drupal 8 price formatter

<?php

namespace Drupal\my_prices\Plugin\Field\FieldFormatter;

use Drupal\commerce\Context;
use Drupal\commerce_order\Plugin\Field\FieldFormatter\PriceCalculatedFormatter;
use Drupal\Core\Cache\Cache;
use Drupal\Core\Field\Annotation\FieldFormatter;
use Drupal\Core\Field\FieldItemListInterface;
use Drupal\Core\Language\LanguageInterface;
use Drupal\Core\Form\FormStateInterface;
use Drupal\views\Plugin\views\field\EntityField;
use Drupal\commerce\PurchasableEntityInterface;

/**
 * Plugin implementation of the 'commerce_price_calculated' formatter.
 *
 * @FieldFormatter(
 *   id = "commerce_cart_price_calculated",
 *   label = @Translation("Cart Price Calculated"),
 *   field_types = {
 *     "commerce_price"
 *   }
 * )
 */
class CartPriceCalculatedFormatter extends PriceCalculatedFormatter
{

  public function viewElements(FieldItemListInterface $items, $langcode)
  {
    $elements = [];
    if (!$items->isEmpty()) {
      $context = new Context($this->currentUser, $this->currentStore->getStore(), NULL, [
        'field_name' => $items->getName(),
      ]);
      /** @var PurchasableEntityInterface $purchasable_entity */
      $purchasable_entity = $items->getEntity();
      $adjustment_types = array_filter($this->getSetting('adjustment_types'));

      $result = $this->priceCalculator->calculate($purchasable_entity, 1, $context, $adjustment_types);
      $currency_code = $result->getCalculatedPrice()->getCurrencyCode();
      $options = $this->getFormattingOptions();
      //  get retail (base), wholesale and promo prices
      $price = $purchasable_entity->getPrice()->getNumber();
      $price_opt = $purchasable_entity->get('field_price_opt')->first()->toPrice()->getNumber();
      $price_promo = $purchasable_entity->get('field_sale_price')->first()->toPrice()->getNumber();

      // get actual (dinamic) price of goods (for comparison with the static prices (see above))
      $current_store = \Drupal::service('commerce_store.current_store');
      $store = $current_store->getStore();
      $cart_provider = \Drupal::service('commerce_cart.cart_provider');
      $cart = $cart_provider->getCart("physical", $store);
      $cart_items = $cart->getItems();

      global $my_prices_id_item;
      if ($my_prices_id_item == null) {
        $my_prices_id_item = 0;
      }
      $actual_price = (float)$cart_items[$my_prices_id_item]->get('unit_price')->getString();
      $my_prices_id_item++;

      if ($price_promo > 0) {
        $discountedPriceFormatter = $this->currencyFormatter->format($price_promo, $currency_code, $options);
        $originalPriceFormatter = $this->currencyFormatter->format($price, $currency_code, $options);

        $markup = sprintf('<span class="product-price-sale">%s</span> <span class="product-price-base"><del>%s</del></span>', $discountedPriceFormatter, $originalPriceFormatter);
      } else if ($price_opt == $actual_price) {

        $discountedPriceFormatter = $this->currencyFormatter->format($price_opt, $currency_code, $options);
        $originalPriceFormatter = $this->currencyFormatter->format($price, $currency_code, $options);

        $markup = sprintf('<span class="product-price-sale">%s</span> <span class="product-price-base"><del>%s</del></span>', $discountedPriceFormatter, $originalPriceFormatter);
      } else {
        $discountedPriceFormatter = $this->currencyFormatter->format($price, $currency_code, $options);
        $markup = sprintf('%s', $discountedPriceFormatter);
      }

      $elements[0] = [
        '#markup' => $markup,
        '#cache' => [
          'tags' => $purchasable_entity->getCacheTags(),
          'contexts' => Cache::mergeContexts($purchasable_entity->getCacheContexts(), [
            'languages:' . LanguageInterface::TYPE_INTERFACE,
            'country',
          ]),
        ],
      ];
    }

    return $elements;
  }
}