Basket.php

<?php

final class Basket implements RecordsEvents
{
    private $basketCanOnlyContainFiveProducts;
    
    private function __construct()
    {
        $this->basketCanOnlyContainFiveProducts = new BasketCanOnlyContainFiveProducts();   
    }

    private function whenBasketWasPickedUp(BasketWasPickedUp $event)
    {
        $this->basketCanOnlyContainFiveProducts->basketWasPickedUp();
    }

    private function whenProductWasAddedToBasket(ProductWasAddedToBasket $event)
    {
        $this->basketCanOnlyContainFiveProducts->productWasAddedToBasket();
    }

    private function whenProductWasRemovedFromBasket(ProductWasRemovedFromBasket $event)
    {
        $this->basketCanOnlyContainFiveProducts->productWasRemovedFromBasket();
    }

    public static function pickUp(BasketId $basketId)
    {
        $basket = new Basket($basketId);
        $basket->recordThat(new BasketWasPickedUp($basketId));
        return $basket;
    }
    
    public function addProduct(ProductId $productId, $name)
    {
        $this->basketCanOnlyContainFiveProducts->tryToAddProductToBasket();
        
        $this->recordThat(
            new ProductWasAddedToBasket($this->basketId, $productId, $name)
        );
    }

    public function removeProduct(ProductId $productId)
    {
        $this->recordThat(
            new ProductWasRemovedFromBasket($this->basketId, $productId)
        );
    }
}