@RestController
public class ProductApiController {

  private final ProductRepository repository;

  @Autowired
  protected ProductApiController(final ProductRepository repository) {
    this.repository = repository;
  }

  @RequestMapping(method = RequestMethod.GET)
  public Page<Product> find(
    @PageableDefault(sort = "id", direction = DESC) final Pageable pageable,
    @RequestParam(required = false) final String nameLike,
    @RequestParam(required = false) final Long priceFrom,
    @RequestParam(required = false) final Long priceTo,
    @RequestParam(defaultValue = "true") final boolean inStock,
    @RequestParam(required = false) final Set<String> categoriesIn) {

    Specifications<Product> specifications = Specifications.where(stockAvaiable(inStock));

    if (StringUtils.isNotEmpty(nameLike)) {
      specifications = specifications.and(nameLike(nameLike));
    }
    if (Objects.nonNull(priceFrom)) {
      specifications = specifications.and(priceGraterThanOrEqualsTo(priceFrom));
    }
    if (Objects.nonNull(priceTo)) {
      specifications = specifications.and(priceLessThan(priceTo));
    }
    if (CollectionUtils.isNotEmpty(categoriesIn)) {
      specifications = specifications.and(categoriesIn(categoriesIn));
    }
    specifications = specifications.and(stockAvaiable(inStock));

    return repository.findAll(specifications, pageable);
  }

}