<?php
/**
 * Shopware 5
 * Copyright (c) shopware AG
 *
 * According to our dual licensing model, this program can be used either
 * under the terms of the GNU Affero General Public License, version 3,
 * or under a proprietary license.
 *
 * The texts of the GNU Affero General Public License with an additional
 * permission and of our proprietary license can be found at and
 * in the LICENSE file you have received along with this program.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * "Shopware" is a registered trademark of shopware AG.
 * The licensing of the program under the AGPLv3 does not imply a
 * trademark license. Therefore any rights, title and interest in
 * our trademarks remain entirely with us.
 */

namespace Shopware\Bundle\StoreFrontBundle\Service\Core;

use Shopware\Bundle\StoreFrontBundle\Gateway;
use Shopware\Bundle\StoreFrontBundle\Service;
use Shopware\Bundle\StoreFrontBundle\Struct;

/**
 * @category Shopware
 *
 * @copyright Copyright (c) shopware AG (http://www.shopware.de)
 */
class GraduatedPricesService implements Service\GraduatedPricesServiceInterface
{
    /**
     * @var Gateway\GraduatedPricesGatewayInterface
     */
    private $graduatedPricesGateway;

    /**
     * @param Gateway\GraduatedPricesGatewayInterface $graduatedPricesGateway
     */
    public function __construct(
        Gateway\GraduatedPricesGatewayInterface $graduatedPricesGateway
    ) {
        $this->graduatedPricesGateway = $graduatedPricesGateway;
    }

    /**
     * {@inheritdoc}
     */
    public function get(Struct\ListProduct $product, Struct\ProductContextInterface $context)
    {
        $prices = $this->getList([$product], $context);

        return array_shift($prices);
    }

    /**
     * {@inheritdoc}
     */
    public function getList($products, Struct\ProductContextInterface $context)
    {
        $group = $context->getCurrentCustomerGroup();
        $specify = $this->graduatedPricesGateway->getList(
            $products,
            $context,
            $group
        );

        //iterates the passed prices and products and assign the product unit to the prices and the passed customer group
        $prices = $this->buildPrices(
            $products,
            $specify,
            $group
        );

        //check if one of the products have no assigned price within the prices variable.
        $fallbackProducts = array_filter(
            $products,
            function (Struct\ListProduct $product) use ($prices) {
                return !array_key_exists($product->getNumber(), $prices);
            }
        );

        if (!empty($fallbackProducts)) {
            //if some product has no price, we have to load the fallback customer group prices for the fallbackProducts.
            $fallbackPrices = $this->graduatedPricesGateway->getList(
                $fallbackProducts,
                $context,
                $context->getFallbackCustomerGroup()
            );

            $fallbackPrices = $this->buildPrices(
                $fallbackProducts,
                $fallbackPrices,
                $context->getFallbackCustomerGroup()
            );

            $prices = $prices + $fallbackPrices;
        }

        $priceGroups = $context->getPriceGroups();

        /*
         * If one of the products has a configured price group,
         * the graduated prices has to be build over the defined price group graduations.
         *
         * The price group discounts are defined with a percentage discount, which calculated
         * on the first graduated price of the product.
         */
        foreach ($products as $product) {
            if (!$product->isPriceGroupActive() || !$product->getPriceGroup()) {
                continue;
            }

            if (!isset($prices[$product->getNumber()])) {
                continue;
            }

            $priceGroupId = $product->getPriceGroup()->getId();
            if (!isset($priceGroups[$priceGroupId])) {
                continue;
            }

            $priceGroup = $priceGroups[$priceGroupId];

            $firstGraduation = array_shift($prices[$product->getNumber()]);

            $prices[$product->getNumber()] = $this->buildDiscountGraduations(
                $firstGraduation,
                $context->getCurrentCustomerGroup(),
                $priceGroup->getDiscounts()
            );
        }

        return $prices;
    }

    /**
     * Helper function which builds the graduated prices
     * of a product for the passed price group discount array.
     *
     * This function is used to override the normal graduated prices
     * with a definition of the product price group discounts.
     *
     * @param Struct\Product\PriceRule       $reference
     * @param Struct\Customer\Group          $customerGroup
     * @param Struct\Product\PriceDiscount[] $discounts
     *
     * @return array
     */
    private function buildDiscountGraduations(
        Struct\Product\PriceRule $reference,
        Struct\Customer\Group $customerGroup,
        array $discounts
    ) {
        $prices = [];

        $firstDiscount = $discounts[0];

        /** @var Struct\Product\PriceRule $previous */
        $previous = null;
        if ($firstDiscount->getQuantity() > 1) {
            $firstGraduation = clone $reference;
            $previous = $firstGraduation;

            $prices[] = $firstGraduation;
        }

        foreach ($discounts as $discount) {
            $rule = clone $reference;

            $percent = (100 - $discount->getPercent()) / 100;

            $price = $reference->getPrice() * $percent;

            $pseudo = $reference->getPseudoPrice();

            $rule->setPrice($price);

            $rule->setPseudoPrice($pseudo);

            $rule->setFrom($discount->getQuantity());

            $rule->setCustomerGroup($customerGroup);

            $rule->setTo(null);
            if ($previous) {
                $previous->setTo($rule->getFrom() - 1);
            }

            $previous = $rule;
            $prices[] = $rule;
        }

        return $prices;
    }

    /**
     * Helper function which iterates the products and builds a price array which indexed
     * with the product order number.
     *
     * @param Struct\ListProduct[]       $products
     * @param Struct\Product\PriceRule[] $priceRules
     * @param Struct\Customer\Group      $group
     *
     * @return array
     */
    private function buildPrices($products, array $priceRules, Struct\Customer\Group $group)
    {
        $prices = [];

        foreach ($products as $product) {
            $key = $product->getNumber();

            if (!array_key_exists($key, $priceRules) || empty($priceRules[$key])) {
                continue;
            }

            /** @var Struct\Product\PriceRule[] $productPrices */
            $productPrices = $priceRules[$key];

            foreach ($productPrices as $price) {
                $price->setUnit($product->getUnit());
                $price->setCustomerGroup($group);
            }

            $prices[$key] = $productPrices;
        }

        return $prices;
    }
}
