package com.xiaopeng;
import com.xiaopeng.POJO.XpUserEntity;
import com.xiaopeng.POJO.XpUserGroupEntity;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

import java.util.LinkedList;
import java.util.List;

public class DatabaseHelper {
    private static SessionFactory factory;

    public DatabaseHelper() {
        try{
            factory = new Configuration().configure().buildSessionFactory();
        }catch (Throwable ex) {
            System.err.println("Failed to create sessionFactory object." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }
    //Add or update group-user-relationships into database
    public void updateRelationship(LinkedList<XpUserGroupEntity> list){
        Session session = factory.openSession();
        Transaction tx = null;
        try{
            tx = session.beginTransaction();
            for(XpUserGroupEntity relationship:list){
                session.saveOrUpdate(relationship);
            }
            tx.commit();
        }catch (HibernateException e) {
            if (tx!=null) tx.rollback();
            e.printStackTrace();
        }finally {
            session.close();
        }
    }
    //Get all users from database
    public LinkedList<XpUserEntity> getAllUsers(){
        Session session = factory.openSession();
        Transaction tx = null;
        LinkedList<XpUserEntity> list = new LinkedList<>();
        try{
            tx = session.beginTransaction();
            List users = session.createQuery("FROM XpUserEntity").list();
            list = new LinkedList < XpUserEntity > (users);
        }catch (HibernateException e) {
            if (tx!=null) tx.rollback();
            e.printStackTrace();
        }finally {
            session.close();
        }
        return list;
    }

    public void updateGoups(LinkedList<XpUserEntity> userList) {

    }



}