package ejava.examples.ejbwar.inventory.ejb;
   
   import java.util.List;
   import java.util.UUID;
   
   import javax.ejb.Stateless;
   import javax.ejb.TransactionAttribute;
   import javax.ejb.TransactionAttributeType;
   import javax.inject.Inject;
  import javax.persistence.EntityManager;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import ejava.examples.ejbwar.inventory.bo.Categories;
  import ejava.examples.ejbwar.inventory.bo.Category;
  import ejava.examples.ejbwar.inventory.bo.Product;
  import ejava.examples.ejbwar.inventory.bo.Products;
  import ejava.examples.ejbwar.inventory.cdi.Inventory;
  import ejava.examples.ejbwar.inventory.dao.InventoryDAO;
  
  /**
   * This class implements the core transactional business logic for the 
   * inventory management. It is implemented as a no interface @Stateless
   * session bean and has JAX-RS and RMI facades that deal with technology-
   * specific communications with remote clients.
   */
  @Stateless
  public class InventoryMgmtEJB {
      private static final Logger logger = LoggerFactory.getLogger(InventoryMgmtEJB.class);
      
  	@Inject
  	private InventoryDAO dao;
      @Inject @Inventory
      private EntityManager em; //used for demo
  	
  	/**
  	 * Returns a list of categories that match the name provided
  	 * @param name
  	 * @return
  	 */
  	@TransactionAttribute(TransactionAttributeType.SUPPORTS)
  	public Categories findCategoryByName(String name, int offset, int limit) {
  		List<Category> categories = dao.findCategoryByName("%" + name + "%", offset, limit);
  		for (Category category : categories) {
  			category.setProductCount(categories.size());
  			dao.detachCategory(category); //detach before manipulating collection 
  			category.setProducts(null);
  		}
  		return new Categories(categories, 0, 0);
  	}
  	
  
  	@TransactionAttribute(TransactionAttributeType.REQUIRED)
  	public Category createOrGetCategory(String name) {
  		List<Category> categories = dao.findCategoryByName(name, 0, 1); 
  		if (categories.size()==0) {
  			Category category=new Category(name);
  			dao.createCategory(category);
  			return category;
  		}
  		else {
  			return categories.get(0);
  		}
  	}
  
  	@TransactionAttribute(TransactionAttributeType.SUPPORTS)
  	public Category getCategory(int id) {
  		return dao.getCategory(id);
  	}
  
  	@TransactionAttribute(TransactionAttributeType.REQUIRED)
  	public void deleteCategory(int id) {
  		Category category = dao.getCategory(id);
  		if (category != null) {
  			dao.deleteCategory(category);
  		}
  	}
  
  
  	@TransactionAttribute(TransactionAttributeType.REQUIRED)
  	public Product addProduct(Product product, String categoryName) {
  	    product.setProtectedValue(UUID.randomUUID().toString());
  		dao.addProduct(product);
  		Category category = createOrGetCategory(categoryName);
  		category.getProducts().add(product);
  		product = dao.getProduct(product.getId());
  		return product;
  	}
  	
  	@TransactionAttribute(TransactionAttributeType.REQUIRED)
  	public Product updateProduct(Product product) {
  	    logger.info("updating existing product: {}", dao.getProduct(product.getId()));
          logger.info("to these values: {}", product);
  		dao.updateProduct(product);
  		em.flush();
  		em.clear();
  		Product dbResult = dao.getProduct(product.getId());
  		logger.info("resulting product: {}", dbResult);
 		return dbResult;
 	}
 	
 	@TransactionAttribute(TransactionAttributeType.SUPPORTS)
 	public Products findProductByName(String name, int offset, int limit) {
 		return new Products(dao.findProductsByName("%" + name + "%", offset, limit), offset, limit);
 	}
 
 	@TransactionAttribute(TransactionAttributeType.SUPPORTS)
 	public Product getProduct(int id) {
 		return dao.getProduct(id);
 	}
 
 	@TransactionAttribute(TransactionAttributeType.REQUIRED)
 	public void deleteProduct(Product product) {
 		dao.deleteProduct(product);
 	}
 }