Add all files

app/Models/InvoiceItem.php

@@ -0,0 +1,61 @@
+<?php
+
+namespace App\Models;
+
+use App\Classes\Price;
+use App\Observers\InvoiceItemObserver;
+use Illuminate\Database\Eloquent\Attributes\ObservedBy;
+use Illuminate\Database\Eloquent\Casts\Attribute;
+use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
+
+#[ObservedBy([InvoiceItemObserver::class])]
+class InvoiceItem extends Model
+{
+    use HasFactory;
+
+    protected $fillable = [
+        'invoice_id',
+        'service_id',
+        'quantity',
+        'price',
+        'description',
+        'gateway_id',
+        'reference_id',
+        'reference_type',
+    ];
+
+    public function invoice()
+    {
+        return $this->belongsTo(Invoice::class);
+    }
+
+    public function reference()
+    {
+        return $this->morphTo();
+    }
+
+    public function gateway()
+    {
+        return $this->belongsTo(Gateway::class);
+    }
+
+    public function total()
+    {
+        return $this->price * $this->quantity;
+    }
+
+    public function formattedTotal(): Attribute
+    {
+        return Attribute::make(
+            get: fn () => new Price(['price' => $this->total(), 'currency' => $this->invoice->currency])
+        );
+    }
+
+    public function formattedPrice(): Attribute
+    {
+        return Attribute::make(
+            get: fn () => new Price(['price' => $this->price, 'currency' => $this->invoice->currency])
+        );
+    }
+}