/**
* Returns the difference of this Money and the given amount.
*
* By default, the resulting Money has the same number of fraction digits as this Money. If the result
* cannot be represented at this scale without rounding, an exception is thrown.
*
* This behaviour can be overridden by providing a MoneyContext instance.
*
* @param Money|BigNumber|number|string $that The amount to be subtracted.
* @param MoneyContext|null $context An optional scale & rounding context.
*
* @return Money
*
* @throws ArithmeticException If the argument is an invalid number.
* @throws CurrencyMismatchException If the argument is a money in a different currency.
*/
public function minus($that, MoneyContext $context = null)
{
if ($context === null) {
$context = new RetainContext(RoundingMode::UNNECESSARY);
}
$amount = $this->amount->minus($this->handleMoney($that));
$amount = $context->applyTo($amount, $this->currency, $this->amount->scale());
return new Money($amount, $this->currency);
}