new helpdesk module

Modules/Helpdesk/Services/AgentAssignmentService.php

@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Modules\Helpdesk\Services;
+
+use App\Models\User;
+use Illuminate\Database\Eloquent\Builder;
+use Modules\Helpdesk\Models\Category;
+
+final class AgentAssignmentService
+{
+    /**
+     * Select the least-loaded available agent for a category.
+     *
+     * @param int|null $categoryId
+     * @return int|null
+     */
+    public function selectAgentId(?int $categoryId): ?int
+    {
+        $query = User::query()
+            ->where(static function (Builder $query): void {
+                $query->where('helpdesk_agent', true)->orWhere('helpdesk_admin', true);
+            })
+            ->withCount(['helpdeskAssignedTickets as open_helpdesk_tickets_count' => static function (Builder $query): void {
+                $query->whereNull('completed_at');
+            }]);
+
+        if ($categoryId !== null) {
+            $category = Category::query()->find($categoryId);
+            $agentIds = $category?->agents()->pluck('users.id')->all() ?? [];
+
+            if ($agentIds !== []) {
+                $query->whereIn('id', $agentIds);
+            }
+        }
+
+        /** @var User|null $agent */
+        $agent = $query->orderBy('open_helpdesk_tickets_count')->orderBy('id')->first();
+
+        return $agent?->id;
+    }
+}