VAT_Trait.php

<?php
namespace App\Helpers;

class VAT_Helper
{
    const VAT_PERCENTAGE = 20;
}
// -------------------------------------
?>


<?php

namespace App\Traits;
use App\Helpers\VAT_Helper;

trait VAT_Trait
{
    public function calcAddVatToAmount(float $amount, int $vat_percentage = VAT_Helper::VAT_PERCENTAGE): float|int
    {
        return round($amount * (1 + $vat_percentage / 100), 2);

        // e.g Gross amount: 10.80
    }

    public function calcVatAddedValue(float $amount, int $vat_percentage = VAT_Helper::VAT_PERCENTAGE): float
    {
        $amount_including_vat = $this->calcAddVatToAmount($amount, $vat_percentage);

        return round($amount_including_vat - $amount, 2);

        // e.g VAT added: 1.80
    }

    public function calcExcludeVatFromAmount(float $amount, int $vat_percentage = VAT_Helper::VAT_PERCENTAGE): float|int
    {
        return round($amount - $amount / (1 + $vat_percentage / 100), 2);

        // e.g Net amount: 7.50
    }

    public function calcVatExcludedValue(float $amount, int $vat_percentage = VAT_Helper::VAT_PERCENTAGE): float|int
    {
        return round($amount - $amount / (1 + $vat_percentage / 100), 2);

        // e.g VAT excluded: 1.50
    }
}

// ---------------------------------------------------
?>



<!-- How to use -->
<?php
namespace App\Http\Services;
use App\Helpers\VAT_Helper;

class CartService
{
    use VAT_Trait;

    const VAT_PERCENTAGE = 20; // you can skip this because default VAT percentage added i VAT_Trait.

    public function createCartItem(Request $request)
    {
        $product_price = $request->input('product_price'); // e.g 9$
        
        $cartItem =  CartItem::create([
            'product_id' => $request->input('product_id'),
            'sku' => $request->input('sku'),
            'total_weight' => $request->input('weight') * $request->input('quantity'),
            
            // single amount
            'price' => (float) $this->calcAddVatToAmount($product_price, VAT_Helper::VAT_PERCENTAGE), // 2nd parameter is optional

            // single amount * quantity
            'total' => (float) $this->calcAddVatToAmount($product_price * 5, VAT_Helper::VAT_PERCENTAGE),

            // check how much VAT added on single amount
            'tax_amount' => (float) $this->calcVatAddedValue($product_price, VAT_Helper::VAT_PERCENTAGE),
            
            
            // check how much VAT added on (single amount * quantity)
            'total_tax_amount' => (float) $this->calcVatAddedValue($product_price * 5, VAT_Helper::VAT_PERCENTAGE),
        ]);
    }
}
?>