package de.mxro.webapiexample.internal.services;
   
   import java.io.FileInputStream;
   import java.io.FileNotFoundException;
   import java.io.IOException;
   import java.io.InputStream;
   import java.util.Properties;
   
   import javax.servlet.ServletException;
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import delight.json.JSON;
  import delight.json.JSONObject;
  
  /**
   * <p>
   * This service provides some metadata information about this server.
   * 
   * @author Max
   *
   */
  public class ApplicationMetadataServlet extends HttpServlet {
  
  	private static final long serialVersionUID = 1L;
  
  	// this service will always return the same response, so we can pre-render it at service initialisation.
  	private String cachedResponse = null;
  	
  
  	@Override
  	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  		
  		response.setContentType("application/json");
  		response.setStatus(HttpServletResponse.SC_OK);
  		
  		response.getWriter().println(cachedResponse);
  		
  	}
  
  	@Override
  	public void init() throws ServletException {
  		super.init();
  
  		readPropertiesAndRenderResponse();
  
  	}
  
  	private void readPropertiesAndRenderResponse() {
  		Properties prop = new Properties();
  		
  		ClassLoader loader = Thread.currentThread().getContextClassLoader();
  		
  		try (InputStream input = loader.getResourceAsStream("versioninfo.txt")) {
  
  			// load a properties file
  			prop.load(input);
  			
  			JSONObject jsonObject = JSON.create();
  			jsonObject.add("version", prop.getProperty("version"));
  			jsonObject.add("description", prop.getProperty("description"));
  			jsonObject.add("lastcommit", prop.getProperty("lastcommit"));
  			
  			cachedResponse = jsonObject.render();
  			
  
  		} catch (FileNotFoundException e) {
  			throw new RuntimeException(e);
  		} catch (IOException e) {
  			throw new RuntimeException(e);
  		}
  	}
  
  }