invoiceninja/app/Services/Invoice/HandleCancellation.php

<?php
/**
 * Invoice Ninja (https://invoiceninja.com)
 *
 * @link https://github.com/invoiceninja/invoiceninja source repository
 *
 * @copyright Copyright (c) 2020. Invoice Ninja LLC (https://invoiceninja.com)
 *
 * @license https://opensource.org/licenses/AAL
 */

namespace App\Services\Invoice;

use App\Events\Payment\PaymentWasCreated;
use App\Factory\CreditFactory;
use App\Factory\InvoiceItemFactory;
use App\Factory\PaymentFactory;
use App\Helpers\Invoice\InvoiceSum;
use App\Models\Client;
use App\Models\Invoice;
use App\Models\Payment;
use App\Models\Paymentable;
use App\Services\AbstractService;
use App\Services\Client\ClientService;
use App\Services\Payment\PaymentService;
use App\Utils\Traits\GeneratesCounter;

class HandleCancellation extends AbstractService
{
    use GeneratesCounter;

    private $invoice;

    public function __construct(Invoice $invoice)
    {        
        $this->invoice = $invoice;
    }

    public function run()
    {
        /* Check again!! */
        if(!$this->invoice->invoiceCancellable($this->invoice))
            return $this->invoice;

        $adjustment = $this->invoice->balance*-1;
        //set invoice balance to 0
        $this->invoice->ledger()->updateInvoiceBalance($adjustment, "Invoice cancellation");

        $this->invoice->balance = 0;
        $this->invoice = $this->invoice->service()->setStatus(Invoice::STATUS_CANCELLED)->save();

        //adjust client balance
        $this->invoice->client->service()->updateBalance($adjustment)->save();
    
        return $this->invoice;
    }

}