package unity.group.task.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import unity.group.task.dto.DiscountDto;
import unity.group.task.entity.Product;

import java.math.BigDecimal;
import java.util.List;


@Service
@Transactional
public class DiscountService implements IDiscountService {

    private final ProductService productService;

    @Autowired
    public DiscountService(final ProductService productService) {
        this.productService = productService;
    }

    @Override
    public void computeDiscountForAllProducts(final DiscountDto discount) {
        List<Product> allProducts = this.productService.getAllProducts();

        BigDecimal sumOfAllProductsPrice = allProducts.stream()
                .map(product -> product.getPrice().multiply(new BigDecimal(product.getQuantity())))
                .reduce(BigDecimal.ZERO, BigDecimal::add);

        allProducts.forEach(product -> {
            BigDecimal sumProductPrice = product.getPrice().multiply(new BigDecimal(product.getQuantity()));
            BigDecimal productDiscount = sumProductPrice.multiply(discount.getValue()).divide(sumOfAllProductsPrice, 2, BigDecimal.ROUND_HALF_UP);
            product.setProductDiscount(productDiscount);
            product.setPrice(sumProductPrice.subtract(productDiscount).divide(new BigDecimal(product.getQuantity()), 2, BigDecimal.ROUND_HALF_UP));
            productService.saveNewProduct(product);
        });
    }
}