refactoring of system messages

app/Models/Message.php

@@ -7,6 +7,8 @@ use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 
+use Illuminate\Database\Eloquent\Relations\MorphTo;
+
 class Message extends Model
 {
     /** @use HasFactory<MessageFactory> */
@@ -16,6 +18,8 @@ class Message extends Model
         'chat_id',
         'user_id',
         'content',
+        'subject_id',
+        'subject_type',
     ];
 
     public function chat(): BelongsTo
@@ -28,6 +32,11 @@ class Message extends Model
         return $this->belongsTo(User::class);
     }
 
+    public function subject(): MorphTo
+    {
+        return $this->morphTo();
+    }
+
     public function media(): \Illuminate\Database\Eloquent\Relations\MorphMany
     {
         return $this->morphMany(Media::class, 'mediable');