? strtoupper(Str::slug($prefix)) : "C{$clientId}";
        $yearMonth = now()->format('Ym');

        $basePrefix = sprintf('INV-%s-%s-', $token, $yearMonth);

        return DB::transaction(function () use ($basePrefix) {
            // Find the last generated code with lock
            $lastInvoice = Invoice::query()
                ->where('code', 'LIKE', "{$basePrefix}%")
                ->lockForUpdate()
                ->orderByDesc('id')
                ->first();

            if (! $lastInvoice) {
                $nextSequence = 1;
            } else {
                // Extract sequence number from the tail end of string
                $parts = explode('-', $lastInvoice->code);
                $lastSequence = (int) end($parts);
                $nextSequence = $lastSequence + 1;
            }

            // Zero-pad sequence to 5 digits (e.g., 00001, 00002)
            $paddedSequence = str_pad((string) $nextSequence, 5, '0', STR_PAD_LEFT);

            return $basePrefix . $paddedSequence;
        });
    }
}