package br.com.caelum.cj05;

import java.util.HashMap;

@SuppressWarnings("serial")
public class Controller extends HttpServlet {

	private Properties properties;

	@Override
	public void init() throws ServletException {
		this.properties = new Properties();
		InputStream in = getClass().getClassLoader().getResourceAsStream("controller.properties");
		try {
			this.properties.load(in);
		} catch (IOException e) {
			throw new ServletException(e);
		}
	}
	
	@Override
	protected void service(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		try {
			String pagina = request.getParameter("pagina");
			
			Map<Class,Object> context = new HashMap<Class,Object>();
			context.put(HttpServletRequest.class, request);
			context.put(HttpServletResponse.class, response);
			
			Action action = criaAction(pagina, context);
			setterInjection(request, action);
			action.execute();
			
			MagicRequest magicRequest = new MagicRequest(request, action);
			
			String view = properties.getProperty(pagina + ".view");
			request.getRequestDispatcher(view).forward(magicRequest, response);
			
		} catch (Exception e) {
			throw new ServletException(e);
		}
	}

	private void setterInjection(HttpServletRequest request, Object action) throws IllegalAccessException, InvocationTargetException {
		for (Method method : action.getClass().getMethods()) {
			String m = method.getName(); 
			if (m.startsWith("set")) {
				String p = request.getParameter(m.substring(3,4).toLowerCase() + m.substring(4));
				if (p != null) {
					method.invoke(action, p);
				}
			}
		}
	}

	private Action criaAction(String pagina, Map context) throws Exception {
		Class action = Class.forName(properties.getProperty(pagina + ".action"));
		Constructor[] constructors = action.getConstructors();
		if (constructors.length == 0)
			return (Action) action.newInstance();
			
		Constructor constructor = constructors[0];
		Class[] types = constructor.getParameterTypes();
			
		Object[] parameters = new Object[types.length];
		int i = 0;
			
		for (Class type: types) {
			parameters[i++] = context.get(type);
		}
		
		return (Action) constructor.newInstance(parameters);
	}
}