generate bill number

app/Listeners/Purchase/IncreaseNextBillNumber.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace App\Listeners\Purchase;
+
+use App\Events\Purchase\BillCreated as Event;
+use App\Traits\Purchases;
+
+class IncreaseNextBillNumber
+{
+    use Purchases;
+
+    /**
+     * Handle the event.
+     *
+     * @param  $event
+     * @return void
+     */
+    public function handle(Event $event)
+    {
+        // Update next bill number
+        $this->increaseNextBillNumber();
+    }
+}