package ejava.examples.blpurchase.blimpl;
   
   import java.util.Random;
   
   import javax.persistence.EntityManager;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
  import ejava.examples.blpurchase.bl.Purchasing;
  import ejava.examples.blpurchase.bo.Account;
  import ejava.examples.blpurchase.bo.Cart;
  import ejava.examples.blpurchase.bo.Product;
  
  /**
   * This class implements basic logic used to implement the purchasing
   * aspects of the application.
   */
  public class PurchasingImpl implements Purchasing {
  	private static final Logger logger = LoggerFactory.getLogger(PurchasingImpl.class);
  	private EntityManager em;
  	private Random random=new Random();
  	
  	public void setEntityManager(EntityManager em) {
  		this.em = em;
  	}
  
  	@Override
  	public Account createAccount(String email, String firstName, String lastName) {
  		int count=em.createNamedQuery(Account.FIND_BY_EMAIL_QUERY)
  				.setParameter("email", email)
  				.setMaxResults(1)
  				.getResultList()
  				.size();
  		if (count==0) {
  			Account account = new Account(email, firstName, lastName);
  			account.setPassword(generatePassword());
  			em.persist(account);
  			logger.debug("created account: {}", account);
  			return account;
  		}
  
  		return null; //don't return legacy accounts -- they have the password
  	}
  
  	@Override
  	public double checkout(String email, String password) {
  		Cart cart = em.find(Cart.class, email);
  		if (cart == null) {
  			logger.warn("cart not found");
  			return 0;
  		}
  		
  		Account account = cart.getAccount();
  		if (!account.getPassword().equals(password)) {
  			logger.warn("wrong password");
  			return 0;
  		}
  		
  		double total = 0;
  		for (Product product : cart.getProducts()) {
  			total += product.getPrice();
  		}
  		if (logger.isDebugEnabled()) {
  		    logger.debug("checked out {} products for {}", cart.getProducts().size(), email);
  		}
  		cart.getProducts().clear();
  		
  		return total;
  	}
  
  	private String generatePassword() {
  		byte[] password = new byte[8];
  		for (int i=0; i<password.length; i++) {
  			password[i] = (byte)('a' + random.nextInt(25));
  		}
  		return new String(password);
  	}
  }