ladill-care/app/Models/Drug.php

<?php

namespace App\Models;

use App\Models\Concerns\BelongsToOwner;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Database\Eloquent\Relations\HasMany;
use Illuminate\Database\Eloquent\SoftDeletes;

class Drug extends Model
{
    use BelongsToOwner, SoftDeletes;

    protected $table = 'care_drugs';

    protected $fillable = [
        'owner_ref', 'organization_id', 'branch_id', 'name', 'generic_name',
        'sku', 'unit', 'unit_price_minor', 'reorder_level', 'is_active',
    ];

    protected function casts(): array
    {
        return ['is_active' => 'boolean'];
    }

    public function organization(): BelongsTo
    {
        return $this->belongsTo(Organization::class, 'organization_id');
    }

    public function branch(): BelongsTo
    {
        return $this->belongsTo(Branch::class, 'branch_id');
    }

    public function batches(): HasMany
    {
        return $this->hasMany(DrugBatch::class, 'drug_id');
    }

    public function stockOnHand(): int
    {
        return (int) $this->batches()->sum('quantity_on_hand');
    }
}