bitrix_api/index.php

<?php
require __DIR__ . "/vendor/autoload.php";
require_once($_SERVER['DOCUMENT_ROOT'] . "/bitrix/modules/main/include/prolog_before.php");

use Psr\Http\Message\ResponseInterface as Response;
use Psr\Http\Message\ServerRequestInterface as Request;
use Slim\Factory\AppFactory;

$app = AppFactory::create();
$app->addRoutingMiddleware();
$errorMiddleware = $app->addErrorMiddleware(true, true, true);

$app->get('/eltech_rest/hello/{name}', function (Request $request, Response $response, $args) {
    $name = $args['name'];
    $response->getBody()->write(json_encode(array("Hello" => $name)));
    return $response->withHeader("Content-Type", "application/json");
});

$app->post("/eltech_rest/order/create", function (Request $request, Response $response) {
    \Bitrix\Main\Loader::includeModule("sale");

    $req_data = $request->getParsedBody();

    $lid = getParameterOrResponseError($response, $req_data, "lid");
    $user_id = getParameterOrResponseError($response, $req_data, "userId");
    $currency = getParameterOrResponseError($response, $req_data, "currency");

    $order = \Bitrix\Sale\OrderBase::createOrder($lid, $user_id, $currency);

   $response_data = array(
       "result" => array(
           "order" => array(
               "id" => $order->getId(),
           )
       )
   );
   $response->getBody()->write(json_encode($req_data));

   return $response->withHeader("Content-Type", "application/json");
});

$app->get("/eltech_rest/order/total", function (Request $request, Response $response) {
    \Bitrix\Main\Loader::includeModule("sale");
    \Bitrix\Main\Loader::includeModule("main");
    \Bitrix\Main\Loader::includeModule("catalog");

    $params = $request->getQueryParams();
    $db = \Bitrix\Main\Application::getConnection();

    if (!array_key_exists("fuserId", $params)) {
        $response->getBody()->write(json_encode(array("status" => "error", "info" => "\"fuserId\" is not provided")));
        return $response->withStatus(400)->withHeader("Content-Type", "application/json");
    }

    $basket = \Bitrix\Sale\Basket::loadItemsForFUser($params["fuserId"], "s2");
    $bitrix_basket_items = $basket->getBasketItems();
    foreach ($bitrix_basket_items as $item) {
        $item->delete();
    }

    $recordset = $db->query(sprintf("select * from api_cart where fuser_id = %d", $params['fuserId']));

    foreach ($recordset->fetchAll() as $item) {
        $product = array(
            'PRODUCT_ID' => intval($item["product_id"]),
            'QUANTITY' => intval($item["quantity"]),
            'MODULE' => 'catalog',
            "BASE_PRICE" => CPrice::GetBasePrice(intval($item["product_id"]))["PRICE"],
            'PRODUCT_PROVIDER_CLASS' => 'CCatalogProductProviderOrderCustom'
        );

        \Bitrix\Catalog\Product\Basket::addProductToBasket($basket, $product,
            array(
                'SITE_ID' => "s2",
        ));
    }
    $basket->save();
    $basket->refresh();


    $discount = \Bitrix\Sale\Discount::loadByBasket($basket);

    $discount->calculate();
    $discount->save();

    $discount_result = $discount->getApplyResult(true);
    $basket->refreshData(array('PRICE', 'COUPONS'));

    $resultedItems = array();

    $coupon_is_activated = false;
    if (array_key_exists("coupon", $params)) {
        $coupon = \Bitrix\Sale\DiscountCouponsManager::getData($params["coupon"]);

        if (!$coupon) {
            $response->getBody()->write("Coupon is invalid or does not exist");
            return $response->withStatus(400)->withHeader("Content-Type", "application/json");
        }
        $coupon = CSaleDiscount::GetByID($coupon["DISCOUNT_ID"]);
        $coupon_is_activated = true;
    }

    foreach ($basket->getBasketItems() as $elem) {
/*      @var $elem Bitrix\Crm\Order\BasketItem */
        $basket_code = $elem->getBasketCode();
        if ($coupon_is_activated) {
            $elem->getFinalPrice();
            $discount_value = unserialize($coupon["ACTIONS"])["CHILDREN"][0]["DATA"]["Value"];
            $sum += $elem->getFinalPrice() - ($elem->getFinalPrice() * ($discount_value / 100));
        }
        else {
            if (isset($discount_result["PRICES"]['BASKET'][$basket_code]))
            {
                $sum += $discount_result["PRICES"]['BASKET'][$basket_code]["PRICE"]*$elem->getQuantity();
            } else {
                $sum += $elem->getFinalPrice();
            }
        }

        $resultedItems[] = $elem->getFields()->getValues();
    }

    $response_data =array(
        "items" => $resultedItems,
        "discount" => $discount_result,
        "price" => round($sum, 2),
        "basePrice" => round($basket->getBasePrice(), 2),
    );

    $response->getBody()->write(json_encode($response_data));
    return $response->withStatus(200)->withHeader("Content-Type", "application/json");


});

function getParameterOrResponseError(Response $response, array|null|object $data, string $key)
{
    if (!array_key_exists($key, $data)) {
        $response->getBody()->write(json_encode(array("status" => "error", "info" => "\"$key\" is not provided")));

        return $response
            ->withStatus(400)
            ->withHeader("Content-Type", "application/json");
    }

    return $data[$key];
}

// Run app
$app->run();