pases 4 ticket updates

Modules/Helpdesk/Services/TicketReferenceService.php

@@ -1,27 +1,58 @@
 <?php
 
+/**
+ * TicketReferenceService.php
+ *
+ * Generates collision-resistant Helpdesk ticket references.
+ */
+
 declare(strict_types=1);
 
 namespace Modules\Helpdesk\Services;
 
+use Illuminate\Support\Facades\DB;
 use Modules\Helpdesk\Models\Ticket;
 
 final class TicketReferenceService
 {
     /**
-     * Build the next human-readable ticket reference.
+     * Build the next human-readable ticket reference for the current year.
+     *
+     * The lookup uses the highest numeric suffix, not the latest database id,
+     * because imported, restored, or manually adjusted tickets may not be in
+     * reference order. On PostgreSQL an advisory transaction lock is also used
+     * so two users cannot generate the same reference at the same time.
      */
     public function next(): string
     {
         $year = now()->format('Y');
         $prefix = 'HD-'.$year.'-';
-        $last = Ticket::query()
+
+        $this->lockReferenceSeries($prefix);
+
+        $lastReference = Ticket::query()
             ->where('reference', 'like', $prefix.'%')
-            ->latest('id')
+            ->orderByDesc('reference')
             ->value('reference');
 
-        $next = $last ? ((int) substr((string) $last, -5)) + 1 : 1;
+        $next = $lastReference === null
+            ? 1
+            : ((int) substr((string) $lastReference, -5)) + 1;
 
         return $prefix.str_pad((string) $next, 5, '0', STR_PAD_LEFT);
     }
+
+    /**
+     * Lock the current ticket reference series for the active transaction.
+     */
+    private function lockReferenceSeries(string $prefix): void
+    {
+        if (DB::connection()->getDriverName() !== 'pgsql') {
+            return;
+        }
+
+        DB::select('select pg_advisory_xact_lock(hashtext(?))', [
+            'helpdesk-ticket-reference:'.$prefix,
+        ]);
+    }
 }