messages implemented

app/Observers/ArtworkReactionObserver.php

@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Observers;
+
+use App\Models\ArtworkReaction;
+use App\Services\UserStatsService;
+use Illuminate\Support\Facades\DB;
+
+/**
+ * Updates the artwork creator's reactions_received_count when
+ * a reaction is added or removed.
+ */
+class ArtworkReactionObserver
+{
+    public function __construct(
+        private readonly UserStatsService $userStats,
+    ) {}
+
+    public function created(ArtworkReaction $reaction): void
+    {
+        $creatorId = $this->creatorId($reaction->artwork_id);
+        if ($creatorId) {
+            $this->userStats->incrementReactionsReceived($creatorId);
+        }
+
+        // The reactor is "active"
+        $this->userStats->ensureRow($reaction->user_id);
+        $this->userStats->setLastActiveAt($reaction->user_id);
+    }
+
+    public function deleted(ArtworkReaction $reaction): void
+    {
+        $creatorId = $this->creatorId($reaction->artwork_id);
+        if ($creatorId) {
+            $this->userStats->decrementReactionsReceived($creatorId);
+        }
+    }
+
+    private function creatorId(int $artworkId): ?int
+    {
+        $id = DB::table('artworks')
+            ->where('id', $artworkId)
+            ->value('user_id');
+
+        return $id !== null ? (int) $id : null;
+    }
+}