/**
 * @author Hyacinthe MENIET
 * Created on 22 août 07
 */
package net.dotmyself.weatherws;

import java.io.IOException;
import java.io.OutputStream;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;

/**
 * Servlet which uses HTTP verbs (GET,POST,PUT and DELETE) to perform a REST web service. 
 */
public class CityServlet extends HttpServlet {

	private static final long serialVersionUID = 7159907909932997509L;
	private static final String characterEncoding = "iso-8859-1";
	private static final String contentType = "application/xml";	
	private CityMemory memory;
	
	public CityServlet () {
		this.memory = new CityMemory();
	}
	
	@Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
		try {
			City city = getCityFromMemory(request);
        	city.setLastUpdate(getCurrentDate());
        	city.setUri(getCityUri(request,city.getId()));
			// Marshalling retrieved City to the given OutputStream
			JAXBContext context = JAXBContext.newInstance(City.class);
			Marshaller marshaller = context.createMarshaller();
			marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
			marshaller.setProperty(Marshaller.JAXB_ENCODING, "ISO-8859-1");
			response.setContentType(contentType);
			response.setCharacterEncoding(characterEncoding); 
		 	OutputStream os = response.getOutputStream();
			marshaller.marshal(city,os);
        } catch (IllegalStateException e) {
        	response.sendError(HttpServletResponse.SC_NOT_FOUND, e.getMessage());
        } catch (Exception e) {
        	response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e.getMessage());
		}
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
        try {
        	City city = getCityFromXml(request);
			Long key = memory.create(city);
			response.setHeader("Location", getCityUri(request, key));
	        response.setStatus(HttpServletResponse.SC_CREATED);
		} catch (Exception e) {
			response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e.getMessage());
		}
    }

    @Override
    protected void doPut(HttpServletRequest request, HttpServletResponse response) throws IOException {
    	try {
        	City city = getCityFromMemory(request);
        	city.setLastUpdate(getCurrentDate());
			memory.update(city.getId(), getCityFromXml(request));
	    	response.setStatus(HttpServletResponse.SC_NO_CONTENT);
		} catch (Exception e) {
			response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e.getMessage());
		}
    }

    @Override
    protected void doDelete(HttpServletRequest request, HttpServletResponse response) throws IOException {
    	memory.delete(getKey(request));
    	response.setStatus(HttpServletResponse.SC_NO_CONTENT);
    }
    
    private String getCityUri(HttpServletRequest request, Long key) {
    	return request.getScheme() + "://" + request.getServerName() + ":" 
    	+ request.getServerPort() + request.getContextPath() 
    	+ request.getServletPath() 
    	+ "/" + key;
    }
    
    private String getCurrentDate() {
    	DateFormat dateFormat = new SimpleDateFormat("dd-MM-yy 'à' hh':'mm");
    	return dateFormat.format(new Date());
    }
    
    private City getCityFromXml(HttpServletRequest request) throws JAXBException, IOException {
    	JAXBContext context = JAXBContext.newInstance(City.class);
		Unmarshaller unmarshaller = context.createUnmarshaller();
		City city = (City) unmarshaller.unmarshal(request.getReader());
    	return city;
    }
    
    private City getCityFromMemory(HttpServletRequest request) {
    	City city = memory.retrieve(getKey(request));
    	if (city == null) {
            throw new NullPointerException("Can't find the requested city");
        }
        return city;
    }
    
    private Long getKey(HttpServletRequest request) {
        String[] parts = request.getPathInfo().split("/");
        if (parts.length <= 1) {
            throw new IllegalStateException("Missing id");
        }
        return Long.valueOf(parts[1]);
    }

}