gruene-seele/app/Models/ProductStockMovement.php

<?php

namespace App\Models;

use App\User;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Database\Eloquent\Relations\MorphTo;

class ProductStockMovement extends Model
{
    protected $fillable = [
        'product_id',
        'direction',
        'quantity',
        'reason',
        'source',
        'note',
        'user_id',
        'reference_type',
        'reference_id',
    ];

    /**
     * @return array<string, string>
     */
    protected function casts(): array
    {
        return [
            'quantity' => 'integer',
        ];
    }

    /**
     * @return BelongsTo<Product, $this>
     */
    public function product(): BelongsTo
    {
        return $this->belongsTo(Product::class);
    }

    /**
     * @return BelongsTo<User, $this>
     */
    public function user(): BelongsTo
    {
        return $this->belongsTo(User::class);
    }

    /**
     * @return MorphTo<Model, $this>
     */
    public function reference(): MorphTo
    {
        return $this->morphTo();
    }

    public function isIn(): bool
    {
        return $this->direction === 'in';
    }

    /**
     * Vorzeichenbehaftete Menge (Eingang positiv, Ausgang negativ).
     */
    public function signedQuantity(): int
    {
        return $this->isIn() ? (int) $this->quantity : -(int) $this->quantity;
    }
}