/**
* The discount amount as a negative price.
*
* @throws \InvalidArgumentException
*
* @return Money
*/
public function linePrice() : Money
{
if (!$this->requirementsAreMet()) {
return Money::fromInt(0);
}
if ($this->offer->isAbsolute()) {
return $this->priceFromAbsolute();
}
return $this->priceFromRelative();
}
/**
* @return string
*/
private function byPercentage() : string
{
$saving = $this->offer->percentage;
if ($this->offer->isAbsolute()) {
$saving = 100 - $this->offer->percentage;
}
if ($this->offer->quantity > 1) {
return "{$saving}% off when you buy {$this->offer->quantity}";
}
return "{$saving}% off";
}