Vat calculating

VatCalculatingService.php

<?php
use Money\Money;

/**
 * Class VatCalculatingService
 * Calculating VAT
 *
 * @see: http://www.achievertalk.com/achievertalkwp/2011/06/vat-in-your-young-enterprise-company/
 */
class VatCalculatingService
{
    protected $vat;

    protected $accuracy;

    /**
     * @param $vat
     * @param $accuracy
     */
    public function __construct($vat, $accuracy = 4)
    {
        $this->vat = $vat;
        $this->accuracy = $accuracy;
    }

    /**
     * @param $amount
     * @return float
     */
    protected function resolvePrice($amount)
    {
        if (is_numeric($amount)) {
            return (float) $amount;
        } elseif ($amount  instanceof Money) {
            return $amount->getAmount() / 100;
        } else {
            throw new \InvalidArgumentException('Amount must have float or Money type');
        }
    }

    /**
     * Calculate the price inclusive of VAT
     *
     * @param $amount
     *
     * @return float
     */
    public function addingVatToPrice($amount)
    {
        $amount = $this->resolvePrice($amount);
        return round($amount * (1 + ($this->vat / 100)), $this->accuracy);
    }

    /**
     * Calculate how much VAT there is on the price of something that already includes VAT
     *
     * @param $amountInclusiveVat
     *
     * @return float
     */
    public function calculatingVatElement($amountInclusiveVat)
    {
        $amount = $this->resolvePrice($amountInclusiveVat);
        return round($amount / ($this->vat + 100) * $this->vat, $this->accuracy);
    }

    /**
     * Calculate the price of amount exclusive of VAT
     *
     * @param $amountInclusiveVat
     *
     * @return float
     */
    public function removingVat($amountInclusiveVat)
    {
        $amount = $this->resolvePrice($amountInclusiveVat);
        return round($amount / ($this->vat + 100) * 100 , $this->accuracy);
    }
}