FavoriteCityService.java

package com.sap.hana.cloud.samples.weatherapp.api;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.NoResultException;
import javax.persistence.Persistence;
import javax.persistence.Query;
import javax.sql.DataSource;
import javax.ws.rs.DELETE;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.SecurityContext;

import org.eclipse.persistence.config.PersistenceUnitProperties;

import com.sap.hana.cloud.samples.weatherapp.model.FavoriteCity;

/**
 * {@link FavoriteCityService}
 * 
 * @author Matthias Steiner
 * @version 0.1
 */
@Path("/cities")
@Produces({ MediaType.APPLICATION_JSON })
public class FavoriteCityService 
{
	@SuppressWarnings("unchecked")
	@GET
	@Path("/")
	public List<FavoriteCity> getFavoriteCities(@Context SecurityContext ctx)
	{
		List<FavoriteCity> retVal = null;
		
		String userName = (ctx.getUserPrincipal() != null) ? ctx.getUserPrincipal().getName() : "anonymous";
		
		Map<String,String> props = new HashMap<String,String>();
		props.put("tenant.id", userName);
		
		EntityManager em = this.getEntityManagerFactory().createEntityManager(props);

		retVal = em.createNamedQuery("FavoriteCities").getResultList();
		
		return retVal;
	}
	
	@GET
	@Path("/{id}")
	public FavoriteCity getFavoriteCity(@PathParam(value = "id") String id, @Context SecurityContext ctx)
	{
		FavoriteCity retVal = null;
		
		String userName = (ctx.getUserPrincipal() != null) ? ctx.getUserPrincipal().getName() : "anonymous";
		
		Map<String,String> props = new HashMap<String,String>();
		props.put("tenant.id", userName);
		
		EntityManager em = this.getEntityManagerFactory().createEntityManager(props);
		
		try
		{
			Query query = em.createNamedQuery("FavoriteCityById");
			query.setParameter("id", id);
			retVal = (FavoriteCity) query.getSingleResult();
		}
		catch(Exception ex)
		{
			ex.printStackTrace();
		}
		finally
		{
			em.close();
		}
		
		return retVal;
	}
	
	@SuppressWarnings("unchecked")
	@POST
	@Path("/")
	public List<FavoriteCity> addFavoriteCity(FavoriteCity city, @Context SecurityContext ctx)
	{
		List<FavoriteCity> retVal = null;
		
		String userName = (ctx.getUserPrincipal() != null) ? ctx.getUserPrincipal().getName() : "anonymous";
		
		Map<String,String> props = new HashMap<String,String>();
		props.put("tenant.id", userName);
		
		EntityManager em = this.getEntityManagerFactory().createEntityManager(props);
		
		try
		{	
			em.getTransaction().begin();
			
			// make sure that we have a unique semantical key 
			Query query = em.createNamedQuery("FavoriteCityById");
			query.setParameter("id", city.getId());
			
			try
			{
				@SuppressWarnings("unused")
                FavoriteCity duplicate = (FavoriteCity) query.getSingleResult();
			}
			catch (NoResultException ex)
			{
				// all good 
				em.persist(city);
				em.getTransaction().commit();
			}
			
			retVal = em.createNamedQuery("FavoriteCities").getResultList();
		}
		catch(Exception ex)
		{
			
			ex.printStackTrace();
		}
		finally
		{
			em.close();
		}
		
		return retVal;
	}
	
	@SuppressWarnings("unchecked")
	@DELETE
	@Path("/{id}")
	public List<FavoriteCity> removeFavoriteCity(@PathParam(value = "id") String id, @Context SecurityContext ctx)
	{
		List<FavoriteCity> retVal = null;
		
		String userName = (ctx.getUserPrincipal() != null) ? ctx.getUserPrincipal().getName() : "anonymous";
		
		Map<String,String> props = new HashMap<String,String>();
		props.put("tenant.id", userName);
		
		EntityManager em = this.getEntityManagerFactory().createEntityManager(props);
		
		try
		{
			Query query = em.createNamedQuery("FavoriteCityById");
			query.setParameter("id", id);
			FavoriteCity city = (FavoriteCity) query.getSingleResult();
			
			if (city != null)
			{
				em.getTransaction().begin();
				em.remove(city);
				em.getTransaction().commit();
			}
			
			retVal = em.createNamedQuery("FavoriteCities").getResultList();
		}
		catch(Exception ex)
		{
			ex.printStackTrace();
		}
		finally
		{
			em.close();
		}
		
		return retVal;
	}
	
	
	/**
	 * Returns the <code>DefaultDB</code> {@link DataSource} via JNDI.
	 * 
	 * @return <code>DefaultDB</code> {@link DataSource}
	 */
	protected DataSource getDataSource()
	{
		DataSource retVal = null;
		
		try 
	    {
	        InitialContext ctx = new InitialContext();
	        retVal = (DataSource) ctx.lookup("java:comp/env/jdbc/DefaultDB");
	    }
		catch (NamingException ex)
		{
			ex.printStackTrace();
		}
		
		return retVal;
	}
	
	/**
	 * Returns the {@link EntityManagerFactory}.
	 * 
	 * @return The {@link EntityManagerFactory}
	 */
	@SuppressWarnings({ "rawtypes", "unchecked" })
	protected EntityManagerFactory getEntityManagerFactory()
	{
		EntityManagerFactory retVal = null;
		
		try
		{
			Map properties = new HashMap();
			
			DataSource ds = this.getDataSource();
			
	        properties.put(PersistenceUnitProperties.NON_JTA_DATASOURCE, ds);
	        
	        retVal = Persistence.createEntityManagerFactory("application", properties);
		}
		catch (Exception ex)
		{
			ex.printStackTrace();
		}
		
		return retVal;
	}
	
	@GET
	@Path("/{id}/weather")
	@Produces({ MediaType.APPLICATION_JSON })
	public Response getWeatherInformation(@PathParam(value = "id") String id, @Context SecurityContext ctx)
	{
		WeatherService weatherService = new WeatherService();
		return weatherService.getWeatherInformation(id, null);
	}

	
}