public class JPADaoImpl {
	protected final Logger logger = LoggerFactory.getLogger(getClass());
	
	@Autowired
	@Qualifier("dataSource")
	protected DataSource dataSource;
	
	@PersistenceContext
    protected EntityManager entityManager;
	
	protected <T> PageData<T> getPageData(CriteriaQuery<T> criteria,Root<T> root,Integer pStart, Integer pSize,LockModeType lockModeType) throws Exception{
		PageData<T> pageData =null;
		try {
			pageData = new PageData<T>();
			
			criteria.distinct(true);
			
			criteria.select(root);
			
			TypedQuery<T> query = getPersistenceQuery(criteria, pStart, pSize, lockModeType);
			
			if (pStart == null || pSize == null) {
				pageData.setData(query.getResultList());
				return pageData;
			}
			
			pageData.setpStart(pStart);
			pageData.setpSize(pSize);
			
			Long rowCount = getRowCount(criteria,root,true);
			pageData.setTotalNo(rowCount);

			pageData.setpCount(rowCount / pSize + (rowCount % pSize == 0 ? 0 : 1));
	
			pageData.setData(query.getResultList());
			
			return pageData;
		} catch (Exception e) {
			throw e;
		}
	}
	
	
	/**
	 * 
	 * @param criteria
	 * @param root
	 * @param distinct
	 * @return
	 * @throws Exception
	 */
	protected <T> Long getRowCount(CriteriaQuery<T> criteria,Root<T> root,boolean distinct) throws Exception {
		Long rowcount=null;
		CriteriaBuilder builder = entityManager.getCriteriaBuilder(); 
		CriteriaQuery<Long> countCriteria=builder.createQuery(Long.class);
		
	    Root<?> entityRoot = countCriteria.from(root.getJavaType());
	    entityRoot.alias(root.getAlias());
	    
	    doJoins(root.getJoins(),entityRoot);
	    if( criteria.isDistinct()){
	    	 countCriteria.select(builder.countDistinct(entityRoot));
	    }else{
	    	countCriteria.select(builder.count(entityRoot));
	    }
		
		Predicate fromRestriction = criteria.getRestriction();
	
		if (fromRestriction != null) {
			countCriteria.where(fromRestriction);
		}
		
	    countCriteria.distinct(criteria.isDistinct());
	
	    rowcount=entityManager.createQuery(countCriteria).getSingleResult();

	    return rowcount;
	}
	
	/**
	 * 
	 * @param joins
	 * @param root_
	 */
	private void doJoins(Set<? extends Join<?, ?>> joins,Join<?,?> root_){
	    for(Join<?,?> join: joins){
	        Join<?,?> joined = root_.join(join.getAttribute().getName(),join.getJoinType());
	        doJoins(join.getJoins(),joined);
	    }
	}
	/**
	 * 
	 * @param joins
	 * @param root_
	 */
	private void doJoins(Set<? extends Join<?, ?>> joins,Root<?> root_){
	    for(Join<?,?> join: joins){
	        Join<?,?> joined = root_.join(join.getAttribute().getName(),join.getJoinType());
	        doJoins(join.getJoins(), joined);
	    }
	}

	
		/**
	 * @param criteria
	 * @param pStart
	 * @param pSize
	 * @param lockModeType
	 * @return
	 */
	private <T> TypedQuery<T> getPersistenceQuery(CriteriaQuery<T> criteria, Integer pStart, Integer pSize, LockModeType lockModeType) {
		
		TypedQuery<T> query = entityManager.createQuery(criteria);
		
		if(lockModeType!=null){
			query.setLockMode(lockModeType);
		}
		
		if (pStart != null && pSize != null) {
			query.setFirstResult((pStart - 1) * pSize);
			query.setMaxResults(pSize);
		}
		return query;
	}

}

public class UserDaoImpl extends JPADaoImpl implements UserDao{
	
	@Override
	public PageData<User> list(User filter, Integer pStart, Integer pSize, List<Order> order, User userAuth) throws Exception {
		CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
		CriteriaQuery<User> criteria = criteriaBuilder.createQuery(User.class);
		Root<User> root = criteria.from(User.class);
		root.alias("root");
		criteria.select(root);
	
		List<Predicate> predicateList = null;
					
		if (filter!=null){
			
			predicateList = new ArrayList<Predicate>();
			
			if (!Utils.isEmpty(filter.getStatus())) {
				predicateList.add(criteriaBuilder.and(criteriaBuilder.equal(root.<Byte>get("status"),filter.getStatus())));
			}
		}
		
		if(!Utils.isEmpty(predicateList)){
			criteria.where(criteriaBuilder.and(predicateList.toArray(new Predicate[predicateList.size()])));
		}
		criteria.orderBy(criteriaBuilder.asc(root.get("last_name")),criteriaBuilder.asc(root.get("first_name")));
		
		PageData<User> pageData;
	
		pageData = getPageData(criteria,root, pStart, pSize);
		
	
		return pageData;
	}

}